Cylinder head question

[Lima Delta]

Hi all,

I am in the process of tearing down an old 351W for rebuild. I pulled the heads off today and the casting is D8OE-AB, which I've read are the least desirable of all.

My goal is to do a mostly stock rebuild, but with an edelbrock cam/lifter set and timing chain/sprockets. Also I plan to ditch the original 2V intake in favour of a 4V intake from a 351W HO. An edelbrock 600CFM 4-barrel will sit on top of the manifold.

Anyway, back to these heads... Looking at tables I have, these D8OE's don't seem any different from later plain-jane castings in terms of compression, valve size and port size. Are they really any "worse" than, say, the E5AE heads which I think are on my HO motor?

Thanks!

Lucas

[Jacob84]

Lucas, I have two 351w HO motors and now have a roller 351w in my truck. The D8 heads are terrible, small valves, big combustion chamber, small ports. I put a set of E7 heads on a stock 351w HO (replaced the stock D8s) and there was a noticeable increase in power. As far as stock heads go the E7 heads are plentiful. They came in trucks, vans, cars. I’ve heard from others that the E5s and E6s are not worth the time. Are they better than the D8s? Sure, but not much. If you’re looking for a cheap and small bump in power then I would find some E7 heads. They’re easy to find.

Now if you can, the GT40 heads are better. They came on Lightning F150s, Cobra mustangs, and very late 5.0s in Explorers and Mountaineers. They are decent heads too. Although some of them have problems with headers as the spark plug angle is different on a certain casting (GT40Ps? Someone correct me please) But if you get them off of a 5.0 you’ll have to drill out the holes for the head bolts because they’re bigger on a 351w

A step above that would be the C9 or D0 casting heads (1969-1970 pre smog). They are harder to find but are the best “stock” head. But you also have to keep in mind that you’ll need to put in hardened valve seats because we no longer have leaded fuel. Good heads though.

If one has the money, the absolute best thing to wake up a SBF is to throw a set of aftermarket heads on it. Dart, AFR, Trickflow, Edelbrock, etc. But then you’re looking at spending $1,200+ for heads.

Do you have the cam and lifters already? What are the specs on the cam card? Depending on what cam you have may sway what heads you want to look for to get the all around best performance. Your choice on carb size and intake is good, perfect for a mild 351w

[Gary Lewis]

Lucas, I have two 351w HO motors and now have a roller 351w in my truck. The D8 heads are terrible, small valves, big combustion chamber, small ports. I put a set of E7 heads on a stock 351w HO (replaced the stock D8s) and there was a noticeable increase in power. As far as stock heads go the E7 heads are plentiful. They came in trucks, vans, cars. I’ve heard from others that the E5s and E6s are not worth the time. Are they better than the D8s? Sure, but not much. If you’re looking for a cheap and small bump in power then I would find some E7 heads. They’re easy to find.

Now if you can, the GT40 heads are better. They came on Lightning F150s, Cobra mustangs, and very late 5.0s in Explorers and Mountaineers. They are decent heads too. Although some of them have problems with headers as the spark plug angle is different on a certain casting (GT40Ps? Someone correct me please) But if you get them off of a 5.0 you’ll have to drill out the holes for the head bolts because they’re bigger on a 351w

A step above that would be the C9 or D0 casting heads (1969-1970 pre smog). They are harder to find but are the best “stock” head. But you also have to keep in mind that you’ll need to put in hardened valve seats because we no longer have leaded fuel. Good heads though.

If one has the money, the absolute best thing to wake up a SBF is to throw a set of aftermarket heads on it. Dart, AFR, Trickflow, Edelbrock, etc. But then you’re looking at spending $1,200+ for heads.

Do you have the cam and lifters already? What are the specs on the cam card? Depending on what cam you have may sway what heads you want to look for to get the all around best performance. Your choice on carb size and intake is good, perfect for a mild 351w

Yes, D8's are the bottom of the curve. Anything earlier or later is typically better. I spent considerable time porting a pair of D8's and got very little gain. Hard to make a silk purse out of a sow's ear.

[Lima Delta]

Yes, D8's are the bottom of the curve. Anything earlier or later is typically better. I spent considerable time porting a pair of D8's and got very little gain. Hard to make a silk purse out of a sow's ear.

Ok, thanks guys. I guess I'll have a poke around for some different heads... I do know where I can find some pre-smog heads but they're bolted to a block sitting in the weeds in the open and looking pretty rough. I'm not sure what kind of condition they'd be in and buddy's firm on wanting $500 for the whole engine, which I thought was too much considering the whole thing is probably rusted solid.

