TheSamba.com :: View topic - 32/36 not idling right after removing top.

Sun Jul 25, 2010 7:35 pm

I'm getting a pair of 2.0L heads instead. Doesn't bother me either way. No matter what I'm not going to pull the motor until I get it running the best it can, which means getting my %&$&$@ intake sorted out. That way I have less potential gremlins to chase when the time comes. There shouldn't be any but I am not a lucky person. I actually have a proper garage this time so that's a bonus.

Please people, confirm / deny for me. Seeing a twitchier vacuum reading is a good thing. i see it drop when the motor has a miss, and can see a more defined flutter between each intake stroke. I assume that a smooth vacuum reading means that when there are spikes in vac, more unmetered air gets sucked in, evening the reading.

Would it be possible that air is getting in around the idle mixture screw? I have some loctite 222 or 262 (can't remember which). the one that is made for that sort of thing. Should I try some? it may be my imagination but I think the mixture screw could be tighter in its hole.

Mon Jul 26, 2010 5:03 pm

towd, or anyone else if possible. Could i please have a top down-ish pic of the float bowl? I need to see the side with the mains.

the internal diagrams, and photos I have seen don't seem to have the other two holes in the float bowl like mine does.

I have the power valve at the bottom, the main jets kind of at the bottom on an angle, and two mystery holes maybe 1/4 way up the float bowl. What are they?

when I get the jets I'll be pulling the carb again because it is easier to work on. Photos will follow.

Fri Jul 30, 2010 8:07 pm

I figured out the two holes in the float bowl. Fuel return and the other dead ends into the top gasket.

Got back from the garage sale and set about installing the jets.

All in and started it up. Worse than ever. I was very happy. Why? Well it wasn't running chokingly rich. The exhaust smelled good, the plugs did their best to keep firing, heaps of horrible popping at lower revs but whatever. Try as I might I couldn't get the revs below about 2300rpm without really upsetting the motor and it was all surge-y but smooth.
Yes this is a good thing. It means that I inflamed an undiscovered vac leak. I'm going to pull and recheck everything, but before that I think I'll get the lowest stable revs I can and spray away to see if I can isolate it.

The garage sale put me in a good mood :) I picked up a really nice amplified carpeted automotive speaker / sub and a small primus stove (like the sort used in the campers) for $60. I also scored a dolphin torch, a 12v truck battery and a canvas tarp for free.

it'll probably be tomorrow or Monday before I can tackle the motor again. My #1 suspect is the carburettor base. The grease i applied was sloppy on one side. That could be why that rubber spacer was there before. Hmm.
That 14-ish ft/pounds seemed an awful lot of torque for those manifolds too, so I may recheck.

Sun Aug 01, 2010 9:51 pm

here's the pic's you wanted.... been bust getting this thing ready for Dune fest, That starts this week, It's a 5 day event .. They say .. It draws between 50 to 70,000 people.. with a fair amount being Tramp stamped females..

I only see one hole in this one,,,, It looks like it's just a vent. I see in the photo of your carb on top you have a tube plugged off, that must be a bowl vent. I would try unplugging it ..

Mon Aug 02, 2010 1:19 am

Thanks towd. very interesting. Here's mine.

If you are talking about that other line I blocked with the bolt, from what I can understand it is a sort of fuel return to help prevent vapour locks, but it caused hard startin gand issues for people until it was blocked.

The top line starts of with one of those float bowl holes, and goes up and into that line, so it is a vent that would be submerged. Not really something I'd like.

Mon Aug 02, 2010 10:39 am

Rat, I blew your pic up.. I don't see the sliver needle in the power valve.

if that's gone there's the problem, wouldn't it suck fuel all the time.. even when that plunger is down, there's still the two slots on each side

Mon Aug 02, 2010 12:17 pm

I think the holes may be a high speed enrichment system, some of these carbs have such. It dumps fuel above the venturi level when there is a very high rate of air flow through the carburetor. Some carbs have it in lieu of a power valve, some in addition to a power valve. Don't think it is very necessary to have it on these engines. There is typically a delayed response with this system when you bunch it and it does nothing at lower air velocities.

Mon Aug 02, 2010 4:00 pm

Hm? I said I traced the holes. one goes to the anti vapor-lock return line on the top of the carb. The other follows a similar path to a point, but for some reason it goes up into the top plate, across a bit and dead-ends into the gasket / casting.
see those two circles on the gasket near the air correction jets? One of those is from the dead-ended gallery. the other ...maybe it's a part of the return circuit too, but still dead ended.

My center needle on the power valve is there. it's just a lousy photo. As you can probably see I have the carb sitting near my engine hatch hole. no headroom to see into the viewfinder to see what the camera is focusing on.
The center needle is brass so it doesn't stand out. the whole valve actually looks smaller than towd's, but I can't say for certain.
.

