C-2 Engine Specs

[Patrick F. McInerney]

My '64 Roadster is equipped with a SHP 365 HP, solid lifter engine. I am doing a complete frame-off.

I'm at the engine stage starting with a compression check. The shop manual calls for 150 PSI. After repeated checks, hot and cold, carb wide open, I'm recording 188 to 195 PSI.

I've removed the heads. Valve diameters are correct and carbon deposits are minimal.Cam lobe lift measured at the push rods is intake .290" and exhaust .320". Manual specs calls for intake .2625" and exhaust .2665". I believe this to be an aftermarket cam and I wonder is this is the source of the high compression.

The engine had been reworked previously and, by all indications, it appears to have been done properly. What I don't know is have the block and or heads been refaced. Are there any benchmarks on the 327 block or heads which would allow me to determine if this has been done?

Perhaps there is a book which can answer my questions. If so, I would appreciate hearing about it.

Thanks very much for your help and Happy New Year!

Patrick F. McInerney

[Gerry Proctor]

Re: C-2 Engine Specs

Cam timing can have a direct affect on cranking compression, Patrick. As to prior surfacing and decking operations, one sure way to tell if the block has been decked is the presence or lack of the block codes on the passenger side front deck pad. These are the codes that people reference in a "numbers matching" assembly. You should find a series of alpha-numberic indentations. When a block is decked, these stampings are generally wiped out. You can also see parallel broach marks in the pad (it must be very clean bare metal). The way the factory machined the deck was to run the block through a parallel lathe that shaved the deck in one pass. Machine shops use a rotary lathe that leaves swirl marks in the machined finish. It's possible that your block could have the stampings, but be missing the broach marks. This would appear to indicate a re-stamping. If you can see the broach marks, your block is unmachined. There is no way that I've ever heard of to replicate the broach marks. The cylinder head can be more difficult to tell. You could "CC" the chambers and see if they are beyond nominal specificiations.

And finally, being that someone has already tinkered with the engine, they could have also installed higher compression pistons in the thing. Depending on when the rebuild was done and what the purpose of the engine was, and the knowledge of the builder, this is a possibility. You'll also get higher static compression on a bored engine.

[Duke W.]

Re: C-2 Engine Specs

The lobe lift specs you quote are for the Duntov cam used up to '63.

The '64 Corvette Shop manual supplement will have the correct lobe lift specs for the 30-30, and I believe they are .323X, and they are both equal, so you undoubtedly have an aftermarket cam.

I would recommend you replace it with the '70 LT-1 cam, which can be bought from Federal Mogul, TP245.

Duke

[Patrick F. McInerney]

Re: C-2 Engine Specs

Gerry and Duke,

Thanks very much for your comments. I tried to respond on Saturday but I couldn't get through to the site.

Both heads and block surfaces appear to be factory. Number stamping on right fron block surface is clear and per Noland Adams. Measured 62.4 cc of water and satisfied myself that the heads are correct.

Piston crowns match book photos. I'll be removing them during the week. If compression height is correct then the primary cause of my high compression is the cam. I'll look into the Federal Mogul part you suggested.

Thanks again.

Pat McInerney