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Topic Review (Newest First)
12-30-2012 11:04 AM
NOlowrider I would check the easy stuff first before I dive into the carbs for a rebuild. Take a can of carb cleaner and spray around the base of the carbs, around the carb fittings. It the idle changes then you found a leak. Make sure the linkage is not binding. Make sure the floats are not sticking alowing the fuel to bypass the needle and seat. Holley's don't need alot of fuel pressure (5.5 psi should do it). It is possible that just the temp change alone it the culprit. The air density changes from summer to winter and minor adjustments are required. Dry rotted and cracked vacuum line?
12-29-2012 05:17 PM
F-BIRD'88
Quote:
Originally Posted by MuscleCarpenter View Post
Thanks for getting back to me. I know rec-90 is low octane. The car typically runs fine on 93 alone, I add the race fuel to fatten it up and to be safe to prevent detonation (and smells better too). It's a low comp. motor (8.5-1), very street-able, doesn't make a lot of boost (between 8-10 lbs. at WOT. Never runs hot, only 185 degrees in stop-n-go traffic. Bad, stale gas makes a car run crappy, and I would agree with what you say normally, but the car is running great other than the fast idle. If its too lean would that make it idle fast?
yup did you create a extra air leak. Blew a vacuum hose off or blew the carb gasket or... power valve diaphram. A air leak will make it idle faster for sure.

I'd be getting it corrected before running that blower motor again under boost.
Cannot endorse using low octane fuel.
12-29-2012 05:16 PM
MuscleCarpenter Ethanol is bad for fuel lines, gaskets, etc. in motors not designed for that right? I know its done a job on my old mower and small gas powered generator (fuel leaks)
12-29-2012 05:14 PM
F-BIRD'88 Looks like your mechanic is going to be rebuilding the carbs, flushing the fuel; system, replaceing the fuel filter
and giving it a tune up. New plugs etc.

Stuff happens when a car sits for extended time and its never good.
12-29-2012 05:12 PM
MuscleCarpenter Thanks for getting back to me. I know rec-90 is low octane. The car typically runs fine on 93 alone, I add the race fuel to fatten it up and to be safe to prevent detonation (and smells better too). It's a low comp. motor (8.5-1), very street-able, doesn't make a lot of boost (between 8-10 lbs. at WOT. Never runs hot, only 185 degrees in stop-n-go traffic. Bad, stale gas makes a car run crappy, and I would agree with what you say normally, but the car is running great other than the fast idle. If its too lean would that make it idle fast?
12-29-2012 05:08 PM
F-BIRD'88 Yup a blown power valve will do that ( from a previous engine backfire)
happens sometimes.

On a blower motor that does not have enough idle timing the chance of a backfire is greatly increased.
It don;t get any better as the plugs foul, either.

Old stale gas is a pain. Ethanol or not. Lots of people try to blame everything including bad luck bad weather and more
on ethanol. Most of that is BS.
12-29-2012 05:02 PM
MuscleCarpenter I haven't tried anything yet. was wondering what would/could cause it to fall out of adjustment so quickly. Was perfectly dialed in. Blown power valve perhaps? Didn't want to start messing around until I had an idea where to start
12-29-2012 04:08 PM
F-BIRD'88 Rec 90 is low octane fuel ethanol or no ethanol its still low octane fuel and a real bad idea for a supercharged motor.

Any fuel will go stale if it sits long enough. Ethanol add or not. Don;t matter. Its just old stale fuel that won;t run good any more. Just drain the old fuel and fill up with the best pump gas 92++ octane and add the race gas as you like to your liking to boost the fuel octane. I recomend you add unleaded race gas 110 or higher rated.

Your carb may have injested some varnish from the old stale fuel. Your spark plugs may now be fouled and need replace ment. clean out the carbs and replace the fuel filter and replace the old fuel.

Again running 90 octane gas in your supercharged engine is not a good idea. Ethanol or not.
12-29-2012 04:06 PM
NOlowrider Are you able to get the idle down by adjusting the curb idle screw? I always back the idle screw completely out on the rear carb and adjust the curb idle by the front carb, assuming you have a 1-1 linkage. Are you able to check the float level while it is running? Also check your fuel pressure. I run 5.5 psi
12-29-2012 03:09 PM
MuscleCarpenter
Carb issues w/BB Chevy w/BDS blower

Hi. hope someone is willing to help. I'm having trouble with the idle on my ride. It's a '69 El Camino with a 468 and it has a BDS 8-series blower with two Holly DP's.

I live in Ft. Lauderdale and am trying to get the car ready to cruise again. It's too hot to ride in the summer down here without A/C, so the car sits for long periods (I frequently start and run around the block, but probably not often enough).

I've read and heard that the ethanol in gas has really screwed with a lot of "old school" rides so i switched to an alcohol free fuel called "Rec-90". I was using 93 octane, with Stabil while car was stored. I also learned that ethanol attracts water in the tanks of stored vehicles. I mix VP C13 race fuel to fatten up the mix about 1 to 4.

Before I made the switch to the "Rec-90" the idle was a little rough/uneven and on the low side (not too bad, still very drivable). I often had this problem after getting the car out of storage, but it always cleared up with some driving and fresh fuel. Normally the curb idle is about 900-950 and about 800 when in gear. right where it should be.

After the switch and a few spins around the neighborhood (with a few mild hole-shots to clear out the gunk), the car stalled out when I came to a stop to turn around. It easily restarted, backfired, and started again no problem. Shortly after, the idle speed climbed to around 1500 and won't come back down. Other than the fast idle the car seems to run great.

Does anyone know what the issue might be? I'm a carpenter by trade and my mechanic is out of town for the holidays. I would like to be able to drive it while I have some time off myself. I would appreciate some advice/help, if someone is willing to offer it.

Thanks in Advance,
MuscleCarpenter

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