Engine won't idle

[Washout]

OK guys I need some help here. I rebuilt my 1.9 and now I can't get it to idle at all. Here's the details of the new engine.

punched out 1.9 to 2.ltr
1.84 intake valves and 1.5 exhaust valves
hardened exhaust valve seats
street ported and polished as per RB
Isky OR66 cam
Balanced all rotating mass
reduced flywheel weight 5 lbs and added S-10 Clutch
Ported intake manifold with diverter installed
Weber 32/36 rebuilt (stock jetting)
Pertronix ignition
mechanical fuel pump

It starts easy and revs up but will not idle, from 1500 RPM down it just dies. I read some other threads that pointed to fuel supply issues so I cleaned the fuel pump screen and found a good stream of fuel coming from the gas tank. What is really odd is if I get the throttle set at around 2300 rpm the engine will cycle on its own from 2300 down to 1600 and then rev back to 2300 taking about 20 seconds for each cycle. It will continue this cycle until you make a throttle change. I initially suspected a vacuum leak so I removed the intake manifold and replaced the gasket. I then boiled the carb, cleaned every passage and reassembled. Ignition timing is correct as far as I can tell, without being able to idle I'm sure I'm getting some centrifugal advance. I'm at a loss to figure this one out.

[madhatterpdc]

Definitely check to make sure the timing is correct and advancing as expected. You are going to need a good timing light to do this. As a matter of conversation, did you recurve the distributor? I don't know the specs on that cam, but a recurve is something that you may want to look into.

My gut feeling here is that this is tied to the carb. You mentioned stock jetting, so my first recommendation will have to be the idle air corrector or idel jets. You mentioned that the carb was rebuilt, so I don't believe that anything is wrong or broekn, it just needs tuning (unless an orifice picked up a burr during the rebuild or an o-ring didn't seat correctly). It could be tied to an incorrectly sized emulsion tube, but I doubt it since that only really kicks in after part throttle, and shouldn't have too much of an effect on idle.

Also, have you driven the car? Have you placed the engine under a load, even set the e-brake and put it in gear and bring the clutch up a little (make sure nothing valuable is in your path in case your foot slips). Any pinging? Does it bog excessivley?

[hrcollinsjr]

If you're using the spacers and heat shield under the carb it is easy to wind up with a vacuum leak. When you rebuilt the carb did you make sure and install the jets back in the same locations. The primary side idle jet is often larger than the secondary side.

The only way I could get the OR-66 to perform decent for me was to advance the timing about 5 deg. initial and limit the total advance to 36-38 deg. but I never had any trouble with it idling. Once I limited the total advance it came alive!

Harold

[Washout]

The problem that exists now was present at startup on this new engine. Only after the problem arose did I rebuild the carb on the outside chance that something had gone wrong with it while sitting. This carb ran fine before the rebuild. I've ordered some jets so I can fine tune it later but for now I just need to try to get it to run. While I don't normally use any kind of sealant on carb gaskets I did put a thin film on them as I reassembled things today. I don't think I have any vacuum leaks, certainly not bad enough to cause this kind of problem.

[Paul]

You seem to be headed in the right direction by first correcting any vacuum leaks.

A couple of observations: advance the timing some as Harold mentioned, the carb may need to be rejetted richer due to the modifications....., due to cam and valves, it may need to be idled up a bit anyway. I bet Otto has listed some jetting recommendations for these mods..., you may what to add a hotter coil... A Pertronix Flamethrower at a minimum...

[Anonymous D]

Insert thin red plastic straw into nozzle
on can of carb cleaner. With engine idling,
spray at vacuum junctions (base of carb
at gasket, at manifold gasket, at manifold
hose fitting on side, etc.). If engine idle
suddenly changes when you spray at one
location, try a brief spray again to confirm.
That is where air is being sucked in.
Seal that location, and try again.

Also, once vacuum leaks are fixed, consider
larger jets on carburetor -- stock jetting is
too small for the larger valves and hotter cam.

Reference:
OMC Tune Up Tech Tips (FREE)
Engine

[hrcollinsjr]

Is the OR66 a hydraulic grind or solid? Double check your valve adjustments and the cam timing. Beyond that I'm presently stumped. Check your static timing marks and double check your firing order. Not trying to insult your intelligence here but most of us have slipped up and made that mistake before.

Harold

[Washout]

The OR-66 is a solid grind cam, I've got the valve lash set a .018. I'll recheck the static timing and see where I am. I've tried the carb cleaner routine without any changes and I've blocked off the vacuum to the brake booster as well as the vacuum advance and retard on the distributer. I had a vacuum gage hooked for the last run and was getting good vacuum until the engine started to die and then of course the vacuum dropped off. This one has me scratching my head.

[ronskydivepops]

I"ve had similar problems with my weber not idling. It's been a while, but one time it wouldn't idle and I sprayed the inside of the carb with carb cleaner and then it ran fine. My GT sits for months at a time and I use a lead additive, so I think it gummed up inside of the carb. Another time it was my float level. I could get it to start (though it took a while) but it wouldn't maintain an idle. I reset the float level and it was fine.

