Rebuilt bottom end - any tips

[Adam]

Hey guys,

My bottom end is off to a machine shop to be rebuilt. Aside from the usual main and con rod bearings, pilot bearing, freeze plugs, water pump, high compression pistons and rings, anything else that I should have done while the bottom is apart? and are the tri-metal bearings really worth the extra few dollars? Is having it balanced worth the money for a street car?

The top half was done last summer. I'm hoping for a reliable street car with rekindled performance.

Thanks,

Adam

[narfire]

I had the stuff balanced including a shaved flywheel. I really like the improvement. Really spools up a bit quicker. I have no issues driving as a street car,drives great,you'll love the improvement.

[mdrburchette]

It's not going to cost much more to have the machine shop balance everything so why not do it? It'll reduce stress, wear and vibration.

[baltobernie]

Also you notice that there is no external harmonic balancer on the Fiat TC, so by all means spend the few extra $$

You do have the adjustable cam pulleys, right? Once you shave the block, head or cam boxes, adjustable pulleys are required to get everything back in sync. I spent a lot of time and money trying to tune my engine after a rebuild until I finally got the cam timing right.

If you have an "interference" engine, this would be a good time to modify the aux shaft assembly to eliminate the possibility of a timing belt failure crash. Search this forum for the procedure.

And I sure hope you're not letting the shop "boil" the block to remove crud, as this process will destroy aux. shaft bearings.

[Adam]

Balanced it is. I do not have adjustable cam pulleys. Being that this is just a daily driver and I got a wedding to pay for this summer, I am not in a position to go crazy. When you say boil, are you refering to an acid bath?

[baltobernie]

No, a caustic (base, opposite of acid) water-based solution, sometimes referred to as a "hot tank", as the contents are heated. Don't know about the acid bath. Might also eat up the bearings. The aux. bearings aren't that expensive, but require special Fiat tools to remove and install. Ask the machine shop to us a "solvent bath" on your block.

Regarding the cam pulleys, they're something you can do later; you may get lucky with the stock ones. But if you can't make it run right after this rebuild, have a mechanic check cam timing before spending time and money on ignition, carburation, etc. Alvon has a thread on DIY how-to.

[brunorahl]

Don't have the block magnafluxed. Boil it, blast it, whatever. The magnaflux is what eats the soft aux shaft bearings.

It would be nice to have it balanced. Your wife will not complain as much if she rides with you. The vibration difference is noticeable.

[manoa matt]

Magnaflux is a non destructive magnetic process used to check for cracks in ferrous metals. The maganflux particles are just metal filings dyed red. If the machineist did not clean the block well after the inspection, then yes the particals would eat up all the bearings, not just the auxiliary bearings. Dye penetrant can also be used on ferrous metals. It is the only process that can be used on non ferrous metals and plastics, but its not as accurate for finding cracks.

The cylinder head, cylinder block face, flywheel, and plastic cam pulleys should be checked for cracks.

[Adam]

Engine is running great, just need to fix a small electrical gremlin. Seems that my radio resets everytime I turn off the car.

[TulsaSpider]

What pistons did you use? Did you lighten the flywheel? How's the performance? I am getting ready to do this sometime soon myself

[Adam]

had to go with a pair of 84.6mm standard compression from Bruce's. My machine shop was not comfortable boring 16 thousandth and Bruce was the only dealer with 24 thousandth. Left the flywheel as is but I did have the engine balance. The performance thus far is good, but I have to break in the block before I can get into the throttle.

Sorted out the wiring, had a disconnected ground that went to the ignition. Re-connected and running great now.