The Stovebolt Site Forums The Shop Area Engine Shop 48 1/2 ton pick-up

Hello to all on this great site. Maybe someone out there can point me in the right direction or to the proper place in the archives to find out an answer to a problem that I am having with the original 216 that I rebuilt. 1st of all let me start by saying that this is not the 1st engine that I have rebuilt. I have been doing this for more than 40 years, & this is the 1st one that has given me a problem like this, theres always one, & it seems to be the most simple, basic one at that. I pulled the original, 27,000 mile motor on this truck, as the oil pan had rotted out & you know what happened from there. I used all the best parts. Good aluminum cast pistons, moly rings,changed to inserts in the rods, stainless valves, hardened seats, new cam, not reground, new oil pump, not rebuilt, new oil distribution valve, matched aluminum cam gear & crank gear, the thrust plate has .0015 clearance & turned freely before installing, etc. etc. etc. Set the pistons up with .004 clearance, .002 on the rods, & .002 on the mains, using shims on only one side & the same side of the mains for proper clearance, had the block align honed & the whole assemly balanced, & made the oiling system a full flow instead of a by-pass system, with all the nec. mods to have plenty of volume. The truck starts & runs fine when cold, & really runs good for a 216, with plenty of power & torque. Oil pressure is around 18-20 pds. when cold & 14-15 when hot idling, after I played with the tension on the oil distribution valve. After you've had the engine running for awhile & it's fully warmed up it will not crank over, like it's seized, which I beleive it is. If I let it sit for an hour or so or turn the flywheel with a big screw driver it will crank right up, but it is really tight. I have now driven this truck over 250 miles, figuring that it was just a little tight from all the new parts & that I set it up kinda tight. I have gone thru the starter figuring since it was never gone thru it might be bad, but it was put on my friends truck & his car & it cranks right up. I even used the starter from his truck that he has no problems with & it works OK. The battery is a new Interstate VH1 heavy duty & the cables are 6 volt cables, at 1 gauge. The grounds are good & clean & the generator puts out 40+ amps. Has anyone ever had a problem like this?? Am I missing something?? I am at a loss at this point & any & all tips & suggestions would be appreciated. Eagerly awaiting any replys, THANKS, TOM TELESCO

Tom, does the engine turn over by hand when it won't crank with the starter? When you used your friends starter, did let your engine get to operating temp? Did you leave your starter on his engine long enough to be up to normal operating temp?

Retard your timing a few degrees and see what happens.

NO it won't turn over by hand, I have to use a big screwdriver on the flywheel to get it to start turning, it's not timing, pulled the coil wire 1st thing, yes the starter was used for a few days on his truck & my truck.[QUOTE]Originally posted by tom telesco:
[QB]Hello to all on this great site. Maybe someone out there can point me in the right direction or to the proper place in the archives to find out an answer to a problem that I am having with the original 216 that I rebuilt. 1st of all let me start by saying that this is not the 1st engine that I have rebuilt. I have been doing this for more than 40 years, & this is the 1st one that has given me a problem like this, theres always one, & it seems to be the most simple, basic one at that. I pulled the original, 27,000 mile motor on this truck, as the oil pan had rotted out & you know what happened from there. I used all the best parts. Good aluminum cast pistons, moly rings,changed to inserts in t

Tom,

Sounds like tolerances are a little too tight for either the pistons or the bearings, or perhaps a combination of both; thus when things are at operating temp, stuff expands enough to make it tighten-up.
Have you tried pulling the plugs and turning it over when she "sticks"?

The old Chevy shop manuals had a method of adjusting the bearing clearances utilizing the starter and an ammeter; I'd suggest cheking your shop manual and reading that particular section and checking out that end of things (no puns intended).

I 've also seen in much older shop books, re-built engines being "run-in" by belt in the shop, to "burnish" everything to a running fit; but that was definitely in the days of poured bearings, etc. Shouldn't need to do that with today's insert bearings.
I beleive you said that the new crank bearings were "align bored" or reamed?
That was necessary with the OEM shell-type main bearings.

If the bearing clearances are okay, you might want to pull the head and check the cylinder walls for evidence of scuffing, which would be caused by piston binding or inadequate lubrication.

Good luck!

Did you have plenty of clearance around the outside edge of the crank were the rod rides on the chamfer? Sometimes you will have chamfer the outside edge of the bearings with a bearing knife.( i assume you used a mic and gauges to check clearances NOT plasticgauge) I think i would pull the oil filter and check it for metal.Than i would pull the pan .If you have done motors you know one will allways bite you,and a tight motor never gets better just blows up.

