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Discussion Starter · #1 ·
Hi All,

My neighbour is restoring a 57 Chevy Bel Air here in Ireland, I just give a bit of help when I can. Neither of us is a mechanic but I'd be a bit more mechanically minded. She hadn't been started since 1978 and the head was removed before my neighbour inherited her. Long story short we got her running, but there is an oil leak in the timing cover seal around the crank.

We removed the harmonic balancer and we have realised the 2 lower bolts in the timing cover are loosened from inside the sump ( I think you call it oil pan).
So we have to drop the sump etc etc. I've read about tapping the bolt holes so new bolts can be threaded from outside the crank case in future. Does anyone have any comments on whether this is a wise idea or not?

I've read a bit about replacing the crank seal in the timing cover and understand a centring tool is required.
Would anyone have any workaround or suggestion of what we could use instead.

Finally any hints for replacing the harmonic balancer without doing any damage to the crank and its bearing. I've read about hitting the balancer on with a block of timber and a hammer after heating the balancer to 250 degrees in the oven....

Many thanks

Niall
 

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Do a search here for 235 timing cover. Then look for "first engine build". Should have the tapping of front main cap and photos. Then look for "235 chevy timing cover alignment". Should have the procedure for making up a tool from a spare balancer. If you send me a pm I can send you a few pictures but only if you promise to post them here for other members
 

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Niall sent me a PM but I thought others may be interested so here goes:

"I'm living in Ireland and the shipping on anything like a spare harmonic balancer from the USA is huge.
Would you think there is another way to make up some kind of timing case seal centring tool.

Sorry for the dumb question but if the seal is pressed into the timing cover and the crank is in place, will the seal self centre the timing cover if the cover is carefully pushed onto the crank. I'm very new to all this so forgive me possibly simplistic understanding"

No problem my friend and no such thing as a dumb question. We are all here to assist one another. I dont know how to post photos and right at the moment do not have time to sort it out. I am happy to send you the photos but you have to post them for me. If you can do that, send me a PM with your email and I will forward the photos. As to your questions, no, the balancer will not self center, well it will, but you cannot tighten all of the timing cover screws with the balancer installed so I will call that a no, lol. Yes, you can make a tool up without a spare balancer. First you will need a micrometer. Measure the outer diameter of the balancer hub. then measure the diameter of the crank nose. These are your critical inner and outer dimensions. Then you will need to find a piece of steel pipe or some other metal that has the exact outer diameter (or something close and have a machinist turn it down to the correct diameter) and inner diameter that is exact or slightly smaller. The balancer is a press fit onto the crank so the tool needs to be a slip fit to work. Get a brake hone and hone the inside until the tool slips over the balancer and there you have it, a seal centering tool. Yes, tap the front main cap. follow the directions on the thread i directed you to. Us six cylinder guys have been doing this mod since the 1950's. I have no clue as to what the thinking was on the bolts from the pan side of the motor, maybe GM was having a pan gasket sale, who knows, but the fix is easy and if you ever have to pull the timing cover again, you wont have to pull the pan to do it. Just dont use a lot of force tightening them down. They dont need it and you will strip the threads. Install the timing cover before the pan, follow the directions on the second thread. After the cover is installed, look closely at the new bolts or screws as they come through to the pan side to make sure no stray metal from the new threads are present. Installing the balancer on a 235 is a bit of a pain because the crank is not drilled and tapped for threads. If you are ambitious and have someone to help you, a few have made up a drilling and tapping jig to drill the crank snout and tap for threads for a balancer retention bolt with the motor in place. Then you can use any of the commercially available balancer install tools. Otherwise you are stuck with using a piece of wood and beating it on. It is a big pain doing it this way but it is what it is.
 

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Discussion Starter · #4 ·
Images from Dragsix



Toll installed. Note screws installed at lower part if timing cover. These are the new screws used after tapping the front cover and drilling the timing plate for the larger bolt





Stock Balancer



Drill out these Rivets

Sorry, some of the images turned sideways.....
 

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Discussion Starter · #5 ·
Timing Seal Centring Tool Part 2


Drive out rivets and the assembly comes apart


Use a brake hone on the inside so that the hub is a slip fit over the crank hub


Like so


This is the hub after cleaning and painting ready to be used as a timing seal centring tool.
 