[opelbits]

A couple of things I'd check:

1 Condition of carb gasket between the body and the top. If it's old, cracked, or torn, you get a vacuum leak.

2 Float level

3 Accelerator linkage and rods.

[Washout]

The intake manifold and carb gaskets are all new. I just checked the fuel pressure and the output volume. The pump is putting out 3 psi steady and in 30 seconds it pumped out a little more than 5 oz.

It doesn't even try to idle, just straight up to 2500 and back to dead when it starts. You can keep it running by either holding the rpm above 2000 or by pumping the accelerator as it trys to die. All four cylinders are running and the compression per cylinder is 200 psi. While it is running the vacuum is 20+ inches.

[Anonymous D]

Did you put enough gasket sealer
on top and bottom of the carb gasket?

Have you checked for a vacuum leak
(with carb cleaner spray)?

Have you checked other possbile places
for a vacuum leak (like th booster hose
and fitting)?

[Washout]

I've blocked off the brake booster, and done a cranking vacuum test that showed 5 inches of vacuum during cranking which indicates a pretty well sealed system (for a 4 cylinder). I've had vacuum leaks in the past, bad leaks that still tried to idle, even if they stumbled and eventually died. This problem is far more immediate and without any attempt to idle.

[Anonymous D]

Regardless of what may have applied
(presumably to other cars) in the past,
Opels can be different. Opels are very
dependent upon vacuum for steady
operation, because of the unusual
90-degree bend that the air/fuel mixture
has to take to enter the cylinders.

So, why not do the carb spray tests,
before looking at other components?

[Washout]

Originally Posted by Anonymous D Regardless of what may have applied (presumably to other cars) in the past, Opels can be different. Opels are very dependent upon vacuum for steady operation, because of the unusual 90-degree bend that the air/fuel mixture has to take to enter the cylinders. So, why not do the carb spray tests, before looking at other components?

Because it has to idle to some extent before this test can be run. As it runs now I have to keep messing with the throttle just to keep it running. I'd LOVE for it to idle enough that I could look for a response to carb fluid, wd 40 or anything else but it just ain't happening. There is no hint of an idle, nothing, nada, zip.

[Anonymous D]

I've seen instances where carb gaskets
leaked so bad, that vehicles couldn't
get enough fuel through to hold an idle.

Was there enough gasket sealer placed on the
carb gaskets?

Where is the mixture screw set?
Did you bottom it in, and back it out 2 full turns
(=720 degrees), to pre-set it for fine-tuning?

Also, is .018" the valve lift spec that came
with the camshaft? (Stock is .012")
An alternative is to use a compression gauge
to fine-tune the valve setting.

And

[namba209]

I'd start with the basics. Obviously the idle circut in the carb isn't working as it should, so start with that and double check the carb bowl venting. It won't take much to plug up the idle circuits, either fuel or air. The carb works on differential pressure between the carb bowl and venturi to get the fuel /air into the venturi for an idle setting, so it could be a restricted carb bowl vent or fuel passage restriction. If the timing is correct or close, as it appears, and the float is set right, then it has to be something in the carb isn't working. HTH.

[Gordy]

I bet you have an electric choke Weber. If so, make sure there is juice going to the connection on the carb. The juice does more than just operate the choke. I had one that ran like %*#@ until I attached the switched wire to the carb and then it purred like a kitten.

[Washout]

Thanks Gordy,
but no I've got the water choke. I can't imagine how it can be blocked but I think Namba209 is probably on the right track. If it were some ignition problem then once it started to die it would not respond to fuel changes. But in this case you can keep it running by pumping fuel with the accelerator pump which points to fuel issues. I've determined that it is getting an adequate supply and pressure of fuel. I just wish I had a spare carb to drop on it to see if that effects the problem. When I cleaned the carb the last time I boiled it for a day in new carb dip and then spent a great deal of time on blowing carb cleaner through all the passages. I checked each jet under a lighted magnifying glass to ensure the jets were open. The only thing I've not been able to find are the circuit diagrams for the carb so that I can actually trace each circuit.

Someone asked if I had put the jets in the right spots, The idle jets are of two different sizes and can't be put in the wrong place. The main jets are both 140, not much chance of a mistake there and the air jets are 170 and 160, if they were reversed I doubt it could cause this kind of problem.

I appreciate all the suggestions, it has to be something simple, these things usually are and I will find it.

Thanks

[Washout]

OK, Guys
I could just let this die and say no more but since I pestered everyone all day yesterday I guess I owe it to you all to say I found the problem. I'm pretty embarrassed about this but the answer is ..... drum roll.....
a vacuum leak. Just as most of you thought and I didn't. I was CERTAIN I had the carb sealed. I finally had to make a remote starter switch so I could start the engine while manually controlling the carb. I then used some starter fluid at the base of the carb and found the leak.

The heat shield was warped and not sealing as it should. I made a new carb spacer out of 3/8 Aluminum and two new cork gaskets, sealed it all up and now it's purring like a kitten.

So, it's with hat in hand that I say, thanks for all the help and I'll NEVER do that again.

[baronbors]

Waiting for Anonymous D to say " Told you so "

[Paul]

Originally Posted by Washout So, it's with hat in hand that I say,

Since you call Texas home........ that makes it a pretty BIG hat.........

Glad you found it!!!

[dallasmanta]

well process of elimination works and the fact that you did not give up and change a part. Good for you Ron

[Gumby]

Man I love the search function!

I had the same issue, this thread proved to be very informative.