I have seen some mechanics/machinist improperly interpret what a "full pressure/full flow" oil conversion is.
I'm not saying that your modifications to the 216 oil system are faulty, I'm just throwing out some tips that I've learned about this setup.

More PSI doesn't always mean more oil quantity to critical bearings, and modifying flow characteristics can alter metered oiling.

Maybe one diagnosis could be done by dropping the oil pan and checking the oil pump for debri; and also check the new rod bearings and main bearings to see IF there is a pattern of gauling. The new bearings would really show a lot of signs if they are not getting enough lube. The old shop manual way of loosening bearings and adjusting them per shims was a painful art, but it gave the mechanic a way of "correcting" an overtight or loose fit. I have read where some old mechanics re-adjusted the main bearing shims after 500 miles.

My feeling is start by pulling the warm pan, and as previously mentioned, check for scuffed piston walls. Check for overtight bearings by loosening rods and mains, one-at-a-time and see if any are really seizing when hand turning the crank. Finally check for crap in the oil pump mesh screen, and general oil pump gear condition. Sometimes re-building can leave loose metal in the system that can screw up a new oil pump?

Wishing you the best of luck.

[ 01-02-2002: Message edited by: lil' johnny ]

John,
I have to disagree that pressure and flow are inversely proportional. Maybe I am misunderstanding your point, but if you want to increase flow through a restriction or orifice you will have to increase pressure.
Jason

Were the rings checked for gap before they were installed?????

Jason,
I edited out the pressure equations cause they just confuse the issue.

My old memories of closed conduit hydraulic flow characteristics are so rusty its better for me to not bring them up.

Thanks for pointing out the source of possible confusion.

ps; my old brain got stuck on psi when it should have engaged in thoughts of velocity as measured in the mean flow in feet per second.

Here's a thought: Say you've got an unrestricted garden hose flowing 10 gallons per minute into a bucket, and you T-off a pressure gauge on the hose and it reads Zero psi. Cause its full open.

You put a squirt nozzle on the hose end and now you get a stream, razor sharp, 1 gallon per minute flow, BUT 35 psi on the gauge.

Its where and how we "measure" the psi that's confusing. Your right about the application, my thoughts were more on the concept.

[ 01-02-2002: Message edited by: lil' johnny ]

I understand your point. Thanks for the clarification.
Jason

Yeah, that really bites when you do everything right and still have troubles. I think Phat may be on the right track with the bearing side chamfer idea, expecially on the rods. I think the pan needs to come off before you run the engine any more to see what is happening. When you set up the old babbit rods, you removed shims from both sides until it took a light blow of an 8 oz. hammer to move the rod back and forth on the rod journal. Then you were supposed to add one .002 shim and you should be able to move the rod back and forth with one hand. (Pretty scientific methods, huh).

I am not sure about setting up insert rods like this, but still you should be able to move the rods back and forth on the crank. Also in the shop manual they show tightening the pin retaining bolt in a special piston vise because if you use a regular vise and clamp down on the rod, Chevrolet says you will twist the rod. I am going to get started on my 261 and will have to figure out some kind of 'piston vise'.

I don't know if I was any help, but be sure to post back with results when you find something. Also, welcome aboard!!!

The "Chilton" shop manuals go a bit further in explaining some of the problems with converting from babbit rod bearings to inserts.

Chilton manuals covering 1940 thru 1955 state the importance of checking crankshaft/rod journals for out-of-round on the full pressure conversion...too much causes excess oil to over-splash into cylinder walls... Versus...too tight a fit and no splash to lube the cylinder walls, pistons, pins, rings. Crankshaft main bearing out-of-round NOT to exceed .003. Connecting rod within .002 Sometimes Chilton says regrind crankshaft when ANY journal exceeds .0015 in. "Use a pair of micrometers and mike the journals in at least 4 places and average the reading."

Chilton manuals also say that " fit the rod bearing & adjust BEFORE new rings are installed". Adjust ALL 6 rod bearing clearances THEN remove the pistons and install rings. The "why" is because "new rings are so tight that it is very difficult to turn the crankshaft...and thus difficult to adjust rod bearing clearance due to "ring-drag".

Hope this helps... Its old time stuff from an old book...
{Source; Your Complete Handbook On How To Fix Chevrolets, a Chilton Book 1955}

[ 01-03-2002: Message edited by: lil' johnny ]