Mon Aug 02, 2010 9:44 pm

I went out and looked at my stash of carbs, both Weber DFV's and Holleys. Every one of the carbs had an enrichment circuit on the secondary side, while only one, a Holley, had an enrichment circuit on the primary side.

On none did the hole in the bowl actually hook up to the vent system, it just looked like it might. I was able to hold vacuum on the vent nipple by just blocking the port where the air cleaner gasket sits.

Mon Aug 02, 2010 10:19 pm

Trying to make a suggestion only here that might help.

I think that if the last photos are of the actual carb you plan to use, the first agenda is put things in a shoe box and clean up the workbench. Not trying to be mommy but seriously if you want to rebuild your carb you need a much cleaner and uncluttered area. I see red clay or rust sediment in the bowl so after we clean the bench we need to clean the carb right. One barrel is much darker, probably primary, and it looks like it may have seen some heat and backfires as the surface is matte. Grab each venturi and wiggle it. It should be snug and not loose. If it is loose then it will suck air and you will have a hard tine controlling the mixture. Those carbs are known for warping venturi over time with heat. The tops also warp from heat and over tightening.

Mon Aug 02, 2010 10:55 pm

Thanks for the advice. I actually work on the carburettor elsewhere. I just take the top off outside so I can completely empty the carburettor of fuel. It just seemed like a good opportunity to take a photo.

What i have done today:

Really ripped into the carburettor base to make sure it was dead flat.
Rechecked and readjusted the secondary stop.
Rechecked and readjusted the float. my minimum setting was a bit off.
Purchased, gapped and installed another fresh set of NGK BP6ES spark plugs.

What I can say is after this round it runs more smoothly and doesn't pop. imagine that.
the "Idle" is far more stable, but I can only get it as low as 1200rpm before I hit a point where it just dies.
the mixture screw is functional still.

Such a shame about the idle speed because otherwise I'm really pleased with it.

SGKent, thanks for the tips. I have overlooked the top plate of the carburetor. It may well be warped like everything else. That will be "fun".
I'll check the venturis too. I'm pretty sure they are in tight but checking can't hurt.

the galleries seem to be clean. I'm unhappy about that fine sediment. The carburettor has two filters upstream.

What bugs me about all this was the idle was fine until the fuel pressure regulator went peculiar.

Mon Aug 02, 2010 11:08 pm

Quote: What bugs me about all this was the idle was fine until the fuel pressure regulator went peculiar.

Go back to the original problem and rethink it.

If the bus dies below 1200 RPM why? Vacuum leak? TIming too retarded? Brake Booster bad? Low compression? Valves out of adjustment so bad the compression is low? Gasoline in the oil causing it to run funny as the gas vaporizes? Carb top warped allowing air to leak? (only solution we ever found was a temp one with double gaskets)

Mon Aug 02, 2010 11:35 pm

since this has happened I have checked the compression. The lowest was 130PSI.
It isn't the brake booster. I have checked with it connected and disconnected. in fact I have to disconnect it to attach the vac gauge.

I have checked the surfaces of the intake ports. Resurfaced the intake manifolds. Checked the runner boots. Removed the rubber gasket thing under the carburettor. Resurfaced the base of the carburettor.
Rechecked the regulator with a pressure gauge.
Replaced the needle and seat.
Changed the oil.
Rejetted to roughly what it should be.
Countless readjustments of the idle.
Checked the choke and fast idle.
...and probably quite a bit I have forgotten here.

the death below 1200rpm or so isn't a slow one. The motor comes to a halt almost instantly after a few half-assed putts.

I can't do much more right now as it ran out of fuel.

Oh yeah I checked the venturis sort of as I can just get a finger and thumb through the throats. Looked and felt solid.

Could it be the top of the carburettor?

Oh one more thing. #3 may have been running a little leaner. Given the state of the old plugs I can't say with any certainty.
If it is there are two checkable places.

I'll pull #3 and #4 tomorrow for comparison purposes and see what it looks like with fresh plugs. If #3 is leaner I'll check the manifold again. If I can't find a problem then ...what? If it were a valve guide it'd burn oil right?
All I can really do is revisit everything. i don't know how to test for a warped carb top plate.

Tue Aug 03, 2010 11:41 am

Ok so, I just got done rebuilding one of these beasts, ie, Holley/Weber 5200.

First clean your workstation. Get a rebuild kit online (Appletree Auto has them for $37). Get one of those carb cleaner paint can dunk tanks for about $20 from any auto-store. Pull it apart. Dunk it. Clean the parts. Blow out all the jets, channels and wiggly-wonk with compressed air and or a can of carb cleaner. Put back together using rebuild kit. Put on vehicle and go.

If your vehicle still doesn't run right after doing this then I'd check elsewhere. These carbs are bulletproof and dead simple. I get plenty of smooth power out of my 1600 DP with this setup.

