More Stupid Jet questions from a new guy

[wagerton]

OK, I've got the 32/36 DGAS, and ever since I put on the new header the car runs poorly, especially when rolling up to a stop sign and using the engine for braking,...the car won't idle and dies (embarassing).
When the choke is on (electric choke) it runs fine. So Given the new free flowing exhaust I figure the carb is jetted too lean.
The Main and Secondary are 140's.
I had previously replced that silly antidiesel solenoid on the idle jet with a brass retrofit through OGTS.
When I pulled the main idle jet again to look at it,...it had no markings on it,...no size no nothing,...it's also quite a bit physically larger than the idle jet on the secondary side. None of my other weber idle jets (I've got a handful) are that size.
Whats the deal with the physically bigger main side idle jet and what size and description should I be looking for to replace it?
I ordered some main jets in sizes: 150 160 and 170 to replace those to try and get some sense of what it will take.
To make matter more complicated I bought a Combination Hydraulic cam from OGTS and I know that what ever I figure out now on jetting will have to be redone again later.
I read the thread concerning Emulsion tubes, but that seems more fine tuning than what I need right now.

[RallyBob]

If you have an idle problem, then I'd deal with only the idle jet and the idle mixture screw for now. Changing main jets randomly is not a good idea at this point.

Plus look for vacuum leaks, most header installs are less than ideal, and often vacuum leaks abound due to improper header flange thickness. If the header flange is thicker than the intake flange for example, there will be insufficient torque to the intake, and you'll likely have a vacuum leak, hence a lean air/fuel mixture.

Bob

[wagerton]

Yes I have inspected and listened with a tube in my ear as well as sprayed WD40 around all the manifold and carb joints, even replaced the carb gasket with the thicker one from OGTS. All with no change. Blocked off the brake booster and other vac lines just in case there was a leak in them,...still no change.
The odd large main side idle jet is the first issue. Since it has no size stamped on it (looked under a magnifying glass) and the 2 places I checked don't have a "large" idle jet I may have to carefully probe it with drill bits to figure out its size. But even then without a source of replacements I'm shooting in the dark. I'm reticent to start drilling it out and playing test pilot with uncalibrated jet sizes,....
I was hoping someone out there had similar experiences with this wierd idle jet and holder and had options. Or a magic cure.

[RallyBob]

Yes I have inspected and listened with a tube in my ear as well as sprayed WD40 around all the manifold and carb joints, even replaced the carb gasket with the thicker one from OGTS. All with no change. Blocked off the brake booster and other vac lines just in case there was a leak in them,...still no change.
The odd large main side idle jet is the first issue. Since it has no size stamped on it (looked under a magnifying glass) and the 2 places I checked don't have a "large" idle jet I may have to carefully probe it with drill bits to figure out its size. But even then without a source of replacements I'm shooting in the dark. I'm reticent to start drilling it out and playing test pilot with uncalibrated jet sizes,....
I was hoping someone out there had similar experiences with this wierd idle jet and holder and had options. Or a magic cure.

The larger idle jet holder is normal on later 32/36 Webers. Older carbs had the same-sized holders on the primary and secondary idle circuits. I believe Weber changed to dissimilar idle jet holders to prevent mixing the jets.

It's probably somewhere between a 50 to 60 idle jet (that would be as in .50 or .60 mm).

Anyway, what is the vacuum that the engine is pulling at idle? Should be in the neigborhood of 18-22 inches at idle.
Significantly less points towards a vacuum leak.

[wagerton]

Hmm,...don't know what the present Vac is. I'll chack when I get back into town.
My main suspect is that mega idle jet as well as being underjetted (main jet) for a header as well.
The car does not seem to have good mid or top range power even at full throttle,...increasing my suspicion of an overall lean carb jetting. I don't recall the air corector size off the top of my head, but a smaller air corrector (which I have plenty of on hand) could also fatten up the top end of the range.

[bigjim5551212]

main jets at 140 are fine. You should be running a 60 or 55 or 50 idle jet. You do have a problem with a vacuum leak however. Does your car have power brakes? check the diaphragm in the master cylinder. vacuum could be leaking there.

Regarding the idle jet physical size. The jet has been larger since about 1985. There is a mark on the bottom of the carburetor indicating year of production -- its a circle with a 2 digit year date.

[opelwasp]

Before you go just ripping jets out and putting new ones in read tis thread first.
http://www.opelgt.com/forums/afterma...e-jetting.html

Changing the E tubes is only for the 38 DGES, not the 32/36. A header is not going to change your jet requirements much either, headers in an Opel are not what they're cracked up to be. Those jet sizes are going to be way too big for your car, even with a big cam. Heck I have a 2.4L and I only use 150's.

