"Stump the Chumps"

If the idle wanders it is usually a vacuum leak in my experience. Try squirting WD40 on the bases of your carbs while the engine is running. If the idle speed jumps up, you have a bad seal where the carbs meet the heads.

Try this and let us know. I bet this is it. If not the jostling around of the carbs may have bent the float bowl needle tang and your float bowl fuel levels are too low or too high. But I still stand behind the vacuum leak. It will be a very small one by your description of how your engine is running.

I loved the Tappet brothers and the car talk show. I listened to it every sat. morning for over 15 years or more.

heard the remaing tappett brother in a radio commercial the other day, cant rember what it was about

When we were commuting back and forth to our winter place (a 2-day ride) I would load up 10 plus hours of Car Talk on my iPod and we would listen to the shows.  Usually around 3 or 4 pm the first day, my wife would tell me she had heard just about enough of car talk and Ray snorting when he laughed so we’d switch over to music.   The two Jack Russells didn’t seem to care, either way.

I have banned WD-40 from my shop, but I can get a can of carb cleaner.  Could it be that the air mixture screws need tweaking?  I haven’t touched them since they came back from the rebuilder’s shop.

@barncobob posted:

heard the remaing tappett brother in a radio commercial the other day, cant rember what it was about

I think it was EBay motors , or ……?..

Why the ban on WD-40?  I recently banned Ben and Jerry's from my freezer --- due to weight gain and sugar content, of course.  Argh, no mo "Cherry Garcia"!

My go-to penetrant is PB Blaster - hate the pee color and odor though!

Think simplest things first. If the engine was running perfect before the carbs were removed from the heads it is most probably a vacuum leak. Carb cleaner or anything that is semi combustible will work to squirt on the carb bases. It is easy to over tighten and warp a carb base. If you start changing and adjusting things make sure you do one at a time and then mark where it was so you can return it to original setting if the issue wasn't removed. Good luck. In my life it has been 99% of the time the simple solution.

Sounds like a vacuum leak to me as well...

I know you've investigated the air leak possibility. Just curious, did you run the engine this season before the mouse nest extraction and notice the rough idle? Perhaps the problem is related to the hibernation?

1pm update:

Had a dentist appointment this morning, so I picked up a large, economy size can of Gumout Carb Cleaner on the way home.  

Before I started blasting away and just for the helluvit, I started it and got it idling and as stable as it got, then turned the mixture screws in and back out, one at a time.  

1-2 stumbled when turned in and settled back down when turned back out.

3-4 didn’t really change much, especially #3 which had no effect at all.

Then with @Jimmy V.’s suggestion, I shot a stream of Carb Cleaner at the manifold base.  Shooting at the #4 end of the manifold didn’t have much effect, but shooting at the #3 side of the manifold base caused a slight decrease in engine rpm.  To be honest, I expected the RPMs to increase, but figured ANY change was a tell-tale.

Something tells me I’m on to something good.

Stay tuned mid-afternoon after lunch.  In the meantime, I got out one of my last two manifold gaskets and greased that puppy up to moisten during lunch.  

Oh, and yes, no WD-40 in my shop.  It is not a lubricant.  It acts as a fruit preservative, moisture displacer and penetrant oil, but isn’t especially good at any of those uses.  It evaporates pretty quickly.

I use CRC 2-26 to get rid of moisture in electrical circuits (like inside/outside distributor caps).

Like Wolfgang, I used to use PB Blaster as a penetrating oil and still have a big can of it (because Marvel Mystery Oil is no longer available near me) but if I really want frozen fasteners to loosen up and lots of heat is not an option, I use a 50-50 mix of automatic transmission fluid and Acetone.  That stuff is amazing, really penetrates and doesn’t evaporate as fast as WD-40.

And the only fruit I need to preserve is Peaches and I put those in a brown paper bag.

I have a little can of WD in my traveling tool bag, but only because it’s, well, little. Probably had it for close to 20 years and used it maybe 3-4 times.

I used to use PBlaster until I saw a YouTube “shootout” that compared penetrants.  SeaFoam DeepCreep beat everything, including ATF/Acetone. The only one they didn’t check was Kroil, which a lot of guys swear by.

Then I found Gibbs Brand, which is also good, but has better anti-corrosion properties, especially on porous metals like aluminum and magnesium.

So now I have 1/2 cans of WD, PB, DeepCreep, and Gibbs Brand to choose from.

@Gordon Nichols I too have been thwarted by removing perfect running carburetors  and experiencing poor performance when re-installing them.

90% of carburetor problems are ignition.

That episode made me a believer.

In my case a late night brain fart on reassembly burnt out my points and condenser. After replacing them, my car would idle perfectly and run WOT, but stutter and sputter in between. After working on my “carb issues” for a couple of weeks I pulled my old school Simpson 260 out of the drawer and discovered the secondary circuit of my coil was out of spec. (It measured fine on my HF digital MM. Go figure)

Replaced it with a FAST PS-20 coil and all was well again.

