In the process of rebuilding a 65 425 for my 65 Starfire,I have the original A heads,also I have a pair of 66 Toro heads with 2.072 valves...I'm not concerned about originality.Would the Toro heads be a better performance choice...Thank you...

 

Your question has grave potential here for discussion. Here is my 2 cents and hopefully contains accurate info. The A heads are good but may have older rocker arms compared to later 65 and up big blocks so they probably wont be compatable with the Toro heads. The A heads are supposed to not have bumps in the exhaust ports for AIR tubes that California cars had in 1966/1967. These bumps restrict flow some and will be on the Toro heads. The Toro heads have bigger intake valves than the A heads. The Toro block had a 39 deg cam angle while the 65 425 had a 45 deg angle. I had pushrod clearance trouble when I used 3/8 rods in an early 425 with 39 degree heads. I solved the problem by using 5/16 pushrods and egging the pushrod holes some in the heads. I used G heads on my 425. So for a street/stock engine I would say you may be better off with the original A heads.

 

B heads with a 39 deg. block will also give clearance problems with 3/8" pushrods. Early heads have 1/2" holes, the holes are 1/32" bigger with later heads.
I'd keep the original A heads for restoration reasons. Their performance will be fine on a street engine. B heads would signal a "repair" in a negative way on the Starfire.

 

i would go with the toro b heads for a couple of reasons:

the b heads should have the commonly available rockers/pivots.
bigger valves.

you will need to have the push rod holes modified for the 45 degree block.

either way you're going to have issues-not big ones though.


bill

 

I'd like to thank all who have replied to my question...I think that I'll stay with the A heads...thanks again...