help with 351w swap

[Mercracer]

yeah, certain late (98-01?) GT40s came from the factory on Explorers with 1/2 inch holes and some sort of washer/spacer arrangement to fit 7/16 bolts

Only 96 and early 97 model year had GT40 heads. None had washer/spacer arrangement for the bolt holes.

[torquelover]

Only 96 and early 97 model year had GT40 heads. None had washer/spacer arrangement for the bolt holes.

So Ford put 7/16" head bolts through heads with 1/2" holes, without any type of special bushing or washer? Interesting. I thought the same thing the first time I pulled the exhaust manifolds off the 351 and noticed there were no gaskets.

[Mercracer]

NO factory intstalled cylinder head on a late model EFI 5.0 had head bolt holes drilled for anything other than 7/16" head bolts. .

There are Mustang Cobra owners who would not agree with you as well as Explorer GT40 head owners....

[Mercracer]

So Ford put 7/16" head bolts through heads with 1/2" holes, without any type of special bushing or washer? Interesting. I thought the same thing the first time I pulled the exhaust manifolds off the 351 and noticed there were no gaskets.

This was definitely the practice on the Explorers. I can not say without a doubt that no F3ZE or F4ZE head ever came from Ford with 7/16" bolt holes, but I have never seen such a beast nor any pictures of such a head. There was one guy on one fo the boards who claims that his engine had one head with 7/16" holes and one with 1/2" holes but offered no proof just as nobody who claims to have seen a set with 7/16" holes has offered any proof. I am patiently waiting..

[DuceAnAHalf]

So Ford put 7/16" head bolts through heads with 1/2" holes, without any type of special bushing or washer? Interesting. I thought the same thing the first time I pulled the exhaust manifolds off the 351 and noticed there were no gaskets.

not really needed since the heads are actually located on the block by the two steel roll pins in the bottom corners of the block.

[Mercracer]

not really needed since the heads are actually located on the block by the two steel roll pins in the bottom corners of the block.

They are more just bushings than roll pins, but your point is valid and should be obvious to anyone who has worked on them.

[1987cp]

I think the source of confusion might stem from the recommendation to use special washers or bushings of some sort when using 7/16" bolts on aluminium heads with 1/2" holes. After reading about aftermarket stuff, I was also surprised when I realized I'd just disassembled an engine with 7/16" bolts in 1/2" holes with no special provisions.

[Mercracer]

If I were using GT40 heads with nitrous or under pressure on a 302, I would use the washers as distorting of the gasket under boost could cause it to fail.

[P72Ford]

I don't doubt what you guys are saying at all... about 7/16" bolts in 1/2" holes.

But I will point out that without having a larger bolt head, the bearing surface of the bolt head on the cylinder head itself is reduced.

A 7/16" bolt used in a properly sized hole has a larger contact area with the cylinder head than a 7/16" bolt in a 1/2" hole. sigma= p/a.

I'm not sure what the tensile strength of the bolts are, but where I work this kind of thing is definitely not acceptable. One of the components would surely yield if the bolt is torqued within close range of the yield strength. The yield would be far worse with aluminum heads, obviously.

However, with the way that most folks 'torque' bolts, they aren't getting a true depiction of the actual torque anyway.

Just an observation.

[mrltd]

I thought the TTY bolts had a larger shank and large head to fit in the 1/2 hole in the head but still a 7/16" thread....

[Mercracer]

I thought the TTY bolts had a larger shank and large head to fit in the 1/2 hole in the head but still a 7/16" thread....

They definitely have a larger shank and what in effect is a built in washer as compared to the standard bolts but they still do not fill the hole as much when compared to an actual 1/2" head bolt.

[1987cp]

I'm not sure what the tensile strength of the bolts are, but where I work this kind of thing is definitely not acceptable.

Then I guess you don't work at Ford, where as you know, "Good enough is."

I thought the TTY bolts had a larger shank and large head to fit in the 1/2 hole in the head but still a 7/16" thread....

What he said. I was able to stick one of my TTY head bolts in a "proper" 302 head when one of the normal bolts I meant to use had temporarily gone missing.

[Mercracer]

What he said. I was able to stick one of my TTY head bolts in a "proper" 302 head when one of the normal bolts I meant to use had temporarily gone missing.

Those are the same bolts used in every other 302 during that vintage...

[P72Ford]

Then I guess you don't work at Ford, where as you know, "Good enough is."

I work in aerospace, specifically with gas turbines/ jet engines. Where, as you know, things are much more controlled, and design is extremely rigorous.

[1987cp]

So no "Yeah, this should run good for about 5 years or 50,000 miles, after which it'll almost certainly blow to bits and the customer will be back for another new car"?