GT-40 Heads on stock 289

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chemeng

New Member

Feb 21, 2004

93

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0

Louisville, KY

Jul 14, 2005

#1

• Jul 14, 2005

• #1

I want to put a set of aluminum GT-40 heads on my (mostly) stock 289. Plan on putting a T-5 tranny and headers next week and figured it would be a good time to change the heads out.
Should I try to reuse my stock rocker arms and push rods? Will the same rocker arm studs from the hipo screw in studs fit these heads? It has a stock cam in it.
I could order all new stuff from Summit, but since this isn't a high horsepower application I didn't think I needed it. Just wanted to get the old gal to breathe a little better, she already has a 4 bbl Holley and Ford Racing aluminum intake on it.

BTW - I got the GT-40's cheap, one of those offers I couldn't refuse.

Any advice appreciated, MikeR

 

LMan

Founding Member

Aug 10, 2002

1,246

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Mom's basement

Jul 14, 2005

#2

• Jul 14, 2005

• #2

I would strongly recommend you not change heads without a cam change. Your stock cam is tiny and you will never see the potential of the heads and you will feel like you wasted your money. Heads and cam together!

 

gbarber

Member

Jan 26, 2004

158

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17

delaware, ohio

Jul 14, 2005

#3

• Jul 14, 2005

• #3

I put iron GT40's on my 289. I had to use longer pushrods for the GT40's.

 

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chemeng

New Member

Feb 21, 2004

93

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Louisville, KY

Jul 15, 2005

#4

• Jul 15, 2005

• #4

Thanks for the info. Does anyone have a cam recommendation? Would like a hydraulic with good idle. I'm not a speed demon, just want a little more pop in the motor.

 

LMan

Founding Member

Aug 10, 2002

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Mom's basement

Jul 15, 2005

#5

• Jul 15, 2005

• #5

well, Im not a cam expert, but since you dont want to have to fool with compression issues, or P2V clearances, and keep power brakes and so on....I think you are looking at a hyd flattappet cam around 212-220* with maybe ~.475 to .500 lift. But thats a SWAG....depends on what drivability requirements you have. With a T-5 going in, perhaps you want to be more aggressive and go longer in duration and lift.

This is where the cam vendors "help lines" come into play. Call Crane, Comp, Lunati, whoever's helpline, tell them what your goals are, and they will give you a recc. out of their product line. Compare a few reccs and you will be fine. You arent looking for an exotic, one-off cam, so this will be relatively simple for them.

See each vendors website for their "helpline" info.

 

302 coupe

Founding Member

Mar 2, 2000

1,952

3

36

Macon, Ga.

Jul 15, 2005

#6

• Jul 15, 2005

• #6

you'll have to run guide plates with those heads, so make sure you get hardened pushrods. You can reuse the rockers, so long as they're not the rail-type that have the lip that goes over the valve.

You could get a summit cam kit p# SUM-K3600, same as the edelbrock performer cam, for $80 with lifters. They have two other cams that are a little hotter for the same price.

 

WantaGT

Member

Jul 13, 2003

336

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ohio

Jul 15, 2005

#7

• Jul 15, 2005

• #7

watch combustion chambers also, depending on which heads you buy they vary from 58-64. With a stock pistons you'll lose close to a full point of compression. Although you will still feel gains, most of it will be negated by the loss of compression. Considering the stock cc's on alot of early 289's were 54, whichever head you buy you will lose compression. That's the problem I ran into when I was looking for heads. I ended up having Thumper port, polish and mill them. Higher flow PLUS more compression =

 

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65stang289

New Member

Mar 5, 2003

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Fort walton Beach FL.

Jul 16, 2005

#8

• Jul 16, 2005

• #8

In my car now I have a 214/224-dur at .472/.496 with stock springs. IT sounds good nice little lope it kicks in at 2500 RPMS and with you going to a stick this should be a nice came for you.