Stripped Cam Belt

[HAWKNORTH]

Your thoughts required please.

I changed the cylinder head at the weekend, swapping a unleaded head for the old leaded one. This is on a 2.1 Pinto. I marked the position of all the pulleys in relation to the timing belt etc.I used the Kent cam, valve springs and cam followers from the old head. I used the valve that came with the replacement head. The old head had been skimmed the replacement is a standard 2.0 litre. I made sure that nothing moved while I did the swap and set the cam in the same position in the replacement head as it was in the old one. I put everything back together and fired her up. The engine started after a short delay and everything apeared ok. After running for a couple of minutes the engine stopped. I tried to start it again but quickly noticed that while the crank was turning the cam was not. The cam belt had stripped a number of teeth. I cut the belt free and tried all the pulleys in turn to see if anything had siezed. The dizzy drive turned by hand, the crank with a spanner on the pulley nut and the cam with a spanner on the pulley nut with resistance as the valve springs were compressed as you would expect. Any ideas as the best way forward please.

[speedtripledan]

Did you use a new cam belt with the head swap? If it were me i,d take the head off again to check no damage has occured if ok rebuild using a new cam belt.

[HAWKNORTH]

No, I used the old one which looked ok. I hope that it's only the belt thats gone. I'm worried that I must have got something a bit wrong although I dont think so. I must admit that i,m not that happy with setting up the timing etc. Its got a vernier pulley which i have no idea how to use.

[Guest chris brown]

Put a new belt on and try again I don't know how much additional lift you get with the kent cam but standard the pinto even with 40 thou off the head is safe. It sounds as if you might have put the belt on so it was running the other way to what it was before, I have come across this before.

[tractor]

as chris said its a safe engine so replace belt and the least you will need is a pretractor to set cam up if you want to set it up properly you will need a dti gauge as well

[Bob Tucker]

+1 for belt replaced backwards. Fit a new one, time up on standard marks, or the ones you made if not standard pulleys.

Bob

[Graham385]

I had the same problem when I rebuilt my first Pinto head. The camshaft had slight turning resistance which made the cambelt slip and strip. I found that I had accidentally interchanged the bolts for the camshaft thrust plate with those at each end of the spray bar. Same head, same thread, different length. The longer bolts in the spray bar had slightly pinched the cam bearing shells to cause the problem. Swopped them back and all was well.

It's a long shot but worth checking.

 

Graham

[HAWKNORTH]

I whipped the head off again just to make sure that it had not done any damage. All looks fine. Turned the cam shaft with a spanner to check movement of valves etc, all ok, just the resistance of the springs as you would expect. Stripped out the cam followers to check free rotation of cam shaft, again no problem, shaft turns freely by hand. I marked the cam belt on the first strip down so Im pretty sure it went on the right way. So in other words Im not sure what caused the problem. With the head still off, whats the best way to set up the timing. Kent cam FB32. All my original marks are in place so will use these if I have to and try again at the weekend with fingers crossed.

[Guest shaggy]

Changed my cam a couple of years ago and thought I had it spot on - ran fine for a couple of minutes but I had a tooth out (been to the dentist since) and started running rough after that. Seems if the belt is out one tooth, compression or whatever gets in the way of running how it should, and puts a strain on the belt, hence your belt perhaps snapping. Set up with a new belt as per manual, and was fine after that, so I would perhaps suggest setting up with the ford manwell as a guide, then tweeking to get the vernier spot on

 

Si

[HAWKNORTH]

Yeah thanks Si, I have a feeling it was perhaps out a tooth or two and maybe over tight as well

[richardm6994]

Taken from Burton's website regarding setting up a camshaft...

 

Rotate the crankshaft clockwise to 90 degrees after TDC. This will make sure all the pistons are half way down the bore. Now position the dial gauge so that it can read the lift of the inlet valve of number 1 cylinder from the top of the valve retainer. Rotate the cam until the gauge shows that the valve is at full lift. As with the crankshaft, there will be a dwell period where the valve is at full lift. True full lift is at the centre of this dwell period. Roughly position the cam at true lift position. Now rotate the crankshaft clockwise to the full valve lift position (as specified on the camshaft data sheet - this figure is typically from 100 to 120 degrees after TDC), fit the timing belt or chain and set up the tensioner.

 

Now rotate the crank clockwise until the inlet valve of number one cylinder is just off full lift position (such as 0.005” or 0.15mm). Record the figure on the timing disc from the pointer. Then continue to rotate the crank clockwise until the valve has fully opened and then closed by the same distance as previously used (0.005” or 0.15mm). Read the figure on the timing disc again. The position of full lift is the middle of these two figures. The full lift position can be calculated by adding the two figures together and dividing by two. Adjustments can then be made to the camshaft timing, using an adjustable cam pulley or offset dowels, if this figure does not agree with the one on the data sheet. Check the timing again after adjustments using the same procedure. Having timed the camshaft, check that there is no piston to valve contact. Minimum clearance is 0.060” (1.5mm). This can only be checked by dummy building the engine with a piece of Plasticine placed on the crown of the piston. As the engine is turned, the valves will indent the Plasticine. The clearance is then measured as the thickness of the Plasticine between the piston crown to the bottom of the valve indent. Before starting the engine, turn the engine over by hand to ensure that it turns freely. Prime the oil system and check that everything is set to ensure that the engine starts straight away. The engine must not be turned over for any length of time on the starter. Once started, do not allow the engine to idle for the first 20 minutes and keep the revs to a minimum of 2500 rpm. This will ensure adequate lubrication of the cam and followers and reduce the contact force between the cam and follower. If any adjustments need to be made within the first 20 minutes, then shut the engine down. Do not allow the engine to idle. Please note that new hydraulic lifters may in some cases operate with excessive noise for a few minutes before they are fully charged with oil.

[richardm6994]

If you've got a vernier cam pulley, after you have set the no.1 inlet valve at full opening then loosen the vernier bolts.

 

Then set your crank at the right angle (edit to say 108 degrees after TDC as per bob's post).

 

Then fit and tighten the belt.

 

Then make sure the crank or cam shaft haven't moved (the pulley may move slightly as you tighten the belt but this is ok as it's not driving the cam because the vernier bolts are loose)

 

Then tighten the vernier bolts.

 

 

Turn it over by hand a few times to check full valve opening still falls at the correct crank angle.

 

 

Check the kent website for the crank angle for your cam.

[Bob Tucker]

FR32 is 108 degrees, but you cant set it up with the head off.

You need to know when the valves are at full lift & you need a dial gauge to do that & a

degree wheel (Kent sell them as part of the cam kit) to fit to the crankshaft

 

Steamer's extract from the Burton site is a good guide.

[Guest mower man]

Not wanting to be pedantic but never use a s/h or used cam belt it is a ,recipe for pain ,re belt tension ,to tight ? I doubt you can !!, if its too slack you would have more probs mower man

[Guest MarkB]

Have you checked the auxiliary pully turns nice and free?