Best stock heads for a 351W?
 

What are the best stock heads for a 351W? Mine isn't totally stock, has a Comp XE250H cam, Comp magnum rockers, Weiand stealth intake. The engine has D8's that were made 2-14-1980 and 5-18-1980. They've been reworked, when the engine was rebuilt 30-40K miles ago. Nothing wrong with them. But I'm just curious, if I were to change the heads so I could get a higher compression ratio (I'd like around 9.3:1 so I could run regular fuel) as well as keeping the stock sparkplug angle since I have Hooker headers, and they are extremely easy to change. Even with the heads my engine has now, it runs like a scalded ape with tons of power. If I were to get different heads, I'd port the exhaust ports and just touch up the intake ports.

Late model GT40s are what you want, found on '96-97.5 Explorers and Mountaineers, '93-'95 Mustang Cobras, and all Gen1 Lightnings.

Thanks! what are the CC of the combustion chamber? 64?

I believe that the GT40s were on the explorers and mountaineers but being a 302 they use a 7/16ths headbolt but to my knowledge the lightnings and cobras had the GT40P heads which are already designed to use the 1/2" headbolt for the 351w

Al of the info I have been able to find says that the GT40P heads (lightnings and cobra) have a 59cc combustion chamber and some reports say the regular GT40s have mid 60s (approx 65.5cc) but cant confirm for sure.

Lightnings did not get GTP heads that was '97.5+ Explorers only, Cobra GT40 heads were often shaved down to a nominal 60-62cc chamber while the regular GT40 found on early Explorers and Lightnings had a nominal 64cc chamber. Production tolerances being what they are means chamber volumes can vary a cc or 2 one way or the other.

You are totally correct I misspoke my apologies. The GT40s on the lightnings and cobras have the half inch head bolts so they do not need machining.

The Cobras we're talking about here had 5.0L motors so they would have 7/16 head bolts. There was also a Cobra R track car with a 351 in it but that thing wasn't sold to the public so you probably won't find it in a scrapyard.

Oh I was told that the cobras, although having a 302, had the same heads as the lightning so they could accommodate half inch head bolts but I may be misinformed.

No.. there are no 302/5.0s with 1/2" head bolts, and all GT40 heads are the same for all intents and purposes they are just machined slightly differently depending what motor they are going on. The difference here is just 1 bolt size and there are locating dowels in the outer corners between the head and block so you could bolt a 351 head on a 302 without any special bolts, the collared bolts are available just as an added measure of security.

So, if I were to get 302 heads, I'd have to drill out the outside head bolts to 1/2. Correct? or do the bolt holes for the inside need drilled out as well?

All the main bolt holes have to be drilled out if you get unmolested heads off a 302, but it's not a super hard thing to do.. I have even done it on my floor standing drill press after making sure the heads are positioned flat and perpendicular to the bit. Because the bolt hole sizes are so close the bit self centers anyway and cast iron is pretty soft so it's pretty easy to drill through.

Doesn't sound very hard to do. I've done everything from body work to major mechanical work. With a 100% success rate. I'm not afraid one bit to drill some holes bigger. I don't have a drill press, but I know people who do.

Ahhhh gotcha that makes sense. I was told that they were the same heads and no modification was required as if you were to pull regular 302 heads and use them. I didn't think about the use of collared bolts. Thank you for clearing that up

I purchased a pair of GT40 heads off a 95 Cobra, and they had 1/2" bolt holes.

I know for sure they came off a Cobra as I looked at the car when I picked up the heads (along with the rockers, intake, camshaft and stock tubular exhaust manifolds).

I don't know the build date of it, but it very well could be that they were running low on the 'Cobra' heads near the end of the 5.0 Mustang production run, and were using Lightning heads.