Engine 93 cobra heads ?

91 quarter horse · Nov 22, 2012

i just bought a pair of F3ZE AA heads that were on a 351 w, from what i understand these are 93 cobra heads. My question is do i have to upgrade my intake,valve covers,headers?? i know i have to change bolts as these are 1/2 in and 5.o are 7/16 i believe. also i was going to look into porting,Also i want to do a cam but dont know what to get as i never had gt40 heads before. i got these heads at a good price and just curious as to what upgrades, porting ect... would be good for these heads. its all going on a 91 lx 5sp. Any input would be great thanks

f8tlfiveo · Nov 23, 2012

The 351 uses 1/2 bolts, you are right. But you will still use 7/16. I personally don't use the sleeves they sell to "properly" align the bolts because of the size difference. It's only a difference of .0625, when you split it your looking at .031 per side. Never had a problem. As for the heads if you are going to run an aftermarket cam I would get a better set of valve springs. You can get advice on here for the cam and springs or just call one of the cam manufacturers, they will help you.

2000xp8 · Nov 23, 2012

Invest the minimum in the heads.
They are an ok budget mod, maybe some springs and a valve job, but they are not worth spending money to port.
Not sure what you paid, but they are about a $250 set of heads.
IMO, don't go over a $500 total investment in them, anymore than that and you could find a set of used aluminum heads that unworked easily outflow ported gt40 irons.

91 quarter horse · Nov 23, 2012

i paid 275 which i didnt think it was bad since i seen some stock explorer heads go for 3-350. i am on a budget so all of this stuff helps me out. It seems they have very little use so i might change springs and cam and sell once i can afford aluminum, thanks for the advice

2000xp8 · Nov 23, 2012

91 quarter horse said:
i paid 275 which i didnt think it was bad since i seen some stock explorer heads go for 3-350. i am on a budget so all of this stuff helps me out. It seems they have very little use so i might change springs and cam and sell once i can afford aluminum, thanks for the advice

Wise choice, use them, have a little fun and when you done with them you should be able to get all your money back out of them.

Engine 93 cobra heads ?

91 quarter horse

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f8tlfiveo

My wife likes my spool and blow-off valve.

2000xp8

91 quarter horse

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Engine 93 cobra heads ?

91 quarter horse

Member

f8tlfiveo

My wife likes my spool and blow-off valve.

2000xp8

91 quarter horse

Member

2000xp8

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