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Discussion Starter #1
Hi all,

I've been thinking that I might get some GT40P heads for my 302. The 302 is from 1980 Ford, bored 0.060" over and my Mustang is a '66 coupe. What should I be looking for (and not looking for) when checking out some heads from an online place like craigslist.

Thanks!
 

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They seem to hold up well for the most part. Ideally you would want to get them off a running motor. Short of that I would pick a set that looks like they came off a well cared motor. Frequent oil changes with no sludge. These motors will easily run 300K miles. I would say you could just bolt them on as is. I’d probably do that.
 

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With any used parts choice you're taking a risk. If I was going to look for a set of "P" heads I'd probably try to score the complete "P" engine, knowing that the heads hadn't been pulled, checked, found to be crap and then eBayed. Other choices would be heads accompanied by a machine shop's bill of goods showing work done to some degree. As a minimum I'd like to see a set of "loose" heads that had been magnafluxed and, perhaps, had the valve guide clearance checked.

To be safe, build into your desired acquisition cost the cost to replace the guides with new press-in ones and to replace the valve springs if you plan on any cam more "radical" than an "RV" cam and a 5,000 rpm redline.

If you think you're up to a little "DIY" porting and port matching then scrap the GT40P's and put the money into your existing heads. Yeah, you'll need to consider milling them to reduce the combustion chamber size and installing some larger valves but you already own them.

Of course, the big question is "what are you looking for" as far as performance is considered? Yes, heads, particularly the exhaust-side are the big "bottleneck" on the SBF, but how does the rest of your motor factor? What pistons (style/compression height) are currently installed? Are you looking for more power production at higher rpms or more low-end "grunt"?
 

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Discussion Starter #4 (Edited)
@Woodchuck,

If I bought used then the idea would be to take them to a machine shop/mechanic and rebuild the heads entirely.

As far as what I'm thinkin? My 302 is from a 1980 Ford (don't know what), was bored 0.060" over so its more like a 311ci. It has an Eldebrock Torker II intake, Holley Street Avenger 670cfm 4 barrel carb, long headers. This was all done by the previous owner. I'm told that the currnet heads came off a later model 90s mustang and has upgraded springs, and that the cam has something like a 276 duration with a 490 lift and that the cam is "flat tappet hydraulic lifters hydraulic cam" (direct quote from text messages).

What I'm looking for is a bit more power, especially on the low end (like taking off and such); but I'm down for just more power in general, as I love that V8 sound and power. Not sure what kind of HP I'm at now, but am most likely losing a lot with the C4 (recently rebuilt) and the rear end (3.73). Also, its currently I just drive it around on the weekends and such, not doing any sort of racing or crazy stuff other than the occasional burnout every now & then - which is hella fun.

Mechanically, about the only thing original on the car is the C4, and that I had rebuilt back in Aug/Sept; so I'm not at all concerned about originality. Just wanting to have a somewhat badass muscle car from the original muscle car days. I've always loved the pony cars.

I'm not sure how much I believe the previous owner about the heads though.
 

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My 302 came out of a 79 f150, was bored 40 over and had a comp 268H cam in it.
I got a pair of gt40p heads from a local junk yard off a 99 explorer for $160. The only problem with them was one broken bolt that had to be extracted.
I got a set of upgraded valve springs from Alex’s parts. Which is a must for anything more than a stock cam.
I also did some light port work.
 

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Discussion Starter #6
My 302 came out of a 79 f150, was bored 40 over and had a comp 268H cam in it.
I got a pair of gt40p heads from a local junk yard off a 99 explorer for $160. The only problem with them was one broken bolt that had to be extracted.
I got a set of upgraded valve springs from Alex’s parts. Which is a must for anything more than a stock cam.
I also did some light port work.
how's it running with the gt40p heads?
 

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Well, the C4 is one of the more efficient automatics as far as parasitic loss is concerned and if you're running an 8-inch rear, which it sounds like from the gear ratio selection then they're not bad either. If you're planning on a complete head rebuild anyway then you could stretch it a bit and pick up some AFR165's and be WAY ahead of the game. If your heads ARE from a late '90's Mustang (E5/E7TE's) then a swap to GT40P's is, at best, going to net you maybe 25-30hp for all the expense. You can probably get pretty close to that in a porting/port-matching of the existing heads... maybe a bit more if you want to get more aggressive with valve sizes and material removal.
 