Believe me, I know how frustrating things like this are. Sometimes you need to just leave it alone for a week or so and then come back to it.

I've enjoyed following this thread so keep it up and good luck!

Tue Aug 03, 2010 2:29 pm

My work area is clean. That is not my work area.

I haven't actually seen those dunk tanks anywhere. What do you dunk the carb parts in anyway? The only carb cleaner I have seen is fairly expensive stuff and in an aerosol. It is quite possible i can obtain it elsewhere if I can find out what is in it. For some reason I can only source what I need through industrial suppliers.

All the galleries and jets are free flowing already with no signs of fouling. That little bit of residue is unfortunate and I think it is because the fuel ran down. I haven't put any in since before it dumped heaps into the sump and gave the motor a good chemical bath. It's amazing really. The motor swallowed over 2L and it didn't leak out anywhere.

The idle circuit seems to be functional, but some X factor is throwing it off.

if I can get my hands on a rebuild kit for a reasonable sum here it'll get it.

I have to go to a large-ish town tomorrow that has a couple of wreckers. I might pay them a quick visit to see if they have any Cortina carburettors. Hopefully they'll have more than mikunis and strombergs. if I can find the location of my favourite wrecker, and if I am lucky enough to find the right carb and the old parts counter man still works there I'm good to go. This guy didn't seem to give a damn about anything so I could get cheap stuff.
The other wrecker tries to rape my wallet unless I beat them down. I guess they do it for the sake of people coming in without knowledge of what is a rip-off. It's not like they take the parts off themself anyway.
No it's not a pick and pull. Neither of them are. It takes time for them to pull parts out/off so they just tell people walking on to do it themself.

I'm going to double check my tracing of the galleries on the top plate. It looks like the only proud part on the top plate is that little restrictor nub thing which I think goes to the anti vapour lock return thing. If this is so then I have a plan B available to me. Remove the nub, block the gallery and resurface the top plate.
Because it is difficult, that is probably where my problem lies. but I won't even attempt it unless there is nothing to lose.

Tue Aug 03, 2010 4:22 pm

I got some more fuel, and if I can find my starter spray I'll start it up and spray around the top plate mating surface. I have a special magic trick that lets me put the air intake point far enough away that it won't skew results, and still keep it filtered.
I'll look at #3 and #4 plugs first. For the tl;dr crowd it is because #3 may be running leaner but I haven't conclusively determined it yet because of the old (1/2 hr of running ha!) plugs.

Tue Aug 03, 2010 4:51 pm

look also at early and mid-70 fiat 124's spyders and coupes had them. Don't remember if the 124 sedan had them or not.

Tue Aug 03, 2010 5:07 pm

SGKent wrote: look also at early and mid-70 fiat 124's spyders and coupes had them. Don't remember if the 124 sedan had them or not.

True, but I'd have to find a euro wrecker for that and the closest would be over 300km away. Diminishing returns and all that. If I were to hit up a place like that I'd get a couple of centrefloat SU's, buy some flanges and mandrel bends, get busy with the mig and get out of the frypan into a completely different frypan ;)

Cortinas were common as dirt so I have a chance of finding a carb for them. As I have said in the past it is also the most likely origin of this carb.

http://datsun1200.com/modules/mediawiki/index.php?title=Weber_32/36_Carburetor says "In Australia, the G180 is a licensed version of the Weber 32/36 and fitted to:

2-liter Ford Escort
2-liter Ford Cortina"

Which really makes sense.

Tue Aug 03, 2010 8:04 pm

I pulled #3 and #4 sparkplug. White and clean, vs. white and clean. That's so much better than instant black carbon fouling!

I added a mad tyte JDM cabin CAI to let me go on a starter spray spraying spree without skewing the results by having the carb huffing the fumes.

it's lucky that the mitsubishi intake tube is a nice fit on the top plate adapter I have.

Had a good spray of the underside of the top plate. If there is a leak it isn't from outside.

Doing the spraying is definitely a job to be played by ear when the revs are high-ish.

3/4 side. I think spraying the manifold/head flange made the motor stumble a couple of times.
1/2 side. 98% sure that spraying caused a rev increase.

This just proves to me that the torque I set the manifold studs to was too much for the steel plate manifold flanges. I guess it's another pull and resurface job. Urgh.

Spraying the runner boots had no effect.

I forgot to spray the base of the carb, but I resurfaced that so hopefully it's good now.

while it was running I put my hand over the air filter hole. nice sharp metal. Mmm. Anyway i could just stand there with my hand over it and the engine would just run faster than before. it isn't the best sealed setup by any means, but it all just says massive vac leak. So here we are. back to the runners.

Tue Aug 03, 2010 8:09 pm

Can't you find a set of FI runners some where and use those? Much sturdier IMO. You can always spread them a bit to fit your center manifold section if need be.

I have been meaning to ask, when do you sleep?