3PM Update:

Pulled off the linkage and removed the 3-4 Carb/manifold and took it gingerly to the bench.  The #3 end manifold nut did not seem as tight as the #4 end, but it wasn't loose or anything.

The bottom manifold flange looks great - Nothing obvious.  Buffed it off with 600 sandpaper.  Just for the helluvit, I removed the air mixture screws and blew some air through the ports, then returned them to 1-3/4 turns, where they were.  I also got in there and cleaned the head flange with 600 sandpaper and carb cleaner to make it squeaky clean, too.

The gasket also looks great - nothing obvious - But I had a new one greased and ready to go, so in it went.  Surprisingly, much of the grease was either absorbed by the gasket or evaporated in the humid air (it's really muggy out there).

I installed my mechanical engine speed tool on the linkage so I can start it up off idle:

First thing I did was re-check the spark advance and found it was around 38º full advance so I knocked that back to 32º .

The next thing I noticed was that it was now idling around 400 rpm (probably from messing with the idle screws when it started out at 1,200 a while back and having the advance too far out), so I got out the snail  gauge and brought both sides up to idle at 700 RPM and balanced.  

OMG!  It's idling WICKED SMOOTH!!!!    

After that I turned the speed up to 2,500 rpm  and checked the carbs again and son-of-a-gun, they were both pretty much identical - Surprised the heck out of me!  

That engine speed tool is pretty trick, especially when using a Snail gauge - It takes a lot of guesswork out of the operation.  Stand at the running engine and turn the knob, watching the tach in the dash to get above 2,500 rpm, then tweak the tool knob to line the snail needle up right on a reference line (they're the same width) and then check the other carb and decide which one to move up or down and do it.  The engine stays put at the same RPM for as long as you need it to check and re-check each side and it is easily adjusted to re-align with a reference line if needed - The resolution of knob turn versus speed is pretty good.  A couple of minutes of checking and tweaking a linkage adjuster, then re-check the idle and I was done.

Then, it started to rain.    😠

So I'll get out in better weather and re-check the air mixture screws, but they should be really close to begin with.

Thanks for the comments, everyone!  Yes, Jimmy V was right on about the manifold gasket leak, and I found that if you spray a leak with aerosol carb cleaner, something happens right off - It might go up or down in speed, so any change makes you suspect.

Oh, and @Michael Pickett asked: "did you run the engine this season before the mouse nest extraction and notice the rough idle?"

No - I started it, but the first thing I noticed was gray/white fluff pushing out between the bottom of the fan shroud and the engine case.  Stopped right there before it even got warmed up and started ripping and tearing everything apart.  Then I kept finding more things to "fix", like the failed clutch plate, a sticking air vane, cracked head tins, etc.  I hope I'm finally at the end of this road to recovery.

Congratulations, Gordon. You win the persistence award. BTW, I've sprayed a lot of things at manifold bases and in general, I prefer things that speed up the engine. If I remember correctly, the red Napa brake cleaner slows it down and the green Napa brake cleaner speeds it up. My never fail is starter fluid.

I had a big Rochester on a very cold school bus cough a BIG flame out at me decades ago when trying to start it.   I've been very leery of starter fluid ever since.

Took a month to grow one eyebrow back......   🫣

Yeah, baby! Feels good, don't it Gordon?  Way to stick it out.

Interesting that even this mostly carb problem was partly ignition. I take this as a sign from the synoptic gospels of Stan Galat,  Jimmy V, and the book of DannyP.  I say that as someone who finds himself after the reformation in the EFI camp. Also, mouse nests are the work of the devil.

@JMM (Michael) posted:

Interesting that even this mostly carb problem was partly ignition. I take this as a sign from the synoptic gospels of Stan Galat,  Jimmy V, and the book of DannyP.  I say that as someone who finds himself after the reformation in the EFI camp. Also, mouse nests are the work of the devil.

Crank-fired ignition has prevented many carb problems

@Michael Pickett posted:

My never fail is starter fluid.

X2. Ether evaporates without a trace, and will absolutely speed the engine up if there's a leak to atmosphere.

Nothing besides just taking the intake off and wrecking the gasket, however, will detect a leak between intake throats where my gaskets have always had a tendency to blow out. Ported heads get pretty thin there (like less than 1/8" thin), and a backfire will spit that sucker right out of there. Ether won't pick that up any better than WD40, Gibbs penetrating oil, or propane.

Ignition seems like it would be a set it and forget it, but with old analog stuff (even with electronic pickups, distributors are ancient analog devices) creep is always a possibility.

90% of all carb problems are ignition.

I’m just happy that the darn thing is running right, again.  

Things like this drive a COD person absolutely Bat$#!+

The rain continues.  Time to pump off the pool…….again!

Glad you got it figured out Gordon.

Yeah, Jimmy - It took a lot longer than it should have before I realized what was going on.  Like when I first started it up back in May or June, the rough idle, snaps and pops should have been enough clue, but I hadn't had to deal with that stuff in a long time, so it didn't immediately register.  Stan's right, though - A leak between intake ports from a sucked out gasket is much harder to find.  I think Jake Raby planes those surfaces flat on a T1 and uses a flange sealant (Locktite 410?) in place of a gasket.  

