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only goes with high RPM
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Author:  der58SC [ Sun May 01, 2016 10:26 pm ]
Post subject:  only goes with high RPM

OK So the last time I drove the SC I had to get the RPMs high in order for the bus to move at a descent speed. So I thought it might be the valves or intake leak. I checked the valves and they were good. I checked the intake and it is good. I am wondering what else it could be? Maybe an intake leak I can't see like a broken gasket? Idles fine but if I put the engine under pressure at low RPMs, it pops and almost backfires.

Thoughts?

Author:  Slayer [ Mon May 02, 2016 2:16 pm ]
Post subject:  Re: only goes with high RPM

Do you have points or electronic ignition?
Checked cap, rotor, plug wires?
Did you check the timing?
Is it hard to start?

Author:  der58SC [ Tue May 03, 2016 9:12 am ]
Post subject:  Re: only goes with high RPM

I have electronic
I did not check the wires, rotor, or cap
I did not check the timing but will. I tried to move the dizzy but it didn't move so I will double check that today.

It starts fine if I start it every day. If I let it sit for a week, it is a little hard to start which it has always been like that.

It will accelerate fine in the driveway and idles fine. I have not taken it out for a spin since checking the valves, changing the oil, or tightening up the carb.

I also have to adjust the choke since it seems it will not let the engine idle low enough. RPMs sit at 2k+ at idle.

Thanks for the things to check Chris.

Author:  der58SC [ Wed May 04, 2016 5:28 am ]
Post subject:  Re: only goes with high RPM

So I checked the timing yesterday and it was 15* advanced. So I adjusted it to 10*. The only thing is that it has been set to 15* since I installed this motor and no issues until now. I did take a minute to tighten up the carb to the manifold since it looked loose.

I will try to take it for a spin today to see if it is really running better.

Author:  Slayer [ Wed May 04, 2016 7:27 am ]
Post subject:  Re: only goes with high RPM

Hope it will run better, keep us informed.

Author:  OB Bus [ Wed May 04, 2016 11:49 am ]
Post subject:  Re: only goes with high RPM

Is that 10 or 15 degrees at idle? Or at 3000+ rpm with max advance?

Author:  der58SC [ Wed May 04, 2016 12:54 pm ]
Post subject:  Re: only goes with high RPM

idle

Author:  Beto [ Wed May 04, 2016 3:41 pm ]
Post subject:  Re: only goes with high RPM

What's your setup?
Carb, dizzy, etc?

Author:  OB Bus [ Wed May 04, 2016 4:50 pm ]
Post subject:  Re: only goes with high RPM

der58SC wrote:
idle


What is the total advance, vacuum off (if you have vacuum) at 3000 RPM or so? s/b 28-32 range.

Author:  der58SC [ Thu May 05, 2016 7:16 am ]
Post subject:  Re: only goes with high RPM

009 dizzy, petronix electronic ignition, 30/31 Solex, single port, 1600. No vacuum stuff at all.

It is hard to say Larry about the degree when at 3000 RPM since I have a stock pulley. No numbers.

Author:  Beto [ Thu May 05, 2016 7:30 am ]
Post subject:  Re: only goes with high RPM

der58SC wrote:
009 dizzy, petronix electronic ignition, 30/31 Solex, single port, 1600. No vacuum stuff at all.

It is hard to say Larry about the degree when at 3000 RPM since I have a stock pulley. No numbers.


009, you need to set your timing to 28-30 degrees total advance at wide open throttle and let the idle fall wherever. Adjust your idle speed afterward in the throttle stop.
Start around 28 and you can advance in tiny increments, just listen for pinging under load. if you ping, retard the timing.
Find someone with a degreed pulley and measure off 28 and 30 degrees. I then used those measurements on my stock pulley and marked with nail polish.

Author:  Beto [ Thu May 05, 2016 8:27 am ]
Post subject:  Re: only goes with high RPM

Plus if it was running fine before then went to crap...
I had this happen in the past. Spent weeks adjusting this, changing that.
It ended up being one of the rubber caps, capping off a vacuum port on the carb. Looked fine, but when I pulled it off, it was dry and cracked, had a split on the backside and was causing a vacuum leak.

Author:  der58SC [ Thu May 05, 2016 9:06 am ]
Post subject:  Re: only goes with high RPM

oooh good idea! I will check the caps. Maybe one is dried out and cracked. I will give it a look. Right after mother's day.

Author:  Slayer [ Fri May 06, 2016 9:50 am ]
Post subject:  Re: only goes with high RPM

der58SC wrote:
009 dizzy, petronix electronic ignition, 30/31 Solex, single port, 1600. No vacuum stuff at all.

It is hard to say Larry about the degree when at 3000 RPM since I have a stock pulley. No numbers.


https://www.google.com/imgres?imgurl=ht ... mrc&uact=8

https://www.google.com/imgres?imgurl=ht ... mrc&uact=8

Author:  der58SC [ Fri May 06, 2016 12:23 pm ]
Post subject:  Re: only goes with high RPM

Slayer wrote:
der58SC wrote:
009 dizzy, petronix electronic ignition, 30/31 Solex, single port, 1600. No vacuum stuff at all.

It is hard to say Larry about the degree when at 3000 RPM since I have a stock pulley. No numbers.


https://www.google.com/imgres?imgurl=ht ... mrc&uact=8

https://www.google.com/imgres?imgurl=ht ... mrc&uact=8



Thanks Chris but how am I going to apply my monitor to my pulley? LOL

Author:  Fish [ Fri May 06, 2016 2:37 pm ]
Post subject:  Re: only goes with high RPM

Idle circuit jet clogged or electronic shut off solenoid not working. Bazinga!

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