116 replies to this topic

[jd lj]

Hi Brent,
Did you get to the bottom of this problem or is it still giving you trouble?

Ps, I got my carb sync tool from eBay. It cost roughly $70from memory. It's made by a company called "SK", one of the grey snail looking ones. It's very simple to use, almost fool proof.

[Brent J]

Hi jd lj,

 

No not yet. Unfortunately I have not progressed with this problem yet as I am rebuilding the shifter in parallel. The shifter parts are currently being re-plated. Once I get the shifter back in and that issue squared away, I will resume with this one.

 

In the interim, I've got a carby sync gauge saved on my watch list on ebay that ill pick up to balance the carbies, as well as re-set them as per the workshop manual so I can confirm they are balanced.

 

Not knowing when they were re-built last (if ever), would you recommend I put a gasket / re-build kit through each carb? Can anyone recommend a suitable re-build kit? There are some on ebay but don't know if they are any good....

 

Brent

[Brent J]

Still working away at the teething problems my car has... this being one of them!

 

While doing some work in the engine bay, I noticed that the harmonic balancer rocks... by that I mean I can grab the fan and rotate it, clockwise and counter clockwise about centre by around 15mm give or take before it takes up. Im assuming it is slop in the harmonic balancer key way (assuming it has one)?

 

Could this be contributing to the heavy vibration under load >4000rpm as described in previous posts?

What about knocking? Could it sound like a bottom end knock?

 

Cheers,

Brent

[S pack]

You best remove the fan belt and check the balancer. If the balancer is loose on the crank it will end up coming off when you least need it to.

[Rockoz]

That would definitely be causing you some dramas.

Sounds like the rubber has gone in the balancer.

The outer section shouldnt move at all around the inner.

If it does you can throw any timing work you have done out the window.

Easy replacement with a puller.

Dont do anything else until you get that replaced

 

[Brent J]

Thanks S Pack and Rock oz.

 

I just had another look this morning and noticed that the whole balance is moving. The outer does not appear to be moving around the inner...

 

Is it possible that the end of the crank could be worn, or are the balancers typically softer and more likely to be the worn part?

[S pack]

Check to see if the crank is moving with the balancer.

[Brent J]

Short answer is no. I could rotate the balancer a good 5 degrees without the crank moving. I could also pull the balancer in and out a few mm too.

 

I went and bought a pull and stripped the front of the car down to get the balancer off. It almost wound off by hand!

 

Unfortunately I didn't like what I saw next. The small half moon key sits very loosely in the keyway on the crank. You can sort of see it in the photos below. There is some play in the keyway on the balancer, but I would say more on the crank. The key itself is worn a little but not too bad.

 

I have ordered a new balancer but does this mean my crank shaft is kaput due to the keyway wear?  I would assume the only way to fix this is to pull the engine out and tear down? Shit I hope not!!

 

 

This car is going to be the end of me!

 

 

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[S pack]

Looks like the keyway slot in the crank is substantially wider than the woodruff key. One or the other is worn. The crank is nodular cast iron and the woodruff key is hardened steel so most likely the keyway in the crank is worn.

The shiney surface on the crank snout looks like the movement of the balancer has polished it so possibly worn there too. How tight a fit is the new balancer?

Also check your old balancer hub for cracks. I have seen the Holden six (red, blue, black) balancer hubs crack from the keyway slot and they then move around on the crank snout.

.

Edited by S pack, 17 April 2017 - 08:33 PM.

[grumpy xu1]

You may be able to get a slightly wider key (skf ect.), check it was correct last time 1st just incase. Don't forget to fit a new seal & use some rubber grease on the balancer so you don't cut the seal on fitment. Paint the balancer evenly & mask of the edge where the seal goes. That's all if you didn't know it, if you did just disregard. Hope it goes well. Gary.

