tempusfugitive

hey all
i mentioned earlier i was having carb problems (high idle 1200-1500 rpm), i recently had vipernicus42 take a look at it. the only possible cause he could find was my total removal of the shutter valve (shaft and all), i was wondering if anyone else who has completely removed it is experienceing high idle? we also swapped my carb for his sterling carb, and discovered that my car would not idle at all with it, it'll stay at 2000rpm only if i hold the throttle manually open. so that may narrow it down somewhat, i dunno. otherwise i'm probably just going to leave it, it's not like it's screaming at WOT on startup.

any thoughts appreciated
thanks steve

IanS

iTrader: (4)

I removed mine, and then had to readjustthe carb. My shutter valve was bouncing open and closed at idle and messing the adjustments up. Sounds like a vac leak to me. Check to make sure you didnt put the phenolic spacer back on upside down. I am assuming you plugged the hole where the shutter valve shaft was. That would be a pretty big leak.

calvinpaul

iTrader: (2)

Yea, triple check for vacumm leaks...then let it warm up and readjust the carb.

WackyRotary

I have a 12a running without a shutter valve on a car I just rebuilt. All passages for the shutter valve are plugged off now. I am curious from some other people how it "should" run after this mod. It does make excellent higher power with it removed, idle is slightly rough, but I think it will improve-I am using old apex seals that need to break-in yet. I do have another intake that has a shutter valve still in it, but I am too lazy to install it to see what would happen.

vipernicus42

iTrader: (4)

We did that. We took the carb off again and checked everything from the intake manifold upward. We checked EVERYTHING having to do with tubes, vacuum, or the carb. The only thing I didn't check was timing, but it was fine before so I can't see why it would change now. The car runs fine, but it just idles between 1,000-1,300rpm

The throttle linkage cannot be pushed further closed, and the butterlies in the carb look to be as closed as they should be. We even tried putting my Sterling (tm) carb on his car, but we couldn't even get that to idle (not sure why.. runs perfect on my car, but won't idle on his. I guess it might be because mine lacks a rat's nest and an ACV).

I'm totally stumped. The ONLY difference I could find was that when he removed his shutter valve, he actually removed the butterfly, which I've heard causes turbulance and widens the hole. On mine it's just wired open. Besides this, his car looks to be as perfect as it needs to be.

Any other suggestions?

Jon

calvinpaul

iTrader: (2)

Yea, remove all that crap in the way and make for less vacumm leaks to be possible. I don't remember off the top of my head but what is the valve hooked up to?

cdrad51

I removed shutter valve, butterfly, shaft, everything. After that, car still idled perfectly (sterling carb). At high rpms and when giving it a good amount of throtle there was a noticeable difference, since the valve was shutting close anymore

There's gotta be a vacuum leak somewhere.

cdrad51

What did you guys use to seal the intake manifold and gasket?

tempusfugitive

we used a thin film of high temp silicon gasket maker.

vipernicus42

iTrader: (4)

Unfortunately we didn't have gaskets for the carb-to-spacer or spacer-to-manifold... hence the use of a thin layer of silicon. We made doubly sure that the silicon would NOT spill over into the vacuum holes.

There are only so many places that vacuum leaks can occur when removing the carb. All the hoses along the spacer, the AAB Valve, Cruise.... that's about it.

I wish I knew what it was! It's gonna drive me crazy! I don't even know why my Sterling wouldn't run on his car?

Jon