Originally posted by Paddy:
Thanks Mike. Could you answer a couple of more questions for me?
The original builder/owner of this motor didn't have the card anymore and wasn't very open about it's internals. This motor came installed in a very nice 78 Malibu drag car I bought.
On teardown everything looked good except #4 wrist pin was loose and deeply scared the cylinder. I hope it can be sleeved cheaper than the cost of machining my spare block. (These are press fit rods)
The other not so good was all of the main bearings had abnormal wear at the forward .25" but normal wear on the rest. The rod bearings looked new but there was a detectable ridge on the journals between the rods. Any ideas why this would happen? I used Mobil 1 syn. 20/50 oil.
I will replace the stock 5.7 rods andcast crank with forged. In this motor, shifting at 6800 and seeing 7200 at the line, would Scat or Eagle be OK to use? It's external balence now but I'll internal balence it this time, I need a SFI flex plate anyway.
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The wear on the crank & bearings is probably from the metal from your cylinder wall.
Don't know why it's on the outer part of the bearing unless the crank is bent, block needs line honing or was line honed wrong, or the crank was tapered in the journals.
What crank was it? Was it fresh? Too many unanswered questions to tell you why & even then it's just a 'uneducated guess"
If you are replacing everything don't spend a bunch of time worrying about it, just be sure the main bores are reasonably straight & the right size.
As for a sleeve, it's not a big deal to install a sleeve & I have done a lot of them but it will effect the cylinders on either side quite a bit so in a performance deal I am not real fond of installing one unless I am going to bore the whole block. Done it & it seemed ok just not real fond of doing it.
I prefer round cylinders
For "budget" cranks, I only use Scat & feel they are the best of the import stuff out there, mainly because they do all there finish work in house. Excellent quality control.
Buy it from a Scat dealer or direct as there are a number of "blems" out there.
Use a 6" rod & it will internal balance without issues plus you will have a lighter piston,, both good things.
There are some that will tell you the pin being high will cause problems because of the support rail.
In my opinion this is second hand information from stuff people repeat without any first hand experience & is crap.
One exception is the KB pistons. They do not use a support rail & I do not like the way they keep the lower oil rail from turning.
I know of a number of instances where the pin has failed & there is a member on here who has had it happen also.
If you email me I can give you a price on a balanced rotating assembly with Scat forged crank, 7/16" capscrew rods (this is a very nice rod) & SRP pistons for a pretty reasonable price or I can sell you the parts & you can have it done locally.
If you buy from a mail order place, just buy the parts & have the balancing done locally by a shop you trust,, I am not a big fan of some of the generic mail order "balance" jobs I have seen
