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9/13/13 12:17pm - Original Message: 'L36 Engine cam replacement'
rep69
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Chesapeake, VA - USA

Vette(s):
1969 convertible 427 4speed

Joined: 7/24/2012
Posts: 130
I own a 1969 427  The cam in the engine is worn and this winter I am going to have to do something with the engine. I know there are a lot of options.  I have owned the car for a year and a half. I have been trying to educate myself on these older engines. The engine is stock.  I am looking for suggestions on how to proceed. Stay with stock flat tappet cam on maybe a roller cam?  Thanks, Bob
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9/13/13 12:40pm - Reply: 'Re: L36 Engine cam replacement'
F4Gary Gold Member
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Grapevine, TX - USA

Vette(s):
1972 LT-1 convertible with factory air.

Joined: 8/26/2006
Posts: 862
I'd go with a modern cam, roller lifters, and roller rockers.  You wouldn't have to worry about what oil to use and it wouldn't change the appearance of your engine.

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9/13/13 1:15pm - Reply: 'Re: L36 Engine cam replacement'
Adams' Apple Lifetime Member
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Duncanville, TX - USA

Vette(s):
#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
Posts: 19447
Flat tappet cams/lifters made today are designed for the low ZZDP content of the oils available, so they will survive much better than the older, original designs. Roller cams are kewl, but require more work and parts to install(and $$$), such as something to keep the cam from "walking" forward, which is usally accomplished with a cam "button", but some require some machining of the block to add a plate to hold the cam in position.
Roller rockers are also kewl, but may not fit under a stock valve cover...especially if you have power brakes.

You can buy/order cams that are copies of the original, older cam profiles, but are made to work with today's oils, or you can bump it up a bit if you want to. Decisions, decisions.....Ermm

Personally, I would go back with a stock type cam, or maybe one with a little more aggressive grind..but that's just me...Thumbs Up

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9/13/13 2:13pm - Reply: 'Re: L36 Engine cam replacement'
rep69
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Chesapeake, VA - USA

Vette(s):
1969 convertible 427 4speed

Joined: 7/24/2012
Posts: 130
Thanks for the replies .  I have options, just need to sit down and decide which direction to go in.  I need to talk with the cam manufactuers and maybe get some information from them too.
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9/13/13 10:32pm - Reply: 'Re: L36 Engine cam replacement'
rod7515 Lifetime Member
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Red Lion, PA - USA

Vette(s):
1974 White 350 Corvette, TH400 Automatic 1972 Tangerine /Go Mango Convertible 383 Stroker, 2004r Automatic

Joined: 10/27/2006
Posts: 1172
I thought about that for weeks when I did an engine upgrade in mine. I would take the time to talk to your local machine shop that you use and listen to what they recommend. There is a higher cost when going to a roller set up. Might be as much as a thousand dollars more. Depending on what all you decide to upgrade. I wish I would have gone roller cam because todays grinds with roller cams are much more efficient then flat tappet cams in my opinion. I decided to save the money. Not a bad decision but I think the Dodge I am doing now will be roller cam not flat tappet. As mentioned earlier either one will work fine, so you cant make the wrong choice. Just remember if you have headers and you break in a flat tappet cam you need to put manifolds on for the break in. Best of luck Rodney

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9/13/13 11:31pm - Reply: 'Re: L36 Engine cam replacement'
rep69
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Chesapeake, VA - USA

Vette(s):
1969 convertible 427 4speed

Joined: 7/24/2012
Posts: 130
Thanks for the info. Did not realize the cost difference was so much.  I will continue to gather more advice.     Bob
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10/24/13 3:10pm - Reply: 'Re: L36 Engine cam replacement'
rep69
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Chesapeake, VA - USA

Vette(s):
1969 convertible 427 4speed

Joined: 7/24/2012
Posts: 130
I am still trying to get some answers before I do anything major to the engine. Had one mechanic have the car for 3 weeks and never got to look at it. Different people tell me different things. The mechanic that replaced my valve stem seals told me the cam is worn. Another mechanic says it is probably just the carb.   The car idles good.  On the road is when you notice the missing and surging of the engine, especially at 2,000-2,500 rpms .  Holley double pumper was rebuilt last year. 
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10/24/13 5:46pm - Reply: 'Re: L36 Engine cam replacement'
nosal1 Gold Member
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Dunedin, FL - USA

Vette(s):
1980 Corvette Torch Red with Gold metallic 370HP/350 CU.IN.Turbo 350 w/shift kit.Originally CA.Car with 305 CU.IN.

