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New Member-Tuning Issue? (1/29)
8/10/10 12:51pm

dry
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tulsa, OK - USA

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74 L82 4 Speed Orange/Saddle

Joined: 8/6/2010
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I am a New Member here long time member on CF. I have a Tuning issue that i am looking here for other opinions, because for the life of me i can't get the tune right... Ouch

Ouch

Ok here is the deal, My car is a 74 L82 4 Speed car 73k original miles with the 3:72 rear end I have not been happy with the performance of the L82's Bottom End Torque so some changes were made.

Block was line bored .30 over and decked. the rotating assembly was balanced, forged flat tops, Crane Fire Ball II 290H Cam (1800-5200 rpm)-224/224 duration, 107 lobe centers,454/454 lift, Performer aluminum intake, Holley 4160-600 cfm single line, stock heads 882 professionally ported and rebuilt with bronge guides etc, stock rockers, crane matched springs,Mallory unilite mechanical advance electronic ignition factory 20 degree mechanical advance "No Curve" timing is set at 18 btdc idling at 800 rpm, nice even compression across all cylinders, runnning 92 octane.......

Here lies the problem the car starts right up no timing drag hot or cold and runs great,no pinging, no stumbles or hesitations, temp stays about 190 drives great on the road 3500 rpm at 70 mph and runs well stop light to stop light when just driving it normal.........PROBLEM is when you try to stand on it from a stop light it doesn't have enough torque to even break the tires loose....this rebuild has about 5,000 miles on it so its broke in well and i am ready to find the right tune the car sounds awesome at idle but the torque performance didn't seem to change from what it was before the rebuild!!!

What am i missing here i just can't seem to figure it out, why have i not realized a torque increase etc...

All opinions and suggestion welcome!!

dry2010-08-10 12:48:55

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New Member-Tuning Issue? (2/29)
8/10/10 12:59pm

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Duncanville, TX - USA

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#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

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If the cam specs you posted are correct, you've got waaay too big of a cam in it to expect a lot of bottom end...302deg of intake duration is massive for a street car, imho. Lower gear in the rear would certainly help, but then it would be a pain to drive on the road.
Also, "massaged" heads doesn't really tell us what was done to them. Were they hogged out(ported)?
You may simply be expecting more than the combo you have can deliver....I'm betting the real power doesn't start coming on until around 3000rpms with that cam....
Perhaps others will have more ideas.
Welcome to C3VR, too!

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New Member-Tuning Issue? (3/29)
8/10/10 1:45pm

dry
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tulsa, OK - USA

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74 L82 4 Speed Orange/Saddle

Joined: 8/6/2010
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Correction Here is the CORRECTED CAM INFO!!!

I dug thru all my paper work and found the actual Crane Cam Specs and Here they are "So does this change anything" sweat

sweat

sweat

Series grind # 3/4 Race 300-06 H (Cam use oval/drag)
SBC Hyd. Rough idle, 283-400CI, good mid-range torque, OK for Auto w/street perf. conv. in 327-up CI, Power brakes req. 99590-1 Vac. res. system, aftermarket carb, int, & exh. advised, compression ratio 9:50 to 10:50 highly advised.
Basic RPM 2200-5200
Dur. @ .050 218* 218*
adv. Dur 300* 300*
Lobe seperation 106*
running clearance hot .000 .000
Gross valve lift .480 .480

My final build sheet reflects a compression ratio of 9.57:1

dry2010-08-12 12:59:43

New Member-Tuning Issue? (4/29)
8/10/10 6:07pm

yostusota
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York, PA - USA

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Wow..sounds like a let down..three things stand out to me..one timing..is 18 degrees advanced at idle to much? Have you a way to check total advance? You need an adjustable timing light to be able to find out..it should be around 30 or so. You may not have enough total advance. Two... What compression is the engine? Not sure if adding new higher compression pistons will help much if the heads have large bowl areas..ie 76cc if I remember right..three..port job..I really hate when people do a port job without a flow bench..I have done many head port tests over the years and have found you lose flow by just taking the casting flash off..it may look nice but really messes the flow of air..it also makes the runners in the heads imbalanced where they are not the same volume anymore..to do a real port job that is volume equal takes more time than money allows..I did a study on this back in the day when camel back heads were easy and cheap to find..I found that it took over 30 hours of tweaking the ports to do a real equal job per head! Sad thing is it only gained 6 horsepower..now that was a let down..what I am getting at is its better to replace the heads with aftermarket ones that have what you want and demand in the first place..I always use the three C's also..cam carb compression..I would also contact the people you got the parts from and see if the are a matched set..most companies offer kits that are dyno tested to do what you want..good luck..
LMK
Rich

