X heads on a 273??

1970Duster said
The 273 bore is small, to say the least and with the x head valves (2.02/1.60) you'll hit the block with the valve do to there size.

Thanks 70D, I was just thinking out loud as I have "spares"

Oldschoolcuda said
The 340 x heads will work on a 273 but only with modification. The Cylinder walls will need to be fly cut from the top of block towards side to accommodate larger valves. Not sure of exact machining but 2.02 + 1.60 valves = 3.62 while the standard bore of a 273 is 3.63.(No room for error) Would think that only benefit would be in upper RPM range if you went this route & port volume would kill bottom end but sure others will chime in. Late model 318(302) heads are the cats meow for 273's IMHO.

Thanks OSC, there is an option...

Oldschoolcuda

Wheels said
hope this helps a bit. Cheers

Thanks Wheels, I dont want to do anything "irreversible" to Dads 273 block....where did ya get the bulletin from??

Thanks all!