K1200 belt alignment.
Turbo Mini Forums

Hi again,

On my trial assemble for a belt tensioner I notice after a couple of turns to the engine the belt tends to go outside the engine, what could be the cause?

Pretty sure that the pulleys are all center align, I also have no guides on pulleys except for the crank, a guide on the mini cam pulley probably will help. Could be some kind off deflection on one of the pulleys causing the belt to go off?

Edited by R.Rodrigues on 4th Mar, 2018.

Belt too tight, I've seen a broken cam due to a tight belt on an 8v before, don't over do it, there's a lot of leverage doe the the belt conversion.

do the pullies line up correctly with a straight edge, if they do then the head may be out of square to the block making the belt track across .


carl

WWW.FORCE-RACING.CO.UK PLEASE CLICK HERE

Will check tension before as i set it by hand and could be a title to tight. Using the 1/64" per inch of span length.

http://www.pfeiferindustries.com/installat...tensioning.html

If I put a ruler on the edge they don't align, different width pulleys (aftermarket vs stock pulleys), so I center align them, the tops are something like 30mm, the bottom and mini cam 28mm, and also the top ones have a chamfered edge, but will double check that.

Thanks,

PS: This photo server is crap, very poor quality after uploading.

Edited by R.Rodrigues on 4th Mar, 2018.

Ok, short update.

Lose the tensioner, definitely more slack than supposed, same problem.

So, first mistake... pulleys are about the same width, only 0.40mm diference from the ones in the head for the bottom ones, that makes the Ex. 0.50mm and Ad. 0.80mm off alignment.

Whit this different values as FastCarl said "out of square to the block"", the head "rotate" anticlockwise, so admission have moved further than exhaust causing this different values?

Also have .20mm of mini camshaft endfloat were is suppose to be .076 to .178mm

Have to lose the head to check, and remove some material from the adapters, will update the topic after.

Is the head sat parallel on the block? also, belt tensioner, the eccentric type, the roller should be on the trailing side of belt rotation. Definitely do not do these belts up tight. You know this to be true when the engine is running you hear unusual sound from cam pulley end. Reduce down oil pump jackshaft end float. also check crank end float is acceptable.

Edited by Sprocket on 4th Mar, 2018.

Ahhhh!

I was looking on my phone beofore, now i am on a big screen I see this is not a kit, but a DIY setup, well done!

that tewnsioner should be fine with the belt wrap, its similar to the other kits,

it looks like you could get away with taking some material off of the bottom pulley to bring the belt back toward the engine,

Tension the belt by rotating it up rather than down.

and this ^^^

I had the similar issue. My belt would walk from a 4/5mm gap to contact the head plate in two turns of the engine.

I checked my pulley alignment many, many times - all was perfectly in line - I knew it was becuase I'd checked and adjusted the pulley positions as I was assembling the engine.

I checked my cam alignment to the head deck with a height gauge - literally .007" variation from the lobes at opposite ends of the head, which is a tiny, tiny angle, and the cams (when measured across the head) where almost perfectly parallel.

I checked my genuine Ford tensioner - which did have a very slight angle on it, so I used a cheap aftermarket one, which had less of an angle, and a shim, and made no difference.

In the end, I said fork it and started machining the back face of the "front" pulley by about 1mm, which allowed me to add a backing plate I turned from a big lump, which I then welded into place. Belt now rides on the side of this plate.

I'm still not satisfied, but it does appear to work. Next time the engine comes out for a rebuild, I'm going to check my pulleys on a CMM as I'm suspecting the "teeth" are skewed relative to the true axis, or the 'teeth" are not parallel to the true axis.

Edited by TurboDave16V on 6th Mar, 2018.

That is not good news to me. I have just completed the assembly, using all SC parts, and have not noticed any "walk" on the belt but am a bit nervous on first startup now that this has been raised, especially as the engine is not for me but a very good friend, who financed it !

If you see no walking when cranking with the plugs out, you’re ok I reckon...

I agree with that,

Have check head alignment and from the best I can measure whith a ruler and spacers, 0.20mm has the maximum value, nothing to worry about I think.

Then I put the oil pump shaft adapter on the lane and its wobbling all over the place, new one to be made until the end off the week I hope.

