Harmonic Balancer Timing Cover Clearance Issue - Pontiac GTO Forum
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post #1 of 6 (permalink) Old 03-24-2018, 09:16 AM Thread Starter
 
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Harmonic Balancer Timing Cover Clearance Issue

Hey Guys,

It has been forever since I've posted anything. I'm working on increasing the HP for my Tempest (1964 Tempest Custom stickied over in the restoration thread). Long story short, it's too slow. It has a 400 CID 1968 Pontiac engine in it with a four barrel AFB and the 'tri-power' camshaft. It moves along okay, but why not go faster? I picked up a period correct supercharger to hide under the hood as a sleeper. This has required reworking the front pulleys.

To Start with, I've purchased a new Butler timing cover and Romac harmonic balancer. They don't fit. The timing cover doesn't seem to be the issue, dimensionally it is very close to the original (my original had the small diameter timing mark and I need/wanted the later model larger diameter mark). The harmonic balancer however has the same dimension from the timing gear face to the pulley mounting face as the '68 and later harmonic balancers but it hits on the timing cover when installed. So I pulled the timing cover off and slipped the harmonic balancer on the crank and it hits the oil pan! After measuring everything, there is about a .100 interference of the components. Has any one else had this happen? A search of the forum lead me to BearGFR's build here were it is mentioned (https://www.gtoforum.com/f170/re-buil...tml#post819306) but it didn't seem to be a big deal.


Anyone been down this road and can shed some light? I'm hesitant to grind, mill or modify either part in case I need to return them or in case I'm missing something.

Thanks in advance for the help!

-Thor
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Last edited by Thor7352; 03-25-2018 at 12:51 PM.
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post #2 of 6 (permalink) Old 03-24-2018, 04:22 PM
 
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Simplest solution would be to email/call Butler and explain your clearance issues. No doubt they will know exactly the problem and/or the fix rather than modify one of your new pieces and not be able to return it should there be an issue with the part or if the wrong piece was sent you.
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post #3 of 6 (permalink) Old 03-24-2018, 06:23 PM Thread Starter
 
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That's my main plan, I did email Butler and will call on Monday to see what they say.
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post #4 of 6 (permalink) Old 03-24-2018, 07:14 PM
 
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Quote:
Originally Posted by Thor7352 View Post
That's my main plan, I did email Butler and will call on Monday to see what they say.
OK, good plan. Don't know why the parts don't seem to work, but sometimes parts can be made incorrectly, ie somebody didn't mill/machine the part as needed or the parts are not compatible in one variation but work in another combo.

Let us know what you find and post it as this may happen again to someone else OR you just might save someone some grief.

Pics and details of your supercharger set-up would be very cool as well - who doesn't love a supercharger?
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post #5 of 6 (permalink) Old 03-25-2018, 01:52 AM
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Hey Thor...

Something's up with the photos in your post - as in I can't see them at all.

My new Romac balancer hit the bottom edge of the timing cover also, but the amount of interference wasn't large. A couple minutes with my angle grinder was all it took to create plenty of clearance. I'll be installing the timing cover for final assembly in the next couple of days now that I've finally gotten the rear of the engine sealed. Once it's on I should be able to eyeball the pan lip to see if it needs some clearancing also. I blamed the fitment problem I had on the aftermarket timing cover (Kauffman) but perhaps that's not the real reason. We'll see.

Bear

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post #6 of 6 (permalink) Old 04-04-2018, 07:11 AM Thread Starter
 
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Spoke with Butler. The issue is the with Romac Harmonic Balancer but the solution is the grind the timing cover and work the oil pan. I was hesitant to implement this fix, but with a couple files and some bluing I was able to get the clearance I needed.

The project moves on! In case you were wondering what he's building in there, its going to be a Latham supercharged 400 cid Pontiac. Its going in a tempest.
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  Pontiac GTO Forum > The 1964-1974 Pontiac Tempest, Lemans & GTO > 1964-1974 Tempest, LeMans & GTO Engine Tuning and High Performance

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