[david jensen]

i have a 69 xr7 351w my seats and valves are bad, i have a set of new 75 351w heads, will they work on my 69. any help appreciated.
thanks
dave

 

[modifiedmark]

Yes and no. The 75 heads will have smaller ports than the 69's. Valves may also be smaller. But they will bolt on and run although performance will suffer. The other problem is the early 69 and 70 heads used a 16 bolt intake manifold and the later heads used a 12 bolt mainfold. You can use a 12 bolt intake on 16 bolts heads but not really the other way around. In other words if you have a original 69 intake you have a 16 bolt intake and I'm pretty sure that 75 heads are 12 bolt. My advice is to sell the 75's and invest the money in a seat of seats, guides and valves for your 69's. Unless you want to go aftermarket. You might end up spending $400-500 on your heads and new world products cast irons ready to go will set you back $750- 800. If you dont care about performance you can use the 75's, just get a newer style intake. mm

 

[david jensen]

both the 69 and 75 heads have the same bolt pattern. the intake manifold is twelve. the original heads are dooe and they are twelve also. the, i was told these new heads were a 75-76 because of the egr hole in the back. what do u think, are u sure the early style is 16 bolt.
do u know any other differences. thanks
dave

 

[modifiedmark]

Dooe heads ARE 16 bolt intake period. If you have a 12 bolt intake, check the # on it as it's not the original for your 69. I don't remember when they drilled the thermactor hole through the head, 75-76 sounds about right though. The EGR was bolted to the intake, not the head. mm

 

[david jensen]

ok sounds right, i have a edelbrock performer on the car. i just got 2 weeks ago so i dont know too much about it. am i gonna loose alot by using these heads. i have a core plug to plug the hole in the back of the heads. anyway what sugestions do u suppose i do with these heads.
thanks
dave
oh what about 302 heads?

 

[modifiedmark]

I already told you what I would do. I would sell the 75's and spend the money on the DOOE's, or buy a set of after markets.

But with that said I can't tell you what to do, it depends what your looking to accomplish. If you dont want to spend alot, are not concered with ultimate performance and already have a set of ready to go 75's by all means use them since you already have a 12 bolt intake to use with them. Just plug the thermoactor holes and your good to go. It will run fine, it just won't have the power the DOOE's would make.

As for the 302's forget them, In my opinion they were barely sufficent for a 302 let alone a 351 and with all the drilling involved it isnt worth it. mm