Technical 327 problem

Before you button this engine up , if that is an overseas made chrome timing chain cover and throw it away , unless you want oil leaks !! Replace with a stock GM cover . Later Bill

 

I hope your machinist checked the crank for being straight before he cut and polished. Checking the crank should be the first thing. Wasn't mentioned by anyone so just food for thought.

 

I give you credit for jumping in the deep end and that's a way to learn but you maybe should of got someone with some experience to lean on while doing it. Then again if they don't do it right then your no further off.

 

I measure between the rods.

 

jimmy six answered your question. You should be able to easily move the rods back and forth on the crank journal. If you have to force them, that’s your problem.



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There is a way to make them fit without leaks, but not everyone does it

 

Sand the chrome off the gasket surface.
(Found it was the only way I could get a chrome oil pan to seal)

 

On the timing cover sandblast the channel where the seal goes, usually works . Later Bill

 

I also am going to give you some things to check and suggestions on how to proceed:

Before you do anything else, look at the pistons in the bores. If there are domes, they should be toward the outside of the block. I taught Autoshop for many years and probably saw this 6 or 7 times.

I noticed that the crank has 010 stamped on the notch in the counterweight. See if your crank guy marks his under sizes like that. Also seems to have a green 10 on the front counterweight. Did you check the clearance on the mains? Doesn't sound like this is your problem, but if the mains are tight, the rest of the assembly will add to that situation.

I'm a little suspicious of a crank grinder that cuts only .002". It can be done, but reground cranks are almost always .010" or more, usually .010", .020" or .030".

Nothing inherently wrong with Plastigage, but something I have seen, guys forget to remove the PG after they measure. It takes up space, so you have to clean it off after you measure. It is oil soluble.

To correct something you alluded to;
A .005" under size bearing will NOT give you more clearance. Under size bearings are thicker to compensate for the material removed during grinding.

Something I ran into in my very first engine rebuild: (283 Chevy) The rear main used a rope seal. I don't know the recommended installation procedure but after installing it, it was very hard to turn the crank. Adding piston/rod assemblies made it harder and harder as I went. By the time I got it done the starter could not turn it over. The solution for a 17 year old? Pull start with a tow bar. After a 20 minute break in, everything worked just as it was supposed to.
I don't know if early 327s had that seal but it can be a source of tightness.

Finally, if it were me;
I would disassemble the entire short block. Wash all the gooey cam lube off everything except the cam and lifters. Look at each bearing as you go. Reassemble making sure the rod bearing tangs are to the outside of the block and are on the same side of the rod journal. Use 30w oil to assemble the lower end.

As others have said, check the ring end gap. For your engine around .012" - .016" would be about right.

As you add pieces, rotate the crank at least one full turn after each piece is added.

If you follow all these suggestions and those of the other guys, you will find the problem and you will be able to fix it.

 

Sometimes the aftermarket tolerances aren't as good as the factory (GM,Ford,etc). Drill the bolt holes slightly oversize, install loosely, and install the balancer, This will center the seal to the balancer. Then tighten the retaining bolts

 

Did you forget there are locating dowels?

 

To be honest, this was a tip I got out of Hot Rod mag I believe it was. I just went out and checked mine, and you are right there are locating dowels. I suppose the tip could still be used carefully, but one would be better off using factory stuff anyway. I always use factory painted ones. I figure dirty paint looks better than rusty cheap chrome

 

I think the problem is with the Rods, either mis-matched are wrong end cap on wrong rod.. IMHO

 

Hmmm but that’s not quite how I roll.

Yes It is .010 and my bearings are stamped the same, not sure why I was saying .002.
Anyway I found that two of my rods are tight on 1 and 2 just one on each will not move side to side, the other is fine. the Chamfer is to the crank and the tangs are to the outside of the block and on the same side on each of them, but those two don't move side to side and the motor is stiff when they are torqued up.
When I loosen or torque the mains nothing changes at all.

 

that is the problem because two won't move side to side when torqued but other 6 are fine. they are all new though.

 

I did that took the chrome off the sealing surface, thanks

 

Yes you were right two are tight.

 

you are right two are tight, but they are not installed wrong.... chamfer to the crank, tang to outside of block and on the same side.

 

Sounds like you need to talk to the guy that ground the crank.

 

You said you plasti-gauged the rod bearings, what was the clearance on this journal. ??

 

Do you have access to a O.D. micrometer to measure cranks 1 & 2 bearing surface?
Could you post pictures of that rod bearing (maybe you can see where it is rubbing) also a picture of the crank bearing surface to see if the grinder left a large fillet radius. Rod and cap surface should be shinny at the contact area.
You could Blue them up (Machinists Bluing) tighten then remove to see whats rubbing.

 

Plasti-gauge is not the most accurate stuff in the world. I trust what I measure before it goes together. With my last engine I had the short block assembled by the builder, I had to put total trust in whoever ground the crank and the shop owner is meticulous about everything. If you take the rod caps off and slide the assembly into the bores, you'll have access to swing a micrometer on the rod journals. Look to see what is marked on the back of the bearing shells to ferret out something oddball.

 

Bob is right, a micrometer, with increments in tenths' and calibrated, otherwise it will be no better than plastigauge.
Someone else mentioned the possibility of dirt under one or two bearing shells causing the problem; it doesn't take much.

 

Ok I have to thank everyone it is solved now, I switched the two tight rod caps and one came free, then I kept switching them until they all became free, now everything is turning properly. and they all float side to side on the crank. This dropped my torque down to about 40ft lbs when I turn the crank, but it feels proper now, it no longer sticks.
to answer Karl Share I was getting about .00125 on the rod journals with the plastigauge.

 

Uhhhh.....switching rod caps is not the best idea....they are machines as an assembly. There is something wrong with either a rod or the crank, just because it turns doesn’t make it right


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Just to inform any of the youngsters (others too) that may be tuning in here; realize that none of us (that I recall) advised the OP to take this approach, regardless of him saying his problem has been fixed.
Looks to me like none of our valuable experience was put to use.

 

Thank you!!!!


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I'm thinking he is not explaining himself well.

 

Maybe they were backwards?


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Yes they have small grey numbers that match up on them, I had not noticed while building it they are not easy to see, I looked closer after getting them to work, now they all match.
That was my problem, actually the problem was that I didn’t understand that the rods float side to side on the crank, had I understood this I may have got it the first time.