LT-1 cam

[Joe L.]

Re: LT-1 cam

Steve-----

I checked and Duke's reference to the Federal-Mogul CS-1145R is, indeed, a duplicate of the GM #3972178. It's also available as a complete kit under KS-1145R.

Plus, Dan's reference to the Crane-manufactured GM kit is also another option that I had not previously paid any attention to. This kit includes a reproduction of the 3972178 camshaft + lifters. The part number is GM #12364054 and it GM lists for $179.00. That's probably one of the reasons that GM discontinued the cam. I'm surprised that the folks at Pace Parts didn't tell you that in the first place. The GM #12364054 is not a GM-catalogued, direct replacement for the 3972178 (since the 12364054 is a KIT and not a camshaft, alone), but the guys at a GM High Performance Parts outfit like Pace should know about it.

[Joe L.]

Re: LT-1 cam

Dan and Steve-----

Yes, that's correct. The number 3972182 is the camshaft core casting number which also identifies the GM #3972178 camshaft.

The GM #12364054 is a camshaft KIT. It contains a Crane-manufactured reproduction of the 3972178 camshaft + Crane mechanical lifters. The reproduction camshaft will NOT contain the GM casting number. It may contain other numbers or stampings, but these will be Crane ID numbers.

The GM #12364054 camshaft kit is a SERVICE-only, replacement item and is NOT comprised of a GM-sourced, PRODUCTION camshaft.

GM small block camshafts used to be manufactured at the GM Flint engine plant and, possibly, at the GM Bay City, MI engine components plant. The Flint plant is gone and I doubt that Bay City would produce a low volume item like the 3972178 camshaft. Since this camshaft is not used in any PRODUCTION engine currently manufactured (or which has been manufactured since 1972), I expect that the GM Toluca Mexico engine plant, the only current GM manufacturing source for Gen I and Gen II small block engines and components, probably wouldn't manufacture them, either. That's likely why the GM-sourced part was discontinued.

When GM engine plants cease manufacturing certain engines, the GM-manufactured engine parts usually cease, too. When SERVICE inventory of these parts is depleted, the "discontinued" sign goes up. The Tonawanda engine plant ceased manufacturing Mark IV big block engine parts quite some time ago. Today, virtually all the GM Mark IV engine parts, including all the camshafts, have "dried up". Just a few Mark IV-only parts remain such as the GM #3963523 crankshaft, GM #6260482 cylinder head, and a few other pieces.

[Duke W.]

Re: LT-1 cam

If any of you fellas want the Hinckley/Williams writeup on how to adjust the lifters on SB mechanical lifter cams including the LT-1 e-mail me, and I will send the Word file to you.

If you purchase a kit, only purchanse one with the "edge orifice" type lifters equivalent to the GM 5231585. These were the lifters used with the LT-1 cam from 70-72 and the Duntov cam from 57-63. The "piddle valve" lifters (GM 5232695) were used with the 30-30 cam in the 64-65 SHP/FI engines and the 302 Z-28 and all mechanical lifter big blocks. The piddle valve lifters increase overhead oiling,which is necessary for a BB, but not for a SB.

The 585s are a one piece lifter. The 695s are two piece and look similar to hydraulic lifters. The two piece design was required to contain the inertia valve that controls overhead oiling. The 585s oil on the basis of lifter bore clearance.

I have a note written in my FMPP catalog (info from Clem) that the F-M equivalent to the GM 585 lifter is AT840R

Duke

[Dan Tewell]

Re: LT-1 cam

Thanks Duke,
The lifters in the 054 cam kit are indeed edge orifice type lifters according to your discription. Now I know why I had trouble adjusting my 64 30-30 cam. Sometimes when I replaced a rocker arm, if I lifted the push rod up just alittle, the "top" of the lifter would come off and drop into the lifter valley. Then I had to remove the intake to correct the problem. I like the 054 kit. Just put it back together with a set of 1.6 roller rockers!

[Steve D.]

Re: LT-1 cam

Joe

Thanks for the confirmation research.

Steve

[Steve D.]

The horse is not dead yet

Joe

I noticed that the specs stated for the 12364054 kit give lift of .459 and .485, whereas the lift for the 3972178 cam is given as .435 and .455. Is this an apples-to-apples comparison?

Steve

[John H.]

Re: The horse is not dead yet

Steve -

Sounds like one includes the ramps (lash) and one doesn't.