Joined: 3/21/2006
Posts: 223

Hello and good afternoon   I have a question relating to the missing at 2000-2500 rpm.Is it a massive miss or subtle miss at those RPM's ?Do you have an OEM points distributor? When a cam takes a hike you general feel it at idle an not above 2000 rpm.It becomes more noticeable at idle. Also,if you still have a OEM points distributor,do you have a condenser that should be attached to the positive side of the coil. That condenser maintains 12 Volts to the coil,and as rpm increases the voltage to dist.decreases to 9.86 volts and would create a slight miss at those RPM's if the condensor is bad..This all is for naught if you don't have a points dist.                Have a great day and good luck.        Sal C



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10/25/13 4:07pm - Reply: 'Re: L36 Engine cam replacement'
CCasey
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New Albany, OH - USA

Vette(s):
1980 Coupe / Snowcrest White / L48, 350 / Comp Cam / Edelbrock Heads / Cyclone Intake / Holley Carb / Holley Fuel Pump / Patriot Headers / Dual Exhaust / Magnaflow Mufflers / 1964 Coupe / Riverside Red / L76, 327, 365hp

Joined: 8/17/2010
Posts: 173
For whatever it's worth, I installed the following parts to my 1980  L48 engine.  I never had it dyno'd but a couple reputable mechanics estimated that she puts-out about 350 - 375 hp.
 
12-000-8         (Comp Cam) Hydraulic Roller Cam

Duration @ .050: 210 intake; 220 exhaust

Lobe Lift: .3340 intake; .3420 exhaust

                                    Lobe Separation: 112-degrees

                                    Gross Valve Lift: .501 intake; .513 exhaust

                       

853-16                   (Comp Cam) Lifters

2100                (Comp Cam) Timing Set

611-16             (Comp Cam) Valve Locks

740-16             (Comp Cam) Retainers

986-16             (Comp Cam) Valve Springs

1412-16           (Comp Cam) Roller Rockers

201                  (Comp Cam) Wear Plate

202                  (Comp Cam) Cam Button

 

5089                (Edelbrock E-Street) Aluminum Cylinder Heads

                                    2.02-inch intake / 1.60-inch exhaust Valves

                                    64-cc Combustion Chambers

                                    RPM Range: Idle 5,500

 

0-80770           (Holley Street Avenger) 770-cfm Carburetor

 

12-834             (Holley) 80 GPH Fuel Pump w/ 3/8-inch Fuel Line

 

52010              (Power+Plus) Cyclone+Plus Dual Plane Intake Manifold

 

51-1572           ECC Distributor Cap

 

51-5582           ECC Rotor

 

323236            (Patriot) Ceramic-Coated Tight-Tuck Exhaust Headers

                                    1 5/8-inch Primaries

                                    2 -inch Collectors

 

323018            (Corvette Central) 2 -inch Aluminum Dual Exhaust

 

323454            (MAGNAFLOW) 2 -inch Mufflers



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Chuck

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10/29/13 3:21pm - Reply: 'Re: L36 Engine cam replacement'
rep69
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Chesapeake, VA - USA

Vette(s):
1969 convertible 427 4speed

Joined: 7/24/2012
Posts: 130
Thanks for the information. I finally got the news about the cam. One of the lobes is worn down and not allowing the valve to open properly. I will have to consider which direction to go with the replacement.  
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11/5/13 12:20pm - Reply: 'Re: L36 Engine cam replacement'
rep69
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Chesapeake, VA - USA

Vette(s):
1969 convertible 427 4speed

Joined: 7/24/2012
Posts: 130
The time has come to start with the cam replacement. My mechanic is going to pull the engine and start the process. While the engine is out I am going to have the engine gone through and other items addressed while the engine is out. Take care of everything at one time. Hopefully it all goes smoothly. 
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11/5/13 1:18pm - Reply: 'Re: L36 Engine cam replacement'
Adams' Apple Lifetime Member
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Duncanville, TX - USA

