Firebuggy's buggy.

[Firebuggy]

Got some more done today. Installed crankcase filter, vacuum tubing, cage and tires. Put in fresh oil and replaced oil filter. Readjusted the rockers. All set to time the engine and adjust the carbs tomorrow. Also scored some old school cool tools for $30! Check it out...dwell/tach meter, timing light and remote starter!

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2110 build for buggy

The cost of building an engine yourself is like converting to metric..."Double it and add thirty!"

[Firebuggy]

So in further news...problems, I got lots. I'm getting frustrated/discouraged now.

Spent the last while (6 days) now screwing around with these carbs trying to get them to run right. Can't even drive the car. Here's what I've done so far...

1) Broke in engine. No problems except pressurized case and needed venting. Done. Didn't have any backfiring while doing break-in, but idle speed screws were in quite a few turns.

2) Checked dwell. I was at 20°. Pretty low so readjusted points and got to 47° bang on. Reved engine up and dwell stayed at 47° so distributor/points are good.

3) Adjusted valves. Running chromoly push rods so adjusted them with no lash but loose enough to rotate by hand.

4) Set timing. 32° and I can barely get the engine to turn over once hot. Backed it off to 28-30° and it is better. No vacuum hose connected when setting timing.

5) Now for the carb adjustment. Set the idle speed screws to 1/2 turn after contact and engine will not idle. Mixture screws were out 1.5 turns. I kept turning in the idle speed screws until I got to 2-2.5 turns past contact and now the engine will idle on it's own. Used the snail, synced the carbs.

6) Started adjusting the mixture screws. They didn't really seem to do anything at first, but then I could hear just slight variations and if I got close to bottoming them out the backfires (popping sound) would start. I backed them out until backfiring stopped slowly and one at a time. While getting them set, I readjusted the idle speed screws at the same time and got them to 1 turn in from contact. I couldn't get them any less than that as the idle speed is really low and the engine quits.

So up to this point I think, ok, I must have them set properly even though the idle speeds should not be more than 1/2 turn in. Nope. If you try to hit the gas or put any load on the engine, it starts backfiring again. It is really bad as in not even driveable. I barely could make it out of the driveway.

Then I did the following...

1)Searched here and the rest of the net for answers. Many folks were discussing using 55 or even 60 idles. I am using 50's and had removed the 55's. So I thought, hey why not give those a try. So I frigged around all day today with those and still have the same issues except the mixture screws run best at only 1/2-3/4 a turn out. Still don't notice a huge change when adjusting them as I assume it's because the idle speed is too far in, but the car won't run otherwise. Still can't give it throttle or it backfires (popping in exhaust) like crazy.

2) Read somewhere that exhaust leaks can cause issues with tuning. As I did not replace my exhuast (baja exhuast) and the engine is a different size than stock, I had some considerable leakage at the 4 into 1 collector as it no longer fits as snug as it once did. Soapy water really confirmed that. So today I purchased a sealant/epoxy/filler (not sure what it is kinda like toothpaste) to fill the joints that will be cured by tomorrow afternoon and hopefully that solves the problem, but it is a long shot.

Things I have also noticed are...
A) when it does idle, it is very unconsistent. By that I mean it runs at like 900 rpm kinda rough (chugging), then shoots up to around 1300 purring like a kitten and then back down to 900 rough and up again. It will cycle like this all day if you leave it.

B)It will not run at all on its own warm or cold with idle speed screws less than 1 full turn in, which according to the instructions is not good, but doesn't say what the problem is otherwise. At cold, it won't run there until engine is warmed up which is probably normal as it has no chokes.

3) I have a new carter fuel pump. I have not checked the pressure, but I am only at idle so it should be able to keep up.

Hopefully one of you who reads this can maybe help out. I am hoping the sealing of the exhaust is the key here, but the way things have been going lately I am not gonna hold my breath.

On another note, still having issues with the case being pressurized, but I assume it's because the rings are not broke in yet as I can't get out of the driveway!!
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2110 build for buggy

The cost of building an engine yourself is like converting to metric..."Double it and add thirty!"

