I have found out that my 1976 351W has 302 heads on it. The casting numbers are hidden under the intake manifold, but I removed a valve cover and found out that the head has date code 0J16 = september 16 1970, there is no 2V or 4V casting instead there is a “T” cast where the 2V or 4V marking is supposed to be. My guess is that these are 2V heads with 58,2cc chambers and thus the engine has a compression of about 8.9:1 (the 76 had a high deck). How can I find out which heads these are? (without removing the manifold) The engine is bored 0.30 over, does that affect compression ratio? The valve springs are light red or orange. I have a new Clevite 77 cam, should I install it? · Lift 472/496 · Adv. duration 280/290 · Duration @.050" 214/224 · Lobe sep. 107/117 If I do I'd like to install roller rockers, wich rockers are good value for money for the street?
do you have rail or non-rail oem rocker arms? if rail, & want to stay that way, either comp or crane make an oem style rocker with roller tips. if using non-rail, go to ohio crankshaft web site. $129 a set. in 70, 302 heads had 7/16 bolt holes; 351 has 1/2" head bolts. dont fit unless someone reamed out the holes in the heads. bore & stroke do affect the comp ratio: if you increase the bore or stroke & keep the same combustion chamber size, the comp ratio goes up.
How can the casting number be under the intake? Not saying you're wrong, I just never saw that. It would have to be on the same surface as the deck or under an intake port. Anywhoo, 351Ws in the late 70s did come with the same heads as 302s. Overboring an engine will increase the static compression ratio. Here's a calculator I like to use, you can plug in your numbers: http://www.fordmuscle.com/calculators/compression.shtml For head info check here: http://home1.gte.net/res03net/faqs/head.htm You'll see the 351Ws and 302s in the late 70s both used D8OE-AB heads.
Actually the casting numbers are on the underside of the heads, but to see them you need to remove the intake manifold and use a mirror to read them. http://www.aacncclub.com/FORD_HEAD_CASTING.html
If the inside of the engine is all stock then your calculations may be correct. but if this change was done by someone rebuilding it then you would have to find out what changes they made to know the compression.