[MICAH1]

Wagerton,
I have a GT (stock engine) with a 32/36 and tubular header. My main jets are 140's (P&S), idles are 60 and 55 (P&S), and air 170,180 (P&S), with 2 inch pipe to a magnaflow exhaust. Those 150, 160, and 170 main jets are too large.......... I have tried those on my carb. Stick with the 140 mains and work with just the idle jets right now. My primary idle jet is thicker than the secondary jet so if you need to order new idle's make sure you take that in mind if those jets are of two sizes.

Also take RallyBob, and BigJim's words as G O S P E L ! ! !



If there is no change........ then the Hunt For Red October (Vac leak) is on!!!!



************ Hey Tekenaar, Do you have to highlight your corrections in RED!!! ********* Each post that warrants an edit does display on the bottom of the page.. YES? Not a sermon, just a thought.

[tekenaar]

The larger idle jet holder is normal on later 32/36 Webers. Older carbs had the same-sized holders on the primary and secondary idle circuits. I believe Weber changed to dissimilar idle jet holders to prevent mixing the jets.

It's probably somewhere between a 50 to 60 idle jet (that would be as in .50 or .60 mm).

Anyway, what is the vacuum that the engine is pulling at idle? Should be in the neigborhood of 18-22 inches at idle.
Significantly less points towards a vacuum leak.

. . . also possibly to accommodate the "anti-smog" ICO solenoid required by CARB?

[RallyBob]

. . . also possibly to accommodate the "anti-smog" ICO solenoid required by CARB?

Very probable Otto, good call.

[hrcollinsjr]

Wagerton,
I have a GT (stock engine) with a 32/36 and tubular header. My main jets are 140's (P&S), idles are 60 and 55 (P&S), and air 170,180 (P&S), with 2 inch pipe to a magnaflow exhaust.

IIRC the air corrector jets on mine are in the opposite positions, 180&170 (P&S).

Harold

[bigjim5551212]

If fact it was to put in the ICO. If you notice, the primary idle jet holder is actually off centre as well. This was to increase clearance from the choke housing.

I dont think this unit was put there to please CARB. There was some engines that ran better with a smaller idle jet but had to have the throttle plate open too far to have the engine run at an actual good curb idle. Remember that the idle jet affects operation up to about 2500 - 3000 rpm.

So if your cylinder temperature is higher from a lean idle jet, you have to cut off the fuel when the engine shuts down because there will be enough heat from glowing carbon etc, to keep the combustion process going, and just shutting off the ignition does not do enough.

[wagerton]

I'm still having engine problems with my GT 1.9.

I bought the hot hydraulic cam that OGTS sells and installed it,...trouble is I just about can't get the car to idle or run well,...didn't idle before I installed it either. At that time I figured I had a vacuum leak and would find it during the disassembly process,...

I have dissassebled the intake and header and ensured the gasket and tabs on the header are the correct height to get gasket sealing (had to grind the header a bit).

I've checked for vacuum leaks,...replaced the base gasket with a thick one OGTS sold me. Plugged the power brake line at the manifold as well as the other line that comes off and goes to the valve cover. Even plugged the distributor. Listened very carefully with a hose in my ear around the carb and intake.

Had the head off during the cam swap and the machine shop said it was in good shape.

I've got about 12" vacuum at 1200 rpm,...which seems a bit low but might be the cam.

I've checked the carb float level and have it per the Weber carb instructions 40 and 50mm.
Adjusted the idle screw numerous times,...it really doesn't seem to change much because the idle is so rough at 1000rpm. I need to adjust the main idle screw so far in that eventually it runs/idles quite well at 1700rpm,...which is on the next fuel circuit I think,...not in the "idle" circuit.
I replaced the electric antidieseling solenoid with a solid brass piece,...so it's not that.
Used a carb cleaner on the jets and venturis, as well as the idle circuit jet. They were clean to start with.

When you drive and coast to a stop with the car in gear (pulling a vacuum) then step on the clutch the car will go to a 400-500 rpm idle and die if you don't pump the gas (again sounds like a vac leak,...but where?).

I have looked down the carb throats and noticed the main venturi is spitting fuel at idle, the secondary is not. I tried turning the idle down with the main screw adjustment and it continues to spit even at 700 rpm,...makes a popping kind of noise. Sounds like a high float level but it's not.

Checked the timing at idle and with the vac advance plugged. Was correct. Timing light shows the spark to be regular,...seems good because I shocked the crap out of myself moving the cap around when a wire got a bit loose.

