Topic: New Member-Tuning Issue?
in Forum: C3 Engines
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Lifetime MemberHot Springs, AR - USA
Joined: 4/24/2004
Posts: 3236
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
[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) 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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Lifetime MemberHot Springs, AR - USA
Joined: 4/24/2004
Posts: 3236
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
[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]
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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Oak Creek, WI - USA
Joined: 5/21/2008
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Vette(s): 1981 Great White Shark. Red Interior, 350/190 hp. PS, PB (SS), A/C CC, T-Tops. Served three years in Active Duty Army, then Retired Air Force after 34 years! Badger State Vettes Car Club. 175,000 Original miles!! Now own a 1998 C-5!
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.
dskopp 2010-08-11 22:25:53
Dan
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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' Apple 2010-08-12 10:04:49
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?
Joel Adams
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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
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.
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
......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. anips 2010-08-12 15:48:49
......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. [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
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!
Lifetime MemberHot Springs, AR - USA
Joined: 4/24/2004
Posts: 3236
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
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=cthulhu]that cam is NOT for regular street use. I knew it the moment you told us your vaccum readings.
dry 2010-08-13 10:14:36
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.
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. anips 2010-08-13 11:42:33
in Forum: C3 Engines
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