Versatility with 351w heads

[haugy]

Well I can't just ask any motorheads as they wouldn't understand boat engine requirements.

But does anyone know if you can put aftermarket heads on the 351w's and still have the PCM exhaust manifolds bolt up properly? I would assume they all have the same bolt and flow pattern, but wanted to know if anyone has done this.

I've got a buddy with a Comp who wants to modify his engine a bit for more power. I warned him against this, but I'm not sure I'm right. He thought about GT-40 heads but they aren't as easy to find as aftermarket custom heads. Plus I think he wants to do more than that so I imagine these heads will be spec'd to suit the motor changes.

But can PCM manifolds bolt up to any heads? I know 351w's come with two different deck heights, but the heads are all the same right? I'm really curious as I've got the 351w from my old Comp in my Jeep, and I bolted up aftermarket headers to it with ZERO problems. This could be good info as I'd like to push that motor harder as well. :D

[92SupraComp]

Go for gt40P's. Better than GT40's. And if he has the HO in his comp he already has GT40 heads unless he blew them up.

Venture over to CCfan and see the engine builds they do. $5,000 engine builds are common with those guys! They buy the Hi-Tek Stainless headers ($2,100), GT40P heads (about $500~$600)(then have the heads shaved down for more compression), sometimes 1.7:1 roller rockers, Edelbrock Proformer RPM intake ($200) (would advise against it as you lose the low-end hole shot power, go for the proformer), Custom Roller Comp Cam, Retro Fit Roller Lifters, sometimes a whole new rotating bottom end (there is 409CUI Windsor build on there, most do a small bore of .0030) , D.U.I. dizzy, 650 CFM Mechanical Secondary Carbs, etc etc.... They are up in the 320+HP range after all that...

Oh and yes, any 351W head will bolt right up with the PCM manifolds, just like any other motor, all the heads have same bolt patterns for the same motor...

[crystal waters]

About a year ago there was a similar post where the respondent came back to say to look into Dart Heads.
Claimed they were a lot less money and produced better results than the GT 40 heads.
Thought I would throw this back out there Haugy .
Good luck

[haugy]

Thanks guys, yeah some of the CC boys also mentioned GT-40P heads for real oomph. I'll look into the Dart heads too, I've seen those run before on other vehicles, seem to work well.

[chris young]

One thing I'd add here. Regardless of which heads you choose, you want to know that the bottom end is good before you do anything. I've heard of several cases, and experienced it once for myself, that if you slap a set of fresh heads on an older motor, you can end up with more compression than the bottom end can handle. In my case it was just a tired Ford 2.3, and the head was cracked, so I put a fresh rebuilt head on it, and within a few months (IIRC) the compression was so low the motor wouldn't start.

[cadunkle]

I am not aware of any different exhaust ports or any significant alterations on port height on small block heads. Personally I wouldn't bother with any factory iron small block heads these days as aluminum heads are cheap around a grand. My cutoff on putting time and money into factory parts is generally around half the cost of new/better parts. Not sure which flow the best as I haven't done a small block in years.

[blackstang]

I am not aware of any different exhaust ports or any significant alterations on port height on small block heads. Personally I wouldn't bother with any factory iron small block heads these days as aluminum heads are cheap around a grand. My cutoff on putting time and money into factory parts is generally around half the cost of new/better parts. Not sure which flow the best as I haven't done a small block in years.

Will the GT40P heads cause plug interference with the manifolds? I've done tons of "P" heads on fox mustangs but I am not familiar with the marine manifolds. I am assuming since they go up you would still have plenty of clearance even with the revised plug angle of the "P' heads?

[92SupraComp]

Thats on mustang. Not PCM manifolds... There is a reason why people buy aluminum GT40P heads for $500 NEW(per Pair!) on ebay for their boats...

[Cusefan78]

Haugy just saw these two ads
http://rochester.craigslist.org/pts/4510272740.html

http://elmira.craigslist.org/pts/4440503440.html

Both of these are close to me.

Supracomp. I'm surprise after all that work they are only getting 320. My stock gt40 proboss mpi gets 320 stock. I will say that 320 is more then enough for me. The hole shot and acceleration all the way through the band is unreal.

[dirtydawg]

I bought gt 40's from Michigan Motorz, they have the "3 line" stamping on the ends but mine a cast iron. I 'm not sure if they are correct but they told me gt 40p heads are for newer fuel injected models. I was a little disappointed they weren't aluminum, but now my engine runs noticeably better than stock.

[92SupraComp]

Sorry, but you are at 310HP RATED from PCM. NO TESTING WAS EVER DONE. PCM does NOT have actual dyno numbers, they literally pulled them out of air and rated the motors. The older 351W with 1:1 and 1.52:1 trannys were rated 230HP. Then with the angled 1.23:1 because of the level motor and now 10* base timing instead of 6* the exact same motor was rated at 240 HP. THen they released the HO model which was rated in the 260's or 270's range.. Then my model, PCM 5.8 HO Pro Boss Pro Tec ignition RATED @ 285HP. Then they came out with Throttle Body Injection which was PCM 5.8 HO Pro Boss EFI RATED @ 320HP, that ended QUICK because the TBI was not good... Then came the PCM 5.8 GT40 EFI MPI RATED @ 310HP...