This was a good effort, though, because with the puny manifold and head flanges we have on T-1 dual-port engines, it is really easy to get an intake leak (or even a clogged jet) so maybe other people will now know what to listen for and some ways to isolate things to cure it.  I was all ready to pull both manifolds off before I isolated it with the carb cleaner to just one side.

Thanks for the quick tip, Jimmy!  

Hey, I jus' wannah report, that I ordered a bunch of intake manifold to head gaskets from CB Performance, and another bunch of fuel inlet Banjo washers from Eurocarbs in the UK.   Everything arrived today, CB stuff via UPS and Eurocarb stuff via Royal Mail/USPS.  It took about a week from placing the online orders to get here.  

I'm impressed!

@Gordon Nichols posted:

  It took about a week from placing the online orders to get here.  

I'm impressed!

Pretty amazing, isn’t it?

https://www.speedsterowners.co...4#713889682601326414

That's not bad. I've ordered several things from Europe in the past couple years. They usually take less than a week. Stuff from here(especially California) takes a good week. It's funny, it's about the same distance to me on the east coast.

Today I received a package that I am very impressed with. There is a one-man band FV shop in Cali run by Dietmar Bauerle called Quixote racing.

I called him late Tuesday. Wednesday he called back and got the details. I ordered new tie rods, 5/8 aluminum rod with new 3/8" Aurora rod ends. He cut them to length, drilled them in his lathe, threaded them, wrapped them up, and shipped them in one day. I think they went out Thursday. I don't think I could have bought the materials for what he charges.  Super reasonable.

The real kicker? He sends you the invoice in the package, and then you send him a check. That's very, very cool in this day and age. I think he's been burned once by a customer in 40 years.

Jake used to use Loctite 517 or 518 along with their primer. These are anaerobic sealants, they cure in the lack of air. On my engine, this was used WITH gaskets.

I ordered from Reutters in Germany twice recently.  For UPS they charge 39 Euro.  That’s steep.  If you select DHL from their drop down it’s only 9 Euro.  The UPS only took a week.  Once the DHL gets here, I’ll report back.  

BTW, what an incredibly class act Reutters is as a company.  

The quality looks the same as our US suppliers, but the price is significantly cheaper on some things.  From examining side by side, I’d be shocked if the OEM quality stuff we get from our typical suppliers is not actually originated at Reutters.

Two Week Later Update!

For only the second time since I built this engine in 2000 and installed the Dellorto Carburetors, I had a clogged jet.  The last time was back in the mid-2000’s.  

It was running poorly, on 3 cylinders, shortly after I left the house, but the stumbling would come and go when driving around, and when I stopped it would idle pretty well - 800 RPM and reasonably stable.

First thing I thought was that I had another intake manifold leak, but this time it sounded different.  No snapping and popping and irregular idle like when I had a manifold leak and with the manifold leak it had power mid-rpms but not full power.  This time the idle was more regular (but not right) and at mid-rpm, one cylinder was definitely not doing much.

I got home and pulled the plug wires one-by-one at idle and pulling #3 didn’t make the engine stumble worse.  “Ah-HA!”  That’s where to look!  That worried me, though, because that’s where I had the last intake manifold leak, too.    
Hmmmmmmm……….

So since removing the carb/intake manifold is a PITA on my car, and since pulling the jets on a Dell is so easy (they’re right up on top) I started there and pulled just the #3 jets, blew them out with carb cleaner and then used the cleaner wand to blast down into the jet holder holes to clean those, too.  Put it all back together, freshened the air cleaner seals and it starts and runs like a top.  

How I love an easy fix!

The crap is probably still in your float bowl. It probably fell back down when you took the jet out.

Did you remove the mixture screw and blow that passage out also? If not, you cleared the passage but put that chunk back into the main well. When I find an offending clogged jet I blow the passage clean from both directions from idle jet holder AND from mixture screw hole.

Cheers.

@DannyP

While I understand and completely agree, I’ll have to do that if it happens again, because as we both know, just getting at the mixture screws facing towards the outside (and blind for cyls 1 & 3 ) is next to impossible in a tight CMC engine compartment without removing both carbs.   For now, I’ll take the chance, but I agree that there might be crud in the bowl.  

I had that carb off a few weeks back and blew out the jets and mixture passages.  This happened since then.   😡

If this happens again I’ll take the carbs off, clean out the bowls and change the fuel filter.  It’s only been happening on the driver’s side - Just something else to ponder.  

Good tip, Dan!

I didn't realize your mixture screws were facing out. Yeah, that's a bummer. I've adjusted many a Speedster set up the same. I'm not a fan, but what are you going to do?

The dirt probably came from removing and installing the carb and air filter. I found that I always got a couple clogs within the first few weeks after a carb was off/apart. After that, it almost never plugged a jet.