Which engines will fit in a 51 Cyclops 75

[Rata Road]

I have some issues with my engine and if I can find a good runner I might consider a transplant.
Which models will fit straight in with no mods?
90, 100, 110 etc
Thanks

 

[jp928]

90 certainly will - had one in a '50 model, which means that at least all the 4 main bearing blocks will fit. Mine had a P3 gearbox with overdrive fitted, and twin trailing shoe front drums off a P5. I would bet that any of the 6 cyls that your gearbox would fit could be successfully mounted, even if a little longer.
This is my 50, also with 90 grille, a few chromed bits.

 

[Rata Road]

Thanks for the quick response.
My car is original column change etc with free wheel. I'm not looking for more power just a good running engine.
How do I know which of the 6cyl engines fit my gearbox?

 

[jp928]

I am 95% sure that a 90 or 105 will fit - same block different heads. A bit less sure - maybe 75% - the 100, 110 or even 3litre block will fit. See if you can find anybody with some of these engines who will give you access to them; find one with its alloy flywheel casing fitted or available and check if it fits on other blocks. Your problem may be just finding ANY P4 6 cylinder motor that is in 'good' condition.

 

[Rata Road]

It wouldn't have an issue a few years back but you could be right about finding a good replacement.
Can the rear main seal be replaced while motor still in car?

 

[jp928]

I have no experience or knowledge of P4 engines at that end - heads, rockers etc, yes, but nothing at the bottom end. Somebody may answer here, or try thersr web site.