8Mike9

Anyone have their Helms manual handy? Can’t find mine. I’m at .0035 for end play, my old MoToRs manuals are too old for Chevy V8’s. but keep coming across sites saying .004-.011 as well as .002-.006.

Would like to see what GM uses.

This is a ‘89 block I’d like to finish the bottom end today.

Thanks

sofakingdom

iTrader: (1)

You need "some" but not "too much". It's not critical at all. Generally, a little too much is better than ANY not enough.

I usually shoot for around .010".

No idea what GM's "spec" for it was. I've seen factory motors with HILARIOUS variation in it, so, even if they had one, they either (a) didn't check it, or (b) decided it wasn't worth scrapping parts & labor to try to maintain it "correct" in production motors. Since it's determined by the crank grind, "rebuilt" motors usually have more than they did originally, however much that might have been. As long as it doesn't get too much past .015" or so, i.e. enough that the small end of the rods at the pins are forced up against the side of the space in the piston that they're supposed to go, it doesn't matter.

As you bolt up the rear main cap, bonk the crank forwards and backwards acoupla times with a BFH and a 2x4, to settle the 2 halves of the main bearing in the same vertical plane.

8Mike9

Oh, crank has been bonked for and aft. So a bit of a back story here is why I’m concerned. I’m using Clevite P series mains. After caps in place and snugged down to 20 ft/lbs, I couldn’t rotate the crank.
I’m just under .003 for all main clearances. So on to the end play rabbit hole.

after taking .003 off the thrust bearings I’m able to freely rotate the crank by hand just with a finger pushing on the throws.

So for grins I check end play without the rear cap torqued at all and had .005, but as I snug it down the cap moves the crank back to .0035.

I’m assuming the crank is walking back off the filet now so taking more off the front thrust won’t get me anything.

I can’t dial in my old 4 jaw chuck well enough to cut on the crank. Well, I could if I was able to rig up a tool post grinder and dress the jaws.

My concern is with some of the “Google” specs I find I’d hate to screw it all together, fire it up and have to pull it out again.

I trust your judgement even from the old days.

Should I have concerns or run it? ( no liability implied )

NoEmissions84TA

iTrader: (1)

When assembling thrust bearings:

1. Tighten main cap bolts to approximately 10 to 15 ft.lb. to seat bearings, then loosen.
   
2. Tap main cap toward rear of engine with a soft faced hammer.
   
3. Tighten main cap bolts, finger tight.
   
4. Using a bar, force the crankshaft as far forward in the block as possible to align the bearing rear thrust faces.
   
5. While holding shaft in forward position, tighten main cap bolts to 10 to 15 ft-lbs.
   
6. Complete tightening main cap bolts to specifications in 2 or 3 equal steps.

The above procedure should align the bearing thrust faces with the crankshaft to maximize the amount of bearing area in contact for load carrying.

8Mike9

I appreciate the info, but that's what I've done all the time over the years. Funny thing (well funny to me) is I've never checked endplay before, if something was amiss tightening down the caps, I'd get it figured out. But after several iterations of no love, I looked into endplay and it is/was the issue.
Then on to the "rabbit hole" and figure since I found some specs, and can't find my manual, I though I'd see if someone here had the Helms available and what it said.

8Mike9

Ya, I know y’all been on the edge of your seat here. So I grabbed a Helms off of eBay, just went through it. No spec for end play on V8’s, only 6’s at .002-.008. I’m gonna screw it together, stick an intake and carb I have on it and run it for awhile on my engine stand and see how it goes.

Will swap the distributor get I have to a points one.

Should be fun

83 Crossfire TA

iTrader: (2)

The reason that the factory variation is so bad is because of the way they (used to? not sure if this is entirely true anymore) assemble engines- take some crude measurements of a few different things that are make or break parts, drop them into bins dividing them up into ranges and then assemble with parts from a series of bins that should put the end result somewhere near the middle of the range. Nothing was measured, weighed, balanced... like a proper engine builder would and this got thousands of engines out the door for $$$ less than if every one was custom matched and built, and only a small percentage were junk and those were replaced by dealers when they were out of that big pile of thousands of cheap engines.

As long as that endplay wasn't in a range that caused something to go boom it didn't matter what it was, and I'd bet that even if it was most didn't check and find out, it got replaced if under warranty (I used to have a friend that worked at a GM dealer and we used to "build" our race engines out of their warranty core pile for the core cost, and usually it meant going through and swapping bearings out unless we wanted something better in them) and if it made it past warranty it was good, it was someone else's problem.

83 Crossfire TA

iTrader: (2)

You know, it's funny, I don't know that I've ever used a factory spec for something like this. When it was in doubt for most stuff it was old '80's Chilton's manuals that covered something like all the fox chassis fords and if it was a real "performance build" it would be out of one of those soft cover books, half of which were written by Vizard and titled something like "How to Build a High Performance Small Block..."

I'll have to look when I get home, I have half a dozen FSM's that cover various small block powered cars and trucks (80's through 90's LT1), I'm curious if any of them even list a endplay spec.

My instinct is that you're a little on the tight side, but what the heck do I know...

RBob

iTrader: (1)

According to the '92 FSM, on V8 engines the crank end play spec is 0.001" to 0.007"

So at 0.0035" you are right in the center of that. I'd say good to go.

RBob.