[RallyRed]

bit hard to tell from the pics, but Id think maybe you'd see more evidence of wear/abnormal shape of the key?....as above in Grumps post ....maybe the last bloke just threw in the key he had in the toolbox?...i.e. not the correct size??

[Brent J]

S Pack - You are right. There is about 1mm clearance either side of the woodruff key I don't yet have the new balancer to test fit it. The old one goes on and off relatively easy.

 

Gary - thanks. It would appear that an oversize key is my only option? That would then mean the over size key wont fit the balancer though?

 

Rally Red - Yes, the woodruff key is worn in places, mostly where the key enters the keyway channel in the crank I just ordered a new key. That said, the old key fits into the old balancer ok. Most of the wear is on the crank keyway and corresponding woodruff key area.

 

Should I just put in a new key, new balancer and hope for the best?? I unfortunately don't have the tools, equipment or experience to replace a crank.

[RallyRed]

If the new balancer fits snug and the key is not to loose something like this product is another option:

http://www.loctite.c...d=8802648424449
 

Bit dodgy, and a loose balancer will cause a whole lot of damage to every part of the driveline so its best fixed properly, but It would probably last fine. 

This stuff can work wonders... I used to race a Suzuki 500 Quadracer ....the magneto/generator assembly is keyed onto a tapered end of the crank .

The whole thing was loose for ages( unknown to me ) and flogged the the taper and the centre of the assembly  quite badly.

I used to take several spare key steels to each event, and usually used 1 during the night ( amazing how fast you can do something when you do it over and over!). in the end it got too bad to persist....cleaned up with some emery, sprayed it all with Loctite Primer and used that Loctite ""Permanant "" assembly stuff.......never had another issue. Suprised me.

[Rockoz]

Check the fitment of the key in the balancer.

If the gaps are about the same as on the crank someone put the wrong key in.

[Brent J]

Rockoz - unfortunately, the key fits quite well in the balancer so i'm relatively confident that it is the right key. Interestingly, when I spin the key 180 degrees I.e. front of the key becomes the rear, it fits in the crank a whole lot better which I believe is because the worn faces of the key are no longer aligning with the corresponding worn shoulders of the keyway (on the crank that is).

 

Thank you for the suggestions guys. Ill take a look at that product from Loctite. A mate has also suggested Devcon which is a 2 part epoxy steel that can apparently be machined, drilled, ground etc. Amazingly I also found a youtube clip of a dude that repaired a SB Chev crank keyway with JB Weld!!! Sounds a bit agricultural though!

 

Not sure I believe 2 part liquid metal type products can adhere to steel well enough to solve the problem... Maybe a new balancer, new woodruff key with the Devcon material, plus the Loctite primer and Loctite 680 may work as an interim repair until I have the means to pull the engine for a re-build...

[grumpy xu1]

Hi Brent, what Rob says, I'd be looking at a couple of different balancers to see if there was any difference in the key way groove. Obviously using verniers, the key should be tap in tight, not interference fit. & then try other options. Gary.

[I'm a Red Motor fiend]

I have my engine out at the moment for a few mods. The balancer is off. The key measures around 18.5 long and 5 mm wide. The keyway is a bees dick under 5 mm wide. If your cranks keyway is wider than this or measures wider at certain points it's flogged out. Measure this before you waste time doing anything else.

[Brent J]

Wow - 5mm is small compared to my components...

 

Pictures below. Crank is worn the most. Upper keyway shoulders are the worst at 10 10.6mm. The foot of the keyway is 9.77mm.

 

The balancer is a little less and I can easily slide it on by hand. They key ranges from 9.8 to 9.68 in the grooved areas.

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[S pack]

THat doesnt sound right, have you zeroed your calipers?

Yeah something amiss there.

Can see in this pic the analogue markings show 5mm or almost 2/10".

Edited by S pack, 22 April 2017 - 08:16 PM.

[S pack]

Haha, just realised his caliper is showing 4mm not 5mm. Need to wear my glasses more the older I get .