Difference In Year Of273 Intake/heads
- Thread starter A/MP
- Start date
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perfacar
Well-Known Member
hi, it's 64-65 has a smaller bolt ( 5/16) and at a steeper angle.
the 66 up has 3/8 bolts at different angle. same as a 340 , 318.
performance, is equal. the 920 head is the one of choice though. they all fit.
64-65 manifold should be used with same heads. bolt holes can be redrilled and tapped.
the 66 up has 3/8 bolts at different angle. same as a 340 , 318.
performance, is equal. the 920 head is the one of choice though. they all fit.
64-65 manifold should be used with same heads. bolt holes can be redrilled and tapped.
Rcuda2
Well-Known Member
64-65 heads & intakes use 5/16" attaching bolts that are at about 20 degrees from perpindicular to the intake surface. 66 and later use 3/8 intake bolts that are perpindicular to the intake surface. 64-67 have small wedge heart shaped combustion chambers (57cc), 68 and later 273 & 318 heads are basicly the same with open combustion chambers (62cc)& all have the same size valves & basicly the same size ports and will bolt on any 273-318-340-360 block. It's harder to get good compression with open chamber heads.
No 273s in 63. 64-69 were the only years. 273s went from solid cams to hyd cams in 68. 66-67 920 head is the best head for a 273. 68-69 the 273 heads were open chamber.
Well spoken guys! toolmanmike
johnnycuda
JohnnyCuda's 68
where do you find the 920?
I think I have a pair of 920's that were going to the scrap pile. They were on a solid cammed 273. If you want them, I can check to make sure they are 920's.
cudamark
Well-Known Member
I'm afraid I have to disagree with the opinion that the 920 casting is the best for a 273. I've found that the '68-74 casting #675 is better for a street motor. It has less crack problems and you can use pump gas without any pinging. If you use the ones off a '72-4 model year, you also get the benefit of hardened seats.
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