Vette(s):
#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
Posts: 19447
 Good luck! Hope it all comes together nicely with no surprises! Thumbs Up

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Joel Adams
C3VR Lifetime Member #56    
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             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
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11/14/13 11:59pm - Reply: 'Re: L36 Engine cam replacement'
rep69
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Chesapeake, VA - USA

Vette(s):
1969 convertible 427 4speed

Joined: 7/24/2012
Posts: 130

The engine overhaul process has begun.  While I have the engine out I want to clean up and coat the exhaust maifolds.  Looking for some feedback on what type of coating to use.  Spray can paint them myself or have it done by professional ?

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12/17/13 2:25pm - Reply: 'Re: L36 Engine cam replacement'
rep69
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Chesapeake, VA - USA

Vette(s):
1969 convertible 427 4speed

Joined: 7/24/2012
Posts: 130

When I bought my 1969 427 390 hp  it was equipped with a Holley Double pumper spread bore carb.  I have been looking at different web sites and reading books and I see that the engine could have been equipped with a Holley or a Rochester q jet carb.   any thoughts? 

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12/17/13 5:03pm - Reply: 'Re: L36 Engine cam replacement'
nosal1 Gold Member
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Dunedin, FL - USA

Vette(s):
1980 Corvette Torch Red with Gold metallic 370HP/350 CU.IN.Turbo 350 w/shift kit.Originally CA.Car with 305 CU.IN.

Joined: 3/21/2006
Posts: 223
Here is some info you might like..
    The 1969 ZL1 version of the 427 engine was developed primarily for Can-Am racing, where it was very successful in cars like the Chaparral 2F and McLaren M8B. The ZL1 had specifications nearly identical to the production L88 version of the 427, but featured an all-aluminum cylinder block in addition to aluminum cylinder heads, which dropped total engine weight into small block Chevy territory (approx. 575 lb or 261 kg dressed).[citation needed] The engine was also fitted with the new open combustion chamber cylinder heads, a light weight aluminum water pump, a camshaft that was slightly "hotter" than the L88's and a specially tuned aluminum intake manifold. Like the L88, the ZL1 required 103 octane RON (minimum) fuel, used an unshrouded radiator and had poor low speed idle qualities - all of which made the two engines largely unsuitable for street use. [102 octane RON (Sunoco 260) represented the highest octane gasoline sold at common retail stations.]

As impressive as the ZL1 was in its day and despite the "larger than life legends" surrounding it, actual engine dyno tests of a certified production line stock ZL1 revealed 376 SAE net HP, with output swelling to 524 Gross HP with the help of optimal carb. and ignition tuning, open long tube racing headers and with no power sapping engine accessories or air cleaner in place. ZL1 DYNO TEST - COPO CAMARO WEBSITE A second engine dyno test conducted on a second production line stock (but recently rebuilt and partially blueprinted) ZL1 revealed nearly identical figures for the various "Gross" conditions.[7]

Period magazine tests of the ZL1 were quite rare due to the rarity of the engine itself. "High Performance Cars" tested a production line stock but well tuned example and recorded a 13.1 second/110 MPH quarter mile, which correlates quite well with the previously referenced 376 Net HP figure. "Super Stock and Drag Racing Magazine" recorded an 11.62 second/122.15 MPH quarter mile in a ZL1 Camaro that was professionally tuned and driven by drag racing legend Dick Harrell, although that car was also equipped with open long tube S&S equal length headers, drag slicks and minor suspension modifications. Using Patrick Hale's Power/Speed formula, the 122.15 MPH trap speed indicated low 11 second ET potential (e.g. with larger drag slicks) and suggested something on the order of 495 "as installed" HP in that modified configuration. This large difference in power suggests that the OEM exhaust manifolds and exhaust system were highly restrictive in the ZL1 application, as was also the case with the similar L88..Sal C


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12/18/13 6:48am - Reply: 'Re: L36 Engine cam replacement'
nosal1 Gold Member
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Dunedin, FL - USA

Vette(s):
1980 Corvette Torch Red with Gold metallic 370HP/350 CU.IN.Turbo 350 w/shift kit.Originally CA.Car with 305 CU.IN.

