Idle speed 4.5 liter

[Dan Suskin]

Good morning

What is the appropriate idle speed for a 4.5 liter? Mine is currently about 1000 rpm but that seems high.

Thanks in advance.

[Chris Card]

Hi Dan,

Mine idles happily at 450-500 rpm. It has a cone clutch and lightened flywheel and, I think, slightly raised compression and a Phoenix crank, which may be heavier than the original light crank.

1,000 rpm sounds much too high to me, unless the engine has go faster mods that mean it won't run any slower. I think that you will be overheating fairly quickly in stationery traffic.

Chris

[Dan Suskin]

Thanks Chris. I have high compression pistons and a phoenix crank. I have been in quite a bit of traffic and it keeps cool, but I will adjust it down I think.

[Chris Card]

Dan - which type of clutch do you have, and how quickly does the clutch stop work when engaging first gear from stationery?
When you depress the clutch, the flywheel should stop in about 1 - 2 turns so that you can engage first silently. If you have the clutch stop too tight, it can cause the gear change between 1 and 2 to lock solid. Very embarassing in traffic!
Chris

PS - presumably the rev counter is recording accurately.

[Dan Suskin]

I'm pretty sure its a plate clutch but not certain - haven't looked yet (too many car projects).

Clutch stop is excellent - almost immediate.

I'll check the rev counter against an external one - but is sounds right