head woes
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Elder User
Joined: Feb 2015
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From: south east kansas
head woes
so first off i have a 1973 f100 with a 68 390fe, one of my head bolts broke and has been cross drilled and i cant put a bolt through it. so my question is would it be cheaper to have a set of cast iron c8 heads done up i know i guy that could do them for a fair, or go to aluminium heads. question 2 would c8 heads take cobra jet sizes valves and if so what would i order?
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Joined: Jul 2002
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From: Long Island USA
I had CJ-size exhaust valves put in a set of C8AE-H heads for the 390 in my highboy, and the exhaust valves fit - the intakes were pushing it, and because they would be so close to the cylinder wall, would actually flow LESS (at least, that was my machinist's say on the matter).
The CJ exhaust valves did require some porting and modification of the exhaust chamber to make everything good. But they did fit.
Problem is, once you're that far into a set of iron heads, with seats, valves, valve guides, etc, it comes close to the cost of a set of aluminum heads, or so I've read. talk to your "guy"
The CJ exhaust valves did require some porting and modification of the exhaust chamber to make everything good. But they did fit.
Problem is, once you're that far into a set of iron heads, with seats, valves, valve guides, etc, it comes close to the cost of a set of aluminum heads, or so I've read. talk to your "guy"
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Elder User
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From: south east kansas
i have a stock set of C8ae-h heads that came off a 360 i could use. i guess i may have to start an aluminium head fund, aluminium heads are 1798.50 ish if i save 50 out of every paycheck in 36 weeks i would have enough... but seriously would the 360 heads be fine on a 390? the heads only have about a 113k on them.
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Elder User
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From: south east kansas
daily driver. i would like to build a 445 eventually so i may worry about aluminium heads then. i currently have a slightly higher than stock cam i think its idle to 5500 so i think the 360 heads will be fine.
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Cargo Master
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From: Harned, Ky
390 and 360 heads have the same size valves, 2.02 intake, 1.56 exhaust.
427 low riser and 428cj have 2.09 intake, 1.66 exhaust.
390gt and 428cj use three bolt exhaust manifolds with a different bolt pattern than the standard two bolt exhaust. Some of the newer aftermarket heads may have both bolt patterns, if a set of headers has both bolt patterns then yes they'll work on ether style head.
427 low riser and 428cj have 2.09 intake, 1.66 exhaust.
390gt and 428cj use three bolt exhaust manifolds with a different bolt pattern than the standard two bolt exhaust. Some of the newer aftermarket heads may have both bolt patterns, if a set of headers has both bolt patterns then yes they'll work on ether style head.
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Cargo Master
Joined: Dec 2015
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From: Harned, Ky
If your doing the c8 heads I'd have cj size hardened exhaust seats put in along with cj 1.66 exhaust valves and have the stock intakes reworked as needed.
Before unleaded gas we'd just grind the exhaust seats out to cj size but that doesn't work well today with unleaded.
Before unleaded gas we'd just grind the exhaust seats out to cj size but that doesn't work well today with unleaded.
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