Did you retorque them after it sat overnight? I've done mine a couple times before start up and haven't had any troubles like you describe. I did get a bit more of a turn when retorquing, it seems the gaskets initially compress then relax.

 

Positive I retorqued, 'cause I do the headers at the same time along with a fresh oil change after the engine heat cycles. I've built a few combos, but this was the first time with the 1250s. I used ROL in the past, but these were in the gasket kit I bought.

The GT40 heads have a pocket in that area and oil can collect there. Most aftermarket heads do not have this. At least my TFS heads don't. The center intake bolt pass through holes on the 1250s are different than the ROLs for the center bolts. I looked at some E7 heads on the shelf that still had the old gaskets on them. On the 1250s they are open to the crossover and the ROLs are not.

My theory now is that the exhaust pulses in the crossover caused oil to seep up the threads.

 

Mine never leaked. I cleaned the heads off and wiped everything down before install... no problems..

Guy

 

you say that you didn't use the exhaust blockoffs, but did you use the "0" shaped gaskets? You need those or it will leak.

 

Where exactly do those O shaped gaskets go?

My heads are emissions legal but I don't have EGR. The holes in the back of the head are plugged. My intake is a Victor Jr carb and there is no hole for the EGR either. Do I need to use these O shaped gaskets?

 

you say that you didn't use the exhaust blockoffs, but did you use the "0" shaped gaskets? You need those or it will leak.

I think we have a winner, the gasket set was for an EFI car and I must have thought they were for part of the EFI stuff. Therefore, I did not use them.

I'm just going to use ROL intake gaskets for a 1969 Mustang with a 351W from now on. Heck, I'm using a $20 stock '69 351W 4BBL carb fuel pump and made 265 rwhp with it with the power passing through an AOD. Fuel pressure stayed right at 7 LBS on the guage and had a 13-1 AF mixture.

The 347 will have a set of stock GT40Y heads, Stelath intake, 750 Holley HP and an older Pure Street cam specced for a similar build. Other than the displacement, everything is just about the same. Dont let the heads trick you into thinking of a low power combo. I have a feeling this combo will rock...

 

Where exactly do those O shaped gaskets go?

My heads are emissions legal but I don't have EGR. The holes in the back of the head are plugged. My intake is a Victor Jr carb and there is no hole for the EGR either. Do I need to use these O shaped gaskets?

Te felpro 1250 gasket has a big open area around the egr area and the gaskets come with two differant inserts. The one set that is used with the egr kinda looks like an "0". The others are for non egr and the have the same outline as the "0", but there is not a hole in the center of them, hence blocking off the egr.

If neither one of the inserts are used, then the intake will leak, bacause there is nothing directly under the egr passage to support the gasket and intake.

I don't know if the felpro 1262's are like this or not, but I am not a fan of them. They like to fall when putting the intake on if you don't use some kind of adhesive. Any stock type gasket won't have this setup, just the aftermarket gaskets meant for aftermarket stuff.