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New Member-Tuning Issue? (5/29)
8/10/10 9:01pm

danascar
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Germansville, PA - USA

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1974 Coupe 358ci 4 speed Black w/Medium Saddle interior w/79 custom leather seats. . 1999 C5 Convertible, 6 speed, Atomic orange, Oak interior.

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I have a nearly identical 74 350 4 speed with crate motor, cam, headers, edelbrock intake, holley carb. Runs great. But I have problem getting out of the hole too. Baby it off stop and then stand on it and it runs like a raped ape. It has tons of torque, pulls up steep hills in 4th gear and gains speed with no effort. My thoughts are the gear ratios in the tranny. These cars were made for top end, hence the 160 mph speedo, not blazing hole shots. Something to think about.

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New Member-Tuning Issue? (6/29)
8/10/10 10:44pm

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Duncanville, TX - USA

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I still think you'd need more compression to run a cam like that. The stock CR was 9:1 on the L82. Flat-tops will only give you another 1/2 point, if that. Anything over a 260-270 deg duration will lose you low end, unless you have the compression to make up for it. It's all about cylinder pressures, and a lot of duration just won't allow that at lower rpms without at least a 10:1 CR, imo.
As Rick says, too, the timing may need to be adjusted to work with all of the mods...18 deg/idle sounds like way too much....10 might be better.
It's gonna take some figuring, and tinkering to get it running better, but it should work out...just maybe not as well as you envisioned. It's still gotta be better than stock, I assume.

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New Member-Tuning Issue? (7/29)
8/11/10 12:13am

anips
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sonoma, CA - USA

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don't worry if the tires don't bark if your rollin when you stand on it, now if you come out at 2500 from a stop and you don't spin the tires then there is a problem, my guess is your motor is puttin out about 350+ hp, the cam sounds ok, sounds like its running good, if thereis a problem my guess its could be in either the heads or distributor, you have a performance rear gear at 3.73 and probabley you don't want it lower than that for the street, if your heads were just port matched cleaned up and some bowl work around the valve guides thats fine, but if the intake and exh ports were hogged out your low end torque #'s are going to suffer,, your dist has 20deg's meh. adv.built in with no vac. adv. plus your 18 deg's initial gives you a total of 38deg.'s, might be a tick or two too much, but its real close,SB's like to run at about 32-38 deg's total, the question you should be asking is when is my advance coming in, all mech adv. distributors are mostly used for racing, where eng rpm are kept hi in the power band, like coming out of the hole in drag racing at 2500-3000rpm or in oval track where its 2500 to whatever, over the counter dist's like you have is most likely not set up for the street, people have different opinions on this but your motor would probabley run better with a vac. adv. distributor set up to your eng. specs, your dist. would then be set up with 24 deg.'built in, 10-12deg.'s initial giving you a total of 34-36 total with the vac. adv. adding a little more at off idle for better low end, search Performance Distributors .com and it will be explained to ya. anips2010-08-10 21:50:33

New Member-Tuning Issue? (8/29)
8/11/10 12:33am

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Hot Springs, AR - USA

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69 Conv #'s match 427, TKO-600/.64, 3.36HD-Posi, HT, T/T, PS, PB, PW, SP, Leather, Comp XE264HR & Roller Rockers & Lifters, Air-Gap RPM intake, Holley St Av 770 VS, MSD 6AL+Dist+Blaster SS, K&N, Jet-Hot Hooker Side-Pipes, Steeroids, Al Rad, Spal Fans

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im not sure what you mean by no curve timing.

can you give us timing at 1000, 1500,2000,2500,3000,3500?

also what is vaccum at idle?

are you sure it isnt loadign up/stumbling off the line? i notice you sized your carb prety good.. didnt over do it but how is your idle mixture? did you adjust idle mixture to maximize engine vac at idle? are you sure you have no vac leaks?

you may not have enough air coming in at low end and it loads up. you can drill small 1/16th - 1/8th inch holes in the primary flaps to give it more lowend air. some newer carbs have air bleed adjustment jsut for this problem.

