Threaded Crankshaft
Thread Starter
Burning Brakes
Joined: Jun 2007
Posts: 1,062
Likes: 10
From: Dallas TX
Threaded Crankshaft
Need some solutions on the threads of my crankshaft snout that appear to be reamed out.
Original crank from an 870 block...I didnt notice how bad until I picked it up from the machine shop.
I've updated this thread with some pics....
The threads are wallowed out to about a depth of 3/8 however the 7/16 balancer bolt I picked up from summit will not start.
(a) is 7/16th the correct thread size? 3/8 bolt wont start either.
(b) if I am going to drill further into the crank for a 7/16 , how far should i drill to ensure enough threads?
(c) what size bit should I use prior to taping for 7/16?
(d) any issues with my plan?
Original crank from an 870 block...I didnt notice how bad until I picked it up from the machine shop.
I've updated this thread with some pics....
The threads are wallowed out to about a depth of 3/8 however the 7/16 balancer bolt I picked up from summit will not start.
(a) is 7/16th the correct thread size? 3/8 bolt wont start either.
(b) if I am going to drill further into the crank for a 7/16 , how far should i drill to ensure enough threads?
(c) what size bit should I use prior to taping for 7/16?
(d) any issues with my plan?
Last edited by TX63CONV; Oct 24, 2010 at 09:32 PM. Reason: Updated
Pro
Joined: Jan 2007
Posts: 524
Likes: 12
From: Auckland New Zealand
Need some solutions on the threads of my crankshaft snout that appear to be reamed out. I am pretty sure running a tap through them is not going to work.
Original crank from an 870 block...I didnt notice how bad until I picked it up from the machine shop.
Should I tap to the next size? Any other solution?
Original crank from an 870 block...I didnt notice how bad until I picked it up from the machine shop.
Should I tap to the next size? Any other solution?
This is what you need - KeySerts.
Look here for info
http://www.afsrecoil.net/uploads/pdf...s_sizes_en.pdf
Also here is a more comprhensive catalog
http://mdmetric.com/pdf/keysert.pdf
They are just the ticket for filling in holes that have become to large for a helicoil.
Hope this helps
Neville
Burning Brakes
Joined: Mar 2004
Posts: 1,108
Likes: 4
From: Plano Texas
Derek,
I drilled out my crankshaft on the 59 with a right angle air drill, 5 or 6 carbon steel drill bits, plenty of patience, measuring and with the engine in the car. Once the hole was drilled, I then used a tap, plenty of oil and again a large amount of patience to finish the crank snout. I installed a Summit racing crank bolt and washer kit to hold the balancer on. If you have to go to a larger diameter bolt to make it work, I would go to Elliott's hardware and match up the bolt you want to use with the proper drill tap so it will work properly. You can also match up a retention washer at the same time. Good luck, Mark
I drilled out my crankshaft on the 59 with a right angle air drill, 5 or 6 carbon steel drill bits, plenty of patience, measuring and with the engine in the car. Once the hole was drilled, I then used a tap, plenty of oil and again a large amount of patience to finish the crank snout. I installed a Summit racing crank bolt and washer kit to hold the balancer on. If you have to go to a larger diameter bolt to make it work, I would go to Elliott's hardware and match up the bolt you want to use with the proper drill tap so it will work properly. You can also match up a retention washer at the same time. Good luck, Mark
Burning Brakes
Joined: Jul 2010
Posts: 755
Likes: 8
From: delco pa
sometimes a metric tap will work in an enlarged hole with out re-drilling,,,
i drilled mine deeper, while the engine was on teh stand, & used a longer, standard size bolt...
it tightened up good and held teh proper torque.....
i drilled mine deeper, while the engine was on teh stand, & used a longer, standard size bolt...
it tightened up good and held teh proper torque.....
Last edited by knockbill; Aug 20, 2010 at 10:32 AM.
Thread Starter
Burning Brakes
Joined: Jun 2007
Posts: 1,062
Likes: 10
From: Dallas TX
Team Owner
Joined: Oct 2000
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From: Washington Michigan
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Le Mans Master
Joined: Aug 2009
Posts: 5,474
Likes: 16
From: Houston Texas
St. Jude Donor '10-'12-'13
I didn't want to drill my crank. I just pressed (pounded) on my 8 inch shp balancer.
I have had no issues with it moving. I had to chase an oil leak. So when I used the puller,it came loose with the proper snap. So I know it stayed seated. That and straight belts and pulleys.
Some may not agree.. I do keep an eye on it.
Last edited by MiguelsC2; Oct 25, 2010 at 01:14 PM.
Le Mans Master
Joined: Aug 2009
Posts: 5,474
Likes: 16
From: Houston Texas
St. Jude Donor '10-'12-'13
I will add, since your crank is out of the car. I would take it to a machine shop and have it properly drilled and tapped. IMHO no reason not to.
If your balancer is GM and has "made in Canada" ? It's the SHP replacement. Would be nice to have the fins for cooling. But I didn't want to spring the extra bucks for the fins. Since they stopped the fins,I guess that means they weren't needed.
If your balancer is GM and has "made in Canada" ? It's the SHP replacement. Would be nice to have the fins for cooling. But I didn't want to spring the extra bucks for the fins. Since they stopped the fins,I guess that means they weren't needed.
Last edited by MiguelsC2; Oct 25, 2010 at 12:12 AM.
Melting Slicks
Joined: Sep 2003
Posts: 2,114
Likes: 33
From: ct
Based on the first photo, that crank never had a bolt in it to begin with; the bolt threads are 7/16"-20, and only the SHP engine cranks were drilled and tapped for a bolt; the others just had a press-on balancer. What you're looking at in the photo is the conical machining center.
There was never a bolt there. Most 327s where just pressed on. Drill and tap it and put a bolt in. It's very cheap insurance.
Le Mans Master
Joined: Aug 2009
Posts: 5,474
Likes: 16
From: Houston Texas
St. Jude Donor '10-'12-'13
They may have had a press at the factory. But in the garage,they are tapped on. Since there aren't threads, a press or pull on device can't be used. To the best of my knowledge.
Le Mans Master
Joined: Nov 2008
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From: columbus oh
Instructor
Joined: Mar 2008
Posts: 203
Likes: 2
From: Suburban Phila. PA
crank shaft
refer to john z's thread above..
if the crank shaft is out of the motor, this would be an opportune time,and i would suggest, that you take it to a good machine shop and have it checked for balance, journals, etc, AND have them drill it out for the crank bolt if you decide to go that way, rather than pressing the balancer on...
btw, the mr.gasket 7/16'-20 nf crank bolt is correct, and takes 23/64"drill to prep it for the 7/16" threading.
also, check youre timing cover to see if --the timing tab--is placed for the 8" balancer, or closer to the crank shaft for the 6" or 6 1/2" balancer..either will work fine....imo..
hope this helps..
good luck
john
if the crank shaft is out of the motor, this would be an opportune time,and i would suggest, that you take it to a good machine shop and have it checked for balance, journals, etc, AND have them drill it out for the crank bolt if you decide to go that way, rather than pressing the balancer on...
btw, the mr.gasket 7/16'-20 nf crank bolt is correct, and takes 23/64"drill to prep it for the 7/16" threading.
also, check youre timing cover to see if --the timing tab--is placed for the 8" balancer, or closer to the crank shaft for the 6" or 6 1/2" balancer..either will work fine....imo..
hope this helps..
good luck
john