None of these CC guys have Dyno'd their motors yet but they RATING them at 320HP+ and they pull MUCH harder than the RATED 310HP GT40 MPI engines... I do a lot of reading and try to make sure I understand things correctly, but please, if I am wrong, CORRECT ME! :)

[Blackntan90]

I have the 351/1:23.1 PCM combo in my Mariah. While you and the book say it is 240 hp, I cannot win a tug of war with it ever! I would love more top end though...without losing hole shot!

[haugy]

My buddy, who I'm trying to get join in here, said his comp was feeling very tired, 86 Comp with some 1,000+ hours. So he's redoing stringers, but really wanted more power while he's at it.

He's looking at stroking it, putting GT-40P heads, new intake, and a 750cfm marine carb on it. That ought to pep it up a bit, by our estimates up to 400hp. On my 351w I think I may go the same route. But with my exhaust manifolds (headers) they are custom made, so I needed heads that match up exactly like factory 1989 351w heads that are non GT-40. I think from what I read I should be able to up the power quite a bit. My concern is bottom end. But since my engine has a 4-bolt main, I think if I stroke it, put a girdle on it, and don't go overboard on the heads, the bottom end with a forged crank should hold together for what I use it for.

He's wanting a monster power ski-boat. But I warned him about long hard high rpms that these boats see. He's a barefooter so he wants some serious speed and power from it.

[92SupraComp]

Any ford 351W or even 289/302W head will bolt right up... They are drop in replacements for a reason...

Also, we have easily 1,500+ hours on the Comp and its missing the GT40 heads, still runs strong. Never rebuilt. Just oil changes, rebuilt the carb once, and leave the electronic ignition alone...

[Jetlink]

My buddy, who I'm trying to get join in here, said his comp was feeling very tired, 86 Comp with some 1,000+ hours. So he's redoing stringers, but really wanted more power while he's at it. He's wanting a monster power ski-boat. But I warned him about long hard high rpms that these boats see. He's a barefooter so he wants some serious speed and power from it.

Is he wanting to pull down trees or a house? Go god man!!!

[blackstang]

If he's going to stroke it I suggest going with a much better head than the GT40P. If he's worried about going with aluminum heads, he could get the Dart Iron Eagle series head that will way out perform the GT40P. The GT40P head is a great budget series head, but will not provide the airflow to achieve maximum benefits from a 351 based stroker motor. Heck if he wanted a budget aluminum head you can get the Procomp head for pretty cheap. I've seen many of those perform out of the box well on 351 based motor in Fox Mustangs. They are not my first choice of a cylinder head but if looking for decent power on a budget they would be better than GT40P.

[haugy]

I thought the GT-40P heads were supposed to be way better than stock and GT-40. I'm clueless and I've never tried any of the other heads or done much reading up on them. If they worked, great. He's on a budget but from what I can tell he'll up the ante for good parts.

But from what I can tell, building up the bottom end with good crank, pistons, rods, etc is all good for solid power. But the wrong heads and intake can kill all that effort and $$$.

[92SupraComp]

Yes the the GT40P heads are a little better than the GT40 heads and far better than the stock heads... The biggest thing is, the stock heads, are complete SHIT! They truly are awful heads that should never have been made... Thats the thing, it doesn't matter what brand, US or china head, the 351W will perform heaps better with any other head that even remotely flows more than the stock ones... Thats why people are happy with just GT40P's. It a HUGE upgrade from the crap heads... The 351W has MUCH potential but ford never bothered... The cheapest Edelbrock heads flow far better the GT40P's. But if you go look at the numbers, the huge gap between the Edelbrock and GT40P heads is just as big as a gap between the stock heads and the GT40P heads, they are that bad...

[haugy]

Wow, didn't know that. Damn, and I've been running stock heads on my 351w from my Comp on my rockcrawler for almost a decade now. :D :D Seemed peppy enough. HA!!!

[blackstang]

I thought the GT-40P heads were supposed to be way better than stock and GT-40. I'm clueless and I've never tried any of the other heads or done much reading up on them. If they worked, great. He's on a budget but from what I can tell he'll up the ante for good parts.

But from what I can tell, building up the bottom end with good crank, pistons, rods, etc is all good for solid power. But the wrong heads and intake can kill all that effort and $$$.

GT40 heads are often confused. GT0 iron heads came on everything from the Cobra Mustang 93-95, first gen Lightning trucks and 95-early 96 Explorer. By late 96 the Explorer GT40 head was revised to the "P" head for emissions reasons according to Ford. The main difference being revised plug angle (PITA) to get to number 5 on a Mustang with shorty headers and a slightly smaller combustion chamber.

They also made/make many different versions of the GT40 head in aluminum that were available through Ford Racing over the years.