8Mike9

Lol. Like I mentioned before, I’ve never checked it, heck, crank turns, let’s keep going. To be honest I’ve only put together a few engines though. Couple of SBCs a few fords and flathead 6’s.

There is a different between an engine builder and an engine assembler

8Mike9

Thats good info. Not any difference between an ‘89 and a ‘92 that I know of.

Going to put in the rods and pistons this weekend, get the cam in and hopefully get the time to take apart and clean the lifters. Might wimp out and buy new ones.

But looks like I’m going to spend some more time on the heads. Way back a member here (I think was Rhuarc?) Did a long post on porting L98 heads. Showed flows, etc. up to the point he had to start filling things in the ports. So I followed his post, picked up a set of 083’s from a member here, tore them down, went to work on them. 20 years later…took them into the shop for a quick shave, valves, ect.

had them bagged and standing up. Buddy came by and sat down, for some reason he thought he’d prop his legs up over this plastic bag. About the time I got the “be” out of be careful, he knocked the heads over. 3 or 4 bent studs on each head. Oh well. Gotta pull the studs, send them back to the shop, may as well go screw in.

83 Crossfire TA

iTrader: (2)

I think of myself as more of a butcher- I know enough to do some really cool things, but in reality, the stuff that I run can end up pretty half-assed and rigged. OTOH, that stuff seems to run better than the stuff that I really spend time and money on.

NoEmissions84TA

iTrader: (1)

Okay children, now it's time for a bedtime story - SBC crankshaft thrust bearing trashed in 1/2 hour.
A buddy of mine bought a 63 Nova with a built Gen1 400 SBC in it. One day he grabbed the crank pulley for whatever reason and it moved back and forth in the block about 1/4"!!! We took it apart and found the sides of the thrust bearing gone and obviously wear to that part of the crankshaft. The block itself luckily had no damage. Not knowing the history of the engine, we installed a new crankshaft and bearings (proper clearances) and the thrust clearance measured .006". And, yes, we squared the bearing by tapping the crank back and forth with a large rubber mallet. Also, everything was flushed and was as clean as possible.
I fired it up on my engine test stand and we ran it for a half-hour at no less than 2500 rpm to break in the new camshaft. Break in oil was used and the cam and lifters were properly coated with Crane Cams moly lubricant. Everything seemed great. After I idled it down, I detected a small noise in the lower end. I drained the oil and saw more silver than I would like to. I dipped a magnet in the drained oil and the silver paste stuck to it. I dropped the pan and found the thrust bearing and crank trashed as before. WHAT COULD HAVE POSSIBLY CAUSED THIS?
We never did figure this out. Anybody?

RBob

iTrader: (1)

Sometimes on new crankshafts the thrust surfaces are not smooth. They are rough, which causes them to eat the thrust bearing. In this case need to polish the crank thrust surfaces.

RBob.

vorteciroc

Do not pound on the Balancer with a mallet, unless you wish to increase end-play.


Try and aim for 0.0060" to 0.0090" Travel (cold).

sofakingdom

iTrader: (1)

Sounds to me like the block was the victim of one of those infamous 60s/70s Problems. Specifically, The Bore Perpendicularity Problem, wherein the bores are not perpendicular to the crank axis, but rather, are "tipped" frontward or backward.

Consider a crank and a block and pistons and rods when the bores are right. The pin can float in the piston pin bore about 1/8", and the rod can float along the rod journal about .010" or whatever; the side clearance, whatever it is. As the pistons go up and down, everything is free to slide in the direction of the crank axis. The small end of the rods is rarely in the exact center of the space between the 2 sides of the pin bore: that would require the bores to be located exactly over the center of the half of the rod journal for that rod; highly unlikely. The small end is usually closer to one end or the other of the space it can occupy.

Now consider what happens if the bores are "tilted". Instead of everything floating and finding its own comfortable "center" to run in, the rod doesn't move stright up and down but rather has a front-to-rear component as well as being "tilted" with respect to the crank axis, the big end of the rod is forced to move front-to-rear along the journal, and the piston pin must do the same in the pin bore. It doesn't take very much "tilt" before the rods run out of side clearance and the small end of the rod is hard against the side of the space in there. When that happens, the up/down motion of the piston, causing the big end to bind on the rod journal, HAMMERS the crank front-to-rear.

In such a motor, examine the sides of the rods for unusual wear (not circular), the sides of the rod journals for wear, rod bearings where the cap half and the rod half are worn heavily on opposite side, the pistons for signs of the small ends hitting them, etc.

sofakingdom

iTrader: (1)

I should perhaps also note, that as we all know, while building a motor, it's normal for the crank to be slightly harder to turn as it reaches a point where a piston is about at the middle of the stroke, because at that point, it's moving the most in relation to the motion of the crank. A motor that has this Problem will be harder to turn when the piston is at the top or the bottom, or both, of the stroke, because that's where the binding is worst. If you're like me and build a motor one side at a time, and when you put in the 1st piston on the 2nd side, and it seems to begin binding heavily, then this is probably what you're dealing with.

8Mike9

Some very good points raised. I think what I’ll do is now hang the rods and pistons. And see what type of crank walk I have.

WTF, it’s just time and effort

NoEmissions84TA

iTrader: (1)

Thanks Sofa. That makes perfect sense.
It really made me say WTF at the time, because all the crank had on it was a balancer and flexplate running on the engine test stand. So no flywheel & clutch or torque converter to cause this. But that engine is long gone now, so it will unfortunately remain a mystery.