Cylinder head question

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

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.

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

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

Jacob84 wrote

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.

LARIAT 85 wrote

Jacob84 wrote

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.

Rusty_S85 wrote

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.

LARIAT 85 wrote

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

Lima Delta wrote

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

Lucas,

I'm one of those guys that got caught in the "upgrades" rabbit hole...lol. I removed a low mile nicely running 302 from my '84 F150 to simply replace all of the gaskets and seals and to clean it up and paint it. I was really only going to install a cam, 4bbl carb and intake, and a better flowing exhaust. I ended up having the block bored with new pistons, the GT40 heads, etc. I had the engine dyno tuned, but my main reason for that at the time was so that it was broken-in properly. Peak HP numbers were not my main concern at all.

GT40 heads are not so easy to find anymore, especially here in Canada. They were only in Mustang Cobras for a couple years, first gen Lightnings, and a small handful of the earlier built 5.0L Explorers. Not exactly a lot of these sitting in junkyards up here.

The factory E7 heads were thee go-to upgrade factory heads for many many years. The cost and availability of aluminum heads have more or less made the factory iron head swaps obsolete, unless you're on a budget (like I was). The E7's are still a good head, and still widely available. I found them locally, with ease, for $100 a set and sometimes less.

The problem (imho only) is that most "upgrades" for the small block Ford engines increase power from 3000-6000 RPM, and most people with trucks spend all of their time between 1500-3000 RPM. Of course you will see improvements all across the board, but the big gains are all in the higher RPM's. You will read reports about low end power gains and improvements, but just keep in mind that they are anecdotal stories.

My truck is just a cruiser and carries nothing but it's own light weight around. The engine works well, sounds great, and it looks awesome. I don't have any regrets per se, but if I were to do it again I'd almost leave the old D8 heads on there.

Lucas, sorry to get back to this thread so late. Been busy with work and putting a new third member in the rear end of the truck.

Anyways, the cam you chose looks good. It reminds me a lot of a stock 5.8 HO cam. There are some differences, I am no cam guru and won’t pretend to be one. I’m a big fan of a couple stock cams Ford produced that give a good bump in power and torque in a truck motor. For a flat tappet cam motor that’s going in a truck, with E7 heads, I’d put in the stock 5.8 HO cam. .444/.452 int/ext, duration at .050- 206/211, 115 degree LSA, intake lobe centerline 117, exhaust lobe centerline 113. Throw an adjustable timing set and advance the cam timing 2 degrees to get rid of the factory retard to bring that power right where we want it. That’s really all a 5.8 HO is. Same bottom end but better cam, 4V intake, and a Holley carb, no difference in other 5.8s of the time.

But that’s my bias towards it. Like I said, it looks a lot like the cam you picked out so I think you’d be happy either way. I wouldn’t think too hard on it, rather, my best recommendation would be to call your cam manufacturer of choice and ask them what you should run for your motor and desired goal. They know what they’re talking about. The calls are free and the advice is good 99% of the time.

I’m looking forward to what you build and how it goes so keep us updated. And ask more questions if you got them. You seem to be in good hands with info on the heads, I learned a little too!

Rembrant wrote

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.

That's a fair statement.

Rembrant wrote

The problem (imho only) is that most "upgrades" for the small block Ford engines increase power from 3000-6000 RPM, and most people with trucks spend all of their time between 1500-3000 RPM. Of course you will see improvements all across the board, but the big gains are all in the higher RPM's. You will read reports about low end power gains and improvements, but just keep in mind that they are anecdotal stories.

I concur.

Most people who upgrade their small block engines end up building a great engine that would work much better in a Mustang or a Fairmont rather than a full-size heavy truck.  For a better truck engine, heads with smaller valves will result in better low-lift numbers.  When you pair that with a high lift, short duration cam and a smaller carburetor, you can get good power with great low-end torque.

LARIAT 85 wrote

Rusty_S85 wrote

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.

Maybe, or like has been said already people were expecting more power than they received and was disappointed.  Ive been guilty of over expectations when it comes to power, years ago I always wanted to do 400 - 500 hp for my small blocks between my 302 and 351W but now I realize 300hp goal is a lot better as that would basically double what the engines had from the factory of 125 hp and 145 hp.

I personally went with the AFR Renegade 165cc heads for my 306 build as I wanted over all improvement over the GT40 heads and I also couldnt find a set locally and have them rebuilt for less money than the AFR`s cost me at $1800 on sale with upgraded 7/16" rocker studs and upgraded valve springs that AFR recommended as being a close match to the Crane recommended springs for my cam.