[Q-Dog]

Check the fuel pressure. Too much pressure can cause inconsistent idle, flooding, backfire, sputtering.
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Brian

'69 Dune Buggy
'69 Beetle Convertible
'70 Beetle

[Firebuggy]

[Firebuggy]

Well success kind of. Exhaust was all sealed up after drying overnight. Looks like hell, but if it works So I was able to get it idling no problem with the idle speed screws at about 3/8 of a turn in after contact. It stopped the up/down cycling and was smooth, smooth, smooth.

No sooner did I get that done and another buggy pulls in my driveway. It's EMPI70IMP. I had seen him around, but since I have been off the road for almost 2 years, never had a chance to stop him and say "Hi". So today we met which was awesome. Nice to have someone else to talk buggies with that is local.

Anyway, after he left I continued the tuning of the carbs. Still can't here the engine change much when dialing the mixture screws in or out, but when you blip the throttle there is a noticeable difference. Too far in and it backfires like crazy. So I adjusted the screws out all about the same around 3/4 of a turn from bottomed out. Took it for a rip. I am about 80% tuned at this point. It doesn't backfire with a load and starts off smooth. It seems to miss/sputter/backfire between 2500-3000 rpm. It doesn't matter if a slowly accerate or hammer it. Sputter, sputter, pop, pop, then zoom.

I will continue to mess with the mixture screws until I get it dialed in unless someone has an opinion on what may be happening. I do know that sealing the exhaust helped a great deal. New exhaust next year for sure. That would make a nice Christmas present!

It sure does move now. 2800 rpm in 4th gear and I'm doing 70mph! Have to really keep an eye out for the Popo! haha
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2110 build for buggy

The cost of building an engine yourself is like converting to metric..."Double it and add thirty!"

[joescoolcustoms]

What carbs are you running?
What are the jet specs on what is in them?
Venturi's
Main Jets
Idle Jets
Air Corrections
Emulsion tubes
Accelerator Squiter

The mixture screw adjustments seem way off and makes me wonder if your base line set up is off kilter somewhat.
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Bad News Racing 2018 NORRA 1000 3rd in Class
Best Day Ever Racing 2022 NORRA 1000 2nd in Class and first All Female team to complete the race

Everyone is gifted. Some just do not open the package.

Looks like it was painted with a live chicken,polished with a brick and buffed with a pine cone

[Firebuggy]

[joescoolcustoms]

Change the following:
Venturis back to 28mm
Air correction back to 200
Main jets back to 115
Keep the idles at 55

One indication you are way out of tune is the idle mixture screws. They should be between 1 1/2 to 2 1/2 turns out. Less means too rich. More means too lean.

The air by-pass screws, (if equipped) should be all the way in, closed.
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Bad News Racing 2018 NORRA 1000 3rd in Class
Best Day Ever Racing 2022 NORRA 1000 2nd in Class and first All Female team to complete the race

Everyone is gifted. Some just do not open the package.

Looks like it was painted with a live chicken,polished with a brick and buffed with a pine cone

[Firebuggy]

Yep air bypass screws are all the way in. When I initially checked them upon disassembly and cleaning, 3 of the 4 were bottomed out and 1 wasn't.

Venurti's back to 28mm. I guess the carbs are coming off. Not looking forward to that, but I'll try anything.

I should mention my exhaust is only 1.5" not 1 5/8" if that makes any difference.
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2110 build for buggy

The cost of building an engine yourself is like converting to metric..."Double it and add thirty!"

[oprn]

You need to get a wide band on there so you can see where you are really at. I couldn't believe how much simpler and faster it makes tuning these carbs!

[Firebuggy]

I have been trying to tune these carbs and I am close, but still not there yet. So I took Joe's suggestion and put the 28 venturi's back in, airs to 200, mains to 115 and idles at 55.

Couldn't get it to idle or tune at all. It was all over the place. Put the 50 idles in, and got it tuned where it should be around 1.5-1 3/4 turns out on mixture screws. However, as soon as you gave it throttle pop, pop, backfire just backing out the driveway. Tried just going down the street and backfires and pops all through 2000-3000 rpm. Never tried going any higher.

Next I put the 55 idles in thinking it's lean, Got it tuned but the mixture screws are only out about 5/8 of a turn. No popping or backfiring backing up (I have a long driveway), but as soon as I get going down the street again between 2000-3000 pop, pop, pop, (You'd think I had a popcorn machine not an engine!)

