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Would I notice a big difference with GT40 heads?

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Old 09-09-2009, 03:34 PM   #1
scootchu
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Default Would I notice a big difference with GT40 heads?

My 302 has 2V heads on it presently and although it runs well I am considering buying another block to rebuild over the winter, provided I can get things sorted out in my head as to what I want.

So while waiting for the guy with the 302 block and complete 302 engine to get back to me, I saw he has a set of DOOE 351W heads for sale.

Also another CL-er has a set of GT40 heads nearby.

Would either of these heads make a noticable difference.
I am not sure of the chamber size on the 2V 302 heads, but I know it's larger than the 4V heads correct.

Both sets are complete.
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Old 09-09-2009, 04:20 PM   #2
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I have the 289 on my engine stand i took out of my mustang.
I had done several things to it. GT 40 heads a new cam, eldel rmp intake, 625 carb and malory ignition. Bored 30 over it all wored well together it Felt like a big improvement.

Now that said the new crop of aftermarket heads are the way to go.
I have afr 185 on my 347 but doing another I would go with the new edelbrock.

The gt 40 is a improvement but not as much as the alu heads out now.
My guess if I took everything except the paxton off my 347 and put it on the 289 it would
be like 2- 289s compared to the way it sits now.
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Old 09-09-2009, 04:26 PM   #3
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The 289/302 heads varied in combustion chamber size, but it was due to the year, not the carb size. The only year for a unique 302 4V head, in fact the only year Ford even MADE a 302 4V was 1968. 289 2V and 4V had identical heads, no difference in part number or construction. The 289 4V and 302 4V had higher compression than the 2V because they used flat-top pistons.

You can get much of the advantage of the GT40 heads by porting your 302 heads. The exhaust was the weakest link in the stock heads, even the 289HP heads flowed no better than 2V without porting. I have mine ported, and the difference was immediate and very noticeable.

The GT40 is the 5.0 version of the 351W head. The combustion chamber is larger, though, to account for the 351 displacement. You'll lose compression ratio if you use them with your 302 pistons.

There is a lot of potential for porting the stock 289/302 head. Crane used to turn service replacement Ford heads into "Fireball" heads by porting them. The exhaust ports were so large they required special headers:


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Old 09-09-2009, 05:14 PM   #4
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here's the skinny.....

the gt40 heads are very close to the early 351w heads, but the gt40 heads are better in stock form.

the 351w heads would be a great buy if they are cheap, because you'll have to pay to get hard exhaust seats installed along with whatever other machine work you have done to them. I'd recommend having .010-.020 milled off either set of heads to help drop the chamber size.

point of reference: my 289 that is zero decked with speed pro lyper flat tops (4 valve reliefs) and milled 351w heads (about 60cc) makes between 8.5-9.0:1. getting pistons that were only 2 valve reliefs would have bumped me between 9.0-9.5:1
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Old 09-09-2009, 05:42 PM   #5
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Holy Moly. My head starts to spin, but I appreciate the feedback. The 351 heads have an asking price of $200. The GT40's have an asking price of $195. My gut feeling was steering me towards the GT40's having read that I could have to sink some dough into the 351's. The 40's seemed as you guys said be better in stock form. I would love to go the AFR route, but man they are expensive. I have a problem parting with large chunks of cash. I like bang for the buck.

I haven't had the heads off of this engine yet and I doubt that they have had any work done to them at all.
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Old 09-09-2009, 06:03 PM   #6
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Quote:
Originally Posted by scootchu View Post
Holy Moly. My head starts to spin, but I appreciate the feedback. The 351 heads have an asking price of $200. The GT40's have an asking price of $195. My gut feeling was steering me towards the GT40's having read that I could have to sink some dough into the 351's. The 40's seemed as you guys said be better in stock form. I would love to go the AFR route, but man they are expensive. I have a problem parting with large chunks of cash. I like bang for the buck.

I haven't had the heads off of this engine yet and I doubt that they have had any work done to them at all.
For a couple hundred you should be able to get your heads port matched to headers or HiPo manifolds. This would give you your most bang for the buck.

Of course, if they need to be rebuilt, with seats, guides, etc., you may as well get the GT40s and have them rebuilt.
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Old 09-09-2009, 07:17 PM   #7
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I'd jump on the GT40's. Add in the cost of a valve job and resurface (200-300 depending on the shop) and you should be into your heads for 4 to 5 bills.

