Won't idle after timing set?

[ggzilla]

If you are smog-exempt, then you can go with more vacuum advance than stock, and pick up a lot of part-throttle performance.

[metalmonkey47]

Whelp, did some basic maintenance to it just trying to figure out why this thing won't idle. It's probably all irrelevent, but I adjusted the valves, replaced fuel filter, etc.

 

I've played some more with the carb, and it still won't idle for shit.

 

 

 

I'm thinking about pulling the weber and rebuilding it.

 

 

 

 

 

 

 

 

 

Is it possible that a failing fuel pump can cause this?

[datzenmike]

No. If there is fuel for high demand things like driving around then there's 20 X what you need for idle requirements.

[metalmonkey47]

Hmmmm.... well I'm stumped. Guess I'm gonna go order a re-jet kit and some other parts and rebuild/rejet this old thing.

[ggzilla]

If the carb is broken, you'll just waste time and money rebuilding it. Why not find out what's wrong? Things to look for are: loose throttle shafts, leaking power valve actuator, warped top, wrong jets installed, wrong gasket or gasket put on backwards. You can check this for free. Look it over carefully for anything that seems wrong.

[izzo]

Did you try fapping it?

[ggzilla]

This thing sometimes goes bad

 

 

More pictures and information at my Weber 32/36 Tuning page.

[metalmonkey47]

Hmm.. guess I need to pull the carby and dismantle it for closer inspection and write down the jets.

 

Should I order any gaskets?

[ggzilla]

Gasket usually comes off fine. In any case it's only critical around the are hole (yellow arrow in the photo above).

[metalmonkey47]

Gonna go break down the Weber in a few. Are the jets easily accessible with the top section off?

 

Haven't much looked at it yet but, does the top section come off without much anguish? Screws only and nothing else I need to worry about?

[Laecaon]

Gonna go break down the Weber in a few. Are the jets easily accessible with the top section off?

 

Haven't much looked at it yet but, does the top section come off without much anguish? Screws only and nothing else I need to worry about?

 

You probably already did it, but the top is 6 screws. (remove aircleaner assembly to access 4 of them). Unhook choke stuff if needed, I do on the manual choke. Pull top off. Jets are very easy to get to.

[metalmonkey47]

You probably already did it, but the top is 6 screws. (remove aircleaner assembly to access 4 of them). Unhook choke stuff if needed, I do on the manual choke. Pull top off. Jets are very easy to get to.

 

lol yup, only problem I ran into was the choke stuff, but that took me about 4 minuets to find the clip and disconnect it.

 

 

 

 

 

It was pretty sick

 

 

_DSC0486[1] by metalmonkey47, on Flickr

 

 

_DSC0487[1] by metalmonkey47, on Flickr

[ggzilla]

Looks pretty badly corroded.

 

Spray cleaner though all the jets and air bleeds, and ensure it comes out somewhere else (not blocked). Also remove the idle mixture screw and spray through that hole.

[metalmonkey47]

Looks pretty badly corroded.

 

Spray cleaner though all the jets and air bleeds, and ensure it comes out somewhere else (not blocked). Also remove the idle mixture screw and spray through that hole.

 

It was pretty nasty. All things considered, I was fairly impressed by the way it ran for the last 12K miles.

 

I opened up all the passages and cleaned each jet one by one with carb cleaner and compressed air. Same with all the passages.

 

Also tested the power valve actuator as per Datsun1200 wiki. Put it all back together and it still won't idle as smooth as it should, however it has gained a little bit more power at WOT.

[metalmonkey47]

Still idles like shit now, even after cleaning the carbie and re-adjusting idle mixture.

 

 

 

Any more ideas?

[kelowg]

disconnect booster vacuum and cap off at card/intake. see what happens with idle

[ggzilla]

Go back to basics:

 

Set the dwell, set the timing. Check your distributor shaft for wear. Do a compression test.

 

Then after all that is confirmed, look for air leaks. Cracked hoses, leaking diaphragm motors. Temporarily disconnect and plug all vacuum hoses, large and small. The engine needs none of them to idle well.

[metalmonkey47]

Go back to basics:

 

Set the dwell, set the timing. Check your distributor shaft for wear. Do a compression test.

 

Then after all that is confirmed, look for air leaks. Cracked hoses, leaking diaphragm motors. Temporarily disconnect and plug all vacuum hoses, large and small. The engine needs none of them to idle well.

 

Alright, I isolated all vacuum by capping all vacuum on the engine, set timing to 5 degrees, replaced all rubber hoses (only one is a brake booster line, go figure) and ran a compression test.

 

Compression is averaging at 135 across all cylinders (varied about 4-5 PSI at the most), and the plugs were a nice golden brown.

 

 

Still idles rough around 800 (if at all) and struggles to idle smooth around 900-1000. I also noticed a slight misfire at idle occasionally too, so I need to dig a little more into this.

[racerx]

Check your spark plugs, maybe they are getting fouled with carbon,,this will cause to misfire...not sure if this is happening to yours but mine, at a stop light after a minute or so, would idle from 900 then go down another 400,,,problem was the needle valve seat, I thought it was my fuel pump, replaced, still RPM would go down. Checked for vacuum leak, OK, checked spark OK, checked coil OHMed out okay, replaced fuel regulator, not the problem.

 

The needle valve seat, look at weber direct's, diagram...the houseing was broken..this is where the needle with a ball would seat. The housings screw broked...so fortunatley, I had anotehr 32/36 sitting in the garage and took the top half and replaced with other one..Idles good now and does not go down. The needle seat controls fuel coming in and the float rest on this mechanism...so what was happening was that the carb was getting flodded. This in turn would foul my spark plugs which caused idling inconsistently, lose power and misfire..so I got tired of cleaning the plugs and replaced with new NGK and been running good for about a week, cross my finger.I also checked my spark plugs and it's running clean...

[ggzilla]

Just Tuesday night a friend's car was shaking at idle. He had been told that he needed new sensors or a $300 tune-up. I took the spark plugs out, did a compression test (it was perfect) and re-gapped the plugs. They were at 0.052 and should have been at 0.044. That solved the problem, and no money spent.

 

These of course may not be your problem.

 

But the lesson is that their is often a single cause to a problem, the trick is finding it. Shops too often just replace a slew of parts, and sure the problem is gone but was all those parts really necessary?

[metalmonkey47]

RacerX,, thanks for the info! I'm gonna look into that a little bit more when I have time to do so.

 

 

 

GGzilla, now that you mention it, I haven't ever taken the time to verify my plug gap. The plugs are about 3 months old and clean. I have an MSD CDI ignition, so I/d imagine I should open up the gap a little shouldn't I?

[ggzilla]

It should run perfectly fine with the stock gap.

 

Or you could use MSD's recommendations. CDI-type ignition can usually fire large gaps.

[metalmonkey47]

Gapped to .54 as per MSD recommendations.

 

 

 

 

 

Is it possible that it has to do with flooding because of an improperly adjusted float?

[datzenmike]

Gapped to .54 as per MSD recommendations.

 

That's a big gap and not saying it's wrong but try 0.035" and see if better and if so, try going up bit by bit. When the coil discharges the spark looks frantically for the shortest, easiest path to ground. A 0.40" gap plug is do able, but a 0.054" jump makes a jump to an adjacent wire, or to the neg terminal on the coil look awfully tempting. Definitely shorten the plug gap to make it easier for the spark.

[metalmonkey47]

video on the way,,,,