Is it possible to run an 80 cubic inchShovelhead lower end with 74 cubic inch jugs and heads and what would need to be done to do that?

 

to understand the difference between the two engines I will explain it this way

74 cubic inch up to 1972 was a side oiler - they then in 1973 changed the oil pump speed and went to an end oiling system - then in 1978 they had both 74 and 80 inch engines

74 inch engine has a piston bore of 3 7/16 inch and a stroke of 3 31/32 inches connecting rod length of 7.470

80 inch engine has a bore of 3 1/2 inch and a stroke of 4 1/4 inches connecting rod length of 7.440

the blocks deck height is the same as well as the cylinder length - so - if you change the flywheels to the 80 inch 4 1/4 stroke and the rods to the 7.440 and well as using a 80 inch 3 1/2 bore pistons - so this is the spot - a 60 over bored 74 cylinder becomes a standard bore 80 inch bore cylinder

other stuff from different years clog up the works a bit but in a shop its not a thing a home owner its a thing

 

So i would have to use a 80 in cam with that?
so i have a 80cubic lower end and 74 cubic jugs and heads i have the 74 in cam in it if i adjust the push rods (solid lift) where they should be i get no compression if i take them out i get compression

 

stock cam is the same cam both engines

you never posted what year motor and what year flywheels you have and what bore the cylinders you have are

its not a novis job BTW

 

The bike is a 77 lowrider, the jugs are off the 77 shovelhead and the lower end is remaned from ultima paper work has it at a 2015

 

Yes you can. I have. I wanted to run the 74 cylinders because on longer life. The 80" cylinders are a .060 bore on 74 cylinders. So I ran the 74 cylinders with zero overbore. You just have to have 74 pistons with the wrist pin shifted up to compensate for the 1/4" additional stroke. They are available on the market from Keith Black, S$S and other makers.

 

Only difference in the cams is the gear, they changed up the pitch in 77 don't get them matched to the pinion & breather gear it will chew itself up.

 

I will say that a slightly modified 74"er can perform very nicely without giving up any longevity.... My 74"er is at 9:1 with a little head work and an Andrews #2 can and an Email carb... Has all that I want and sounds good.. 72/68....