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Topic: carb...too rich, or too lean?

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DickDanger Male

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Posted: May 30 2004,2:06 pm

Post # 1

Since I am not a carb master at all, my question is this to the masses: is my carb running too rich or lean if it is backfiring at lower rpm? We're talking 1500 rpm and below. It doesnt seem to want to idle, but in the upper ranges, it sounds strong. All 4 of the needle screws on my Holley double pumper are at 1/2 turn out. Or should I only be adjusting 2 of the needles? Remember: there is a needle screw on each sides of the 2 float bowls. Thanks for any help!!! -DD Out

Edited by DickDanger on May 30 2004,2:07 pm

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Sleek-Jet

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Posted: May 30 2004,2:21 pm

Post # 2

Is it backfiring through the carb or through the exhaust??

A good rule of thumb is that a backfire through the carb is an indicator of a lean condition. Ã‚Â Some of the more "senior" gear heads here will probably be able to diagnos better than I can.

I am assuming this is a problem that's surface since moving to Idaho. Ã‚Â How high are the lakes/river's your running??

Edited by Sleek-Jet on May 30 2004,2:22 pm

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DickDanger Male

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Posted: May 30 2004,3:13 pm

Post # 3

Actually, I had the carb rebuilt this winter, and it just isnt properly dialed in yet. It is backfiring thru the carb itself, not the exhaust. I am not sure what the 4 different needle screws are for. I am assuming that 2 of them are for the float adjustment. The other 2 I dont know. Or maybe all 4 are for the float adjustment? See what I mean, I am not a carb specialist by any means!!! -DD Out

In New Orleans, women get fake jewelry to show real boobs,
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Sleek-Jet

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Posted: May 30 2004,3:21 pm

Post # 4

Are you talking about the 4 needle screws on the side of the metering blocks?? Am I correct in thinking this is a Holley??

A dog doesn't care if you're rich or poor, educated or illiterate, clever or dull. Give him your heart and he will give you his.

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DickDanger Male

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Posted: May 30 2004,8:41 pm

Post # 5

Yep, its a Holley double pumper. -DD Out

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riverblender Male

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Posted: May 30 2004,11:11 pm

Post # 6

The float is adjusted by the flat bladed screw and jam nut on the top of the float bowls and removing the sight plugs on the side of the bowls the fuel should just start to seep out of the holes on the side with screws removed and fuel pump running if elect of motor running if mech. Check a the float level first. Holly carbs are metered with jets that get screwed in to the metering blocks this is where you change the fuel mixture of the carb. Also check for vacume leaks make sure that all open plugs are sealed off if they are get a can of carb cleaner and with the motor running spray the base of the carb and along where the intake manifold meets the heads and listen for any changes in engine speed or smoothing out. Vacume leaks cause motors not to idle very well and will cause backfires
Riverblender

Edited by riverblender on May 30 2004,11:18 pm

www.a1ofsocal.com :drink

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Bullitt Bob Male

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Posted: May 30 2004,11:50 pm

Post # 7

Quote (riverblender @ May 30 2004,11:11 pm)

Couldn't have said it better myself. :good

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GoFastRacer Male

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Posted: May 31 2004,6:27 am

Post # 8

Quote (DickDanger @ May 30 2004,2:06 pm)

Since you have an 850DP, it has 4 corner mixture adjustment which are the small screws in the side of the metering blocks, the ones on the top are for the floats. To adjust the mixture, run the motor till it gets up to temp, then turn the needles in or out a quarter turn at a time until it reaches it's highest idle. Usually a starting point is to turn the screws in all the way and then back them all 1 1/2 turns out, then fire it and adjust each one equally. Adjust floats as mentioned..If it won't idle after adjustment, you may not have enough manifold vacuum due to your cam having a lot of overlap!. If that's the case, there's another adjustment for that. If you can let us know what you have for a cam!..Also make sure the timing is set corectly!..

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AZKC

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Posted: May 31 2004,10:30 am

Post # 9

Exactly

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DickDanger Male

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Posted: May 31 2004,3:00 pm

Post # 10

Okay, I will start with the simple things that you have suggested first. The cam is a 3/4 race cam, and that is all I know about it. The guy that built the motor couldnt remember the exact specs on the cam. Anyone that has ridden in my boat here knows how strong it runs and maintenance free it has been in the last 4 years that I have had it. This is why I am not as familiar with carb adjustments as I should be. I will start with all 4 adjustments at 1 1/2 turns out, and go from there. Can someone explain about the float adjustments on the top, and how doing what affects them? Thanks for your patience. -DD Out

Edited by DickDanger on May 31 2004,3:01 pm

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AZKC

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Posted: May 31 2004,5:18 pm

Post # 11

There are screws on the side of the bowls and you want the fuel to be right at the bottom of the hole after you remove the screw. You adjust it with the screw nut dealio on the top of bowl. Sounds like your not flooding which would be a float adjustment unless your emptying the front bowl which would cause it to go lean, I would ck your timing and and play with the air screws that are the ones you start with 1 1/2 turns out :good

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GoFastRacer Male

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Posted: May 31 2004,8:02 pm

Post # 12

Wow a "3/4 race" cam, ain't heard that in ages! :laugh

.Seriously that may be your problem, since you had your carb rebuilt it was probably put back to "out of the box" condition so now it has to be readjusted back to your application!. Those "3/4 race" cams has a lot of overlap so you don't have hardly any manifold vacuum!. If the adjustments mentioned above don't work and you still have the same condition, we'll go from there!.. :good

Waiting for results!..