So not sure what to try next...
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2110 build for buggy

The cost of building an engine yourself is like converting to metric..."Double it and add thirty!"

[Firebuggy]

Okay, tinkered with it some more. Found that the carbs weren't opening together but that is from removing them when I changed venturi's because they were inline before.

I put the 50's back in. All 4 mixture screws are about 1 1/4 turns out from bottom, the engine stumbles if I turn in or out from that position. The idle speed screws however have to be a one full turn in on the 3-4 side and three quarters of a turn in on the 1-2 side. It is still popping, but no where near as bad as before. So close now. Should I change the main or air jets now to solve this last little bit of stumble/popping or should I try the 55's again first.

Maybe a video would help???

One thing I did notice was the throttle doesn't seem as snappy as when I had the 32's in with the other combo of jets.
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2110 build for buggy

The cost of building an engine yourself is like converting to metric..."Double it and add thirty!"

[joescoolcustoms]

First, don't mess with the Air Corrections, their size is configured with the venturi and throttle sizes.

What distributor is on the engine, and what is the timing set to?

When you say popping, is it up through the carbs, or out the exhaust?

You may need 60 idles.
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Bad News Racing 2018 NORRA 1000 3rd in Class
Best Day Ever Racing 2022 NORRA 1000 2nd in Class and first All Female team to complete the race

Everyone is gifted. Some just do not open the package.

Looks like it was painted with a live chicken,polished with a brick and buffed with a pine cone

[Firebuggy]

[joescoolcustoms]

The dual Webers typically are not a good combination with a SVDA. They need a purely mechanical distributor. The twin dual throat carbs just do not make enough vacuum to advance a dist. May be why it feels boggy because you are not getting the advance to "pick" the engine up.

I really hate suggesting a 009, but if you can get your hands on one to test with, you then may be able to get the engine close to tuned with it.

The combination of jets I suggested has ran on 1600's up through 2165's with a minor one step jet adjustment on either a idle or main to taylor to the specific engine.
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Bad News Racing 2018 NORRA 1000 3rd in Class
Best Day Ever Racing 2022 NORRA 1000 2nd in Class and first All Female team to complete the race

Everyone is gifted. Some just do not open the package.

Looks like it was painted with a live chicken,polished with a brick and buffed with a pine cone

[manxvair]

You might also want to try hitting each carb with some quick start, start at base intake gasket and work your way up, hit the area around the throttle shafts, inner & outer bushing areas. I had some similar tuning issues. i tried replacing just about everything and then found the throttle shaft bushing in the crotch on 1 of a set of 44 IDF's (cyl 4) was worn out and creating a minor vacuum leak. When I swapped on another set of IDF's I was able to dial them in, in a matter of minutes.

[Firebuggy]

[Firebuggy]

[62kellison]

my 1600 started popping when I was driving today under load.got worse if I hammered it.i pulled the plugs they were all dark soot again.tried to clean the plugs up.it didn't work.plugs r junk now.put new plugs in it and it runs great again.i am on my 3rd set of plugs.they soot up right away and last a week.i am running dual webers.the idle jet is a 50....gonna go to a 45 and hopefully it will be fine.i may try a hotter plug also.if this helps.it always kills just one plug out of the 4.usually number 1 cylinder on mine.

[Firebuggy]

Well I am not sure what to do anymore. I've tried just about everything. Put in new plugs, set carbs with the 50 idles in and it idled great but put any load on it and it sputters and pops. Mixture screw about 1.5 turns out. Hammer the throttle, goes like stink, let off and cruise around 3k rpm and pop, stumble, pop. Tried adjusting the mixture screws a little, but doesn't help any.

I just tried putting the 55 idles back in, runs even worse. I stink like gas and you can see puffs of black smoke when you crack the throttle at a stand still. Any load, and it pops and stumbles.

When I say pop, it's coming out the exhaust not the carbs and by stumble I am referring to the jerking motion of the car.

I think I may try yanking the carbs off and putting the 32 venturis back in. I might also post in the engine forum section as there are more folks that have experienced problems similiar to this over there.

The following things I have also checked or done repeatedly are...
valves, timing, air leaks, fuel pressure, replaced points with pertronix, synced with snail, etc...
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2110 build for buggy

The cost of building an engine yourself is like converting to metric..."Double it and add thirty!"