Originally Posted by techinspector1
As was said already, the problem will be with the extremely large chambers which could easily be 122 cc's and will make it necessary to use a domed piston to achieve a decent static compression ratio.
Boring to a larger bore size piston will help, as will a longer stroke crank. Both will increase the cubic inches which raises the static compression ratio. I'm sure you know this, but I like to spell it out for others who may be reading this thread.
A professional engine builder that I know will not build a BBC with a flat tappet cam unless the buyer signs a liability release form. He says he has had too many of them roached in the BBC. Therefore, I would use a retro-fit hydraulic roller in such a motor, based on his experience.
The 049 heads may not be the whiz-bang performers that you perceive them to be. They're pretty mild.
I agree on the retro roller cam, with the oils today it's just not safe to run a flat tappet cam.
As for compression that kind of depends how much HP you want to make. If you want 450hp then 9.5-10:1 compression is going to be needed.
The 454 I built for my '71 GMC has dome pistons and a hydralic roller cam. The dome on the piston is small, but it does give me 10-10.5:1 compression with the 781's head that I am running. The 781's have some of the largest oval ports that came in GM BBC heads. I installed 2.19 and 1.88 valve and had a little pocket porting done to them. As for the cam it's a Comp Cams Nitrous grind, NX279HR, it has 279/294 duration and .537/.541 lift on a 113 LSA, 2000-6200 power range. I figure this setup is good for 450-500hp.