I have a 74 360 in my dart, I know nothing about the motor the owner had it built but then he passed on. When I tried to see what heads were on it I see no external markings on the pads near the spark plugs. Just wondering what was available in 74 for heads and if some are better than others. Any help would be much appreciated. Thanks.
1974 360
- Thread starter Hemi331
- Start date
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If they are 74 heads 360 heads they will probably have 1.88 intake valves and 1.60 exhaust. The exhaust valves will have hardened seats under the valves which help them to work better with todays fuel.
I would just drive it for a while before ya start tearing into it.
Post some pics.
Welcome to the site.
I would just drive it for a while before ya start tearing into it.
Post some pics.
Welcome to the site.
Locomotion
Well-Known Member
* OEM 1974 heads tend to be 3671587.
* 3418915 heads tend to have letters by the spark plug holes and originally have 2.02" or 1.88" intakes, including T/A heads.
* 2531894 were all X heads with 2.02" intakes.
* At some point the casting number was moved from the top of the intake runners (under the valve covers) to the underside of the mouth of the intake ports. i.e.: 4448308. - ('80's?)
*Later heads also started getting the larger pushrod holes. Not sure exactly when that started - ('80's?) May be associated with the transition to OEM roller cam & lifters.
As others mentioned, 1.88" is plenty for street/strip. But it's the age, number of valve jobs and the quality of the valve job that are the biggest factors in performance. A 1.88 can outflow a 2.02. Multiple valve jobs "sink" the valve & hurt flow. Cutting a 1.88 head for 2.02 valves can help air flow because the seat ends up fresh & high in the chamber. "Quality" of the valve job & angles depends on the machinist. Aftermarket small block stainless intake valves have more of a "nail" head and tend to flow better than OEM intakes which have more of a "tulip" shape.
Lots of variables in play.
* 3418915 heads tend to have letters by the spark plug holes and originally have 2.02" or 1.88" intakes, including T/A heads.
* 2531894 were all X heads with 2.02" intakes.
* At some point the casting number was moved from the top of the intake runners (under the valve covers) to the underside of the mouth of the intake ports. i.e.: 4448308. - ('80's?)
*Later heads also started getting the larger pushrod holes. Not sure exactly when that started - ('80's?) May be associated with the transition to OEM roller cam & lifters.
As others mentioned, 1.88" is plenty for street/strip. But it's the age, number of valve jobs and the quality of the valve job that are the biggest factors in performance. A 1.88 can outflow a 2.02. Multiple valve jobs "sink" the valve & hurt flow. Cutting a 1.88 head for 2.02 valves can help air flow because the seat ends up fresh & high in the chamber. "Quality" of the valve job & angles depends on the machinist. Aftermarket small block stainless intake valves have more of a "nail" head and tend to flow better than OEM intakes which have more of a "tulip" shape.
Lots of variables in play.
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