GT-40 Head Problems

['88Cobra]

I recently purchased a new 302 block and aluminum GT-40 heads. I used ARP head bolts and it wasn't until after the engine was all together that I was told that I need to use a stepped washer with the head bolts. The reasoning behind this, so I'm told, is because the holes in the heads are 1/2 inch and the bolts are 7/16 inch, and if I don't use them my heads will float around on the engine, obviously giving me problems. Has anyone used GT-40 heads? And if so, did you have to use this type of washer, or did you just use the flat type that come with the ARP bolts? Many thanks for any info, I'm going crazy!!!

 

[RydeOn]

The 1/2 bolts are for 351w motors. Were these heads drilled for a 351w motor? No. Ok then ur good to go.

 

['88Cobra]

I bought the heads and engine at the same time right from Ford, so they should be for a 302.

 

[Michael Yount]

If the block has the dowels to locate the head, the head shouldn't move around on the block.

 

[JadeFalcon]

all incorrect.


outside of e6 and e7 heads, all ford heads (oem or aftermarket) will be 1/2" holes. Why you ask? It would be pointless to make 2 pairs of heads for a 302 and then a 351 when they are the same engine, except different head bolts, so all heads are drilled for 1/2" bolts, this includes GT40 Irons, GT40Y's, GT40X's, Trickflow, AFR, Edelbrock, all of them are 1/2" ... you will need to remove the head and put a new gasket on, and then buy some trickflow brand 1/2" to 7/16" bushings, they snap in the top of the bolt hole on the head, and keep your head on.

 

[9 Deuce GT]

JadeFalcon,

You are incorrect. My AFR 165's have 7/16" holes in them. No AFR 165 head came with 1/2" holes. Only the 185's come with 1/2" holes from AFR.

 

[JadeFalcon]

JadeFalcon,

You are incorrect. My AFR 165's have 7/16" holes in them. No AFR 165 head came with 1/2" holes. Only the 185's come with 1/2" holes from AFR.

That's odd, I was not aware of that, heres a snippit from AFR's website:

"These heads come ready for the maximum street/strip Small Block Ford performance possible! They are not emissions legal. With the 165 coming with 1.900 intake and 1.600 exhaust valves and the 185 sporting 2.020 intake and 1.600 exhaust valves. Both heads feature 58cc or 61cc combustion chamber with 69cc exhaust ports. Both the 165cc and 185cc have available as an option nitrous or blower exhaust ports featuring either a 75cc or 80cc ultra high flowing exhaust port. With AFR's trademark 3/4" thick head deck, it's no problem handling that additional cylinder pressure. Each head is also drilled for the larger 1/2" head bolt hole for maximum head gasket retention as a standard feature of this serious race piece in street disguise."

 

[TrickStang37]

Actually, your wrong about TFS, atleast on their Twisted Wedge Heads. The heads come set for 7/16 head bolts and must be drilled out for the 1/2 head bolts if you need it (351 or prepped 302 block).

 

[Michael Yount]

My Ford Racing Y heads are located by the 2 hollow dowels, one on each end. The stock-sized 7/16" ARP bolts go through whatever hole is in the head with no snap-in bushing from TrickFlow or anyone else. The same is true for AFR165, GT40, E6 and E7 heads that I've worked on/with. Two hollow dowels, one on each end of the block/head center the holes in the head over the holes in the block. Once the bolt starts into the threaded hole in the block, it's located in the center of the hole. The washer under the bolt spreads the clamping load accordingly. Seems to be holding multiple heads on multiple engines seeing the normal amount of abuse for multiple years and multiple miles. Mine went on this way 14K and 2 years ago with no doubts, little drama and no problems since.

The bolts don't keep the head from moving laterally - the dowels do. The bolts apply the clamping force to seal the head to the block.

 

[rd]

I would just get the washers from FRPP, ARP, etc if I had the 1/2 head bolt holes on my heads. I have two sets of iron GT40's and used a special bolt set on one and a washer set on the other. Did not seem like a big deal.

It did seem that if you omitted the washers you had much less bolt head surface contact, so it seemed appropriate. It may work without them, but why risk a problem you don't have to have.

 

[maverick0716]

Edelbrocks need a bushing, they're drilled for 7/16"