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Forums->Hot Heads Tech Talk->Crankshaft drilling??

32desoto
Crankshaft drilling??


I have a NE354 Hemi from an auto trans car. I traded a Hot Heads Hemi to 727 auto trans adapter for a NP A-833 (Chrysler) 4 speed trans, mid 60's Transdapt Hemi bell housing, starter, flywheel and clutch. The trans came off a running 331 Hemi so I know this setup works. The issue is my 354 crankshaft isn't drilled for a pilot bushing. The 331 this trans came from had a hole .9375 dia x 2.210 inches deep and the pilot bushing pressed into it. I am concerned that drilling a hole that deep could be a problem. T Waters said he has a Hemi truck crank drilled 3" deep and a 241 Dodge crank drilled 2 3/4" deep and hasn't had any problems. A bronze bushing is pressed into these bores. My flywheel has a hole 2.75 dia and the trans output shaft is .75 dia. Does anyone out there know of a pilot bearing 2 3/4" OD and 3/4" ID that presses into the flywheel as I feel drilling 2 1/4" deep into the crank can't be a good thing. The motor is a street motor not a race motor if that makes a difference to drilling a hole that deep. I can also cut off an inch of so off the trans input shaft to lessen the depth of the hole in the crank. Anybody out there in Hemi land have a crank with such a deep hole drilled in it? Any other ideas?
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on: Wed 21 of Dec, 2016 [17:54 UTC] reads: 1381

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hemistude
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Re: Crankshaft drilling??
on: Fri 06 of Jan, 2017 [14:38 UTC] score: 0.00
32,

You may have already read the the HAMB's Early Hemi Tech forum dealing with Early Hemi tranny, clutch, bellhousing and starter stuff but if you haven't, check it out here:

http://www.jalopyjournal.com/forum/threads/hemi-tech-transmission-adapters-flywheels-starters.118607/

It's an active thread that has been running for 10 years. There's a wealth of information in there and maybe some of it might help you out. Might be a good place to ask your question again. Good luck!

Dave

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jgrady
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Re: Crankshaft drilling??
on: Wed 04 of Jan, 2017 [16:21 UTC] score: 0.00
> I have a NE354 Hemi from an auto trans car. I traded a Hot Heads Hemi to 727 auto trans adapter for a NP A-833 (Chrysler) 4 speed trans, mid 60's Transdapt Hemi bell housing, starter, flywheel and clutch. The trans came off a running 331 Hemi so I know this setup works. The issue is my 354 crankshaft isn't drilled for a pilot bushing. The 331 this trans came from had a hole .9375 dia x 2.210 inches deep and the pilot bushing pressed into it. I am concerned that drilling a hole that deep could be a problem. T Waters said he has a Hemi truck crank drilled 3" deep and a 241 Dodge crank drilled 2 3/4" deep and hasn't had any problems. A bronze bushing is pressed into these bores. My flywheel has a hole 2.75 dia and the trans output shaft is .75 dia. Does anyone out there know of a pilot bearing 2 3/4" OD and 3/4" ID that presses into the flywheel as I feel drilling 2 1/4" deep into the crank can't be a good thing. The motor is a street motor not a race motor if that makes a difference to drilling a hole that deep. I can also cut off an inch of so off the trans input shaft to lessen the depth of the hole in the crank. Anybody out there in Hemi land have a crank with such a deep hole drilled in it? Any other ideas?


I had this issue way back in 61, 392 with packard OD ( never made a stick 392, except a few special 300's) .Had 392 in back of PU truck, took to auto machine shop, he insisted crank had to come out of perfect assembled engine--to get hole right ..no way. So , get this, I drilled an oversize hole maybe .80 with a magnetic drill base , gripped back of block, centered as best I could , ..need not be perfect or straight--about 1/2" in but best you can do ; then machined a disc of steel, maybe 1/2" thick to be like .0005 bigger than the slight factory recess in 392 crank , chilled it way down (today LN2)-- in center was a bore for oilight bushing for packard, maybe .6 long ; cut nose off blank part of trans shaft , moved trans back with spacer so splines ended at clutch disc hub. Worked perfectly through about 6 tramnsmisions no grief and $ still in pocket.

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jgrady
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Re: Crankshaft drilling??
on: Wed 04 of Jan, 2017 [16:10 UTC] score: 0.00
> I have a NE354 Hemi from an auto trans car. I traded a Hot Heads Hemi to 727 auto trans adapter for a NP A-833 (Chrysler) 4 speed trans, mid 60's Transdapt Hemi bell housing, starter, flywheel and clutch. The trans came off a running 331 Hemi so I know this setup works. The issue is my 354 crankshaft isn't drilled for a pilot bushing. The 331 this trans came from had a hole .9375 dia x 2.210 inches deep and the pilot bushing pressed into it. I am concerned that drilling a hole that deep could be a problem. T Waters said he has a Hemi truck crank drilled 3" deep and a 241 Dodge crank drilled 2 3/4" deep and hasn't had any problems. A bronze bushing is pressed into these bores. My flywheel has a hole 2.75 dia and the trans output shaft is .75 dia. Does anyone out there know of a pilot bearing 2 3/4" OD and 3/4" ID that presses into the flywheel as I feel drilling 2 1/4" deep into the crank can't be a good thing. The motor is a street motor not a race motor if that makes a difference to drilling a hole that deep. I can also cut off an inch of so off the trans input shaft to lessen the depth of the hole in the crank. Anybody out there in Hemi land have a crank with such a deep hole drilled in it? Any other ideas?

