Vacuum Leak (Likely Culprits)
Discussion
Hi all, I'm now more sure than ever "Ol Gasbag" has a vacuum leak.
The car goes like ship off a shovel & drives beautifully, but there's an idle issue & on both fuels.
I'll be giving her a good spray with easy start tomorrow to see if I can locate the leak & I already have some ideas of likely culprits.
But before I get spraying, I'd thought I'd ask the wise people who've been around this engine for years where they most commonly suck air.
RV8 experts, I'd be very gratful if you can share your wisdom on vacuum leaks with this engine.
Thanks in advance, Dave.
The car goes like ship off a shovel & drives beautifully, but there's an idle issue & on both fuels.
I'll be giving her a good spray with easy start tomorrow to see if I can locate the leak & I already have some ideas of likely culprits.
But before I get spraying, I'd thought I'd ask the wise people who've been around this engine for years where they most commonly suck air.
RV8 experts, I'd be very gratful if you can share your wisdom on vacuum leaks with this engine.
Thanks in advance, Dave.
Bodgers fingers around the purge valve? Pipes/seals into plenum ~ poor seal at joints twixt manifold - trumpet base - plenum, pipework stuff (purge, servo, FPR vac, dizzy vac, PCV pipes!, idle bypasses & galleries in plenum).
Don't underestimate the effect of poorly mapped ignition timing either.....
Don't underestimate the effect of poorly mapped ignition timing either.....
I found a leak around the elbow joint from the AFM to the manifold, so went round and retightened all the clips on hoses. I also put a small smear of Vaseline around the inside of each plenum hose and the vac advance and Hylomar around the plenum base. Some have also recommended checking the base idle screw.
chris1972 said:
I found a leak around the elbow joint from the AFM to the manifold, so went round and retightened all the clips on hoses. I also put a small smear of Vaseline around the inside of each plenum hose and the vac advance and Hylomar around the plenum base. Some have also recommended checking the base idle screw.
Think the leak need to be the other side of the throttle plate ..Mine was leaking from a bung in the side of the plenum ..
You could try gas leak detector .. it bubbles up !go the the local plumbers merchant,get the aerosol version .
Thanks for the input chaps.
Went for a 210 mile run today, ran superbly pulling an easy 110 leptons on gas, it accelerates like a rocket
But the idle is still an issue.
Spent an hour on it when I got back, sprayed carb cleaner in all the likely areas but only got a small improvement in idle quality when I sprayed in the area of the Bosch 2 wire idle control valve.
Took the plenum off, checked everything in that area, found a few potentials for the air leak but nothing conclusive.
Put the plenum back on, no change
I'll keep looking & see what's happening with the idle valve on the lap top.
Thanks again, Dave.
Went for a 210 mile run today, ran superbly pulling an easy 110 leptons on gas, it accelerates like a rocket
But the idle is still an issue.
Spent an hour on it when I got back, sprayed carb cleaner in all the likely areas but only got a small improvement in idle quality when I sprayed in the area of the Bosch 2 wire idle control valve.
Took the plenum off, checked everything in that area, found a few potentials for the air leak but nothing conclusive.
Put the plenum back on, no change
I'll keep looking & see what's happening with the idle valve on the lap top.
Thanks again, Dave.
ChimpOnGas said:
Super rich Daz, that's the problem.
Mine was running 12.7 afr ,lovely and smooth but I did get a strong smell from the exhausts .I`m now running 13.5 ish goes up to 13.9 ,a bit lumpy bit I like it .I suppose the timing should be changed bit that's beyond me ..
Could it be one of the valve seats ?
Edited by SILICONEKID343HP on Friday 26th July 21:44
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