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Discussion Starter · #6 · (Edited)
Home Made Wood Turned Seal Centring tool

Just wanted to share a picture or two of our seal centring tool and seal inserting tool. We called in a favour with a pal who has a wood lathe.


This is our seal inserting tool.


In the background on the table is our seal centring tool. Sorry I thought I had a better image of it.
 

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Thank You

Greetings,

My car is actually not one of the Tri Five for which this forum was created, it's a '52 Chevy Sports Coupe of the Styline family but I have a 235 in it and I have no experience working with that engine. Finding this thread prompted me to register so that I could thank you for sharing your knowledge as it helped me avoid some hiccups.

I'm not sure I understand the need to center the crank seal yet but I'm sure I'll find out today when I try to put it all back together after cleaning and replacing seals / gaskets. (My engine is out and mounted on a stand.)

It seems to me that the reason the timing cover bolts are inside the oil pan area is so that the bolts can remain loose while the harmonic balancer is put back in place through the seal. Once the balancer is all the way in, it's auto-centered. You can tighten up the bolts from behind afterwards.

I'll give it a go today and see what I end up with. I may end up simply tapping the holes so I can bolt the timing cover from the front. (I understand the maintenance benefits.)

Thank you again.

--Ray
 

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My method: with timing cover unbolted (new seal and new sleeve on balancer if needed), slide the cover onto the balancer, then slide balancer in place on end of crank. Then push cover against the motor with the balancer as your centering tool. Bolt up cover and now it's time for a pint, Slante'!
:anim_32:
 

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So I will reveal that this past August, I got the new 261 motor in and running. Used the centering tool, centered the seal to the crank snout, tightened the screws, and installed the balancer. A day or two after getting the motor and cam break in finished, found a little oil on the garage floor. Could not find the source. It was coming from the front of the motor, but not from the timing seal. Discovered the timing cover gasket had failed, it was a brand new gasket and I had used copper gasket spray. Because I had tapped the front main cap and drilled the cover out, all I had to do was pull the radiator, jack the motor up two inches, pulled the balancer and timing cover, and installed a new gasket. I did not have to pull the pan, a major pain in the rear end to do in the car and the expense of another set of pan gaskets. So let me encourage you to do the front main cap modification. You just never know.

As for the need to center the seal, if the timing cover seal is not centered to the crank snout, off centered just a speck, you will get an oil leak past the seal. Makes a mess so better to be sure it's centered when you are putting the motor together. Just a little extra step to help minimize any issues that could potentially arise when you get the motor running.
 

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So I will reveal that this past August, I got the new 261 motor in and running. Used the centering tool, centered the seal to the crank snout, tightened the screws, and installed the balancer. A day or two after getting the motor and cam break in finished, found a little oil on the garage floor. Could not find the source. It was coming from the front of the motor, but not from the timing seal. Discovered the timing cover gasket had failed, it was a brand new gasket and I had used copper gasket spray. Because I had tapped the front main cap and drilled the cover out, all I had to do was pull the radiator, jack the motor up two inches, pulled the balancer and timing cover, and installed a new gasket. I did not have to pull the pan, a major pain in the rear end to do in the car and the expense of another set of pan gaskets. So let me encourage you to do the front main cap modification. You just never know.

As for the need to center the seal, if the timing cover seal is not centered to the crank snout, off centered just a speck, you will get an oil leak past the seal. Makes a mess so better to be sure it's centered when you are putting the motor together. Just a little extra step to help minimize any issues that could potentially arise when you get the motor running.
this is exactly the same way I do it but I use studs instead of bolts. Dont know if it matters or not but its how I have done the last couple
 

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Have to commend you guys for your innovative fabrication skills....I checked the Shop Manual and saw where that is the way it is supposed to be done:http://chevy.oldcarmanualproject.com/shop/1955/55csm0620.html

However, for the life of me, I can't remember going through all that, when I replaced the fiber timing gears that stripped on my 57, 235....Of course that was in the 60's, when I just through things back together the best I could with the limited knowledge that I had. :)
 
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