Jacob, I haven't pulled the trigger yet but looking at the edelbrock 2182 cam and lifter set:

https://www.edelbrock.com/performer-plus-camshaft-kit-for-small-block-ford-351w-v8-2182.html

I've been going over a few different options. End goal is to have a motor that pulls and lasts while not spending more than needed. Seems like this cam will probably fit the bill and play nice with the stock parts and carb I plan to use, though I'm no expert. With my aged C6 and a 5000lb trailer behind it, I'm not doing more than 100kph on the highway anyway lol. Have you got any other suggestions for a good towing cam?

Cheers,

Lucas

[Lima Delta]

You know, I meant to ask...

I also have an '85 302 with EFI that I use for parts. Just guessing with the use of a table here, but do you all figure the heads should be E5's on that engine?

Thanks again,

Lucas

 

[LARIAT 85]

Now if you can, the GT40 heads are better. They came on Lightning F150s, Cobra mustangs, and very late 5.0s in Explorers and Mountaineers. They are decent heads too. Although some of them have problems with headers as the spark plug angle is different on a certain casting (GT40Ps? Someone correct me please) But if you get them off of a 5.0 you’ll have to drill out the holes for the head bolts because they’re bigger on a 351w

E7 heads came stock on the 1987 - 1996 Ford F150 (5.0/302 AND 5.8/351 engine).

The 1987 - 1993 Ford Mustang GT (5.0/302) used the same heads.

GT40 heads came stock on 1993 - 1995 Ford F150 Lightning (5.8/351 engine). These had smaller chambers and bigger valves than the E7 heads.

The 1993 Mustang Cobra (5.0/302 engine) used the same heads.

The 1996 and early 1997 Ford Explorers (5.0/302) also used the GT40 heads, but the later 1997 - 2000 Ford Explorer (5.0/302) used the GT40P heads. The GT40P heads used the same size valves as the earlier E7 heads for better emissions and low-end torque. Because of the unusual spark plug angle, the GT40P heads require special headers.

For a larger 5.8/351 truck build, I would definitely recommend the GT40 heads.

But for a 5.0/302 truck build, I think the E7 heads are the better choice because they will give you a better low end. The GT40 heads will give you better top end power, but at the expense of low end torque.

 

[Rusty_S85]

Now if you can, the GT40 heads are better. They came on Lightning F150s, Cobra mustangs, and very late 5.0s in Explorers and Mountaineers. They are decent heads too. Although some of them have problems with headers as the spark plug angle is different on a certain casting (GT40Ps? Someone correct me please) But if you get them off of a 5.0 you’ll have to drill out the holes for the head bolts because they’re bigger on a 351w

E7 heads came stock on the 1987 - 1996 Ford F150 (5.0/302 AND 5.8/351 engine).

The 1987 - 1993 Ford Mustang GT (5.0/302) used the same heads.

GT40 heads came stock on 1993 - 1995 Ford F150 Lightning (5.8/351 engine). These had smaller chambers and bigger valves than the E7 heads.

The 1993 Mustang Cobra (5.0/302 engine) used the same heads.

The 1996 and early 1997 Ford Explorers (5.0/302) also used the GT40 heads, but the later 1997 - 2000 Ford Explorer (5.0/302) used the GT40P heads. The GT40P heads used the same size valves as the earlier E7 heads for better emissions and low-end torque. Because of the unusual spark plug angle, the GT40P heads require special headers.

For a larger 5.8/351 truck build, I would definitely recommend the GT40 heads.

But for a 5.0/302 truck build, I think the E7 heads are the better choice because they will give you a better low end. The GT40 heads will give you better top end power, but at the expense of low end torque.

I think the GT40 heads would be good cause they were on the 5.0L explorers with the F4TE explorer cam. I was going to go this route but then I couldnt locate a NOS or Ford stock of F4TE cams when I called ford and searched online I ended up going aftermarket on the roller cam for my build and decided to get away from the GT40 heads and went with AFR heads that are considerably better.

But for a stock rebuild GT40 heads or if you can find a pair of the old Windsor Jr cast iron heads from World Products those were very similar to the GT40 heads.

[LARIAT 85]

I think the GT40 heads would be good cause they were on the 5.0L explorers with the F4TE explorer cam.

