TheSamba.com :: View topic - Engine Backfires and Bogs when cruising ***FIXED***

Thu May 08, 2014 8:35 am

Hi guys,
I recently decided to rebuild my carbs. It was a simple rebuild and im more than certain that I did everthing correctly. I followed along with instructions that are on the kaddieshack website. Ever since I did this the car has been having a problem running at high speeds. Driving around town, everthing is fine but when I get up to cruising speed in 3rd or fourth gear it starts to act up. The car will backfire a couple of times, start to cut out and jerk and then bog down. the bogging reminds me of a chainsaw brake. Once this starts, if I pull over and let it idle for a minute, its back to normal until I take off and it happens again.

about the car

1835 engine
kadron solex h40/44eis carbs
valves are adjusted to .006
timing set to 30° at 3500rpm ish
new plugs
009 distrubuitor with petronix ignition(no points)
fuel pressure is set to 1.75

I did recently notice that there was an external resistor hooked up before the coil. I tested the resistance of the coil and it was 3.5 and the outside of the coil even said "for use without external resistor" so I bypassed the external resistor. The made the engine run a little better, but it did not solve the problem.

any suggestions??

Thu May 08, 2014 10:13 am

Fuel starvation caused by disturbing crud in the fuel system when the fuel lines were moved ?

Thu May 08, 2014 10:21 am

Sounds like it's not getting enough fuel for sure.

Thu May 08, 2014 11:16 am

You're going to have to go back in. Could be a sticky float valve or dirt or gel in your main.

Thu May 08, 2014 1:46 pm

Ive pulled both back off and looked em over and blew carb cleaner through the jets.. no change..

just a thought.

right about the same time I rebuilt the carbs, I changed the plugs. I set the new gap to .028

today on my way out the door to work I randomly picked up an old plug and checked the gap. .040

that is wider than normal but it got me to wondering. hmmm.. ive read on here that some people run the gap a little wider with the electronic ignition. ill run it with the old plugs tomorrow just to see what happens.

Thu May 08, 2014 2:03 pm

mykafone wrote: Ive pulled both back off and looked em over and blew carb cleaner through the jets.. no change..

just a thought.

right about the same time I rebuilt the carbs, I changed the plugs. I set the new gap to .028

today on my way out the door to work I randomly picked up an old plug and checked the gap. .040

that is wider than normal but it got me to wondering. hmmm.. ive read on here that some people run the gap a little wider with the electronic ignition. ill run it with the old plugs tomorrow just to see what happens.

Save yourself some grief and stick with .028

Thu May 08, 2014 2:54 pm

Did you try increasing the fuel pressure? Try it at 3 and if you have smoke or flooding, back it off .5 at a time until it cleans up.

Wed May 21, 2014 9:09 am

So I took it out for a spin and got it to start bogging down, backfiring and sputtering. Luckily I got it to do it right around the corner so I limped it into the garage and pulled the carbs.

The left Kad is almost completely dry.

The right carb is a little low but a lot higher than the left carb.

both carbs side by side

Like I said earlier the fuel pressure when measured with car running is spot on 1.75 at both carbs. I just T'd the fuel pressure tester in next to carb inlet. I do notice that when I rev the engine up, the pressure does drop but that should be normal correct?

I pulled both lines to the side and turned the key on to let the pump run. It seems to me like there is not near enough fuel flowing, regardless or pressure, to keep the car running . here is a video to check out of the fuel streams.
https://www.youtube.com/watch?v=Sg-BaZHK2Ec&feature=youtu.be

The fuel pressure regulator I am using is one of those silver round ones.

Wed May 21, 2014 9:21 am

The round silver "regulators" with the arrow and dial are restrictors, not regulators. Get a real regulator, around $40.

Wed May 21, 2014 10:02 am

So John,
You believe that I am restricting the flow too much in order to get the correct psi?

Wed May 21, 2014 10:13 am

I'm having similar issues and have EXACT same setup.
But I do think you need to listen when people tell you to up your pressure to around 3psi. I've been told 3-4psi elsewhere as well and that's what I plan to do. Only I think my problem is opposite - flooding from too high pressure - because I have tons of soot coming out the exhaust and mixture screws don't help.

Good luck and let us know what pressure you ended up at to fix it.

Wed May 21, 2014 11:01 am

Yes, because a good regulator won't restrict the flow AT ALL while regulating pressure. Those Chrome Arrow Dial jobs just change orifice sizes, it's not a regulator. They also have a history of blowing up and creating crispy VWs when the car catches fire.

mykafone wrote: So John,
You believe that I am restricting the flow too much in order to get the correct psi?

Wed May 21, 2014 11:14 am

John out of curiosity do you have a pic of those chrome arrow jobbies you speak of?

I just procured one of these basic Holleys for under $30 and I'm hoping it does the trick.
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Wed May 21, 2014 11:46 am

http://www.jegs.com/images/photos/800/865/865-2517.jpg

They used to have a stick on arrow, there are slight variations of this, they all suck eggs.

They have also been sold under a lot of different brand names, including

Spectre
Mr. Gasket
and dozens of others.

Wed May 21, 2014 11:55 am

spend some quality time really eyeballing the fuel/float level too

Wed May 21, 2014 1:25 pm

ORANGECRUSHer wrote: I'm having similar issues and have EXACT same setup.
But I do think you need to listen when people tell you to up your pressure to around 3psi. I've been told 3-4psi elsewhere as well and that's what I plan to do. Only I think my problem is opposite - flooding from too high pressure - because I have tons of soot coming out the exhaust and mixture screws don't help.

Good luck and let us know what pressure you ended up at to fix it.

I'm getting 1.75 from the Kaddie Shack which is a carb shop that specializes in these carbs. And I have cranked up the psi and it just made it run horrible all the time.

Does anyone have any good advice when it come to setting the correct float level in these boogers?

Wed May 21, 2014 8:30 pm

http://www.lowbugget.com/main_page.html

AJ has pretty good info on his site and I recently done some buisness with them. I'm having similar problems with some Kadrons and been through the entire fuel system. Holley low pressure regulator, Holley pressure gauge, Carbs synched perfect and still runs like a dog. Problem only shows up in 3rd and forth bogging. AJ's sending me some mains and idles along with new rebuild kits. The kits I used originally were the EMPI cheapy rebuilds. I should know whats up by this weekend and let you know.

Thu May 22, 2014 9:40 am

I looked at your video. :shock: Ha ha , That dribble can't be called a fuel stream. Lack of fuel would be the cause of your troubles. :lol: hope you get it sorted out.

Thu May 22, 2014 11:33 am

YAY.. Fixed..

Sure enough I ditched that crappy round regulator and got a real one like John suggested and oh man what a difference. Dialed in the psi and I had a steady FULL fuel stream. It runs like a dream. Thanks everyone for the input.

Thu May 22, 2014 5:45 pm

Way to go! I too narrowly escaped burning down my ride with that POS empi crap. Why do vendors continue to insist that a part is good when MANY people are having the same issue.

If you think it runs good now put some IDF/DRLA/HPMX on it and you will wonder why you wasted all the time on the duds.