Using 2 different halves

[vector mike]

Do you guys remove the pins when using 2 different halves so they will self align themselves? Or do you just drill the holes out bigger on one half? I'm talking about my BP motor.

[Sparkroost]

IF? You can get the journals to line up correctly, you would re-drill new holes after you get it positioned and use larger taper pins, or drill a new location if one is available.

[Travis Fulton]

every body that i have talked to just gets rid of the pins?

[Sparkroost]

that works too! The pins are there for a reason though. They line up the bosses perfectly to where the block was machined, originally.. Those pins are put in first during assembly. There is some slop in the bolt holes that would allow your halves to not be aligned perfectly.

You will have to put the halves together and indicate the bores, tighten down, then make your taper pin holes.

[patchesII]

i just had a motor ported by JSRE and my front half wasn't a numbers matching piece. jay removed one of the dowel pins and he said that will allow it to align on the crank when i put the motor together. i cranked it for the first time sunday and so far it hasn't grenaded. i would hope not, it's just got idle time on it right now.

[Travis Fulton]

i would say jay would definatly know

[Reese]

what is keeping the two halves from shifting or pinching over time?

[patchesII]

--

[Hooty]

I install the crank and mains in the block and then put the cover on, align it with the pins and torque the six main bearing bolts (V6 OMC). I then install the flywheel nut and with a socket and ever short handle wrench, turn the crankshaft and feel for any binding. The short handle wrench makes it easy to feel if there is any binding.

c/6

Hooty

[LAZZER65]

Not to step on anyones toes, but here goes:

Where you run into a problem is not neccesarily the alignment deal but the off center alignment. What I mean is that if they were above or below center when they line bored the journals from one block to another you will wind-up with an out-of-round bearing bore. Bad on bearings and they won't live. Jay is right about letting the crank and bearings line the two halves up, but you gotta watch out for collapsing or worse yet..not having sufficient (EQUAL) force to capture the outter race of the bearing. Sure, the motor may live for a while, but it will never be a long lived motor if something is out of whack.

Now...If you wanted to do it the right way. You would probably have to experiment with several front halves to find one that was within specs. To do that would be a god awful pain in the butt. You would basically have to have a horizontal boring mill and attempt to line both halves faces up then with a line bore bar go through each journal to check for concentricity.

I am not saying there is a right or wrong way here. I am just recommending, maybe a precise way to do it so that you have what was produced in the factory. In otherwords, everything lined up and lasting as long as they were intended.

Hope this helps.

Dale