engine run on - Page 2

Excaliber · #21 (**permalink**) 08-25-2008, 01:24 AM

I like 1st gear myself, it's the 'danger' thing you see...

Being as I'm running a VACUUM ADVANCE MSD there is a way I can lower my idle speed. Simply hook up the vacuum advance, which will speed up the idle rpm well above my current 1000-1100 and then adjust the mechanical idle speed screws on the carb to bring the speed BACK to a 1000 rpm. Now when I shut down the engine the throttle plates close off more completly, making it difficult for the still turning over engine to draw in additional air/fuel through the carb. No air/fuel, no detonation, engine simply quietly stops.

I DID have this setup before and it worked great. But lately I've been 'messing with the timing' and have currently disconnected the vacuum advance. When I get the base and mechanical advance dialed in (darn close now) I'll revisit the vacuum advance issue and that will totally solve my current 'run on' condition and STILL allow for a 1000-1100 rpm idle.

I switched to a flat tappet after my solid roller ate a lifter for lunch, by the way...

69boss429 · #22 (**permalink**) 08-25-2008, 05:27 AM

It's not a Cobra but,I had a run on issue with my Boss 429 and changed to colder plugs and backed the timing off 2 degrees,problem solved.

Bartruff1 · #23 (**permalink**) 08-25-2008, 08:14 AM

I had all kinds of possible solutions suggested

but my installer and a master tuner simply turned the idle down to 800-850...no charge, problem solved.

patrickt · #24 (**permalink**) 08-25-2008, 08:17 AM

Quote:

Originally Posted by Bartruff1

I had all kinds of possible solutions suggested

but my installer and a master tuner simply turned the idle down to 800-850...no charge, problem solved.

I have a pleasant, slightly lumpy, idle in that range with my solid flat tappet, but a solid roller might be another matter....

blykins · #25 (**permalink**) 08-25-2008, 09:44 AM

Yes, it is another matter. A solid roller won't wipe the lobes down on your cam and make you have to rebuild the entire engine because it scattered metal throughout the oiling system.

I know Ernie, your solid roller dumped on you....but you were running crappy lifters.

It would be nice if an idle adjustment would fix the problem, but I would find another way around it if I could.

patrickt · #26 (**permalink**) 08-25-2008, 09:49 AM

Quote:

Originally Posted by blykins

It would be nice if an idle adjustment would fix the problem, but I would find another way around it if I could.

Brent, meaning you do not feel comfortable idling a solid roller down in the eight hundreds?

blykins · #27 (**permalink**) 08-25-2008, 10:01 AM

People do all the time, especially on "street roller" grinds. However, if I had a choice, I'd probably keep it idled up a little bit. The main reason in this case is because he hasn't mentioned which lifters he's running. It's hard to find lifters that are not pressure fed anymore, but I don't know how old this engine is that he's working with.

Solid roller lifter technology has come a long way. These days, correctly matched lifters/springs will probably last many more miles than any of us would put on our Cobras.

Excaliber · #28 (**permalink**) 08-25-2008, 10:41 AM

My solid roller came with the car and was installed sometime in the late 80's. That engine had about 8,000 miles on it when the roller bearings in the lifter made good there escape. I've heard some say about 8 to 10,000 is what you can expect from a solid roller. Even WITH a high idle, I'd still 'blip the throttle' on occasion to toss some oil up there if the engine was going to idle for a long stop light.

Archrms · #29 (**permalink**) 08-25-2008, 11:44 AM

I had the same problem earlier this year. It cleared up after adding octane booster, but I think it was caused by Stabil that was added to the tank before putting it away for winter. Hasn't happened since, and I haven't added any octane boost since then either.