26 replies to this topic

[NZMini1275]

Right need a little help
Car is nearly ready to hit the road
New engine-Cam has been run in.

Engine specs
1312 cc
Swiftune sw8 camshaft
Minispares mse4 Big valve head
Hif44 carb
Aldon amethyst ignition system

I have a wide band afr gauge and fuel is set to 14-14.5 at idle
Timing is set at 12 degrees at idle

Engine starts easy, idles and revs fine but it vibrates a lot.
Now I haven't had a mini for years and never one with a lumpy cam but I reckon somethings not quite right.
Engine is nicely held with no movement as all steadys and bushes etc are new. Subframe has been solid mounted which I guess makes it worse also.

I'm wondering if the flywheel and clutch could be out of balance.
Would this cause vibrations at idle or only higher up the revs?

Anything else that would cause vibration?

Thanks
Dan

[Carlos W]

Is it verto or pre verto?

AC Dodd has done some great videos on how far out verto ones can be

[NZMini1275]

Is it verto or pre verto?

AC Dodd has done some great videos on how far out verto ones can be

Its a pre verto and I know they never balanced it or clutch

[Chris.Williams]

Did you not get everything balanced?

[Chris.Williams]

Maybe do a video

[Mini Manannán]

This is a verto but a pre-verto could easily be the same: https://youtu.be/bQWBcCKpeeE

Edited by Mini Manannán, 08 February 2017 - 09:23 AM.

[Carlos W]

This is a verto but a pre-verto could easily be the same: https://youtu.be/bQWBcCKpeeE

 

Thanks mate, that's the one

[nicklouse]

 

Is it verto or pre verto?

AC Dodd has done some great videos on how far out verto ones can be

Its a pre verto and I know they never balanced it or clutch

 

who never balanced it?

 

the pre verto fly and back plate came balanced as standard.

 

what have you got?

[nicklouse]

also a video of the engine running would be good.

[NZMini1275]

I have a couple of short vids of it running but I would need to get one inside to show how bad it is.

%5BIMG%5Dhttp://i1366.photobucket.com/albums/r776/dangerraty/th_IMG_1834_zpsitvszh86.mp4

%5BIMG%5Dhttp://i1366.photobucket.com/albums/r776/dangerraty/th_IMG_1839_zpskkidnjbl.mp4

Probably have to try a new flywheel and clutch that has been balanced to see if that tames it.

[Carlos W]

Is it running on all 4 cylinders?

[tiger99]

In case you have not done this yet, you should positively establish whether it is engine or drive train. Does it vibrate with engine running, clutch depressed? Now do the same, in gear, so part of the gearbox including drop gears is locked and not spinning idly due to clutch drag. Now on-road tests, running downhill in neutral, engine off. Then in the appropriate gear for the conditions, clutch down, engine off. (CAREFUL! DO NOT ENGAGE STEERING LOCK!!!)

After doing that, you will know whether it is engine or transmission. It probably is the engine but it would not be good to waste time and money on it if the problem was elsewhere.

Oh, and check that you do have some compliance in the mounts. RUBBER, not poly, in at least one end of the top and bottom steadies.

Then make sure the engine is running properly. Missing a cylinder was suggested above and ought to be the first think to check, followed by valve clearances, timing (check all 4 sparks), carburettor etc. If you have the information necessary and can check your actual camshaft timing by using a dial indicator on the valve gear, that would be useful.

In other words, please check everything external or accessible before assuming that the engine internals are off balance. That may be the case, but it is best to be absolutely sure before stripping anything.

[NZMini1275]

Is it running on all 4 cylinders?

It appears to be. All plugs are firing and when I take a lead off one at a time it makes a difference.

[NZMini1275]

In case you have not done this yet, you should positively establish whether it is engine or drive train. Does it vibrate with engine running, clutch depressed? Now do the same, in gear, so part of the gearbox including drop gears is locked and not spinning idly due to clutch drag. Now on-road tests, running downhill in neutral, engine off. Then in the appropriate gear for the conditions, clutch down, engine off. (CAREFUL! DO NOT ENGAGE STEERING LOCK!!!)

 

 

 

After doing that, you will know whether it is engine or transmission. It probably is the engine but it would not be good to waste time and money on it if the problem was elsewhere.

Oh, and check that you do have some compliance in the mounts. RUBBER, not poly, in at least one end of the top and bottom steadies.

Then make sure the engine is running properly. Missing a cylinder was suggested above and ought to be the first think to check, followed by valve clearances, timing (check all 4 sparks), carburettor etc. If you have the information necessary and can check your actual camshaft timing by using a dial indicator on the valve gear, that would be useful.

In other words, please check everything external or accessible before assuming that the engine internals are off balance. That may be the case, but it is best to be absolutely sure before stripping anything.

No difference if clutch is pushed in or if gear is selected.

Should be ready for a run on the road next week

 

I think engine mounts are all poly so might get some rubber replacements

 

Will check valve clearances again

 

I did notice whilst timing that there is a bit of timing scatter. 

[nicklouse]

I have a couple of short vids of it running but I would need to get one inside to show how bad it is.%5BIMG%5Dhttp://i1366.photobucket.com/albums/r776/dangerraty/th_IMG_1834_zpsitvszh86.mp4%5BIMG%5Dhttp://i1366.photobucket.com/albums/r776/dangerraty/th_IMG_1839_zpskkidnjbl.mp4Probably have to try a new flywheel and clutch that has been balanced to see if that tames it.

to be honest sounds quite normal.

You mention there is some timing scatter that could just be it.