Btw, if they are GT40P heads, your gonna need headers that will fit because the spark plug is at a different angle. Also just for the info, the P's have smaller exhaust valves than the regular 40's.
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Old 09-09-2009, 07:42 PM   #8
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Is the larger chamber size going to knock the comp ratio down?
I know my engine is 68,69,70 era. The 68 2V heads were 63cc and the 69-76 were 58.2cc

The Cast Iron GT 40 are 65cc or so.
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Old 09-09-2009, 07:50 PM   #9
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Oh crap maybe I should just go and buy these.
Click the image to open in full size.
Guy is asking $1200. Says they are new and the springs have been upgraded to Pac racing beehives.
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Old 09-09-2009, 08:18 PM   #10
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I heard that there are two different sets of GT 40 heads you gotta watch out for though, one you can put most regular headers on to and the other you gotta have a specific header to those heads or it won't work. Is this true?

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Old 09-09-2009, 08:41 PM   #11
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I heard that there are two different sets of GT 40 heads you gotta watch out for though, one you can put most regular headers on to and the other you gotta have a specific header to those heads or it won't work. Is this true?

Lynn
Yep. The GT40 is interchangeable with the 289/302 head. The GT40P has a unique plug angle, where the plugs stick almost straight out, and would hit most manifolds and headers.
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Old 09-09-2009, 08:53 PM   #12
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For $1200, I'd go with the AFR's.

If that falls through, PM me and I'll let you know how to get a good deal on a set of Trick Flows. I just put a set on my 331 and I love them
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Old 09-09-2009, 09:00 PM   #13
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Bang for your buck? Slap leather and get aluminum heads-don't forget a good cam.

That's bang for the buck.
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Old 09-09-2009, 09:43 PM   #14
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Quote:
Originally Posted by LynnBob Mustang View Post
I heard that there are two different sets of GT 40 heads you gotta watch out for though, one you can put most regular headers on to and the other you gotta have a specific header to those heads or it won't work. Is this true?

Lynn
Yep the GT40p's are the ones you heard about. These are the run of the mill GT40's.
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Old 09-09-2009, 09:54 PM   #15
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trick flows are the best bang for the buck, even with 202 160 valves they work great on small displacements as the int ports are smaller than most 202 valved heads so to keep up velocity yet the int valve is closer to the intake mani giving larger cross section area thus flowing like a larger head, at low and mid lift theres not many heads made that flow like a TW, also with the rotated int valve they give better PV clearance than ANY 202 valved head. Will make more power than an AFR 165 in almost all cases and will be maybe 5-8hp less (peak) than an afr 185 on a compatible engine but much more low end TQ.
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Old 09-10-2009, 12:36 AM   #16
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also keep in mind the gt40s will not need bolt bushings for the head bolts the 351ws will
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Old 09-10-2009, 05:50 AM   #17
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Quote:
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Yep the GT40p's are the ones you heard about. These are the run of the mill GT40's.
The '65 I'm looking at will be coming with a '95 5.0 and GT 40 heads with a Cobra R intake set up on it, how do I know if I got the GT 40p heads?
What do I look for so I know what headers to get that will fit?
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Old 09-10-2009, 09:46 AM   #18
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Quote:
Originally Posted by LynnBob Mustang View Post
The '65 I'm looking at will be coming with a '95 5.0 and GT 40 heads with a Cobra R intake set up on it, how do I know if I got the GT 40p heads?
What do I look for so I know what headers to get that will fit?
Lynn
I have read that besides the different plug angle the GT40's have "GT" stamped in them, GT40p's have "GTP" and the GT40's have 3 lines cast in the front of the and the P's have four.
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Old 09-10-2009, 09:53 AM   #19
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Now I am starting to wonder if I buy the complete 5.0 HO engine this guy has if I would be killing two birds with one stone.
It most likely has E7TE heads, which may be a decent byproduct of the sale. I know that they can't compare to aftermarket aluminum heads, but have read they can be worked into a decent head. Opinions?

I haven't ruled out spending money down the road, as I would like to build a 331 stroker over the winter and I need a decent block anyway, but I would like to play around with something for now.
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Old 09-10-2009, 10:26 AM   #20
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They can be worked into semi-decent heads, yes. I'm still not a big fan of putting money into stock heads, though. By the time you're done, you'll be pretty close to spending the same amount as you would on a set of aluminum heads.
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Old 09-10-2009, 10:26 AM
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