Help! Joe Lucia, et. al.

[gary mancuso]

I'm rebuilding my 67 427/435 and would like to replace my cam/lifters. GM Performance Parts has what they refer to as a "blueprinted factory repalcement (P/N 3925535) for the 435 H.P. 427ci early L-88 camshaft." It's advertised to have a RPM range of 4400-7000; compression ratio 11:5 to 12.0; duration at .050 lift (intake/exhaust) is 264*/269*; valve lift is 560*/580* with a lobe centerline of 112*. Crane blueprint series (P/N 968561) and Elgin (P/N E906) also offer the same specs. I want to rebuild as original. Are any of these cams correct for my motor? I can't seem to find info regarding what was originally used. Any help would be greatly appreciated. Once again thanks in advance.

Gary

[Tom Freeman]

Re: Help! Joe Lucia, et. al.

Take a look here for Vette Cam specs: http://www.geocities.com/MotorCity/D...00/cmspec.html

Appears that the 67 L71 had 336/336 duriation (@ .5197 lift) with an Intake Lobe Center of 114 and an Exhaust lobe center of 66. Distance between centers of 132 and an overlap of 108.

tom...




Corvette Cam Specs

[Duke W.]

Re: Help! Joe Lucia, et. al.

There's an error in the GMPP catalog. The L-88 was officially rated at 430HP, not 435, so the "435" reference leads to confusion. You definitely don't want to run this L-88 cam on a street engine as its extreme overlap is specifically designed to take advantage or the wave dynamics generated by headers and open exhaust, but with manifolds and mufflers there will be so much exhaust gas residual in the cylinders due to overlap at low to medium revs that torque production in this range will be very poor, not to mention atrocious fuel ecomomy and lousy driveability.

The cam mentioned by Tom appears to by the correct L-71/72/78 cam.

Duke

[Duke W.]

P.S.

Federal Mogul Performance parts TP165 seems to be a correct OEM replacment, but this part number may now have a different prefix. The original GM part number for the SHP big block cam is 3863143.

Duke

[Tom Freeman]

Re: P.S.

Run a Google search for that part number, 3863143, and "Camshaft". I came up with 32 references and several were list cams as a replacement for the 3863143 cam.

One list a GMPP cam, 12364057. They are at: http://www.flatlanderracing.com/liftersgm.html

tom..

[Joe L.]

Re: Help! Joe Lucia, et. al.

Gary-----

Yes, as has been mentioned, you definitely don't want to use the GM #3925535 camshaft (or equivalent reproduction) in your engine. That L-88 cam is WAY too radical for street operation.

Use GM #12364057 camshaft kit. This is a Crane-manufactured reproduction of the GM #3863143 camshaft which was likely originally used in your engine (GM #3904362 MAY also have been used, but both cams will provide similar performance). The kit includes camshaft and Crane mechanical lifters. The GM-manufactured big block mechanical cams and lifters have been discontinued for quite some time.

The GM #12364057 kit carries a current GM list price of $179.00 (less through discount GM dealers), so it's a very good value.

[Chris H.]

Re: Help! Joe Lucia, et. al.

Gary, I agree with what folks have said. However, I had a 396 with the L88 cam, and I liked it. Not much low end, but above 3000 rpm, oh lordy. And the exhaust note (roar through the side pipes) to 6500 rpm+ was so nice. Not to mention the bad-ass high idle. An added benefit of all that overlap was that the cam bled off cylinder pressure, so I was able to run straight 93 with the stock 11:1 compression, and alot of advance...17 degrees BTDC @1000 rpm.

[gary mancuso]

Re: Help! Joe Lucia, et. al.

Thanks guys for the info. You've been most helpful.

Gary

[Craig S.]

Re: P.S.

Duke - I just bought a FM blueprint for my 66 L72. SpeedPro, as they badge them now, lists it as CS165R. Also, it you are installing it in a bonna fide 65/66 block, it needs the rear groove cut, FM didn't do this for you....so it needs a trip in my metal lathe.....Craig