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My 302 came out of a 79 f150, was bored 40 over and had a comp 268H cam in it.
I got a pair of gt40p heads from a local junk yard off a 99 explorer for $160. The only problem with them was one broken bolt that had to be extracted.
I got a set of upgraded valve springs from Alex’s parts. Which is a must for anything more than a stock cam.
I also did some light port work.
how's it running with the gt40p heads?
Hasn’t ran yet.
It currently sits on the test stand awaiting finishing touches and some assistance from my neighbor.
 

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Discussion Starter #10
So this is on my current heads. This picture was taken of the driver's side head. These numbers face the radiator. I'm not sure what the number "3" that is engraved on the head means, if anything.
 

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Put the Axel’s springs in. Don’t waste your time port matching or porting.

Tooslow86 used a 100k motor that the heads were never off, custom cam and springs

 

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Discussion Starter #13
just pulled the valve covers off, this wasn't what I was expecting. I'd read that there's a "302" or "289" stamped into the heads, but that didn't seem to be the case here.

there's a "7F6" and "L6135" and a "78" and a "CP" or "CCP" and a "4" stamped into the heads. Anyone got any idea as to info regarding this? If it helps, the pictures below are from the head on the driver's side.

Attached are some pics.
 

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That's a Cleveland Foundry logo on the head and the date code would indicate casting on June 6th of what I'd guess, with what appear to be screw-in studs (can you see threads going into the bosses?), would be 1977. What I also see are head bolt WASHERS. To my knowledge, the factory didn't use them so either these are 351 heads with washers to accommodate the 1/2" holes in the heads and 7/16" studs or somebody put an aftermarket bolt kit on. The key is going to lie in the casting number, which is going to be on the UNDERSIDE of the head between the intake runners.

The reason I don't think these are '87 heads is that they used pedestal mounted sled rockers retained by a bolt.
 

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Discussion Starter #15
hey @Woodchuck

here's what I've found on the date and the "4", does this make sense?

7F6 breakdown

7 = year. 67, 77, 87, 97 <-- one of those possibilities
F = month. A=Jan, B=Feb, C=Mar, D=Apr, E=May, F=June
6 = day of month.

So year ending in 7, June 6th.

The 4 means 351Cleveland 4V heads.


Not sure what the "78" means, and it appears that the wheel of "L6135" is actually a wheel of "13579"

I didn't know 351C heads would work on 302 (never even thought about it).
 

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hey @Woodchuck

here's what I've found on the date and the "4", does this make sense?

7F6 breakdown

7 = year. 67, 77, 87, 97 <-- one of those possibilities
F = month. A=Jan, B=Feb, C=Mar, D=Apr, E=May, F=June
6 = day of month.

So year ending in 7, June 6th.

The 4 means 351Cleveland 4V heads.


Not sure what the "78" means, and it appears that the wheel of "L6135" is actually a wheel of "13579"

I didn't know 351C heads would work on 302 (never even thought about it).
Not a 351 Cleveland head per say Just a Windsor style head just cast at the Cleveland foundry fairly common
 

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Discussion Starter #17
Not a 351 Cleveland head per say Just a Windsor style head just cast at the Cleveland foundry fairly common

Ahh ok, that's my bad.

So at least is it safe to say that these are 351 heads?
 

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cylinderheads

rdu, I wouldn't buy any new heads just yet. Yes, those have to come off, or at least the rockers have to be swapped. You have no pushrod guideplates and your rockers don't have tip guides, and you have to have 1 or the other. If you take the intake off, we can tell you whether you have the good 351 heads by the water passage shape. And your TII intake should come off anyway. If you want 'grunt' get a Weiand Warrior 8124 intake. LSG
 

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Discussion Starter #19
rdu, I wouldn't buy any new heads just yet. Yes, those have to come off, or at least the rockers have to be swapped. You have no pushrod guideplates and your rockers don't have tip guides, and you have to have 1 or the other. If you take the intake off, we can tell you whether you have the good 351 heads by the water passage shape. And your TII intake should come off anyway. If you want 'grunt' get a Weiand Warrior 8124 intake. LSG

@LSG,

Thanks, but a few questions. Why do I have to have either the pushrod guideplates or rocker tip guides? Is the lack of either of those two going to cause me an issue? Would it be worth it to get both of those?

Also, why do you say that about the TII intake? Is that not a good intake?
 

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the rocker could fall of the valve tip without one or the other ,guide plate or rail type rockers
The Torker II is kind of an oxymoron .single plane intakes are not really designed to make down low torque although some seem to work well with fuel injection
 
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