23 replies to this topic

[ACDodd]

Idle speed should be 925 to 950rpm

Ac

[Spider]

Also increasing the revs slightly (pretty much I think) stops the rattle. Like idling at 800-850 and increasing it to 950 -1000rpm

 

It sounds like the clearance maybe a tad excessive. The other thing is that you need the carb in good condition and a low over-lap cam profile to get a very solid steady state idle speed. As soon as that speed changes, on the up or down speed, the gears, being helix, will flap from thrusting on one side to the other fairly sharply.

The other thing is what oil are you running with ?

[alex-95]

Thank you, I’ll double check the idle, I think in the video it was around the 950 mark and fluctuating between 920 - 980. Carb has roughly 10k miles on it since a full rebuild.

Idler clearance was set to 4 thou.

I’m running the Minispares oil.

[Spider]

Here's a Flywheel Housing I removed just today. To show the value of aligning these to the Gearbox Case, this one has done 75,000 km, it was one of the first I did;-

 

 

It's clear to see where the thrust has been running, but there's zero wear, nothing I can feel or measure. The Gearbox side was even better in appearance.

[alex-95]

Here's a Flywheel Housing I removed just today. To show the value of aligning these to the Gearbox Case, this one has done 75,000 km, it was one of the first I did;-



It's clear to see where the thrust has been running, but there's zero wear, nothing I can feel or measure. The Gearbox side was even better in appearance.

That’s impressive! I’ll definitely be doing that for my next build. I looked how you machined yours and should be pretty easy to do.


Do you think 4 thou clearance is too much? What clearance was your idler running? And is that a fast road engine?
I’ll check the idle this evening and if it stops the rattle I think I’ll run it for the rest of the year.

[Spider]

That’s impressive! I’ll definitely be doing that for my next build. I looked how you machined yours and should be pretty easy to do.

Do you think 4 thou clearance is too much? What clearance was your idler running? And is that a fast road engine?
I’ll check the idle this evening and if it stops the rattle I think I’ll run it for the rest of the year.

 

Cheers for that.

This one was set at 0.004". and it's what I like to aim for. It's not on a powerful engine per se, a stock 1275, but it does seriously get hammered - quite literally. It's seen off a couple of broken drive shafts if that's any indication.

 

When idling and running, the Idler is silent.

[alex-95]

That’s impressive! I’ll definitely be doing that for my next build. I looked how you machined yours and should be pretty easy to do.

Do you think 4 thou clearance is too much? What clearance was your idler running? And is that a fast road engine?
I’ll check the idle this evening and if it stops the rattle I think I’ll run it for the rest of the year.

 
Cheers for that.

This one was set at 0.004". and it's what I like to aim for. It's not on a powerful engine per se, a stock 1275, but it does seriously get hammered - quite literally. It's seen off a couple of broken drive shafts if that's any indication.
 
When idling and running, the Idler is silent.

Ok cheers, so clearance should be good on mine, mines a fast road engine, haven’t broken any drive shafts though haha .
I’ll have to check all the drop gears when I next build an engine and gearbox and align the dowels to the transfer case.
I’ll check the idle etc and run the car, if it gets worse I’ll have to sort something.

[stuart bowes]

I think Spider's is more of an 'off-road' engine.  must have really grippy tires though because they're all upside down over there

[alex-95]

Managed to check the idle today and was 850. Raised it to 950 and the rattles stopped, it fluctuates between 925 and 960 ish, so pretty good I think.

Thanks for your help