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Engine Help

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stevebn2bj7

Jedi Warrior
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Just got the ngine in my new BN7 and got it up and running ove the last week. Yesterday I got everything connected and got it up to full operating temperature with no problems other than not being able to get it to idle. When I played with the carbs I could still not get it to idle. I went to move it and when I pushed the clutch in the mototr stopped abruptly and seized. I quickly got it out of the car and took it apart and when I loosened the bearing caps it spun right up again so luckily no serious damage found at this point. When I put it together the machine shop said that the journals all spec'd out at the original dimensions so I bought standard bearings for both main and rod from Moss. It was cold out when I put it together and the plasti gauge measured out near the smallest tolerance.

My guess is that when it came up to full operating temperature everything expanded and then bound up. That may explain why it would not idle. Does this make any sense? If so, is it possible to sdjust the bearings to make the tolerances larger? Any other ideas/

Thanks,
Steve
 
Have you checked the thrust washers? You said when you pushed the clutch in is when the engine got tight some I'm wondering if there is a problem with the thrust washers. Are the thrust washers in correctly? The side with the groves faces the crankshaft. The groves are there to provide oil lubrication to the bearing thrust surface of the crankshaft.
 
This probably isn’t the culprit, but I’ll throw it out there anyway. The PO of my car (my dad) had installed the clutch disc backwards. The evidence was the inner half of the flywheel bolts had been worn away, almost to nuthin’. It was tough getting a socket on them to remove the flywheel. If the engine is out of the car, that could be an easy check.
 
Terry,

That is one thing. They were in backwards. I assume the grooves you are talking about are at the top and bottom and are vertical. Will have to check with the machinist if the fine grooves left by having them in wrong are a problem.

Thanks
 
Steve,

I wouldn't think fine grooves (scratches) would be a problem. Coarse groves would be a problem. Yes, the vertical groves are what I'm talking about as far as the lubrication for the crankshaft thrust bearings.

Can you check the crankshaft end float? This can be checked with the engine in the car. Use a magnetic base and dial indicator. Using a crow bar, prise the crankshaft towards the back of the engine, careful not to damage the front pulley. Note the reading on the dial indicator. Next, push the clutch down, which will push the crankshaft forward. Note the 2nd reading on the dial indicator. The difference is the end float. If the end float is too tight, I could see how this could cause the engine to get tight. Did you use stock thrust washer or have you fitted oversized thrust washers?

Have you tried turning the engine since it cooled down? You may want to pull the plugs and turn it by hand to see if you can feel any binding with the engine cool.
 
Terry,

I took the engine out of the car as soon as the problem happened. I am at the end of a restoration process so there is no body on it yet and I just put it in a week ago so it coame out quickly. I have it mostly apart at the moment and yes it is turning very easily again. It freed up as soon as I loosened the main cap with the thrust washers in it. I used the standard thrust washer and am trying to find a way to measure the end float. I am going to get new washers as the ones I used have some wear from the faulty installation.
 
I assume you know about plastigage:

OEM OEM Aftermarket Aftermarket Ordernow Ordernow Master Master Diametrical Diametrical Cross Reference Cross Reference Individual Rings Individual Rings Order Now Order Now Tech Tips Tech Tips Distibution Centers Distibution Centers Order Now Order Now Plastigage
Check bearing clearances the modern, fast, accurate way with Hastings Plastigage. Plastigage is a special extruded plastic thread with accurately controlled "crush" properties. Extremely handy for checking main and connecting rod bearing clearances, oil pump cover-to-gear clearances, and for many other clearance checks.

Envelope
Part No. Size Color.
HPG1 .001 to .003" -- .025 to .076 MM Green
HPR1 .002 to .006" -- .051 to .152 MM Red
HPB1 .004 to .009" -- .102 to .229 MM Blue
HPY1 .009 to .020" -- .23 to .51 MM Yellow

Each box of Plastigage contains 12 strips in individual calibrated envelopes usually enough to check 12 engines. Available in four clearance ranges.

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