[babell7738]

what modifications do you have to make to 302 heads,to use them on a 351W block?

[JeffB]

The 351W uses 1/2" head bolts the 302's use a 7/16" head bolt so you would have to redrill the the heads to 1/2", which would be a total waste since there is zero advantage in doing it.The majority of aftermarket heads are just the opposite which require a bolt spacer or a step down bolt which is available from A.R.P.

[babell7738]

Thanx for the info.There is no advantage whatsoever?Trying to increase performance,with a very tight budget & parts that are readily available-I have the 5.0 302 that I removed from my '93 F150 XLT,and an extra set of 351W heads that have emission ports on the ends. The 351W currently installed in truck has developed a lower end knock (either the #5,or #8 spun a rod bearing or a bad wrist pin?) after I replaced the formentioned heads due to loss of compression,which turned out to be caused by a blown head gasket.The heads I replaced the old ones with do not have the emission ports on the ends.so I plugged off the hose that went to them to avoid having to remove the air pump & having to buy a shorter serpentine belt.Would any of these actions have caused the lower end knock?

[JeffB]

None of what was done should have caused your problems with the 351, your 5.0 will lack some of the torque of the 351 but as far as heads go the 351's have a larger chamber and would actually decrease compression and cost HP on the 5.0/302.Try to sell the 351 heads and pickup a set of GT40 heads which will give you somewhat of a performance increase and no mods will be needed with the headbolts,you do not want the GT40P heads as they have a different plug angle that can make exhaust fit a pain.

[Irelands child]

There are good 302 heads, but most OEM/as delivered are not really suitable for a 351. Many 302's have very small valves and many have exhaust runner EGR obstructions. Then you can run into a few cases where you can raise the compression ratio to the point of either having to use high test or racing fuels. You will also have to use the correct intake manifold gaskets. Another is what kind of rocker arm bolting - stud or bolt down.

[babell7738]

since I'm on a fixed income,I will most likely just use the stock bolt down rocker assemblies.-where would I most likely be able to find a set of "GT40"heads & what did they come on?

[Irelands child]

Originally Posted by babell7738

since I'm on a fixed income,I will most likely just use the stock bolt down rocker assemblies.-where would I most likely be able to find a set of "GT40"heads & what did they come on?

Ebay will occasionally have GT40P heads as well as Craigslist - they came on 5.0L Explorer's for sure and I have been told, Expeditions, but not positive of that one. This is as good an OEM iron head as Ford made, but be advised that you will need different headers to access the plugs - see the closeness. I have a specially 'modified' socket for the LHS, especially:

[zildjian4life218]

Originally Posted by Irelands child

but be advised that you will need different headers to access the plugs - see the closeness. I have a specially 'modified' socket for the LHS, especially

I remember reading that the GT40 heads are just as good as the GT40P heads but don't have the revised spark plug location that gives issues with header clearance... ill see if I can find the link. That way you can use regular headers.
http://forums.mustangworks.com/f8/gt40-vs-gt40p-38436/
http://www.allfordmustangs.com/forum...der-heads.html
These links also tell you what model and years you can find the heads on and how to identify them. You could probably get them from your local u pull for $60. Thats what they cost me.

[babell7738]

I'll be using my stock exhaust manifolds,will I have to get the stock exhaust mnflds for the GT40-or-GT40P heads?or will my current 351 manifolds fit them?

[Irelands child]

Originally Posted by babell7738

I'll be using my stock exhaust manifolds,will I have to get the stock exhaust mnflds for the GT40-or-GT40P heads?or will my current 351 manifolds fit them?

The will probably bolt in place, but with those heads, especially the GT40P, you will never service the plugs - so yes, you will need new exhaust manifolds.

Go back a couple of posts - look at my engine photo and response

[babell7738]

Thank you !for the info*much appreciated*