3.73 rear end should run very stoutly in low end.

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New Member-Tuning Issue? (9/29)
8/11/10 2:34pm

dry
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tulsa, OK - USA

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74 L82 4 Speed Orange/Saddle

Joined: 8/6/2010
Posts: 7

[QUOTE=anips]don't worry if the tires don't bark if your rollin when you stand on it, now if you come out at 2500 from a stop and you don't spin the tires then there is a problem, my guess is your motor is puttin out about 350+ hp, the cam sounds ok, sounds like its running good, if thereis a problem my guess its could be in either the heads or distributor, you have a performance rear gear at 3.73 and probabley you don't want it lower than that for the street, your dist has 20deg's meh. adv.built in with no vac. adv. plus your 18 deg's initial gives you a total of 38deg.'s, might be a tick or two too much, but its real close,SB's like to run at about 32-38 deg's total, the question you should be asking is when is my advance coming in, [/QUOTE]

The car runs like a striped a$$ ape from about 3k on and pulls strong up to 5500 or so here is some addittional info that may help with some suggestions. I am not necessarily trying to burn rubber and ruin my tires but you would think 60 series radials shouldn't bite this well.

Ok, Thanks everyone for the input and opinions let me start by trying to answer some of the response questions.

(1) Yes it is a close ratio 4 speed winds out in 1st gear about 55 mph with a 3:72 posi.

(2) It is a Zero decked blocked but is not using short decked pistons it is using the actual factory .60 over forged replacement pistons.

(3) The 290H Cam was picked due to its nasty sounding old school street profile along with the fact Cranes profile and tech's assured me i could get respectable low end grunt with it.

(4) The car pulls real strong from 3k rpm on to about 5500.

(5) the intake is the performer rpm sorry i left that part out.

(6) Timing static is 18 degree BTDC +4 cam advance and the mechanical advance is factory +20.

(7) Advance is active at 850 rpm from off idle ,All in at 3200 rpm for a total of 42 degrees BTDC.

(8) There are no headers just factory logs into a 2.25" magnaflow system true dual from logs out.

(9) This a Non A/C Car so no accessories other than water pump and alternator.

****Anytime you turn the car off you smell gas--NO LEAKS or DRIPS--And you always have to depress gas pedal one time prior to starting cold or hot***

New Member-Tuning Issue? (10/29)
8/11/10 10:41pm

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#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

Joined: 11/8/2003
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[quote=dry](6) Timing static is 18 degree BTDC +4 cam advance and the mechanical advance is factory +20.[/quote]

Why is the cam advanced to begin with? That helps in high rpm situations, but it will absolutely kill any low end torque, in my experience. IF in fact the cam has been advanced with a multi-slotted crank sprocket, I would seriously consider putting back to "0".
Unless I'm mis-reading something...

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New Member-Tuning Issue? (11/29)
8/12/10 12:58am

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Hot Springs, AR - USA

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69 Conv #'s match 427, TKO-600/.64, 3.36HD-Posi, HT, T/T, PS, PB, PW, SP, Leather, Comp XE264HR & Roller Rockers & Lifters, Air-Gap RPM intake, Holley St Av 770 VS, MSD 6AL+Dist+Blaster SS, K&N, Jet-Hot Hooker Side-Pipes, Steeroids, Al Rad, Spal Fans

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[QUOTE=dry][QUOTE=anips]

(1) Yes it is a close ratio 4 speed winds out in 1st gear about 55 mph with a 3:72 posi.

(2) It is a Zero decked blocked but is not using short decked pistons it is using the actual factory .60 over forged replacement pistons.

