Dear SBF Gurus
As stated in title I have a prob or two....... I am assembling a pre-75 302 which had a severe valve failure rendering one head pretty much useless.......I have a newly machined set of what are supposed to be 91 Mustang 302 heads....... they bolted up perfect...... but there were no rockers with them.....so digging thru my parts pile I found a set of pedestal rockers(bolts) for an 85 351W.... I used the push rods from the pre-75 engine which had non-pedestal rockers (nuts)....the push rods seem quite loose.....do I need a set from a roller 302??? or are the 351W rockers not compatible???
Also the sparkplugs I got for a 91 Mustang do not want to thread into the holes????? They look like the right ones, they thread into the 85 351W heads fine..... but I can not get them to start in the 91 heads......... seems like the threads are either too far in for the plugs to reach or they are a different thread ????
Any ideas to fix these probs.... Thanks

 

The pushrods may be loose because the lifters have bleed off. You could get a adjustable pushrod, and check the length with the rocker torqued down and the cam lobe on the base circle. measure the pushrod and add about .020 for lifter preload.

 

What is the casting number on the heads you got? By the description of the plug hole I suspect you have either E6(1986) heads or Gt40p heads.. both of which require special plugs. Any Ford SB pedistal rocker will do but you will likely need custom pusrods, get a pushrod length checker to figure out what you need.

 

Thanks for the info...... it isn't my engine so I will get the casting number the next time I drop by my friends place........ kind of figured the pushrods were too short as I thought all the SB rockers were interchangeable...... but my "rememberer" isn't what it use to be

 

The pushrods should be the type used with pedestal rockers, i.e. from about 1978 and up. The early ones you used match up to the earlier "sled type" rocker arms.

 

Little update I got some numbers from my friend but they do not match the chart posted here....... it is either E7531 or F7531 and those numbers are around the outside of a circle about 1/2 in diameter next to the valve springs, to the right of it is 5K7 and at the opposite end of the head is a ford oval... there are no stripes or lines on the ends of the heads.......and no other numbers I can see... other than an S on one end of the head next to the lower head bolt and a 6 on the other end.....
I am confused as I thought 302/5.0L heads were fully interchangeable.............. never even heard of GP40, or whatever, heads till he had this problem........ any other ideas??? Thanks.

 

I should have mentioned but the casting numbers are on the head gasket side near one of the center intake ports..

 

Ok I guess it is time to dig out the mirror :-) Thanks again.

 

Ok got the casting numbers, I hope
E6SE-AA
So I guess they are from an 86 something or other...... so why the werid spark plug holes?????
Thanks again for any answers.

 

Uh oh... I think you'll hear a little bit of criticism about those heads.

I believe they are 1986 only items. A friend has them on his 1986 HO Mustang motor and is happy with the engine, but he's not revving it high (it's in a 1983 TBird with an AOD).

 

I do not think high reving comes into the equation, as they are now in a 66 Mustang that never sees rain let alone high revs
So the spark plugs I need are from an 86 GT then I guess......

 

Yes, you need the long reach plug (Motocraft AWSF44C or Champion RS14LC). These heads were a 1 year experiment in combustion chamber design, it's kidney bean shaped instead of D shaped. The idea is this will promote more A/F mixture and better ignition flashover which should make more TQ... and it does. But because the chamber is more recessed in the head it also shrowds the intake valve, and for some reason Ford decide to put a massive air injection hump in the exhaust port that year as well, so these heads really choke the motor and limit peak HP. Bottom line is if this isnt going to be a high performance motor these heads will be fine, but somebody lied to you or just didn't know any better.

 

Thanks for the info that fixes the spark plug problem..... on to the push rods next.... they appear to be .060" or so too short........ so on another note can a fellow just grind off those massive air injection humps????

 

Because of the recessed combustion chamber the valves are further off the deck so longer pushrods will be needed.


Yes.. but you want the heads off the motor and the valve removed to do it, don't want all the metal going in the motor.

 

No wasn't planning on doing the grinding with the heads installed....just wondering as I may end up with the heads in the future if this doesn't work out for him
So are would the push rods for the engine these heads came off the correct length??
Thanks again.