Home 455 Reconstruction

I've got Hyper pistons .030" over and the recommended TA rings. In this case I'll have what I have, I don't have the luxury of controlling the exact piston to wall clearance. Ring gap spec. recommendations would be great so at least I could open them if they are on the tight side.

I guess I should go about .022" end gap on the top ring, I found this after a search, sound right? I think my pistons came from Poston's.

 

Well I'm back in town and I just picked up my block, crank, rods/pistons this morning. I checked the main bearings at home and they are on the loose side. Can't you take a piece of sand paper and a flat board and slide the (empty) cap back and forth over it to reduce your clearance?

Here are the clearances; #1 .0030", #2 .0027", #3 .0025", #4 .0026" and #5 .0025". I want to reduce the clearances of #1 - #4 to .0020".

Thanks to Kerry S. for the rods! It turns out the #1 rod, the rod with the spun bearing, was bent and had to be replaced.

Here are the weights the shop gave me after reconditioning the "new" rod.

Piston 784 g (.030" Hyper's)
Piston pin 220 g
Total rod 736 g
Recip. end of rod 242 g
Rot. end of rod 494

These numbers look about right? I know I've got some pretty heavy components here.

 

Oh... mercy no...

The only way to fix that is to have the block re-line honed. You have race motor main clearances now.. that will give you lower oil pressure at idle, but there will be no other bad side effects. You will prolly 15-20 psi, with a straight 40 race oil.

If you want it more toward my street motor specs, then have it re-line honed.. otherwise run it..

JW

 

I've heard you can do this with the rod caps, why can't you do this with the main caps? I'm only talking a .0005" reduction in clearance

 

Craig,

Let's think this thru..

What happens to a round hole, when you split it at the middle, and then remove material from one side..

The hole is out of round.

even .0005.. my max acceptable out of round, for a bore, is .0002, up to about 15* from the parting line. On occasion, I have run some of my personal stuff up to .0005, but have not liked it..

Your likely to do more harm that good by fussing with the bottom of the main or rod caps.

JW

 

Thanks for the input Jim, keeping things within 2 tenths sounds good.

Next, rear seal question. The instructions mention using RTV, "apply a thin coat of RTV material to the bearing cap chamfer and to the cap mating surface adjacent to the seal NOT ON THE SEAL END".

Does this mean to apply the RTV to the groove (block and cap) before installing the seals? Here's the II's from TA

 

Yes,

A very small amount behind the seal, and a thin film on the cap parting line surface.

Be careful not go get any on the seal end, especially the end that will be below the parting line surface of the block and cap.

JW

 

Look at this #3 rod bearing installation. I've tried different (new) bearings and with each one an end extends above the mating surface when the other end is flush. I've only seen this with this rod. This rod, and all other rods except #1, are un-touched from last assembly.

I know main bearings are labeled but rod bearings can go on either side (rod or cap).

Is there a measurment that can be taken from this rod to identify the problem?

Installing this rod/bearing would result in crushing the end of the bearing, right?

 

Well, I checked the cap/bearing install and the reverse case is evident there (the bearing does not quite come up to the mating surface). How often does this happen? Anything I should double check or do to ensure functionality?

I'll measure the diameter of the rod/cap without the bearing...What should this dimension be?

 

Well I looked back at one of Jim W.'s posts.

Now, the Rod bore, without the bearing, should be 2.3740-2.3745, and with the bearing, in a .010 under deal, I typically want to see 2.2410, on everything but race motors.

I got 2.3733" top to bottom and 2.3750 bolt to bolt, not ideal but the circumference should be very close.

 

Craig,

Measure the rod end with the bearing in it.. torqued up.

I think your going to find that the clearance is pretty dang tight, if your crank is a "standard" spec regrind.

I often grind my cranks to the low side of the standard spec, which is 2.2388-2.2390

with a 2.2410 rod bearing diameter, you have your 0020-.0022 rod clearance.

Now, measure your rod dia, without the bearing, at about 45* from the parting line.

If it varies more than .0005 from the vertical dimension to the 45* dimension, I would suggest a re-size. I think you going to have to dust those out anyhow, to get the rod clearance to where it should be. You can just bring them to your machinist with them all torqued up, and ask him to just put them on his rod hone, and bring the vertical dimension up to at least the bottom of the spec.

Stock rods can be a real pain to re-size.. due to the fact that the original bolts did not align the cap real well.. it's referred to as "doweling up" on the bolts.. IF the big end was bored originally with the cap not centered on the original bolts, then it was fine with the sloppy stock bolts, but when you put the ARPs in, then you end up with a cap that is shifted way off to one side, as it now dowels up on the new bolts. The only way to fix that is to cut a bunch of the rod, and then resize it, to get the cap side of the bore to line back up with the rod side of the bore.. and then you end up with a rod that is short.. and stock rods vary in length to being with, and this can compound this issue.

I can't ever recall seeing a bearing stick up that far about the parting line of the cap. It almost looks like the rod was made that way.. but I am not familiar with the exact process used to manufacture the rods... but I imagine that the rods were forged, with the big end in one piece, and then they were cut... maybe that one was cut off center. Not a real big issue, as long as the sizing is correct, and the rod bore fits perfectly with the cap bore.

Typically 1 or 2 rods out of every set have this cap misalignment problem, and are discarded.

And what your seeing with this rod size deal, can directly related to the rod bearing failure you had.

FIX IT!

JW