(3) The 290H Cam was picked due to its nasty sounding old school street profile along with the fact Cranes profile and tech's assured me i could get respectable low end grunt with it.

(4) The car pulls real strong from 3k rpm on to about 5500.

(5) the intake is the performer rpm sorry i left that part out.

(6) Timing static is 18 degree BTDC +4 cam advance and the mechanical advance is factory +20.

(7) Advance is active at 850 rpm from off idle ,All in at 3200 rpm for a total of 42 degrees BTDC.

(8) There are no headers just factory logs into a 2.25" magnaflow system true dual from logs out.

(9) This a Non A/C Car so no accessories other than water pump and alternator.

****Anytime you turn the car off you smell gas--NO LEAKS or DRIPS--And you always have to depress gas pedal one time prior to starting cold or hot***
[/QUOTE]

1 the close range four speed works against you on the bottom end 2.2:1 first gear sucks 8.2:1 final drive ratio is a bit low.

4 sounds like you really have it setup for high end

5 the performer rpm is a high rpm intake

6 advancing the cam does lend itself to more low end torque. retarding the cam is for high end horse.

7 id still like to know what your timing is at 1000,1500,2000,2500,3000,3500 it sounds like you have this mapped out theoretically, not expirementally.

8 are these stock 2" manifolds? lettign the engine breath certainly wont hurt.

finally i believe you are loading up at idle. i think you have too much fuel and not enough air at idle and that is why it stumbles off the line but then runs like a scalded dog up top.

you need to properly adjust your idle mix... turn all the way in one by one and then back out to peak vaccum. once all 4 this way.. go through it all more more time.

drilling a small hole in each primary butterfly will cure the lack of air at low end.

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New Member-Tuning Issue? (12/29)
8/12/10 12:59am

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69 Conv #'s match 427, TKO-600/.64, 3.36HD-Posi, HT, T/T, PS, PB, PW, SP, Leather, Comp XE264HR & Roller Rockers & Lifters, Air-Gap RPM intake, Holley St Av 770 VS, MSD 6AL+Dist+Blaster SS, K&N, Jet-Hot Hooker Side-Pipes, Steeroids, Al Rad, Spal Fans

Joined: 4/24/2004
Posts: 3231

[QUOTE=Adams' Apple][quote=dry](6) Timing static is 18 degree BTDC +4 cam advance and the mechanical advance is factory +20.[/quote]

Why is the cam advanced to begin with? That helps in high rpm situations, but it will absolutely kill any low end torque, in my experience. IF in fact the cam has been advanced with a multi-slotted crank sprocket, I would seriously consider putting back to "0".
Unless I'm mis-reading something...

[/QUOTE]

joel .. i disagree

advancing helps low end... retarding helps top end

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New Member-Tuning Issue? (13/29)
8/12/10 1:24am

dskopp
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Oak Creek, WI - USA

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1981 Great White Shark. Red Interior, 350/190hp. PS, PB (SS), A/C CC, T-Tops, Going to remain as Stock as possible. Served three years in Active Duty Army, then Retired Air Force after 34 years! Badger State Vetts Car Club. 175,000 Original miles!!

Joined: 5/21/2008
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I got a headache from reading all this stuff!!! Seriously, its gotta be a simple fix. Something "we" are not even considering! Most pain in the butt issues turn out to be simple things, like Adams carb problem that came down to vaccume hose leak!! Sometimes we can't see the Forest thru the Trees.

Dan

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dskopp2010-08-11 22:25:53

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New Member-Tuning Issue? (14/29)
8/12/10 1:02pm

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Duncanville, TX - USA

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#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

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I did say "In my experience"...

Back in the day, when I was doing a ton of engine building for oil field trucks, I found that the timing gears were different for truck engines compared to car engines. For truck engines, the gears were made to retard the cam timing about 2 deg., and that allowed for better towing/tugging power. If I used a regular car gear set, the trucks would barely pull their own weight from a standing start. I don't pretend to understand the engineering aspects of stuff like that, so I can't state why that worked at the time, just that it did. Who knows?

