Rt132 18rc rough idle and car nudges while accelerating and running

[remo80s]

I don't mind man, all info are welcome as i am keen to learn more and work on my car all your posts are very helpful actually. I've changed the fuel filter already. The idle only roughens up after driving a while. But it's stable before the engine warms up.

[o_man_ra23]

A lot of 18R-C's have automatic chokes. These will alter the fuel/air mix until the car warms up. Check your spark plugs after a good long drive and have a look to see whether they are going white. If they are a dark grey, they are good, if they are whiteish, then you are lean, if they are really black with signs of fuel still on them, you are super rich (really black is still on the rich side).

[MorgzMods]

+rep for all the user information Owen, thanks again

[remo80s]

Thanks guys! I'll have a look later,been busy latety, I used the car for more than three weeks without the car hesitating while accelerating. I drive it less than an hour straight everyday, buy today i drove it to sydney, it hesitated after 50 mins of straight freeway driving. It went back to normal after 5 mins. I'll be driving back lately, i'm afraid that would happen again later. Is it still the mixture that us causing this? Thanks again

[MorgzMods]

did you check the spark plugs after the long drive?

[remo80s]

I have checked it yesterday after a long drive, they were black. So i had to make it lean a bit,when i turned the air/fuel screw to the left, i noticed my car was creating white smoke and the idle was still gettin rough. I don't know if this has got somethin to do with the idle, but i noticed that my fuel gauge keeps on moving up and down when the engine is running.

[remo80s]

Sorry morgzmods, i lost internet access for a long time. I checked the plugs and the color greyish. Looks fine to me.thanks to everyone for all the info.

[j75]

very late response i know.

I had this problem with my 18rc which was resolved by running premium fuel with slightly advanced timing.

I think the use of premium fuel is required to do this as lower grade fuels may damage your engine.

[MorgzMods]

What fuel do you run j75?

I've been told you can run any fuel (which i believe) but i'm not sure if i should be aiming for a higher quality fuel.

[j75]

I have only ever run premium (98 from memory) fuel in my RA40 and I'm sure it likes it.

[remo80s]

Nice. I'll try that on my next tank. I'll update tou guys. Thanks

[o_man_ra23]

The 18R-C has 8.5:1 static compression, a 1500-4500rpm useable rev range, and a pissy little tiny carby. A stock 18R-C can run happily on any fuel, including low rent E-10. Japan had unleaded fuels in the 60's, so no need to worry about running additives etc.

I never hurts to run a bit of premium every now and then, and wouldn't damage the engine to run it permanently. However, there shouldn't be any noticeable gain, unless there is too much timing dialled in, the carb is set too lean, or there is some other engine problem causeing the motor to run incorrectly on the low rent fuels. If running good fuel in a stock 18R-C fixes a problem, I would be looking for something a little more sinister going on.

That's my experience anyways (3 RA40's, an RA23 and an RA28, all running stock 18R-C's when purchased and originally registered/driven, some even running them when decommissioned/sold)

[j75]

I believe it was advancing of the timing that fixed the problem for me (engine hesitation cruising in 5th gear) not premium fuel - probably could have explained it better initially.

I read somewhere that if using premium you can advance the ignition timing to take advantage of the higher quality fuel so I tried it and it fixed the hesitation problem.

Weber 32/36 dgv carb fitted to my 18r-c which could be the sinister component if it starts to play up again.

When it's running as it should the 18r-c engine actually performs very well.

[o_man_ra23]

Stepping from a poor 18R-G to a good 18R-C you notice the leap down...

Yes, running premium allows more advance on the timing, however the cam profile, low compression, small ports, and generally restrictive nature of the 18R-C will let you down. It takes a lot of work to make the R-C a decent engine (and there have been a few people brave enough to do so)