Thread: Picked up some GT 40 P heads

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Originally Posted by bluestang67

Didn't mean to hi-jack your thread, Bobby. Hopefully, this will be useful info for you.
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Randy not hi jacking improving is what I call it . Jay is at sbftech alot been sitting there reading a lot seems he sets up a lot of engines for what you want .

I've followed some of Jay's cam thoughts on SBF's for some time. Seems to know his stuff, and has the performance numbers on engines to back it up vs. just somebody just looking at specs and thinking they have a better idea!!!!!!

Originally Posted by DennyW

The only thing I see with going over your cam specs, is you will have 2= Over Drive gears... 4th gear for 45-50 mph, and 5th gear for 80+ mph...

Do you mean that with the 3.0 rear gears or the 3.50 rear gears?

Here are some calculations based on my 5th gear at .68:

R&P ratio 70mph 5th gear .68 RPMs
3.0 1714
3.50 1999
3.89 2222
4.11 2348

Since you said I'd have 2 overdrives, here are the numbers for 4th gear at 1.0:

R&Pratio 70mph 4th gear 1.0 RPMs
3.0 2520
3.50 2940
3.89 3268
4.11 3452



I may end up with a 29" tire which would change these numbers a little but not too much.

This chart didn't post the way I intended but I think you guys can figure it out. It's all figured at 70mph with the different rear gear ratios with a 28" tire. The same is applied to both 4th & 5th gear.

Originally Posted by randyr

Do you mean that with the 3.0 rear gears or the 3.50 rear gears?

Here are some calculations based on my 5th gear at .68:

R&P ratio 70mph 5th gear .68 RPMs
3.0 1714
3.50 1999
3.89 2222
4.11 2348

Since you said I'd have 2 overdrives, here are the numbers for 4th gear:

R&Pratio 70mph 4th gear 1.0 RPMs
3.0 2520
3.50 2940
3.89 3268
4.11 3452



I may end up with a 29" tire which would change these numbers a little but not too much.

This chart didn't post the way I intended but I think you guys can figure it out. It's all figured at 70mph with the different rear gear ratios with a 28" tire. The same is applied to both 4th & 5th gear.

looks like some good cruizin' rpm to me!!!! Had 4.56's in my '83 for awhile, with a 3 pedal 5 speed car it works just fine!!!! Heck, used to play on the street with the Mighty Mav with 6.50's on a spool with a Windsor and my trusty old Nash 5 speed!!!!! Absolutely the most fun you can have with yer clothes on!!!!!

Yes great stuff definitely going to talk to him once I figure out what the bottom end will be . If this block is a C9 neighbor said he see's it I haven't put my eye to it totally yet but it doe's look like it . Some cleaning and a little rust dabbing I will bring it out . . But should have 9.5 compression If it is a C9 .

These heads and that compression will make a great street engine , driveable with some performance .

Now I just need Dave here a few days to help me sheet metal it

Originally Posted by bluestang67

Now I just need Dave here a few days to help me sheet metal it

Well, the Plymouth will be on the rotissierie sometime this week, depending on how long it takes my crippled old body to get the tin work done.... I can be had, but I ain't no cheap date!!!!! Somebody has to furnish the coffee and donuts on house calls!!!!!

Originally Posted by Dave Severson

looks like some good cruizin' rpm to me!!!! Had 4.56's in my '83 for awhile, with a 3 pedal 5 speed car it works just fine!!!! Heck, used to play on the street with the Mighty Mav with 6.50's on a spool with a Windsor and my trusty old Nash 5 speed!!!!! Absolutely the most fun you can have with yer clothes on!!!!!

Yeah, I don't know what rear gears I'll end up with yet. Depends on what kinda deals I find out there but while I want some performance on the low end, I want to at least have a shot at some ok mpg's when highway cruisin'.

Coffee ,donuts ,STEAK ,blonds with flat heads what ever you want . Even a real comfy bed with color tv and oh yeah it has a remote too . LOL

Best part about the 5 speeds, gives you some choice in the final gear.... That's why I like using a 9" rear, not all that spendy to set up a couple extra rear carriers. Kind of like having a "Hallmark" drivetrain.....you can have a gear ratio for any occasion....

With my old Doug Nash tranny, really easy to change gear ratio's around, too. When I want to go draggin', can make 5th gear be a 1:1, for cruizin' and traveling, can make it an overdrive.... Then add a couple extra rear gear sets....I want to get a Gearvendors behind a five speed one of these days.....

Originally Posted by randyr

Yeah, I don't know what rear gears I'll end up with yet. Depends on what kinda deals I find out there but while I want some performance on the low end, I want to at least have a shot at some ok mpg's when highway cruisin'.

Randy they say the 3.55 is a great gear with the T-5 trans . Performance and mileage . Now with the EFI it even gets higher but looks out of place under a 37 hood . But hey we could try it and see it for ourselfs right .

Hey, if you like the looks of an EFI in the '37 then it ain't out of place!!!!! Some really good looking add on components for the SBF EFI engines, too!!!!!

Originally Posted by bluestang67

Randy they say the 3.55 is a great gear with the T-5 trans . Performance and mileage . Now with the EFI it even gets higher but looks out of place under a 37 hood . But hey we could try it and see it for ourselfs right .

I've seen the EFI in a couple of them and it didn't look too bad to me! LOL! The only thing I think looks funky in a 37 is a V6! It just seems wrong though I'm sure some have done it! LOL!

Well parts are building for the 37 and EFI's are cheap with the looms and cpu . I guess it could always be a dapted later once she is rolling . I do figure it to be of modern or what is available now days . Seen a 5.0 , tranny and a 8.8 on Craig's list for If I remember right $600 or $700 with the puter and looms .

Let use know how it works out when you get it Running .

For those of you who are running SBF's, Camshaft Innovations is a wealth of information on heads and cams!!!! Good place to have a cam custom built, too.

http://www.camshaftinnovations.com/

Should be a dandy combination for the street. Lotsa hp and lumpy sounding too. I have the P heads, B303 cam 1.72 rockers with port and polish in a standard bore with flat top slugs zero deck. It pleases me.

A porting site I will use with my extra p heads is here. http://www.diyporting.com/gtpex.html

and some of my projects here. http://s6.photobucket.com/albums/y237/w2zero/