So i just picked up a 350 short block from a friend at work for 200 bucks. Been sitting in his garage and had some dust in it due to having no oil pan, and a little cylinder rust. The rust cleaned off really easy with some pb blaster, and I started disassembling it to check the clearances and de-glaze the cylinders for the new rings. I really dont have much money to spend so im just looking to do a basic rebuild. Going to re ring, deglaze/hone the cylinders, new freeze out plugs, and i would like to put new rod/ crank bearings.

Today i pulled all the pistons, and labeled everything accordingly. My question is, could i install new rod and crank bearings without having to get the crank machined? The crank journals are in great condition and do not have any scratches or schoring. Before i pulled all the rods and pistons, i plasti-gauged the rod bearings and everything was at .003 which according to my chilton manual is within spec. Like i said i dont have much money to spend, so any help would be appreciated. Would new bearings be a good idea, or would i be better off using the orginal bearings without machining the crank? Thanks

 

.003" is about the max. Mic the crank and make sure it's ok. I try to get .002 clearance. A high volume oil pump would be a good idea otherwise.

 

Ok thanks, what spec should i be looking for on the crank?

 

Check the back of the bearings for std, .010, .020. Standard is 2.10/2.45 ...double check those. I'm trying to remember.

 

I called up the machine shop and they said it would cost 60 bucks to have the crank mic'd and polished. Think im gonna go that route.

 

hey just figured Id post an update. Payed 195.00 with parts to have the work done. This included hot tanking, cam bearings, and freeze plugs, as well as polishing the crank. He did a great job for the price. Crank is still within spec at 2.448 mains, and 2.099 rod journals. Heres a pic after paint.

 

Alright, I'm running into some issues with main bearing oil clearance. I know plasti-gaiuge isn't the most accurate method of measuring bearing clearances, but i don't have any special measuring tools to use otherwise. Im using Sealed power standard size bearings. The issue i am having is with the rear bearing before the main seal. Im getting around .003-.0035 of clearance which seems very loose. Every other main journal is around .002-.0018. I ordered a new set of ARP main bolts, but I don't think that is going to tighten anything up.

Not sure where to go now. Is there a better quality bearing i can try, or should i replace the crank?

 

Could i replace the rear bearings with a .001 undersize, and leave the rest alone? That should bring it to around .002 like the others.

 

Yes you can.
Pros sometimes even use 2 different size bearings on one rod or one main. Its how they tighten the clearance to what they want. (part of blueprinting)
Don't use a high volume oil pump unless you have a 7qt pan.
Use a normal standard volume and psi oil pump for the car.

 

Ok thanks. I ordered a set of the same sealed power bearings, but the little more expensive aluminum set. They were a favorite on rock auto over the ones i bought before. Gonna re measure with those bearings and the arp bolts. If its still loose on the rear bearing, ill get that one bearing .001 undersized. Ill post my results. Thanks again .

 

I would run it. If I plan on using a light oil I use a high volume pump. I use 20w 50 in my race car so I use a standard pump. You can use a high volume pump and put a lighter spring in since the pressure will be too high with the hv pump.

 

HV pumps suck a stock pan dry at high rpm. No need for them, they cost some hp and wear the dizzy gear faster..

 

What rpm is too high?

 

I have seen it happen as low as 4,500 rpm

 

I got my rings in today and noticed that the top ring isn't as deep as the original rings. I checked the ring gap, and the top and bottom rings are both in spec though. The rings are sealed power plasma moly. Is this difference in depth going to effect anything? Not sure if i got the wrong rings.

The sealed power rings are on the left, and the original rings are on the right. You can see the top sealed power ring on the left isnt as deep as the rest.



Here you can see the new ring sitting on top of the old top ring, and difference in depth. The thickness however is the same.

 

Well with the arp bolts and new bearings i got all the clearances down to exactly .002 except the rear main cap, which is at .003. Ordered a .001 undersize bearing which is coming tomorrow, so well see how it goes.

 

Got the crank in today. The .001 undersize worked great so all my main caps are between .0018 - .002. End play is within spec, rear main seal is in, and everything is spinning smooth and freely. I started putting in the pistons, and measured the first two rod caps with plasti-gauge.

#1 was about .0028 and #2 was at .002. What clearance should i aim for with the rod caps?

 

Bottom end is together. I lucked out on the rod bearings, every one was at .002. Rod side clearance was perfectly within spec as well. Gonna order the cam when i get my tax return, going with a comp cams xr276hr. On a budget so Im picking up a nice set of 64cc dart aluminum heads with 2.02 inch valves, plus a port and polish. Gonna finish it off with an edelbrock performer 75013 and holley ultra double pumper carb. With 10.2:1 compression it should make around 400hp .

 

I'm going to start a 350 rebuild within the next few days, never messed with the bottom end of an engine, just cam/heads swaps etc, so I'm new to it. Mind if I pm you and ask the occasional question?

C.