popping through the carb or back fire, how can a lone driver tell what is what? Options

[SUNAB914]

What gas octane are you using? I switched from 87 to 89 and my popping has mostly gone away. I have and found in both my cars they run better with 89. It takes awhile to tweak your dual carbs, it took me almost 2000 miles to fine tune them.
Good luck

[Root_Werks]

What gas octane are you using? I switched from 87 to 89 and my popping has mostly gone away. I have and found in both my cars they run better with 89. It takes awhile to tweak your dual carbs, it took me almost 2000 miles to fine tune them.
Good luck

91 always.

One item I thought it could be was the 050 dizzy I am currently running. Maybe hung weights or something, but the running issue isn't global. It's down to specific cylinders. Bow out passages, runs great until they get gummed up again.

I'm thinking it's gotta be the tank and sludge getting by the filter. I honestly haven't even looked what pump/filter combo was installed for the carb set-up.

It's a 75', so everything is behind the plate in the front trunk. I'll dig into it, post pics and info here. Who knows, there may not even be a filter!

[VaccaRabite]

Put in another fuel filter. Make sure that your air cleaners are clean and oiled (assuming that you are using the K&N filters). The passages are small, so it does not take much to gum them up.

Zach

[Root_Werks]

Put in another fuel filter. Make sure that your air cleaners are clean and oiled (assuming that you are using the K&N filters). The passages are small, so it does not take much to gum them up.

Zach

K&N, yup, don't like those either. Clean and oily though. (IMG:style_emoticons/default/wink.gif)

I'll see hopefully tonight what's under the trunk plate. The pump never makes any noise, so I kinda assumed it's a rotary pump, maybe even one of the CB internally regulated ones?

I have a new filter sitting on the shelf at home so that should be easy to replace.

[Gint]

Here's another observation I've made over the years. After resurrecting a carb'd 914 whether you've rebuilt the carbs or the car was just sitting around, you can clean out the idle jets several times initially. Eventually after a few repeats of this process you get past the crap and then they'll maintain a tune for a good long while as long as nothing else changes. That doesn't mean you don't have crap in your tank, lines and/or filter at this point though. In which case you'll forever be cleaning out idle jets until you resolve the root cause. And you already know how to do that, so I'll shut up now.

[Root_Werks]

Worked on a buddies boat all last night. (IMG:style_emoticons/default/dry.gif)

I'll try again tonight to replace the filter, see what I have, post a couple of pictures.

[Tom]

Dan,
Something to try. Take the fuel line loose on the carb that keeps plugging up and pump a little gas in a jar. Let it sit and see if you have anything coming through the system. Pretty easy to check.
Tom

[Root_Werks]

Also good advice, I might try that.

Had a little time tonight, so I decided to see what's behind the plate. (IMG:style_emoticons/default/dry.gif)

[Root_Werks]

The pump will have to go, it's a cheap 'thump, thump, thump' pump, not a rotary like I had wished.

I'll probably get one of the internally regulated CB rotary pumps.

So, looks like a stock filter with the flow correct, but then it goes into another filter that may or may not be designed to flow backwards like that?

Then into the "IN" side of the pump.

[Root_Werks]

For tonight so I can keep the 914 on the road is a simple carb metal can filter. Just one of the $4 universal ones for now. The flow is correct and restriction is not there.

I did try to blow through the stock filter, it was hard. I had to put a lot of pressure behind it before it broke through and I couldn't blow through it backwards, but can't remember if they have a little flap in them for that function.

Started the 914, ran decent. If the filter(s) truly did fail allowing gunk to pass by, I still have gunk in the carbs and line back to the carbs. This weekend I'll clean out the idles again and see what happens.

I didn't notice anything from the small amount of fuel I drained out, no rust or gunk, but I know it doesn't take much to gum up the little carb passages.

[Root_Werks]

I wanted to give an update to this thread even though it wasn't started by me.

I replaced the fuel pump with an internally regulated CB rotary pump. Much better. Nothing clogging the filter that I can see.

Took carbs off, cleaned, new seals etc. Set, dailed in, run great except I still get lots and lots of popping out the intakes.

Lean popping?

Stock 2.0, anyone have a good known combo for jets/e-tubes/mains etc.?

I think I'm running 50's idles and F11's on 32's.

Should I go 55's, F7's and 30's?

(IMG:style_emoticons/default/idea.gif)

Still seems like it "misses" or stumbles a lot.

[Root_Werks]

Just talking to myself:

Self, you should try some 55's, see what happens, they're cheap.

You know Self, you've gotta a good point, let's do it!

Stopped off on the way home today and snagged some 55's.

Better, not perfect yet, but much better. No more popping and smoother.

Good advice.

[VaccaRabite]

Carbs need to warm up to run right. Even well tuned they still can tend to pop and piss you off until they are fully warmed up.

But, yes, what you described sounded like lean pops. Sounds like you are zeroing in. I just bumped from 55s to 60s for my 2056. Was not popping, but thought I would try them to see what happened with my head temps and performance. I might just end up putting the 55s back in.

Zach