304 rebuild question

[st3dnut]

Hello everyone,
I've been reading and learning lots of good info on the forum but this is my first post. I have 304 that will be going into a CJ8 that I'm restoring. Just got the engine back from the machine shop. New valves were installed and I have new pistons to install due to haveing bore cylinders out. I'm going with an edelbrock performer cam and intake. So here's my question.... If I buy the new rods with the smaller diameter hole would I new to replace rocker arms also?

Thanks in advance!
Sean

[tufcj]

Welcome to Bulltear!

If the rockers don't show any abnormal wear (at the pivot, push rod, and valve stem surface), you can re-use them. Just coat all the contact points with a high quality break-in lube when you assemble the engine.

Bob
tufcj

[st3dnut]

Thanks for the welcome,

I appreciate the reply, I'll clean the rockers up and give them a look. This is my first engine build so I'm trying to learn all I can. As far as using the pushrods with the smaller diameter holes. I see there are bearings and rockers with smaller holes also. I've read some posts where other people have asked about using a combination of these different parts and the answer has been that it would cause too much oil pressure. My assumption would be(and I still have alot to learn) that these parts were created because AMC engines as originally built could benefit from more oil to the crank? Please tell me if that is not correct.

So for my engine which will be used mostly on trails at hunting camp and around town, are the smaller diameter hole pushrods something that would be a benefit for me or should I just use the stock pushrods?

[tufcj]

You are correct. The oiling path on AMC engines takes oil to the cam and lifters before the mains and rods. By decreasing the flow to the top end, it pushes more to the bottom. My 390 uses the cam bearings with smaller holes. The trouble is that most home mechanics don't have the tools to swap cam bearings, so the smaller hole push rods are the next place to slow the oil. Even with those, there is still plenty of oil to the top end. You don't want to use small cam bearings and pushrods, as you could starve the top end for oil. The big thing is the oil pump. Make sure the housing and cover plate aren't scored, and the gears are good. Check that clearances are to spec. If they aren't, replace the cover and gears. Restricting the oil flow won't help if the pump isn't moving enough oil.

With a quality rebuild, and normal use, the engine should run another 100K miles, it did from the factory. Most of the mods are for regular performance use. I drag race and autocross my AMX occasionally, and rev it to 6000+ RPM. My Jeep (360) is a rock crawler, seldom revs above 3500, and it's oiling system is BONE STOCK, rebuilt about 50K ago, with over 160K on the block.

Bob
tufcj

[st3dnut]

Ok folks now I'm really gonna bug ya'll!

Please excuse the coming long winded post. I had the machine shop work done on my engine by a local retired engine builder on the recomendation of a mechanic friend of mine who has had engines built by this same builder. He does mosltly race engines. My mechanic friend offered to help me assemble the engine after machine work was complete. So, as stated in earlier post I have engine back from machine shop. Head is assembled, all rings installed on pistons, crank polished, cam bearings installed. Builder purchased all gaskets and std main bearings and std connecting rod bearings. Due to reasons that there is no need to explain here, I no longer want to ask for the help of my mechanic "friend" to assemble the engine. I am assuming that I cannot take for granted that just because the builder provided the std bearings that I can just assemble the engine without checking bearing clearences. I have a FSM and have read the procedure for checking with plasticgauge and I'm sure I have the ability to do this. However, according to the procedure for the main/crank bearings, only one cap should be taken apart and checked while the others remain torqued. So can ya'll help point me in right direction or explain to me the procedure on how to check clearences of main and connecting rod bearings on a freshly machined engine? Again, I have the FSM which gives the tolerances and what bearings to use depending on micrometer measurements, so can I just measure with a micrometer checking for roundness and overall size or do I assemble with std bearings and the check one at a time with plastic gauge? Again, sorry for long post. I'm sure I left out some information.

Thanks in advance for any help!

[tufcj]

I've assembled many engines using plasticgauge. I install the crank with the bearings dry (don't turn it). Torque all the main caps, then remove one cap at a time, set the plasticgauge crosswise on the main, re-install and torque the cap. Remove the cap and measure. If it's within spec, clean off the plastic with a clean lint-free cloth, oil the bearing, retorque the cap, and move to the next. You just want to be careful not to turn the crank until all the bearings are checked and lubed.

Rod bearings are done the same. I usually do both on the same journal, then move on to the next.

If you have a GOOD inside and outside micrometer, you can measure the journal, then install the bearings in the cap, torque to spec, and measure the inside diameter. Subtract the journal diameter from the inside diameter of the bearing and you have the oil clearance, no need for plasticgauge. You do need good tools, better than you get a Harbor Freight.

If you measure the crank journals, it will be pretty obvious if they are cut other than standard, normal cuts are .010", .020" and .030" undersize (some go to .040 and .050).

Bob
tufcj

[ironman_gq]

plastigauge is very easy to do yourself as long as you follow the directions and can use a torque wrench. If you havent ordered your cam yet, Look at Engle racing. I think the edelbrock performer cam is 110LSA cam, I got one from Engle that is ground to make power from idle to 4500rpm's with a 112LSA which gives a smoother idle and more torque early on with a flatter torque curve. Price is pretty close to the edelbrock. I had the edelbrock first and didnt really like it that much. I am much happier with the Engle one

[st3dnut]

Thanks guys for the help. That's the same procedure described in the manual I have. Was just unsure if I could do it the same way with an unassembled engine. I was able to contact the guy at machine shop how did the work and he assured me that he mic measured the crank and that it was ready to assemble with the standard size bearings. Is there a need, and if so, a way to check for any "slop" between the bearing and the main caps?

[tufcj]

I always check the bearing clearance no matter what assurances the machinist gives me, just for my peace of mind.

A friend who's into Toyota's bought a pre-built 22R motor from LC Engineering, one of the best Toyota engine re-manufacturers out there. Once we got it in and started, it had a knock when revved over 2000 RPMs. We called them, checked and re-checked everything, finally threw our hands in the air and pulled the pan. A quick check of the crank showed it was cut .030", it had been assembled with .010" bearings, by a pro. LC sent us .030" bearings and new gaskets, we put it back together, and it ran for years.

Bob
tufcj

[st3dnut]

Trying to install the crank and already I'm having a problem. The crank doesn't want to sit down on bearings. Problem seems to be at rear bearing. I've attached pictures so you can see the problem I'm having.

[tufcj]

The bearing you're showing in the pics is the thrust bearing. It goes in the #3 journal on an AMC. The rear bearing is just flat. The extra slot in the rear journal is for the oil seal. This isn't a Chebby.....


Bob
tufcj

[spike_africa]

This post and those pics helped me tons! Thanks guys!