Author Topic: My 427/452 autopsy results are in  (Read 5727 times)

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My427stang

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Re: My 427/452 autopsy results are in
« Reply #30 on: September 22, 2020, 10:36:35 PM »
What are you putting for thrust clearance when you assemble? Do you check it before and after cap install?

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Ross
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- 70 Fastback Mustang, 489 cid FE, Victor, SEFI, Erson SFT cam, TKO-600 5 speed, 4.11 9 inch.
- 71 F100 shortbed 4x4, 461 cid FE, headers, Victor Pro-flo EFI, Comp Custom HFT cam, 3.50 9 inch

FERoadster

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Re: My 427/452 autopsy results are in
« Reply #31 on: September 22, 2020, 10:37:04 PM »
I know nothing about your issue but do/did you need the reinforcing ring on the flex plate? That's the only X factor I do not see but it could be a non Issue to the convertor?  Think I forgot the ring on my sons 59 T=Bird so we are pulling the engine.

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AlanCasida

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Re: My 427/452 autopsy results are in
« Reply #32 on: September 22, 2020, 10:47:57 PM »
What are you putting for thrust clearance when you assemble? Do you check it before and after cap install?
I don't know off the top of my head but it was within spec. The thing is, it has worn about an .080" groove in the thrust area of the crankshaft. If it had been that tight when I got it all together I would have known it right off. I watched a video of a transmssion that had too much line pressure and you could see the converter being pushed forward when they revved the motor up. It was a GM transmission but it may still be applicable to a C6. My next move is to pull the valve bod and see if the pressure spool valve is stuck. 

Rory428

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Re: My 427/452 autopsy results are in
« Reply #33 on: September 23, 2020, 02:43:35 AM »
Alan, I mentioned your situation to a buddy who does a ot of transmission work, and he told me that he has seen a similar case, where the transmission cooler was clogged, which caused the transmission line pressure to climb, which caused the torque convertor to move forward. He recommends checking the transmission line pressures at both the cooler lines. They should be equal, if not , you have a restriction , like a clogged cooler, pinched hose or kinked cooler line, that can cause such a condition. Something to look at.
1978 Fairmont,FE 427 with 428 crank, 4 speed Jerico best of 9.972@132.54MPH 1.29 60 foot
1985 Mustang HB 331 SB Ford, 4 speed Jerico, best of 10.29@128 MPH 1.40 60 foot.
1974 F350 race car hauler 390 NP435 4 speed
1959 Ford Meteor 2 dr sedan. 428 Cobra Jet, 4 speed Toploader. 12.54@ 108 MPH

Falcon67

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Re: My 427/452 autopsy results are in
« Reply #34 on: September 23, 2020, 02:52:26 PM »
I don;t know about a C6, but even with a manual valve body in a C4 the pressure to the cooler only runs about 30 lbs, not anywhere near the internal pressure to the clutches and servos. 

I have personally run a motor with .100 endplay and the only thing that cause a problem was the counterweights rubbing the internal bulkheads, slowing the motor.  All the bearings looked great except for the thrust.  And the crank got a nice machined groove about .250~.300 x .100 deep or so.  The converter was a built unit that did not ballon, that same unit is in the car now with another 1000 passes on it and works fine.  I attributed the crank problem to some debris or issue with the crank thrust face as nothing else stood out.  That's the only thrust issue I've ever had with a motor.  The dragster engine is apart after splitting a cylinder.  It runs a Powerglide built for a lower end alcohol funny car so you can imagine the internal pressures.  Three years before the mast, end play was .008 going in, .009 coming out. 

I'd agree that if the crank didn't move with the converter bolted up then there is a mechanical issue somewhere.  The engine I referenced above, you could see the belt misalignment up front.  A push on the crank pulley moved the entire assembly - talk about a weird feeling to see your crank pulley move backwards about 1/10 of an inch.  "Well...heh, that's a problem."