Replacement Crankshaft

[72Jesse]

Is this a decent replacement for crankshaft for my 1972 302 powered Bronco? https://www.summitracing.com/parts/esp-103023000#overview Existing crank has already been turned once and now the bearing surfaces are trashed so thinking replacement vs machining it again.

 

[DirtDonk]

Can't help with the replacement, but what happened to damage the old one? Is that known yet?
Good luck.

Paul

 

[72Jesse]

Not 100% but the bearing were shot and that's what did in the crank. I've had it 30+ years and don't know how old the motor was before that. Guessing just old age and to many miles?

 

[DirtDonk]

Sounds reasonable.
Since you mentioned it was already turned down slightly, and that it had been torn up, I initially thought you were talking about a fairly short term thing. Maybe pretty low miles.
But now I see it may be just old and tired!
Although there have been plenty of engines with crankshafts that have survived perfectly with more years, and maybe more miles on them, maybe it’s just simple wear and tear.
Could’ve been maybe one or two extended oil changes that got a little polluted. Maybe something else going on. May be a PCV valve, not working right and letting a little more acid buildup in the crank case.
Who knows at this point. But I’d say you got your miles, money and smiles out of it.

 

[gnpenning]

Do you know if it has stock factory pistons??

My experience was with a scat crank NOT a eagle crank so keep that in mind. A number of years ago I needed a crank for my 74. After searching the net I found a good price on a scat crank out of a business in South Dakota. I called to verify if it would work for my STOCK motor. I talked with the owner of the business and told him what I had, he said it would work. I ordered it and installed the crank. When I tried turning it over the throws hit the piston skirts. I called him back and told him the problem after he said it would work. His response was it does work with a stock motor, just not stock pistons??? Needless to say it was going to cost me as much to send it back and have it polished, even though the motor never made a 1/4 revolution. He did offer to sell me pistons that would work at full price!!

Maybe someone else can tell you if it will work for sure, just wanted to give you a heads up in the meantime.

 

[72Jesse]

Replacing the pistons to so shouldn't be an issue, but thanks for the info.

 

[Broncobowsher]

Is the rest of the engine rebuildable? Usually by the time the crank has been turned to the point there are no undersized bearings left anymore the bores are to the point they are tissue paper thin to the water jacket. The whole engine is beyond rebuilding.

So if you know the rest of the engine is actually rebuildable then a replacement crankshaft is a viable fix. The key is finding the right one. It needs to be an early 302, pre '81. balance changed in '81 so the plethora of newer crankshafts won't work. Don't be surprised if you have to get a whole engine just to take the crankshaft out of it.

Before you go ordering new parts, go talk with your machinist. Very often they have a stock of crankshafts. Already turned and polished, ready to drop in.

 

[bronkenn]

As mentioned, make sure the block checks out. I took my block in to the machine shop and the crank was also worn out, They told me the new cranks, if they could find them, were going to be around 800 bucks. They said the cranks were getting pretty scarce. I ended up getting a kit from Competiton Products, who I have dealt with before, for around 1100 bucks. It included crank, bearings, pistons, rings and everything needed for the rotating assembly. The machine shop did the block and I brought it home and installed the kit. Worked out very well. By the way I did use the 331 kit.

 

[73azbronco]

Sounds like a great time for Mr Explorer 5.0 to show up.

https://www.usapartsonline.com/prod...wM2w1SWx__n6OCz5uQyHhq3HZd0KjTjkaAiLNEALw_wcB

can be found locally for half or less.

 

[bmc69]

Is this a decent replacement for crankshaft for my 1972 302 powered Bronco? https://www.summitracing.com/parts/esp-103023000#overview Existing crank has already been turned once and now the bearing surfaces are trashed so thinking replacement vs machining it again.

How badly trashed?...cranks can be turned to quite a few undersizes before they are used up. It's very rare that a crank can't be turned to the next undersize. The ones I have to throw away are usually the ones too badly worn on the thrust faces at #3 bearing....something that can happen with manual transmissions.

 

[73azbronco]

I was going to say same thing, as above, but, if it's so bad, there could/probably be a lot wrong with the rest of the motor as well.

 

[Timmy390]

I wouldn't spend a dime on an old block when you can bet a 5.0 explorer on the cheap. It will run circles around the old 302. It's money WELL spent.

Tim

 

[72Jesse]

Existing crank that is messed up was already turned so turning again seems feasible, but not great. Block looks decent. No ridges at the top of the cylinders or any scoring.

 

[Teal68]

I got one from O'reilly's recently shipped to the door with crank and rod bearings for under $200. I can't get a crank turned and new bearings for less than that.