Planing on add a guide on the oil pump shaft also, like Turbodave, machining 1mm from the front face off the oil pump shaft pulley and tig weld a guide.

My belt doesn't come off that much, about 2 to 3mm after 6 or 7 full turns and then stops at the crank pulley, but was enough to touch the fan pulley before I put the gasket on the pump.

And yes this is not a kit, handmade top and bottom plates, honda pulleys, and lots and lots off head scratch on measures and figuring belts and "bolt on" tensioner.

Not sure if i can run this until IMM, but beer I will have...

Thanks,

Thanks TurboDave - reassuring because it has been cranked a lot to circulate oil.

Little update, belt still tends to go outside the engine, after 8 to 10 turns I star to hear the belt rubbing on the crank guide.

Took .80mm off the cam adapters to align all pulleys, new adapter to oil shaft and set end float to .06mm.

I'm starting to think in some misaligned in the crank pulley as I machine the interior to fit.

Going to fit a guide in the oil shaft pulley and give it a try.

hmmm,

I'm wondering if there is a "crown" on the tensioner pulley, i doubt it but worth 2 mins with a set square to check,

https://woodgears.ca/bandsaw/crowned_pulleys.html

also, is it possible to reverse any of the cam pulleys? centanly the jack shaft one looks like it could be swapped round, it any are taperd they could be causing it.

The test for angular miss alignment is to turn the drive system in one direction as the belt tracks from one side to the other, the more turns the better the alignment. Stop and reverse the rotation. If the belt still tracks to the same side, then there is an angular miss alignment. If on the other hand, the belt tracks back towards the other side, it's not angular miss alignment.

Belt tension higher on one edge of the belt than the other will cause the belt to track to the lower tension edge of the belt.

the degree of angular miss alignment is tiny in synchronous belt systems compared with V belts. I don't remember the actual number, but it was certainly less than 1 degree angle.

Will try to reverse rotation tomorrow to check.

Pulleys are all in they "natural" position, as I suspect some misalignment to the crank I went looking for old photos and original timing marks say its all good.

I doubt it but, could the 5/16 bolt to the tensioner flex and cause more tension in one side.

Photos from the bottom pulley, will have to check, if possible, if the "teeth" are "skew??, they could be deformed wend drill and tap or the secure bolts bottoming out.



Edit: Rotating the engine backwards the belt goes back to the other side, so can I skip head miss alignment, and most likely to be pulleys alignment.

Tensioner is GATES Ref: T41305, Flat, not crowned.
http://media.cdn.mister-auto.com/gates/ten...033t41305-1.jpg

Edited by R.Rodrigues on 21st Mar, 2018.

mmm,

I'd be suprised if the drilling and tapping of the pulley caused the issue, but a good thought.

another thought, have you tried turning the belt around, in case it is compromised in some way.

Yes, already tried to turn the belt around.

Went to my machinist this morning to do the guide to jack shaft pulley, "that wont solve your problem, will only chew the belt" he said.
He give me the idea to shim the head one edge at time to se if that makes any diference, and them check the head face parallel to the cam center line and also the block to crank center line.

good thought,

you could put a wedge ( bit of gasket or card) under the cam end and then use a head stud to " adust" the gap the other end, then check with feeler gauges.

its bound to be somthing obvious, simple and daft,

I just noticed that the pulleys you are using are almost identical to mine.

I checked everything out on my engine. Only thing I havent done is to run my engine backwards, which I’ll do when I pull it out in a few weeks.

As it climbs one way. Then reverses with opposite rotation, there really is limited things it can be assuming nothing is loose. I’m thinking the pulley teeth are skewed to the axis; almost like a helical gear is cut. The belt will want to leave the pulley in a direction normal to the teeth, so if they are cut at an angle, it’ll leave at an angle. And as you reverse direction, it’ll go in the same angle, but in the opposite direction.

Really, this is the only thing it can be.

Edited by TurboDave16V on 23rd Mar, 2018.

Other day when I shim the head, i see no diference and I put up to two stripes of gasket under one side at the time, even rotating backwards

Then I start to think about the belt being old and to hard, the store i bought add it in stock for years and that was probably about 3 years now, next thought was the pulley's, after all they are cheep eBays.

Edited by R.Rodrigues on 23rd Mar, 2018.