1966 Flexplate

Can a later Flexplate be used on 1966 273 engine or is the registry hole specific , have the correct converter but only the later Flexplate.

Depends on how LATE as in year ?

273 and some early LA318 motors had smaller crankshaft registers to center the flex plates and flywheels than the later one did, you need the correct flex plate or flywheel for YOUR motor

Difference in the crank flange register is the inside diameter, outside is the same I think. An early 904 converter hub is 1.550", later is 1.810" same as the 727.

Ok I have the correct converter for the small 273 registry , so I guess I need a small registry flexplate also to fit the 273 crankshaft , correct , does anyone have the correct hole size for the flexplate .

What part of the outside register is the same and that the flexplate registers on that outside diameter do you not understand?

You can reuse your existing flexplate.

Let's try this , I have a1966 273 engine with a 904 transmission . The crankshaft has the small registry hole for the converter. I have the correct converter and need a flex plate . My question is will a 1968 and up flexplate work or is the the registry hole in the flexplate a different size for the 1966 .

On the Slants the OD of the registers were different too. I always figured the small blocks were the same?

I believe what Sniper was trying to get across is the Flexplate "registers /centers) on the crankshaft "LIP" OD that raises anbe the flange and only needs to match the converter 4 hole pattern size wise.

And the converter Hub should match the crankshaft ID

FWIW, the 273/904 flexplate part number for '66 is 2204403 (same for the /6), for '68-later it's 2400885.

Ok so the raised lip on the crank might be smaller also for the flexplate

Measure the OD of the register.

Crankshaft is in machine shop was trying to get the correct register size before it came back while I had the extra time , will have to wait for it to come back and try the 68 flexplate.

just ask them to do a kwik measurement

Ok , took the 1968 flex plate to machine shop and it fit the 1966 crankshaft perfectly , thanks

Sorry, late to the game.
I thought the change in the register diameter was done in 64/65. 66 should have been the later version.

For what its worth, as long as the flex plate fits over the crank flange, the larger diameter register flexplate still works on the small register flange. The 6 bolts will hold it fine. At least it did on the one I beat the crap out of for nearly 60,000 miles.

ballsy IMO, LOL but hey it worked

Geeez, I wonder why engineering spent all that time and money developing the fit and function of the flex plate pilot hole to crank flange radial and lateral runout spec.?

Better buy lottery tickets.

I ran into a problem using a later model ,1967, flex plate on an early 273 crank years ago in the mid 1980s or the late 1970s CRS
Maybe it was the inner register