Did I buy a 351 Windsor w/ my Bronco?

[sykanr0ng]

Those are GT40 heads, not GT40P
The sparkplugs are angled and there are three bars on the end not four.

Good find.

 

[darrell82]

Have you done a compression or leak down test yet? My only recommendation is to check overall engine health before throwing money at performance upgrades.

The preference is a leak down test (to determine if & what is wrong). Although if you have a compression gauge it can tell you if something *is* wrong.

I bought a compression gauge and performed the test. Says to warm up first but had all the plugs off and ready so I did it with a cold engine. Anyway, here are the results from cyl 1-8: 150, 165, 147, 165, 160, 155, 155, 145 PSI. So it seems all is well with the heart of my steed.

 

[darrell82]

Ok Y'all, so I bought the GT40 heads and they are currently waiting to go to the machine shop to get bead blasted magnaflux tested, valve job and ported and painted black. I was checking my current head bolts that are in my 302 with 302 heads and they should be 7/16 right? but, no they are not. They are not even 1/2. They are 11/16 bolts! Has anyone ever seen this and have any insight on this. I don't have a clue. I just hope that when it's time to install the GT40 heads they will go in.

 

[Broncobowsher]

Are you measuring the head of the bolt or the shaft?
I can guarantee you don't have 11/16 bolts, that's nearly 3/4"

 

[darrell82]

Are you measuring the head of the bolt or the shaft?
I can guarantee you don't have 11/16 bolts, that's nearly 3/4"

OK, so obviously excuse my ignorance as I am still new to the Bronco and mechanic life but, i did measure the head and I thought the head determines the shaft. So, I guess I will remove it and measure it.
And good news it is a 7/16.

GT40 head swap is back on track

 

[bronconut73]

Will be interested to hear how much of a difference those GT-40's make.

I have stock oem smog era heads that I worked over a bit, it was 20+ years ago, I was a poor college student, couldn't afford any better heads etc, etc.... .
There's only so much you can do with the passages without knowing what you are doing but I cleaned them up a bit and replaced the springs and push rods with Edelbrock and Comp Cams guide plates with Harland Sharp Roller Rockers and Rhodes Lifters. They have been great but I always wondered how much better it would have been to start with much better heads like your GT-40's.

Keep us posted on your results.