Early 351W C90E heads vs GT40

[FirstTimer67]

Seems like general consensus that the GT40 heads are an upgrade over stock but I read recently that the early (69-70) 351W heads are better than later years and that the GT40 heads were only a slight modification and improvement over that original design. Is there any truth to that or anyone have an opinion on whether I should go GT40 or stick with what I got? Any idea what performance gains I might see?

For what it’s worth, the GT40s would likely come from a 200k +/- miles Explorer versus the unknown mileage of the 351W swapped into my 67. The truck has 143k on it but I don’t know when the engine was swapped or where it lived its previous life.

 

[hucklburry rev2]

I am no expert, from what I've paid attention too, overall, they are very similar.

I wouldn't go out of my way to get one over the other in stock form. In your case, I wouldn't swap them out for the GT40s. At this point either have the C9OE ported and worked, or get aftermarket heads, preferably aluminum. I think that is where to spend the money.

This shows the GT40p flowing better than the 69s, is it worth the money? I don't think it is, I'd apply the money towards aftermarket stuff. Also, I don't know what CC chambers you have now, so I don't know if you would lose a little compression going gt40 or not.

https://www.fordmuscle.com/archives/2000/05/heads/index1.php

If you went with the GT40s and had them gone thru, with upgraded springs, you'd probably have $300? in work to them plus getting them. So $500? apply that towards some aftermarket heads or put that money into porting what you have if on a budget around $500, is my opinion.

 

[triracer67]

Heads

I have two sets of C9OE 351w heads. One set has had hardened valve seats, valves, and exhaust port work. The second is stock. Big difference, but, you are looking at hundreds of dollars, and you need the hardened seats. The GT40 heads are good, but, will probably need work also. Sometimes a new set of aftermarket heads are worth the 1,000 dollar price tag. Here is a great link... https://www.fordmuscle.com/archives/2000/05/heads/index1.php

 

[Broncobowsher]

Finding a good set of C9 heads is hard to do. You are looking for 50 year old castings. If you actually find a pair they are more than likely need to be completely gone through. And typically this won't be the first time, probably not even the second. How much life is left in them? Providing you get a set that are not cracked (they are generally good, not usually a problem) you are probably looking a full rebuild. Guides, seats, springs, valves themselves. I really consider the C9 heads more of a bench racing theory these days. By the time you get them usable you are in the price range of a good modern aftermarket set of heads, without the modern flow.

The GT40(P) heads are highly available. Nearly every junkyard has a 5.0 Explorer ready to give it up. If they even need a rebuild, you are going to be doing the first rebuild. This is the head I give you good chance of actually owning. Nobody is adding a vintage parts price premium to them. Highly available thus affordable.

This is all providing you are just looking to but junkyard parts together. If you are halfway serious about making power, aftermarket heads.

 

[bigmuddy]

I would throw out that if you have a lumpy cam, you would also need to need to pony up for a better of springs anyway for the GT40's as they are limited on lift without flattening out or worse.

 

[jckkys]

Carbedford.com flow tested both heads and the difference is minimal in terms of flow. Most of the advantage in flow for the GT40s comes with the valves open more than .400". Even then it's still minimal. The early 351W heads were unchanged from '69-'76 except for internal air passages added in '75. So the '69/'70 heads were far from unique. Also there were no 4bbl heads. They were all the same. The combustion chambers are 60.4 cc. in the 351 heads and '96 Explorer GT40 heads are 65cc. The Mustang Cobra GT40 heads were milled to about 62cc. Mine were milled to 60cc. I use '96 Explorer heads that have hardened exhaust valves and pressed in seats. There are no internal air ports either. Some GT40 heads may be different depending on the DSO. The biggest advantage to the GT40s is that they were made for unleaded gas. The early 351 heads have 4 additional manifold bolt holes for the early 4bbl intakes. '77 up and after market 351 intakes don't use the extra bolts. Both heads would benifit from a valve job with new springs. I did a pocket porting and blending on my GT40s to smooth the exhaust flow. Any small block head could use that. My goal is a broad power band not just HP. Interestingly the 351 heads were referred to as GT40 style when they came out in '69. I hope this helps.

 

[Speedrdr]

When my stroker was being built, the shop guy was going to install a set of GT40 heads he “thought” he had in the shop. Turns out he couldn’t find them. I decided to go with AFR heads. Yeah, they were pretty pricey but I know I’m getting new.
Randy

 

[FirstTimer67]

All good info guys, thanks for the input. I’ll be holding tight with what I have and include the cost of aluminum heads in the engine budget.

 

[rguest3]

The Edelbrock E-Street 170cc heads are very nice Aluminum Heads for the money. I would consider those too. Just make sure they are set up for the Cam you end up installing.

 

[AZ69EB]

Google E street heads before purchasing them. I think you are better off buying bare heads, then stuffing them with whatever parts your cam manufacturer recommends. Then all the parts are matched / working together.

FYI- There are many people building Chinese knock off aluminum heads with quality parts for the same price range of the E Street heads.

Good luck

 

[bigmuddy]

My engine guy locally, said that the only heads he would buy and install would be AFR heads. Everything else he would have to spend some time, tweaking or polishing before installation. I went GT40 however as AFR wasn't in the budget.

 

[jckkys]

I kind of thought this thread was about a comparison between 351W and GT40 heads.

 

[AZ69EB]

The C9OE were stud mount and the GT40 heads are pedestal mounted rockers. Hi If you decide on the GT40’s, you will need to purchase new pedestal rockets and different length pushrods.