Adams' Apple2010-08-12 10:04:49

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New Member-Tuning Issue? (15/29)
8/12/10 4:06pm

dry
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tulsa, OK - USA

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74 L82 4 Speed Orange/Saddle

Joined: 8/6/2010
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Re Checked and reverified some things last night here is some corrected info:

Cam Corrected data from my old catalog it was purchased thru......
Series grind # 3/4 Race 300-06 H (Cam use oval/drag)
SBC Hyd. Rough idle, 283-400CI, good mid-range torque, OK for Auto w/street perf. conv. in 327-up CI, Power brakes req. 99590-1 Vac. res. system, aftermarket carb, int, & exh. advised, compression ratio 9:50 to 10:50 highly advised.
Basic RPM 2200-5200
Dur. @ .050 218* 218*
adv. Dur 300* 300*
Lobe seperation 106*
running clearance hot .000 .000
Gross valve lift .450 .450

My final build sheet reflects a compression ratio of 9.57:1

piston numbers i found on a receipt from GM DIRECT and the # is 1464695-GM.

The heads are 882 with bronze guides and screw in studs etc, they were cleaned up, port and polish, decked for squareness,stock rockers. internal rotating assembly balanced.

The block was bored .60 and decked for squareness.

The dizzy is a mallory unilite with stock 20 degree mechanical advance.

holley 4160-600cfm out of the box

performer intake

stock exhaust logs and magnaflo exhaust

Timing is at 18 degree BTDC at idle

Also I RECHECKED some numbers last night and quit going from my memory crap-------Ok the vacuum is around 7.5" and bouncing at a 750 rpm idle if you raise the idle to 1000 rpm it almost quits bouncing and holds at 10". I also rechecked the cold cranking pressures all plugs out and carb closed 163-165 across the board, i am sure the cam duration is hurting these numbers. Also i noticed my fuel pressure gauge is bouncing from 3-7lbs (i am guessing it has gone bad, its not oil filled, i plan on replacing it today for verification)This is all recent data without trying to rely on my memory.

Sorry for any inconvience this is all the actual data for this engine.......relying on my memory was why the data was incorrect and a couple of misinformed phone calls as well.

dry2010-08-12 17:01:21

New Member-Tuning Issue? (16/29)
8/12/10 6:26pm

anips
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sonoma, CA - USA

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EVERYBODY STOP!... we can't help Mr. Dry until he gets the build sheet from the engine builder with the correct figures, there have so many #'s being tossed around, I'am confused, lets start with the build sheet, and if Mr. Dry can supply us with the correct parts spec's maybe we can help, without them we are just spinning our wheels Rolling On The Floor Laughing

Rolling On The Floor Laughing

......Joel, Bens got it right, According to Isky Adv. the cam adds to the bottom, Retard adds to the top end....got to know the head #'s,what was really done to the heads, what the advertized compression are the pistons with what size combustion chambers and so forth. anips2010-08-12 15:48:49

New Member-Tuning Issue? (17/29)
8/12/10 8:03pm

dry
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tulsa, OK - USA

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74 L82 4 Speed Orange/Saddle

Joined: 8/6/2010
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[QUOTE=dry]

Re Checked and reverified some things last night here is some corrected info:

Cam Corrected data from my old catalog it was purchased thru......
Series grind # 3/4 Race 300-06 H (Cam use oval/drag)
SBC Hyd. Rough idle, 283-400CI, good mid-range torque, OK for Auto w/street perf. conv. in 327-up CI, Power brakes req. 99590-1 Vac. res. system, aftermarket carb, int, & exh. advised, compression ratio 9:50 to 10:50 highly advised.
Basic RPM 2200-5200
Dur. @ .050 218* 218*
adv. Dur 300* 300*
Lobe seperation 106*
running clearance hot .000 .000
Gross valve lift .450 .450

My final build sheet reflects a compression ratio of 9.57:1

piston numbers i found on a receipt from GM DIRECT and the # is 1464695-GM.

The heads are 882 with bronze guides and screw in studs etc, they were cleaned up, port and polish, decked for squareness,stock rockers. internal rotating assembly balanced.

