Any guesses on HP for this 403

[Csilvy2000]

I'm going to get a few time slips with this car and see what kind of figures the clock gives.

 

[olds307 and 403]

Glad to do it.
Your compression ratio came out at 8.42/1. I used 18cc for the piston dish which may be on the small side.

It is, the factory are 21cc dish with the pistons .020" in the hole. Plus the heads will probably be 84cc at minimum.

 

[Csilvy2000]

It is, the factory are 21cc dish with the pistons .020" in the hole. Plus the heads will probably be 84cc at minimum.

Is that piston to deck height pretty typical for a stock engine?

 

[olds307 and 403]

Yes, that seems to be one improvement in 77 and later motors, along with 1/2" head bolts. The 76 and earlier motors were .025" to .030" in the hole.

 

[Pronto-]

Get some 3.42 gears in there! You'll be much happier. I was able to run 13.4 in my old 403 TA. I had #7 heads. Compression makes the diff.

 

[olds307 and 403]

As said compression, then more cam, better head flow, stall and gears make a huge difference.