68 400 engine small bore,long stroke with c heads. Can big valve c heads be ran on this engine without worrying about valve/piston clearance and valve/bore clearance? It's a low compression engine 9 to 1 originally a 2 barrel carb engine. Thanks. Steve

 

If it's the original '68 442 400 engine it came from the factory with large valve "C" heads.

 

Even though it's a low compression 9 to 1 , two barrel carb engine? I thought for sure the originals were 2 inch intakes.

 

OK you have the Turnpike cruiser option.

Unless you are the original owner of the car, it is really hard to tell what is truly original to a 44 year old car. My car has a numbers matching blue motor in it.


Is swapping heads the only mods you are going to do?

If everything else remains constant, is a .072 larger intake valve going to make cost effective difference?

I have the upgrade itch also, so I am having a mild street 455 built and pickling the numbers matching 400. To really confuse everyone I'll paint the 455 bronze, but I think the lakewood bellhousing is going to give it away!

Steve where are you located?

 

I'm in central ct, I have the turnpike cruiser all original. I'm doing the heads cause I have bad valve guides but I have a set of big valve heads laying around. While I'm doin the heads I'm gonna do a cam,lifters,timing chain,push rods new springs and keepers. Cutlassefi is doin a roller cam lifters,etc for me, nothing crazy just wanna freshen the engine up a bit. Steve

 

Steve,
I measured a few things, looks like the big valve heads will fit.

 

All G-block 400s have the same bore (3.890") and all came with C heads. All 442 G-block motors came with big valves, so yeah they fit just fine. Olds changed compression with the size of the dish in the piston - all C-heads have the same size chambers. Just have your existing heads machined for big valves.

 

Thanks guys! Then I will have the big valve c heads redone and use those. Thanks again! Steve...

 

68442convert: all 68 442's with the factory 400 cid, would have bronze color engine, not blue.

Gene

 

Gene,

I know.

I was trying to point out that you really don't know what previous owners have done. When I first saw the blue motor, I assumed a replacement 455 had made its way into the engine compartment. Upon further inspection I realized they must have rebuilt the original motor and repainted it the 455 blue.

Stevec Are you planning on using the stock rocker arms? I'm assumimg a four barrel and intake as well.