Play in HEI shaft? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

lukecp · 07-29-2003, 06:59 PM

I installed a Crane adjsutable vaccum advance and re-curved my HEI with the blue and silver springs in the vaccum advance kit. While i was putting on the springs, i noticed that the little platform that the mechanical advance weights are mounted on would move up and down about 1/16-1/8 of an inch, if i rotated it counterclockwise. Is this normal or is my HEI worn out? After i got the timing dialed in (blue and silver springs, 11 degrees of base timing, and the vaccum advance turned 4 turns counter-clockwise), the truck runs great without any spark knock. I do have a spare HEI i can throw in it if mine is worn.

Thanks for any help

JimKshortstep4x4 · 07-29-2003, 08:31 PM

My guess is that what you are seeing is the play in the shaft, (up and down). I usually set the end play to .008-.010. I believe the factory spec allows up to .019 and I have seen them at over .030.
I keep a selection of washers that fit the shaft but are not larger than the gear hub for adjusting the end play.

When the shaft has too much end play it can change your timing as the gears are curved.

Jim

lukecp · 07-29-2003, 08:46 PM

Well....my timing usually stays nailed down....it was unchanged after about 3000 miles between the last time i timed it and today.
Will the excess endplay (proably .060-.125) mess up anything besides possibly putting my timimg a few degrees off until i can afford a brand new HEI?

Thanks for the help!

JimKshortstep4x4 · 07-29-2003, 08:58 PM

No, it will not mess up anything, it is just one of those little details
that is nice to do when you are trying to get the most out of your engine. Most HEI's have too much play in them but they will run forever.

It is easy to adjust the end play. Just remove the gear by removing the roll pin and insert the the right thickness washer, (s). The only problem that I have run into is that the washers that you need are not standard, so finding the right size is the key. I have been able to buy thin hardened washers of the right size, but I have not seen any lately.

Jim

07-29-2003, 06:59 PM	#1
lukecp Formerly yellow72custom Join Date: May 2001 Location: Austin, TX Posts: 7,531	Play in HEI shaft? I installed a Crane adjsutable vaccum advance and re-curved my HEI with the blue and silver springs in the vaccum advance kit. While i was putting on the springs, i noticed that the little platform that the mechanical advance weights are mounted on would move up and down about 1/16-1/8 of an inch, if i rotated it counterclockwise. Is this normal or is my HEI worn out? After i got the timing dialed in (blue and silver springs, 11 degrees of base timing, and the vaccum advance turned 4 turns counter-clockwise), the truck runs great without any spark knock. I do have a spare HEI i can throw in it if mine is worn. Thanks for any help __________________ '72 Chevy C10 Mild 350/TH350/3.07. Ochre/White. Old high school ride. '70 GMC C2500 '62 327 4bbl/SM465/4.56-geared Dana 60. White/White. Project or parts truck. '97 Saturn SL DD. 1.9/5-speed. 40+ highway mpg

07-29-2003, 08:46 PM	#3
lukecp Formerly yellow72custom Join Date: May 2001 Location: Austin, TX Posts: 7,531	Well....my timing usually stays nailed down....it was unchanged after about 3000 miles between the last time i timed it and today. Will the excess endplay (proably .060-.125) mess up anything besides possibly putting my timimg a few degrees off until i can afford a brand new HEI? Thanks for the help! __________________ '72 Chevy C10 Mild 350/TH350/3.07. Ochre/White. Old high school ride. '70 GMC C2500 '62 327 4bbl/SM465/4.56-geared Dana 60. White/White. Project or parts truck. '97 Saturn SL DD. 1.9/5-speed. 40+ highway mpg

07-29-2003, 08:31 PM	#2
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	My guess is that what you are seeing is the play in the shaft, (up and down). I usually set the end play to .008-.010. I believe the factory spec allows up to .019 and I have seen them at over .030. I keep a selection of washers that fit the shaft but are not larger than the gear hub for adjusting the end play. When the shaft has too much end play it can change your timing as the gears are curved. Jim

07-29-2003, 08:58 PM	#4
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	No, it will not mess up anything, it is just one of those little details that is nice to do when you are trying to get the most out of your engine. Most HEI's have too much play in them but they will run forever. It is easy to adjust the end play. Just remove the gear by removing the roll pin and insert the the right thickness washer, (s). The only problem that I have run into is that the washers that you need are not standard, so finding the right size is the key. I have been able to buy thin hardened washers of the right size, but I have not seen any lately. Jim



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