Edited by GoFastRacer on May 31 2004,8:03 pm

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DickDanger Male

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Posted: June 02 2004,10:05 am

Post # 13

I will be taking the boat out either thursday, or saturday, so I will post my results. Thanks for your patience!!!! Yep, 3/4 race cam is what I was told. Maybe the next time that I have the manifold off, someone that knows cams can take a peek in there :jumpie

-DD Out

In New Orleans, women get fake jewelry to show real boobs,
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GoFastRacer Male

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Posted: June 02 2004,2:36 pm

Post # 14

The only way to find out what it is would be to take it out and see if there is a number on the back end, if not you can degree it and it will tell you what you have!. :good

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RVRGIRL

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Posted: June 02 2004,4:14 pm

Post # 15

"carb...too rich, or too lean? " WOW.. I thought this topic was about the ATKINS diet.. Boy am I stupid. O I mean blonde. :stupid

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HAVE A PHENOMENAL DAY!

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GoFastRacer Male

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Posted: June 02 2004,8:10 pm

Post # 16

Quote (RVRGIRL @ June 02 2004,4:14 pm)

"carb...too rich, or too lean? " WOW.. I thought this topic was about the ATKINS diet.. Boy am I Ã‚Â stupid. O I mean blonde. :stupid

Ã‚Â

Nope no Adkins diet here, the dude died from his own diet!. :rotflmao

That's ok stick around and you'll learn!. :good

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DickDanger Male

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Posted: June 03 2004,7:31 pm

Post # 17

Well, I officially give up on this. I had the boat out today, and after about 10-15 minutes of trying to get it started at the dock, it finally fired. Made one trip around the lake, and it actually didnt feel like the carb was too far out, but it still wouldnt idle right, and there was a slight hesitation over 4000 rpm. Then I shut the boat off not too far from the launch, and it never wanted to really fire again. I had flames shooting out of the top of the carb, and even from the exhaust a few times. This scared the shit out of my fiance too!!! Also, I think that something is shot with my turnkey ignition, as the starter wouldnt stop when the key was in the off position, and just kept winding out. I had to shut it off at the perko switch. This is f**king so frustrating. I was totally bummed with the problems today, and not knowing how to solve them. Ã‚Â

-DD Out

Edited by DickDanger on June 03 2004,7:34 pm

In New Orleans, women get fake jewelry to show real boobs,
In SoCal, women get real jewelry to show fake boobs.

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GoFastRacer Male

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Posted: June 03 2004,8:13 pm

Post # 18

Quote (DickDanger @ June 03 2004,7:31 pm)

-DD Out

Well if you're shooting flames out of the carb and the exhaust and from the description of how it runs, it sounds like timing or an ignition problem or both, what kind of ignition do you have??...Has anything else been done other than the carb?, any engine modifications that we don't know about??? That would help solve this problem!.

As far as the starter deal goes, it's time to replace the swith, never did like those, I like an on off toggle and a button!.. :good

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BigBoyToys Male

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Posted: June 04 2004,6:09 am

Post # 19

Yep....That's usually my problem....too much timing

better be careful with that though if the timing is the problem. I backfired 1 too many timesonce last year and blew a big hole in a 990 head, and also cracked it. It still ran(Ran bad that is), but was never the same again until I replaced the heads. ($$$$ :eek

)

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GoFastRacer Male

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Posted: June 04 2004,6:11 am

Post # 20

OUCH!

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DickDanger Male

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Posted: June 04 2004,10:11 am

Post # 21

I think that I have fidled with the carb too much at this point, that I am going to have to start from scratch again. When the carb was sent off, the intake manifold was taken off of the block for powdercoating, which meant removing the distributor. We marked it prior to removal, and once the manifold was put back in place, stabbed the distributor back in at the marks. I have a simple points ignition, no fancy MSD ignition here, just a simple set up. I traced the starter winding out to the ignition switch itself, as the starter was just rebuilt a month ago, the solenoid is also new, and all of the battery cables new. I will be ordering a new ignition from Rex today, cos I cant do anything with the boat until that is taken care of. GoFast, you think that the toggle and push button is the way to go huh? -DD Out

In New Orleans, women get fake jewelry to show real boobs,
In SoCal, women get real jewelry to show fake boobs.

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GoFastRacer Male

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Posted: June 05 2004,12:12 pm

Post # 22

Well when get you so far out of whack, it's best to go back to square one and start over, it's a lot easier that way!..As far as timing goes that mark is a reference, put a light on it!...

I believe in the KISS method and sinceI hate electrical, I have the least wiring that I can get away with, that's why I run a mag, one wire. Two wires to start with a toggle and a kill switch in the line and a button that's it, nothing there to take a shit!..

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DickDanger Male

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Posted: June 09 2004,4:40 pm

Post # 23

It seems as if the fuel problems are solved. My timing was way out of whack, so that was taken care of. Also, one of the float bowls had fuel streaming out of that side inspection hole, (where the brass screw is), so I readjusted that. I had the boat hooked to a garden hose, and adjusted the idle to 900 rpm, and there was no backfiring or dying of the motor. The only thing left to do is adjust the choke, but the weather started getting shitty, so I called it a day, and will adjust that when the weather gets better. I will let everyone know how it runs this weekend out on the water. Thanks for everyone patience and help!!! :good

-DD Out

In New Orleans, women get fake jewelry to show real boobs,
In SoCal, women get real jewelry to show fake boobs.

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AZKC

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Posted: June 09 2004,5:33 pm

Post # 24

See it was something pretty simple

This time

Good job DD hope its back to normal for ya :beer

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GoFastRacer Male

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Posted: June 09 2004,8:10 pm

Post # 25

Glad to hear things are working out for ya!.. :good

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25 replies since May 30 2004,2:06 pm

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