Ok guys here I am again with another one of my questions. I am "refreshing" a 350 to put in my Regal as a temporary motor until I rebuild the 403 that is in it. The 350 is a 1971 model year and has the heads that I want to use for my 403 on it. I am wondering if I can use my 403 heads on the 350. I know the 403 heads are about 20 cc bigger in the combustion chamber than the 350 heads and I would have low compression. What I am wondering is if the compression will be too low for the engine to run or perform correctly? I really want to keep the 350 heads on my bench so I can get the porting & machine work done to them and still be able to drive the car in the meantime. Any help would be appreciated.

 

Cr would be around 7.5 to 1, give or take, may be in the low 7.xx range. Pretty low. Dowell pin might be in the wrong place, too, but not certain about that. Not worth the trouble, IMO.

 

Yep, I agree with captjim.. Put the 350 heads back on the 350 and look for another set of early SBO heads. By the time you're done with the 403 short block, you'll be ready to get em' done and slap em' on the 403, IMHO...

 

Thats what I have been thinking too. Also I didn't even think about the fact I have to drill the 350 head bolt holes out to fit the 403 so those 403 head bolt holes will be too big for my 350. Thanks for all the advise guys!