Building a 255 from a 221 block, help needed.

cas3 said:
Its not a big deal to cut the gear off the merc cam and slot it for a crab dizzy. Even a dope like me can do it !
Click to expand...

And plug the oil hole - as it is not needed with a crab dizzy. I'd also put the early cam/crank gears on it - so the thrust it toward the block and not toward the timing cover.
 
Bored&Stroked said:
FlatJack9 has it right. The reason you want to change the crank/cam gears to the earlier 59 series ones is that the thrust is opposite from the 49-53 gears. On the earlier gears, the thrust is towards the block, on the 49-53 - the thrust is toward the timing cover.

Also, run the 49-53 oil pump and the special oil-pump pickup tube that Speedway has (to fit your earlier 59 series rear-sump pan).

For connecting rods, run the 49-53 rods with the insert bearings - a lot easier to setup than the full-floater bearings from the 59 series engine (especially if you've never done it before).

Have everything balanced . . .
Click to expand...
Is the later oil pump a better pump? The speedway pickup looks truck pickup. Would that be correct?
 
39fordtruck said:
Is the later oil pump a better pump? The speedway pickup looks truck pickup. Would that be correct?
Click to expand...

The 49-53 pump has helical gears, has it's own pressure relief and will flow more oil than the earlier pumps. The 'standard volume' version is what most of us use in just about anything (other than in certain "keep it stock" situations).

The pickup you need is the truck pickup (the one from Speedway) - which is what you'd use with 39-48 oil pans. I usually use a true 'Mellings' pump - not a Speedway knock-off. In a prefect world, a NOS original or high quality used pump is a great way to go.

If you use the later pump, then "stretch" the oil-pressure relief spring in the front of the block about 3/8" -- this makes the rear relief spring "the boss". The original 39-48 pumps did not have the relief valve that the 49-53 ones have.
 
cas3 said:
Its not a big deal to cut the gear off the merc cam and slot it for a crab dizzy. Even a dope like me can do it !
Click to expand...
The slot would have to be indexed correctly.
Ol' Ron said:
Why would you want to run an early distributor, when you can run the best one for the application. Modified SBC unit.
Gramps
Click to expand...

Want to build a short engine with what we have, plus a have a restored crab distributor.
I do have one mercury cam, marked 8CM 2.
Also have 5 earlier cams. 91A ; 17 ; 59t ; 2 ; 21A.
Which is the best cam to use?
Which is the best mercury cam?
 
You must log in or register to reply here.
Back
Top