Engine Frustration

R

RonLey

Member
Forgive me as this a long post. When I bought my '28 Roadster it came with the engine matching the frame and was supposedly rebuilt "ready to go". I already had a '29 engine rebuilt and was trying to get ready to get ready for a tour so I used it. As this winter approached I thought a great winter project would be to get the original engine in the car.

It has been nothing but problems as the entire rebuild had been poorly done. I tore it down and have been working to get it back together. I got the mains back to .001 to .0015 clearance, camshaft in and I can turn the crankshaft as approximately 20 ft-lb so happy. So some drag but acceptable.

On to the rods and here is where I am totally lost. Just as a note I have had the pistons out and checked clearances now 3 times. I put in #1, clearance .0015 at 35 ft-lb and I can turn the crankshaft with a little more drag due to the piston. Put in #2 and clearance is .001 and can still turn crankshaft. Put in #3 and clearance is .0015 and can still turn crankshaft. Put in #4 and clearance at .0015. Can't even budge the crankshaft, it is stuck. I back off #4 to hand tight and crankshaft turns.

I back all of the nuts off to 20 ft-lbs and can't turn the crankshaft. I back off #1, #2, #3 and #4 hand tight and crankshaft turns. I tighten down #4 and it crankshaft won't budge.

One factor I am not pleased with is that the rods are not matching but mismatched caps. I would still think if bored correctly I would not have this issue. I had marked the caps when I took the engine apart so I know I am putting them back as they were assembled.

I am at a loss. I am not seeing any shiny spots on #4 that would indicate a problem. The pistons move on the wrist pins fin so it's not binding there.

I am at the point of a slightly bent rod or crankshaft. Anyone have any other ideas of what to try?

Thanks

Ron
 
agree with the hammer

there are new repop forged rods coming thru with out-of-round big ends by as much as .020. That defines 'oval' That will ruin ur day.
I am at a point where I mic every dimension of every part and have all the rods I lay my hands on re-sized

Sadly ur experience with a 'fresh rebuild' is all too common
 
Take that numer 4 rod and use a permanent marker pin to coat all surfaces of the bearing including the sides of the bearing and see if there are any high spots after you turn it a couple of revolutions. If you see them you'll have to scrape the bearing in.
 
Bent rods could do the same thing, as will improperly bored rods. After you are sure the crank is not oval or egg shaped I would use pression blue or a candle to coat the bearing surface. Put them in hand tight and turn the crank. Then check to see if the crank is in complete contact with the bearing surface. Tighten a little more if got have to.
 
RonLey said:
Forgive me as this a long post. When I bought my '28 Roadster it came with the engine matching the frame and was supposedly rebuilt "ready to go". I already had a '29 engine rebuilt and was trying to get ready to get ready for a tour so I used it. As this winter approached I thought a great winter project would be to get the original engine in the car.

It has been nothing but problems as the entire rebuild had been poorly done. I tore it down and have been working to get it back together. I got the mains back to .001 to .0015 clearance, camshaft in and I can turn the crankshaft as approximately 20 ft-lb so happy. So some drag but acceptable.

On to the rods and here is where I am totally lost. Just as a note I have had the pistons out and checked clearances now 3 times. I put in #1, clearance .0015 at 35 ft-lb and I can turn the crankshaft with a little more drag due to the piston. Put in #2 and clearance is .001 and can still turn crankshaft. Put in #3 and clearance is .0015 and can still turn crankshaft. Put in #4 and clearance at .0015. Can't even budge the crankshaft, it is stuck. I back off #4 to hand tight and crankshaft turns.

I back all of the nuts off to 20 ft-lbs and can't turn the crankshaft. I back off #1, #2, #3 and #4 hand tight and crankshaft turns. I tighten down #4 and it crankshaft won't budge.

One factor I am not pleased with is that the rods are not matching but mismatched caps. I would still think if bored correctly I would not have this issue. I had marked the caps when I took the engine apart so I know I am putting them back as they were assembled.

I am at a loss. I am not seeing any shiny spots on #4 that would indicate a problem. The pistons move on the wrist pins fin so it's not binding there.

I am at the point of a slightly bent rod or crankshaft. Anyone have any other ideas of what to try?

Thanks

Ron
Click to expand...
I will look at the shop this morning and post a item to look at and see if I can help.
 
Super Bowl interrupted me yesterday. Tonight I am going to take measurements and if I don't find something obvious move #4 to #3 position and see if the problem follows. The other idea is to put plastigauge on top and bottom and compare clearance. I will also stop by and get some prussian blue tonight.
 
Was there football yesterday? :confused::D

I spent a couple hours running after groceries and bought some tools at the pawn shop. BTW, why is it a pawn shop and not a pawn store? :confused:
I bought 3 spark plug sockets, a 3/8" socket extension, and a 12" Proto Professional adjustable wrench, all for $5. It's unusual that I find a bargain in a pawn shop.

As far as the engine being tight when #4 rod is tightened, I'd lay a strip of plastigauge across the full length of the bearing surface to see if it's even all the way across. Remember to oil the plastigauge as you lay it on the crank.

Can you move each of the rods sideways to feel freeplay as they are tightened?
 
Once a friend called, "Every half turn, my engine binds, I think it has a krooked crankshaft"------"Just take the plugs out"----------"OH"!
Bill Curious
 
You may already be doing it this way, but Pop taught me to mic each journal as I adjusted them, and always adjust them at the widest spot...each one...one at a time.

Also, I've noticed that some of the older babbits are so soft that you can't use plastigauge with them. The just sink into the bearing and don't give an accurate reading.

Just some thoughts...

Ken
 
Here's a picture of the bearings after using Prussian Blue. The babbit is soft and what you see is the indent from the platigauge.
 

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Bent crankshaft my guess, it can be reground and still get bent by the grinding operation itself if some kind of support not used opposite grinding wheel when grinding for center main. Also one thing on at a time, then two full rotations of crank for every step. Takes longer but no mystery's as to where the problem is located. By the details you have given and your willingness to go above and beyond I salute you in your moment of frustration we have all been there it sucks, mystery's are the worst. But I have good news, you are now as deep into the rabbit hole as it gets, all additional mystery's will be easier than this one. Someday you will thank the moron who put this together for what you had to learn to fix it, not today, but someday. Steve
 
The rods should have grooves to spread the oil across the surface. See this picture from J&M Machine Shop.
 

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The picture looks like the Babbitt may be hitting hard on the edges by the radius. There should be slight side to side play(the amount escapes me). Ron W
 
Maybe this will help someone else but the problem doesn't appear to be the babbit but rather the plastigauge I used. I purchased a pack at my local autoparts. A member suggested that it might have been old plastigauge that had hardened. I ordered a packages Clevite plastigauge from Jeggs and no indention in the babbit. I am getting good spread and measurements. Whether is was the brand or age I don't know.
 
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