Joined: 3/21/2006
Posts: 223

Data you might be interested in having.. Sal C

69 VetteBase 350L46 350L36 427L36/L68 427L71 427L88 427
HP @ RPM300 @ 4800350 @ 5800390 @ 5400400 @ 5400435 @ 5800430 @ 5800
Torque @ RPM380 @ 3200380 @ 3600460 @ 3600460 @ 4000460 @ 4000550 @ 4000
Compression Ratio10.25:111:110.25:110.25:111:112.5:1
Bore & Stroke4.00 x 3.484.00 x 3.484.251 x 3.764.251 x 3.764.251 x 3.764.251 x 3.76
Cylinder BlockCast IronCast IronCast IronCast IronCast IronCast Iron
Main Bearings555555
Valve LiftersHydraulicHydraulicHydraulicHydraulicMechanicalMechanical
Carburetion4bbl Rochester4bbl Rochester4bbl Rochester3x2bbl Holley3x2bbl HolleyLarge 4bbl Holley
Intake ManifoldCast Alloy IronCast Alloy IronAlloy AluminumAlloy AluminumAlloy AluminumAlloy Aluminum
Oil Capacity5qts w/filter5qts w/filter6qts w/filter6qts w/filter6qts w/filter6qts w/filter
ExhaustDual, 2.0"Dual, 2.0"Dual, 2.0"Dual, 2.0"Dual 2.0"Dual 2.0"
Spark PlugsACR44SACR44SACR43NACR43NACR43NACR43XL
 


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12/24/13 12:45pm - Reply: 'Re: L36 Engine cam replacement'
rep69
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Chesapeake, VA - USA

Vette(s):
1969 convertible 427 4speed

Joined: 7/24/2012
Posts: 130
Thanks for the info
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12/27/13 2:25pm - Reply: 'Re: L36 Engine cam replacement'
SteveC
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, - Canada

Vette(s):
1969 427/390 Sport Coupe *Stored since 1984*

Joined: 12/2/2012
Posts: 29
Curious which cam you decided to go with?
 
I have the same engine (1969 L36) and am in the process of reassembling my engine after a stock rebuild. I ordered a Comp Cams Magnum 280H and as I try to decide if the stock springs are going to work with this cam and it's 0.520 valve lift, I am having second thoughts. I have new lifters, pushrods, timing set and the heads were done with new bronze guide inserts, valves, stem seals, etc. The existing cam is OK according to bench measurements of lift but I am tempted to give it a bit of a lopey idle...
 
BTW the carb was originally a Rochester Quadrajet 7029215 EH. They are extremely difficult to find an original because they were a one year carb and only used a few cars including the Corvette L36 with Manual Transmission. There are many carbs that are very similar and it is not too hard to have one rebuilt with the correct metering/calibration to match the 7029215 EH.
 
Photo below is current state of assembly with my son doing all the hard work and me supervising, as it should be.
 


|UPDATED|12/27/2013 11:25:45 AM (AZT)|/UPDATED|


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1/9/14 4:25pm - Reply: 'Re: L36 Engine cam replacement'
rep69
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Chesapeake, VA - USA

Vette(s):
1969 convertible 427 4speed

Joined: 7/24/2012
Posts: 130
Thanks for the information. My engine is still being rebuilt. Hopefully next week I will get it back from machine shop??  When I bought the car it had the Holley carb. The original rochester is long gone. It would have been nice to have it.
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1/24/14 11:21pm - Reply: 'Re: L36 Engine cam replacement'
rep69
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Chesapeake, VA - USA

Vette(s):
1969 convertible 427 4speed

Joined: 7/24/2012
Posts: 130
My L36  engine is finally ready to go back in the car.  New Comp cam and rocker arms and timing chain. new pistons.  The machine shop went through the entire engine and they did a great job. The aluminum manifold needed some work. The mechainic explained how important it is to keep a check on the antifreeze condition. My manifold had some pitting and small cracks.  He told me to check the PH level of the antifreeze. I will get a PH test kit and monitor my system. 
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