main and rod bearing clearance question

E

ericjimmysfla

New Member
Joined
Nov 1, 2014
I just got my motor back from the machine shop and I had the crank turn 10/10, recondition the rods and line hone the mains. I plastigaged the mains and rods to check my clearance and got these results

main bearing #1 00.12

main bearing #2 00.1

main bearing #3 00.8 or 00.5 this one was really tight

main bearing #4 00.15

now for the rods

rod journal #1 00.18

rod journal #2 00.1

rod journal #3 00.15

rod journal #4 00.15

rod journal #5 00.1

rod journal #6 00.1

is this normal for these motors?? or do I have a problem and what should I do???
 
No, this is not what you want for clearance. You need to put a dial bore gauge to your block main caps and your rod big ends and take a micrometer to your crankshaft. All measurements need to go .0000 one-ten thousandth resolution. Something is wrong somewhere. Did the same shop do all of your work?
 
Plastiguage is not the correct way. Those are all over the place and a bit tight IMO. I like .0015-002. I have ran them looser and no issues as well. But .0025 is the max I like to see. How does the crank spin with just oil?
 
Do you have the right bearings in it ? Your readings should be like this
0.0015

Bryan
 
You're nomenclature is off. But I think I kinda followed you. With the exception of #3 you look OK. That's assUming the plastigauge is halfway accurate.

you really need to put a bore gauge in the mains and rods... then load in the bearings and stick the bore gauge in there again, and go from there.


Just for comparison, my loosest main is .9 thou (.ooo9") and my loosest rod is 1.1 thou (.oo11")
 
I installed the crank last night with out the rear main seal, only using motor oil and torqued it to 110 in 3 step inquirement's, I have arp main studs. the crank would not turn by hand, I had to put a wrench on the crank bolt to make it turn. I loosen the the #4 main cap and the pressure was off and I could turn it with my hand. I don't rebuild a lot of motors so I don't have any mics or measuring tools, that's why I was using plastigauge, and one machine shop done all the work
 
ericjimmysfla said:
I installed the crank last night with out the rear main seal, only using motor oil and torqued it to 110 in 3 step inquirement's, I have arp main studs. the crank would not turn by hand, I had to put a wrench on the crank bolt to make it turn. I loosen the the #4 main cap and the pressure was off and I could turn it with my hand. I don't rebuild a lot of motors so I don't have any mics or measuring tools, that's why I was using plastigauge, and one machine shop done all the work
Click to expand...
You could start by going back to the shop that did your work and having them recheck everything, are they a reputable shop thats familiar familiar with performance/buick work? I am gonna guess that your main bores and possibly rod bores are out of round and or wrong size. If they are just a every day shop your probly screwed. I made the investment many years ago in the tools needed to check everything after I had a after a situation like you are in. Its way more common than most realize for machine shop work to be off on something and I am including well known shops in that statement, I have encountered Many issues over the years on stuff that goes out the door to people. At least you checked it as best you could and realized something is wrong. Do you know what torque the mains were tightened to when the shop did the align hone? The bores distort drastically with different torque values. And no you cant just loosen the nuts alittle and be ok. Where are you located at maybe there is someone in your area that could help you out or we could recomend a shop nearby to help you?
 
ARP main studs are #125 ft lbs. Take them the entire engine with crank installed, show them it won't turn. If they are a reputable shop they will make it right. If not find a new shop.
 
ARP main stud torque have different instructions depending on what lube they came with. Old sets are 95 ft lbs with original moly lube. The newer sets with Ultra Lube are 110. Motor oil is 125. The crank should turn easily no matter what the torque is. What machine shop did the work? PM me if you prefer not say in this post.
 
With the arp specs and lube type all over the place is the reason that the correct torque and lube is what the machine shop used for the align - bore/hone. If you use a different torque than the shop used your bores will be distorted. Same for the lube but to a lesser extent. Ive seen bores that came back nice and round at 40 Lbs, and 2 1/2 thou out of round at 100. This told me they were not torqued right prior to align hone. And the crank would not turn just like the OP. And was from a well known shop.
 
fastblackracing said:
With the arp specs and lube type all over the place is the reason that the correct torque and lube is what the machine shop used for the align - bore/hone. If you use a different torque than the shop used your bores will be distorted. Same for the lube but to a lesser extent. Ive seen bores that came back nice and round at 40 Lbs, and 2 1/2 thou out of round at 100. This told me they were not torqued right prior to align hone. And the crank would not turn just like the OP. . .
Click to expand...
^^^ This.
That is exactly why I let the shop handle the bottom end, or I am forced to measure everthing they did.
If "I" have to dissassemble the block to confirm clearances, I will find another shop. My $0.02
 
its a place here in tampa fl called 3d service every one always says great things about them and they all say they do a perfect job. I taking them the block and crank and pistons today, he told me bring back everything and he will double check and/or correct anything that's not in spec
 
Don Cruz is in Tampa area if you need it done right by someone else

Bryan
 
Good luck and ask if he will give you build sheet with all the dimensions before and after repairs so that you can learn a little bit about how it all works. Keep us posted with what happens and any other questions you may have.
 
with the exception of the thrust bearing main and the rear main it is pretty easy to get the other two turned about backwards.....double check that especially if the crank won't turn by hand....its hard to think that even a bad machine shop would foul up clearances THAT much.
 
If you're going to build bottom ends yourself, you really need a set of mics and a dial bore gauge. There's just too much stuff to check and measure before you start assembly.

First torque the caps, and measure the vertical clearance, then a tight 'X' above and below the parting line to make sure the cap is centered.

If that's OK, take it apart, install the bearings, and torque them down again. Take your mics, and verify the journal is round and not tapered. Set the bore gauge to each journal and measure the torqued up bearings that journal's married to.

That's the only way to know what's going on.
 
Fowler makes some budget priced micrometers and bore gauges. They work fine for occasional use at home.
 
Harbor freight ones will work too as long as they have tenths as checking mics
but what should be done regardless is they should be checked with your machinists standards so you know where your at
 
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