AFR Renegade 165 specs are below

1.900" Intake valve
1.600" Exhaust valve
58cc chamber
166cc intake port volume
68cc exhaust port volume
251cfm @ 28" water Intake @ 0.500" lift / 255cfm @ 28" water Intake @ 0.550" lift
208cfm @ 28" water Exhaust @ 0.500" lift / 212cfm @ 28" water Exhaust @ 0.550" lift

Then I went with a truck cam from Crane, it was their rebranded Xtreme line up now known as the TruckMax in OE roller format and the specs for that one is as follows

112* Lobe separation
107* Intake center line
216*/224* @ 0.050" lift
278*/286* adv.
0.520"/0.542" lift
5* advance ground into cam

Exhaust Open 49* BBDC
Exhaust Close 5* BTDC
Intake Open 1* BTDC
Intake Close 35* ABDC

For me the heads with the cam I picked should be a good match for low end and high end power.

Based off DD2000 with all the most accurate specs put in I am making more hp at 2,000 rpm than my smog 302 made peak.

RPM / HP / TRQ
2000 / 141 / 371
2500 / 181 / 381
3000 / 224 / 392
3500 / 267 / 401
4000 / 308 / 405
4500 / 343 / 400
5000 / 368 / 386
5500 / 382 / 364
6000 / 374 / 327

It does exceed my goal of 300hp and most of my driving will be highway driving after I move which will be between 65 and 75 mph which would be for me between 2,500 - 3,000 rpm and when I nail the throttle to pass someone I would still be making torque for another 1,500 rpm Ill still be building torque before it starts to drop off.

I really dont believe the GT40 heads would have really worked out that good for me with the cam I picked for my truck even if I tried to source some out to save some money.  Crane just doesnt offer a truck cam for daily driving in roller format smaller than the one I got.

When I get it all built and get my sniper dyno tuned I look forward to seeing what results I get to compare them to my DD2000 estimates.

This is a great thread and one that I've enjoyed learning from. Corey, I especially appreciated your comments about your 302 build. I have, in the past, been guilty of spending a lot of money on stuff that I either didn't really need or didn't get the results I was hoping for. I don't want to make that mistake when I rebuild my 351HO. In a couple of years, I'll pull that motor and rebuild it. I've not done a lot of looking, but would I be correct in saying that my engine is equipped with the D8 heads?  

I’ll check my SBF books tomorrow as I have some downtime to do some reading, but I think just about every 302 or 351 built from 1978 until about 1985 will have the low compression D8 heads. There were some real brief ones the E5 and E6, and then the E7’s showed up in 1987 and were on every regular 302 or 351 until the end of them in 1997. I’m not sure if the trucks got the E5 or E6 heads or if it was only the cars. I don’t know much about those ones, but I’ll check my books tomorrow.

Actually, my book was almost within arms reach lol. 351 heads see below. This book is not always 100% accurate, but it’s not too bad.

Rembrant wrote

The problem (imho only) is that most "upgrades" for the small block Ford engines increase power from 3000-6000 RPM, and most people with trucks spend all of their time between 1500-3000 RPM. Of course you will see improvements all across the board, but the big gains are all in the higher RPM's.


Rembrant,
I've noticed this. In researching my engine build, it seems that most marketing for aftermarket parts is directed at developing racing-type engines and not basic truck engines. I can see how easy it would be to get sucked into the "rabbit hole". I am interested in upgrades that may make the engine more reliable or durable, but I figure sticking to something close to a stock configuration is probably best for truck-type performance. I mean, Ford must have known something about how to put together a truck engine when they built these things in the first place lol.

Cheers,
Lucas

Jacob,
Where do you get your numbers for the Ford HO cam?
I've got quite a few SBF books and an '85 Ford engine manual here at home, but haven't ever come across any specific details about the HO engines.

Thanks for your interest in my project, I'm looking forward to seeing how it turns out too. The core I'm using is a plain vanilla 2V I pulled from an '82 F150. I just pulled all the pistons the other day but haven't measured anything yet. So far everything about the bottom end looks really good. The idea is to build it into a short block over winter then finish it off with the intake and other parts off my existing HO during the engine swap, maybe spring/summer. The old HO is still going pretty strong but starting to feel a bit tired - 35 years old and just over 300000km now.

Anyway, I'll make sure to post anything that might be of interest.

Cheers,
Lucas

A bit earlier Cory/Rembrant said "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."  And the "351" bit of that statement is my thinking as well.

There's just not a lot that can be done to any bore/stroke combo to gain low-end torque.  You can add compression, but doing much there then requires higher octane fuel and that is more expensive to operate.

However, more stroke gives you more mechanical advantage and increases the torque.  So, put a stroker kit in.  But, that's expensive so why not go with an engine that is already stroked?  In stock trim it won't cost any/much more to build and will give more torque.

The downside is it will probably use more fuel.  But will the lower cost to get more torque pay for the fuel?  I don't know, but it is a question that should be thought through.