The block was bored .60 and decked for squareness.

The dizzy is a mallory unilite with stock 20 degree mechanical advance.

holley 4160-600cfm out of the box

performer intake

stock exhaust logs and magnaflo exhaust

Timing is at 18 degree BTDC at idle

Also I RECHECKED some numbers last night and quit going from my memory crap-------Ok the vacuum is around 7.5" and bouncing at a 750 rpm idle if you raise the idle to 1000 rpm it almost quits bouncing and holds at 10". I also rechecked the cold cranking pressures all plugs out and carb closed 163-165 across the board, i am sure the cam duration is hurting these numbers. Also i noticed my fuel pressure gauge is bouncing from 3-7lbs (i am guessing it has gone bad, its not oil filled, i plan on replacing it today for verification)This is all recent data without trying to rely on my memory.

Sorry for any inconvience this is all the actual data for this engine.......relying on my memory was why the data was incorrect and a couple of misinformed phone calls as well.

[/QUOTE]

This is all of the actual corrected data that i have available in print, sorry for the bad data but it wasn't that far off. Any opinion is still appreciated!

New Member-Tuning Issue? (18/29)
8/13/10 11:41am

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69 Conv #'s match 427, TKO-600/.64, 3.36HD-Posi, HT, T/T, PS, PB, PW, SP, Leather, Comp XE264HR & Roller Rockers & Lifters, Air-Gap RPM intake, Holley St Av 770 VS, MSD 6AL+Dist+Blaster SS, K&N, Jet-Hot Hooker Side-Pipes, Steeroids, Al Rad, Spal Fans

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that cam is NOT for regular street use. I knew it the moment you told us your vaccum readings.

low end cams have good idle vacuum high end cams have crappy idle vacuum

the ok for auto with street perfomance converter means you have to have a stall converter to use.. ie have to engage trans at higher rpm than stock. meaning no low end torque. you need to drop the clutch at 2500 to get it moving.

that cam was not designed for low end and advancing it 4 degrees was a waste of time.

also is that 18 degree with vac advance connected or not.

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New Member-Tuning Issue? (19/29)
8/13/10 1:14pm

dry
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tulsa, OK - USA

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[QUOTE=cthulhu]that cam is NOT for regular street use. I knew it the moment you told us your vaccum readings.

low end cams have good idle vacuum high end cams have crappy idle vacuum

the ok for auto with street perfomance converter means you have to have a stall converter to use.. ie have to engage trans at higher rpm than stock. meaning no low end torque. you need to drop the clutch at 2500 to get it moving.

that cam was not designed for low end and advancing it 4 degrees was a waste of time.

also is that 18 degree with vac advance connected or not.

[/QUOTE]

The 18 degrees is with a mechanical advance "no vacuum advance"" and before before the mechanical 20 degree starts to come in.

dry2010-08-13 10:14:36

New Member-Tuning Issue? (20/29)
8/13/10 1:55pm

anips
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sonoma, CA - USA

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72 LT-1 AC coupe,69 l-36 coupe

Joined: 8/9/2002
Posts: 784

the short block sounds fine to me, Dry has a little over 9.5 compression according to the paper work and if they surfaced both the block and heads it might be closed to 10to1 which is good, the cam sounds alright to me, I compared it to the chevy L79 cam that came in the special performance 327 350hp motors that came in the corvette, Nova that had 11to1 motors, if you ever had one you know they were a great street cam that produced great power and torque straight up, Drys cam is just about identical but a hair smaller, my guess its in the heads or the ign. setup, port and polish nowadays with a die grinder is an art form which needs a flow bench, CNC would be the way to go, but I don't know how or what was done, good luck. anips2010-08-13 11:42:33

New Member-Tuning Issue? (21/29)
8/13/10 3:05pm

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Hot Springs, AR - USA

Vette(s):
69 Conv #'s match 427, TKO-600/.64, 3.36HD-Posi, HT, T/T, PS, PB, PW, SP, Leather, Comp XE264HR & Roller Rockers & Lifters, Air-Gap RPM intake, Holley St Av 770 VS, MSD 6AL+Dist+Blaster SS, K&N, Jet-Hot Hooker Side-Pipes, Steeroids, Al Rad, Spal Fans

