Gt-40p Head Roller Rocker Conversion

Gibatheviking · Aug 16, 2013

Greetings

New Foxbody owner with a question. I am attempting to convert my convert my engine to a roller motor with using a mild stage 1 cam or the ford x cam. I've looked at the tfs springs TFS-2500100 http://www.summitracing.com/parts/TFS-2500100 as replacement springs however, my question was whether anyone has used the GT-40 heads with a roller convertion and used crane cams
http://www.summitracing.com/parts/crn-36655-16 5/16 to 3/8th stud conversion kit with any luck. I would use the car for small amount of racing but mostly a street car. I am on a tight budget and would prefer to avoid any machine work if possible.

Thanks

Chuckman · Aug 16, 2013

that stud conversion is probably a waste of money, why not just get a set of crane cobra pedestal roller rockers? http://www.summitracing.com/parts/crn-44746-16/overview/make/ford

you'd have to get new rockers anyway with the stud kit, and the studs wont be any stronger than the stock pedestals (both use 5/16-18 threads into the heads).

Gibatheviking · Aug 16, 2013

Chuckman said:
that stud conversion is probably a waste of money, why not just get a set of crane cobra pedestal roller rockers? http://www.summitracing.com/parts/crn-44746-16/overview/make/ford

you'd have to get new rockers anyway with the stud kit, and the studs wont be any stronger than the stock pedestals (both use 5/16-18 threads into the heads).

Would I have to worry about these backing out considering the roller cam setup and no poly locks?

Chuckman · Aug 17, 2013

theyre bolted through the pedestal just like the stockers, as long as theyre torqued right (22-25 ft/lbs) theyre fine......im assuming youve never actually been inside one of these motors, but when they say its a "roller motor," theyre talking about the lifters riding on the cam, and not the rockers (although obviously there are roller rockers too). there are some good stickies in the tech section to help get you more familiarized with what youre trying to do

Gibatheviking · Aug 17, 2013

Chuckman said:
theyre bolted through the pedestal just like the stockers, as long as theyre torqued right (22-25 ft/lbs) theyre fine......im assuming youve never actually been inside one of these motors, but when they say its a "roller motor," theyre talking about the lifters riding on the cam, and not the rockers (although obviously there are roller rockers too). there are some good stickies in the tech section to help get you more familiarized with what youre trying to do

I've assisted friends with a some work on the top end of engines such as blown head gasket etc. It is my first time going this far into an engine though (replacing cam and listers) I just figured with the change in the lifters, more pressure higher revs stronger springs would affect the rockers.

Thanks for the info

Gearbanger 101 · Aug 17, 2013

Pedestal rockers are what you want, not a stud mounted conversion like you have listed above. The GT40's use bolt down style rocker arms, just like stock. Stud mounted rocker arms are reserved for the high RPM crowd and for heads that require them like some of the higher end aluminum castings. Yours do not.

Also....think a little harder on your cam selection. There's a biiiig difference between a "mild Stage 1 cam and an X303 cam".

GT40 heads don't have the volume to support anything really big, so stick with something a little more sedate that'll retain lower torque figures and good street manners. You're on the right track with the springs though.

If you're on a budget, search around for a smaller used alphabet cam like a B303, E303, or a smaller comp XE264HR, etc. A nice lopey sounding bumpstick sounds cool and all, but if you don't have the rest of the top end parts to support the airflow they capable of making, you'll not reach near their potential and hurt low end power and streetabiity will suffer in the process.

jAEded · Aug 17, 2013

What about the shaft mount? Think its worth it or would the same apply as the stud conversion?

Gearbanger 101 · Aug 17, 2013

jAEded said:
What about the shaft mount? Think its worth it or would the same apply as the stud conversion?

Shaft mounted rockers are also designed for high RPM operation and would be worth more than your heads, cam and intake combined.

Why so resistant to the Pedestal Mounted rockers? I run them on my GT40X's with zero issues.

jAEded · Aug 17, 2013

Lol... Thats true. I'm only running the stock cam.

I'm not resistant to them. It just doesnt seem like the best design. I read somewhere, and I don't know if its true, but the pedestal were the easiest to assemble at the factory without messing up the preload?

Gearbanger 101 · Aug 17, 2013

jAEded said:
Lol... Thats true. I'm only running the stock cam.

I'm not resistant to them. It just doesnt seem like the best design. I read somewhere, and I don't know if its true, but the pedestal were the easiest to assemble at the factory without messing up the preload?

They're fine for your intents and purposes. I mean....GT40 heads are far from the best design, but you aren't that worried about running them are ya?

Don't spend too much time worrying about it. They're designed to be a simple, direct bolt on replacement rocker. You'll more than likely be able to use your stock pushrods to boot.

stykthyn · Aug 17, 2013

93-95 cobras came from the factory with pedestal mount roller rockers. Cannot be that bad of a design.

Chuckman · Aug 17, 2013

the only thing a stud-mounted rocker has over a pedestal (at least as far as this kind of power level goes) is some increased adjustability without additional parts (shims), and a tad more strength due to the larger o.d. of the stud (which is negated with the conversion since it still necks down from 3/8 to 5/16). the worst part of the stock system is the stamped rockers themselves, almost anything roller is a huge upgrade in both friction and stability.

you may be able to get by with stock pushrods, but dont be suprised if you have to go to the next longer size depending on which head gaskets and lifters you go with (i had to go to longer ones to get mine to not sound like a broken sewing machine, .060 over with a .030 shim under the pedestals iirc).

as far as a cam goes, the alphabet cams are old single-pattern designs, and there are much better off-the-shelf options. the comp xe264 mentioned above and the tfs stage 1 are popular, well documented options. the stock h.o. cam is also decent enough in its own right if youre on that severe of a budget.

Gt-40p Head Roller Rocker Conversion

Gibatheviking

New Member

Chuckman

GTFO you fat, heavy bastard

Gibatheviking

New Member

Chuckman

GTFO you fat, heavy bastard

Gibatheviking

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Gearbanger 101

Straight Outta Locash

jAEded

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Gearbanger 101

Straight Outta Locash

jAEded

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Gearbanger 101

Straight Outta Locash

stykthyn

I want to measure mine. It doesn't look that tall.

Chuckman

GTFO you fat, heavy bastard

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Gt-40p Head Roller Rocker Conversion

New Member

GTFO you fat, heavy bastard

New Member

GTFO you fat, heavy bastard

New Member

Straight Outta Locash

Active Member

Straight Outta Locash

Active Member

Straight Outta Locash

I want to measure mine. It doesn't look that tall.

GTFO you fat, heavy bastard

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