The car will start normally then won't run above idle until warmed up,...what is curious is that the car will run at the same speed even with my foot flat on the floor (throttle plates wide open). Thought the choke might be the problem,...but it won't rev even with the choke held open. After a few minutes the car will pick up rpm and then "clear" with a big vroom,...runs better but seems drastically down on power.

Pulled the plugs,...they look ok,...cleaned the carb, installed 150 main jets and 155 secondaries,...no change,...still runs crappy,...especially at low rpms.

The cam timing was done correctly per the instructions with the cam(ie mark on the gear radially with the tab, not straight up and down).

When I turn the car off, it stops and about 2-3 seconds later I get a muffled bang in the exhaust. I think this may have something to do with the idle position screw (not the mixture screw) being so far open that the engine can get some post ignition, sort of a half hearted run on (diesel situation).

I'm thinking some weird carb problem or ?? Maybe need to replace the carb fuel float valve needle seat?

I think the car is possessed by Satan, or at least the fuel system is,.... Any ideas? I'm missing something big here and I cannot for the life of me see it.

[Anonymous D]

It's a common problem with older, California-emissions Webers, that owners don't like the look of the anti-diesel solenoid "hanging loose" on the side of the carb, so they screw it all the way in. This scores the idle jet passage inside the carb, and renders it unable to idle below 1250rpms (sometimes 1400-1500 rpm's). Changing the idle jet or its holder, won't fix this.

To identify this problem, remove the primary idle jet, look into the passage, and see if there is a "mark" (particularly on the angled/bevelled portion). If this is the problem, the passage will have to be remachined (to the correct angle) and a compensating spacer sleeve will have to be placed behind the idle jet in its mounting screw.

[RallyBob]

When I turn the car off, it stops and about 2-3 seconds later I get a muffled bang in the exhaust.

Definitely sounds like a vacuum leak. I had a car that did this and it ended up being a warped Weber 32/36 baseplate, due to one carburetor hold-down bolt being undertightened (I got the car that way). I had to throw the Weber away, it actually was warped almost .100"!

Bob

[jvandyke]

My GT had the post shutdown gun shot when I got it. Carb hold down bolts were all loose: vacuum leak. Of course I changed so many things so fast hard to know what "fixed it". I think you need to look harder for vacuum leaks, reseal the carb to intake again?

[wagerton]

OK,
I'll pull the carb off again, check all the idle circuits and the antidiesel solenoid area for flaws/marks etc.
I'll look at the throttle baseplate and try to figure out some way to see if it is flat or not,...thinking a piece of plate glass might work better than a straight edge.
If it's flat and no flaws are found I'll use another gasket and use RTV to seal the crap out of it and try again.
I would think I could hear a vacuum leak with a hose in my ear,...but maybe not,...

[N61WP]

What fuel pump are you using? Webers demand very low fuel pressure or the needle comes off seat.

A few years back I had a 38 DGAS that would not idle. I got to looking and saw that it would pour raw fuel down the throat. I had to add a fuel pressure regulator, even though the same fuel pump worked fine with the old 32/36 that was on it before it. That took care of the idle problem.

Just another thing to check.
Jc

[tekenaar]

What fuel pump are you using? Webers demand very low fuel pressure or the needle comes off seat.

A few years back I had a 38 DGAS that would not idle. I got to looking and saw that it would pour raw fuel down the throat. I had to add a fuel pressure regulator, even though the same fuel pump worked fine with the old 32/36 that was on it before it. That took care of the idle problem.

Just another thing to check.
Jc

. . . Weber and Solex carbs should be run at NO MORE THAN 3.5 PSI FUEL PRESSURE!! They're what's known as "volume" carbs, not "pressure" carbs . . . i.e. as long as you have 2.5-3.5 PSI pressure, adequate fuel volume is the only thing that's critical to keep the carb's fuel bowl filled under all operating conditions . . .

[Turbo X]

OK,
I'll pull the crab off again, check all the idle circuits and the anti diesel solenoid area for flaws/marks etc.
I'll look at the throttle baseplate and try to figure out some way to see if it is flat or not,...thinking a piece of plate glass might work better than a straight edge.
If it's flat and no flaws are found I'll use another gasket and use RTV to seal the crap out of it and try again.
I would think I could hear a vacuum leak with a hose in my ear,...but maybe not,...

Your ear in not a good instrument for tuning an engine. so stop using it and go out and buy a vacuum gage and tac & dwell , It's not like you'll never use them again. RTV is not a good sealant with gas.., any ways if the surfaces are flat and true a good gasket will work fine. glass is a good idea for checking the surface, a lite coat of oil on the carb surface and put to the glass might show flaws.. good luck