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anips.. i disagree... no offense dry but I think you had some schizophrenia in the design of the engine. some things seem to have been done to maximize top end HP and others to maximize low end torque. you can set things up in conflict and achieve nothing. I dont think he is getting 10:1 out of it. assuming 9.5 on block after surfacing and just from surfacing heads you might get 9.7

that is still quite aways from 11:1.

the l-79

The 327-350hp "L-79" cam is 221in 221ex duration @.050" .447" .447" lift 114LSA. Commonly referred to as the "151" cam. Needs 10:1+cr and 4.10's. A 2800/3000stall converter helps too.

he has neither the 10+ or 4.10 gears.. and probably isnt dropping the clutch at 2800-3000 either.

the 68 vette with the 327/350 produced 350 hp @ 5800 and 360 lb ft @ 3600rpm wth 11:1 compression.

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8/13/10 6:47pm

anips
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sonoma, CA - USA

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72 LT-1 AC coupe,69 l-36 coupe

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Ben, I used the l-79 as a comparision, Dry's cam is smaller in all areas accept for max lift which is .003 more, GM reccomends a compression ratio of 9:5- 10:75 for the l-79 cam, he's in the ball park lookin for his seat.....my new 66 SS L-79 Nova came with 3:73gear and the performance gr.'s for 66-67 327 350 hp vette's were also 3:73's, ...what do you suggest he do?

anips2010-08-13 18:38:11

New Member-Tuning Issue? (23/29)
8/14/10 8:31pm

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Hot Springs, AR - USA

Vette(s):
69 Conv #'s match 427, TKO-600/.64, 3.36HD-Posi, HT, T/T, PS, PB, PW, SP, Leather, Comp XE264HR & Roller Rockers & Lifters, Air-Gap RPM intake, Holley St Av 770 VS, MSD 6AL+Dist+Blaster SS, K&N, Jet-Hot Hooker Side-Pipes, Steeroids, Al Rad, Spal Fans

Joined: 4/24/2004
Posts: 3231

[QUOTE=anips]

Ben, I used the l-79 as a comparision, Dry's cam is smaller in all areas accept for max lift which is .003 more, GM reccomends a compression ratio of 9:5- 10:75 for the l-79 cam, he's in the ball park lookin for his seat.....my new 66 SS L-79 Nova came with 3:73gear and the performance gr.'s for 66-67 327 350 hp vette's were also 3:73's, ...what do you suggest he do?

[/QUOTE]

i suggest he not expect any low end torque.

I did enter all the parameters into desktop dyno and when in doubt I gave him the benefit of the doubt and went higher.. ie 10.0 compression. even advanced the cam by the 4 degrees.

in his curent config ... his peak horse is about 290 @ 5500 and his peak torque is 295 or so @ 4500.

the biggest improvement he can make with that cam is ditch the ex manifolds and run headers

small tube headers have a slight advantage on the torque side and large tube have a slight advantage on hp side.

using small tube headers with mufflers moves his peak hp up to 371@6000 and peak torque to 364@4500

cthulhu2010-08-14 18:29:35

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New Member-Tuning Issue? (24/29)
8/14/10 11:34pm

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Hot Springs, AR - USA

Vette(s):
69 Conv #'s match 427, TKO-600/.64, 3.36HD-Posi, HT, T/T, PS, PB, PW, SP, Leather, Comp XE264HR & Roller Rockers & Lifters, Air-Gap RPM intake, Holley St Av 770 VS, MSD 6AL+Dist+Blaster SS, K&N, Jet-Hot Hooker Side-Pipes, Steeroids, Al Rad, Spal Fans

Joined: 4/24/2004
Posts: 3231

check these out

manifolds

http://direclynx.net/~cthulhu/manifolds.jpg

headers

http://direclynx.net/~cthulhu/headers.jpg

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New Member-Tuning Issue? (25/29)
8/15/10 12:06am

anips
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sonoma, CA - USA

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72 LT-1 AC coupe,69 l-36 coupe