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hemistude
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Re: Crankshaft drilling??
on: Fri 23 of Dec, 2016 [18:03 UTC] score: 0.00
"Have you, or anybody else out there, seen a hole this deep (2.210") in a Hemi crank? "

I haven't. My feeling is that it's not necessary to go deep in the crankshaft with the input shaft. That's what the bushing is for. Trimming the snout on the input is, to me, more sensible than potentially causing a crank problem. Plus, you can do it yourself.

Bob or Eric at HH are quite knowledgeable on that stuff though. They've been quite helpful every time I've ever needed info. I encourage you to give them a call.

In my sometimes failing mind, better to cut a replaceable and relatively plentiful item like the input shaft (low chance of a problem) than potentially ruin a harder-to-find and more expensive original forged Hemi crankshaft. I guess the good news is that others have gone before you and the answer is out there.

Keep digging.

Merry Christmas to all!

Dave

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32desoto
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Re: Crankshaft drilling??
on: Thu 22 of Dec, 2016 [18:46 UTC] score: 0.00
> I have a NE354 Hemi from an auto trans car. I traded a Hot Heads Hemi to 727 auto trans adapter for a NP A-833 (Chrysler) 4 speed trans, mid 60's Transdapt Hemi bell housing, starter, flywheel and clutch. The trans came off a running 331 Hemi so I know this setup works. The issue is my 354 crankshaft isn't drilled for a pilot bushing. The 331 this trans came from had a hole .9375 dia x 2.210 inches deep and the pilot bushing pressed into it. I am concerned that drilling a hole that deep could be a problem. T Waters said he has a Hemi truck crank drilled 3" deep and a 241 Dodge crank drilled 2 3/4" deep and hasn't had any problems. A bronze bushing is pressed into these bores. My flywheel has a hole 2.75 dia and the trans output shaft is .75 dia. Does anyone out there know of a pilot bearing 2 3/4" OD and 3/4" ID that presses into the flywheel as I feel drilling 2 1/4" deep into the crank can't be a good thing. The motor is a street motor not a race motor if that makes a difference to drilling a hole that deep. I can also cut off an inch of so off the trans input shaft to lessen the depth of the hole in the crank. Anybody out there in Hemi land have a crank with such a deep hole drilled in it? Any other ideas?

Dave
I plan on using a pilot bushing. My concern is the depth of the hole in the crank. I was told to use a pilot bearing in the flywheel of a Hemi but I have only used pilot bushings in the crank on wedge motors(this is my first Hemi). Have you, or anybody else out there, seen a hole this deep (2.210") in a Hemi crank?

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hemistude
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Re: Crankshaft drilling??
on: Wed 21 of Dec, 2016 [23:49 UTC] score: 0.00
>"My flywheel has a hole 2.75 dia and the trans output shaft is .75 dia. Does anyone out there know of a pilot bearing 2 3/4" OD and 3/4" ID that presses into the flywheel"


I may not be getting your drift, but the pilot bushing needs to mount in the back of the crank, where the old torque converter registered, not in the flywheel. The O.D. of your bushing needs to allow a light press fit in back of the crank. I've never measured a hemi crank from an automatic but if by some stroke of luck that opening in the crank is 1.81 (the register size for late Mopar converters) then the part you need is FC69907 made by National Bearing and Seal. It's a needle bearing already fitted in a bushing.

That piece is used by the Mopar muscle car guys when installing an A-833 behind a late Mopar engine from an automatic car. The dimensions are: 1.816 in. housing diameter, 0.751 in. shaft diameter, 0.565 in. width. They're cheap too. $12 from Summit. AutoZone has them too.

If the bushing is a fit and you're ready to go all in, you'll definitely need to trim some off the input shaft, but that can be done carefully with a cutoff wheel and a little dressing. Better measure twice, sleep on it, and measure two more times before you fire up the cutter. Too long... trim a little more. Too short... uh-oh!

The business end of the input shaft needs to be clear of the bottom of the crank hole by at least 1/16th after assembly to allow for heat expansion. If the two are in constant contact, then there will be problems up to and including a blown crankshaft. The crank needs to float within the tolerance of the thrust surfaces on the center main bearing. Bad things happen when you deny the thrust bearing those few thousandths oil clearance. You can always drill the crank a 1/4" deeper by hand or in a drill press to give it more clearance without any structural harm. It doesn't have to be super-precise, it's just for clearance.

Proceed at your own risk but if that part number is a fit, you're close to in-business with something you can do in your own shop if you're handy. No precision machining.

Dave


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