They would be good if you wanted to get more top-end power from your truck. If you wanted a more streetable truck with better bottom-end torque, the E7 heads paired with the F4TE cam would be the better choice.

Every time I have seen someone (on the forums) with the 5.0/302 engine replace their stock heads with the GT40 heads on a full size pickup truck, they have always complained that they lost some bottom end power. Every time. It is very disappointing when you go through all that trouble only to be slower off the line than you were to begin with.

[Rembrant]

Every time I have seen someone (on the forums) with the 5.0/302 engine replace their stock heads with the GT40 heads on a full size pickup truck, they have always complained that they lost some bottom end power. Every time. It is very disappointing when you go through all that trouble only to be slower off the line than you were to begin with.

I'm one of the people with GT40 heads on a 302 and I had the whole engine professionally built and dyno tuned by a performance shop. I've never complained of losing low end power, but I have complained that I didn't gain as much low end power as I wanted to. I would say that the people that complain of losing power are people that didn't gain much power. This stuff is a bit difficult to discuss (or debate) because the majority of people don't actually measure anything.

I personally went with GT40 heads because they were the best bang for the buck for performance heads. The GT40P's are more plentiful, but as noted they're problematic due to the spark plug angles, and aftermarket aluminum heads were just too expensive and too much overkill for what I was going to be doing with the truck.

My only disappointment is that I spent too much money on my 302. I should have left it much closer to stock, or if I was going to spend all that money I should have just replaced it with a 351. Hindsight is 20/20, so this is how it goes. We learn by doing.

But back to the original question of a good budget head for a 351, my personal recommendation would be for a set of E7's. They're plentiful and cheap, and they're significantly better than the 70's-80's D8 heads. Just swapping on a set of E7 heads along would bump compression from 8.3 to almost 9:0 which in itself is a nice boost. D8 chambers are like 69cc, and the E7's are more like 61cc. I wouldn't bother with the E5 or E6 heads...I don't think there's much benefit with them considering they were only available for a year or two and were followed by the E7's that were in every SBF for almost a decade.

I personally wouldn't bother with GT40 or GT40P heads. If you can get some pre-D8 heads they may be a good option. I personally prefer the D8 and later cylinder heads for the simplicity of the pedestal rockers.

That's all. My 2 cents worth.

 

[Lima Delta]

Every time I have seen someone (on the forums) with the 5.0/302 engine replace their stock heads with the GT40 heads on a full size pickup truck, they have always complained that they lost some bottom end power. Every time. It is very disappointing when you go through all that trouble only to be slower off the line than you were to begin with.

I'm one of the people with GT40 heads on a 302 and I had the whole engine professionally built and dyno tuned by a performance shop. I've never complained of losing low end power, but I have complained that I didn't gain as much low end power as I wanted to. I would say that the people that complain of losing power are people that didn't gain much power. This stuff is a bit difficult to discuss (or debate) because the majority of people don't actually measure anything.

I personally went with GT40 heads because they were the best bang for the buck for performance heads. The GT40P's are more plentiful, but as noted they're problematic due to the spark plug angles, and aftermarket aluminum heads were just too expensive and too much overkill for what I was going to be doing with the truck.

My only disappointment is that I spent too much money on my 302. I should have left it much closer to stock, or if I was going to spend all that money I should have just replaced it with a 351. Hindsight is 20/20, so this is how it goes. We learn by doing.

But back to the original question of a good budget head for a 351, my personal recommendation would be for a set of E7's. They're plentiful and cheap, and they're significantly better than the 70's-80's D8 heads. Just swapping on a set of E7 heads along would bump compression from 8.3 to almost 9:0 which in itself is a nice boost. D8 chambers are like 69cc, and the E7's are more like 61cc. I wouldn't bother with the E5 or E6 heads...I don't think there's much benefit with them considering they were only available for a year or two and were followed by the E7's that were in every SBF for almost a decade.

I personally wouldn't bother with GT40 or GT40P heads. If you can get some pre-D8 heads they may be a good option. I personally prefer the D8 and later cylinder heads for the simplicity of the pedestal rockers.

That's all. My 2 cents worth.

Thanks for all the replies guys.

I had suspected the GT40 heads were not really what I was after here, but it's good to hear some other experiences that support that.

Rembrant, thanks for sharing your story re the cost of your engine build. Cost is something I'm trying really hard to control, but it's so easy to start going of the rails with things I don't really need. I think I'll try to find some E7 heads though. Unfortunate in a sense cause these D8 heads are in really nice condition.

Cheers,

Lucas