Joined: 8/9/2002
Posts: 784

there ya go, much better, when you did your pull did you program in long or short headers and did the small tube headers have 1 1/2" ID primary's ? anips2010-08-15 06:43:25

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8/15/10 10:07pm

dry
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tulsa, OK - USA

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74 L82 4 Speed Orange/Saddle

Joined: 8/6/2010
Posts: 7

[QUOTE=cthulhu][QUOTE=anips]

Ben, I used the l-79 as a comparision, Dry's cam is smaller in all areas accept for max lift which is .003 more, GM reccomends a compression ratio of 9:5- 10:75 for the l-79 cam, he's in the ball park lookin for his seat.....my new 66 SS L-79 Nova came with 3:73gear and the performance gr.'s for 66-67 327 350 hp vette's were also 3:73's, ...what do you suggest he do?

[/QUOTE]

i suggest he not expect any low end torque.

I did enter all the parameters into desktop dyno and when in doubt I gave him the benefit of the doubt and went higher.. ie 10.0 compression. even advanced the cam by the 4 degrees.

in his curent config ... his peak horse is about 290 @ 5500 and his peak torque is 295 or so @ 4500.

the biggest improvement he can make with that cam is ditch the ex manifolds and run headers

small tube headers have a slight advantage on the torque side and large tube have a slight advantage on hp side.

using small tube headers with mufflers moves his peak hp up to 371@6000 and peak torque to 364@4500

[/QUOTE]

Thanks guys that is the type of information i am looking for i would just like to be able to optimize my current set up. What headers anybody have any ideas for a good brand? diameter?

Thanks

New Member-Tuning Issue? (27/29)
8/16/10 12:05am

anips
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sonoma, CA - USA

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72 LT-1 AC coupe,69 l-36 coupe

Joined: 8/9/2002
Posts: 784

I run hooker "long under chassis headers small tube 1 1/2" ID or 1 5/8 OD with a 3 1/2" collector on the LT-1, my engine is a 30 over 350 9:75 comp forged flat tops, stock Lt-1 bottom end with the stock Lt-1 solid lifter cam straight up, stock 202- 160 heads "performance Distributor" dist. 3:55 ger. stock ratio1.5 roller rockers,works for me, you might ask Ben what header info he programed into the dyno run, glad to help. anips2010-08-15 21:09:17

New Member-Tuning Issue? (28/29)
8/16/10 10:29am

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Hot Springs, AR - USA

Vette(s):
69 Conv #'s match 427, TKO-600/.64, 3.36HD-Posi, HT, T/T, PS, PB, PW, SP, Leather, Comp XE264HR & Roller Rockers & Lifters, Air-Gap RPM intake, Holley St Av 770 VS, MSD 6AL+Dist+Blaster SS, K&N, Jet-Hot Hooker Side-Pipes, Steeroids, Al Rad, Spal Fans

Joined: 4/24/2004
Posts: 3231

[QUOTE=anips]I run hooker "long under chassis headers small tube 1 1/2" ID or 1 5/8 OD with a 3 1/2" collector on the LT-1, my engine is a 30 over 350 9:75 comp forged flat tops, stock Lt-1 bottom end with the stock Lt-1 solid lifter cam straight up, stock 202- 160 heads "performance Distributor" dist. 3:55 ger. stock ratio1.5 roller rockers,works for me, you might ask Ben what header info he programed into the dyno run, glad to help. [/QUOTE]

I just used generic small tube headers... those sound good

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9/1/10 8:11am

Gary Lacoursiere
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, - Canada

Vette(s):
1976 L-48 Coupe Vortec Heads; Roller Rockers, 625 Demon, 700R4; Electric fan, Aluminum Rad, Full-lenght headers w/ sidepipes, fiberglass bucket w/ 5-point quick release harness.

Joined: 7/19/2010
Posts: 10

I agree with the headers. Any full-lenght, small-tube headers will boost your bottom end. Also, like one of the guys suggested, try dumping the clutch at 3000-3500 RPM. By that point, you're into your cam and you will be sideways before you know it, smoking the skins like a 16-year old!!

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