Gt40 heads

[Joshrabbitt14]

Im picking up some gt40 heads for cheap this weekend and I am going to replace everything on them. Just wondering what I should use to rebuild them

 

[O'Rattlecan]

Reuse the valves, when you have the machine shop work them, have them do a double angle valve job and call it good.

The intake side has a lot of air flow, but the exhaust ports are a little restrictive. If you feel crazy you can clean up the floor of the exhaust ports on the heads to help airflow.

The springs and whatnot need to be chosen based on the other components like camshaft.

Ryan

 

[Joshrabbitt14]

I'm not exactly sure what cam I have. I have been trying to figure out. The guy bought the motor from said it was a Howard's cam with .478 lift or something. I don't know if that's right because I haven't found a Howard's cam with that lift yet.

 

[O'Rattlecan]

I'm not a cam expert. I am building an engine and bought a comp cams kit that came with the right valvetrain to match the cam I wanted. Sounds like you really need to find out what cam it is if you want to reuse it and do so effectively.

Ryan

 

[Joshrabbitt14]

I'm definitely using that cam so without taking it out how will I fight the right numbers? Think I could use a rough estimate?

 

[Joshrabbitt14]

These are all the cams that I found that are somewhat close to .478 but none are .478

http://www.summitracing.com/compare.aspx

 

[DNFXDLI]

Call Howards directly is what I would do.

 

[Joshrabbitt14]

I think I'll try to contact the guy I bought it from. But do I really need to know the exact spec of the cam?

 

[DNFXDLI]

Always best to find out..less chance for error.

 

[O'Rattlecan]

If nothing else, you need to know the lift for spring clearances and whatnot.

Ryan

 

[Joshrabbitt14]

I'll try and figure out. Assuming its around .478 lift what springs do I need? Also i can reuse the rockers and stuff for a bigger cam right?

 

[dustybumpers]

If they ate GT40 P heads, your stock exhaust manifolds, or ford f 150 headers won't work.

the gt40 P head has a straight in plug instead of an angle plug.

You will need to order a set of Summit Pacesetter shorty headers, and put a dimple on #7 and #8 primary tubes, to clear the plugs. You will also need a set of plug wires for a Explorer.



As far as the valve springs, use the ones off the heads you have now if they match the cam that's in the block now

 

[Joshrabbitt14]

They are normal gt40s and the block I bought never came with heads so I need to find springs and whatnot to match

 

[dustybumpers]

Valve springs have to match the cam. You will need the numbers off the end of the cam, then contact the manufacture about what you need.

This is important, because some cams require that you do NOT use rotators on the exhaust valves.

Was there heads on the block when you got it?

 

[Joshrabbitt14]

No there were no heads on the block. And he didn't really seem to remember what he put in it. He said he was planning on doing gt40 heads though

 

[dustybumpers]

Is the timing cover already in place? If not, you need to pull it, then the timing chain and cam gear. On the end of the cam will be the manufacture, and all the numbers for the cam. Unless you have this info, you are just shooting blanks.

 

[Joshrabbitt14]

Yeah the timing chain cover is already on

 

[Joshrabbitt14]

What are the difference between stock rockers and roller rockers? Should I run roller rockers on my DD? Also I can keep pushrods stock right?

 

[O'Rattlecan]

I tried to keep all the stock ratios and lengths and whatnot on mine.

If someone says the engine is a 'roller' they are talking about the roller lifters.

Roller Rockers are a totally different thing, refers to the rocker on the head.

They roll on that pivot rather than a standard rocker.

Ryan

 

[Joshrabbitt14]

So what are the benefits of a roller rocker?