Powerboat Forums at SpeedWake banner
Cancel
Create thread New Forums

Carb Help

Jump to Latest
1 - 18 of 18 Posts

Thunderman98

· Registered
Joined
·
1,835 Posts
Discussion starter · #1 ·
My problem is with a set of Holley 800 cfm carbs on a pair of 540 bulldog motors. The port side I never have a problem with. The starbord side likes to act up every now and then. The starboard side likes to pop once in a while if you give it a quick rev. I have blown out 2 power valves in the last year. They do not seem to be running rich, (very little blackmarks on transom), but I dont think that they are running to lean either since I can run both motors up to 5200 with no problem.The motors never stumble when warmed up and have great power from the 3000-5200 rpm range. Also they like to load up after idleing awhile.The carbs are stock. I spoke to Nickersons regarding this and was told that they could do a Stage 5 rebuild at the price of $695.00 per carb. Was told that these carbs have many issues with them stock and that my motors would run alot better with the rebuild. Also was told that I would gain around another 30hp by redoing the carbs. Any input on what I should look at first, or just send them out and have them redone.
 
#3 ·
I know squat as far as carbs go. But, I sent my 850 to Nickerson. It was/is on a ZZ502/502 GM crate motor. I sent it to Nick to get it "marinized". When I got it back the elec. choke was gone, 4 corner idle screws {instead of just the front two} power valve changed, throttle shafts re-worked. More was done to it, but I'm carb stupid so can't give you the entire list. I bolted it on the ZZ ran the bejeebers out of it, and did the usual plug checks, and plug color is good. Cold starts are much better, and never even a burp from the engine any time. Runs perfectly. HP increase?.....I can't say that I noticed any more.

I don't remember exactly how much it cost. But it was right around $425.00 including shipping. My engine is a "stock" crate ZZ502 and not very exotic, which may be the reason for the lower price.

Good luck!!
 
#4 ·
A Holley will "lean pop" or sneeze if it's too lean @ idle. Once it pops, it usually blows the power valve. Then it will definately load up @ idle. When it's cold, it needs the choke to work right or be compensated with a happy medium on the mixture screw. Accelerator pump may need to be replaced or adjusted too.

30 HP on a carb rebuild? WOW!

CFM is the expert on that stuff so hopefully he will get back to this thread. :)
 
Discussion starter · #5 ·
Thanks guys so far for the info. I at least know where to start. As far as the HP increase, I am going by what Brad said over there. I was really surprised by what he said. I didnt think you would increase HP with carb rebuild. Mybe I misunderstood him. I dont think that they would give me any false info. I have only heard great things about them.
 
#7 · (Edited)
FTM said:
A Holley will "lean pop" or sneeze if it's too lean @ idle. Once it pops, it usually blows the power valve. Then it will definately load up @ idle. When it's cold, it needs the choke to work right or be compensated with a happy medium on the mixture screw. Accelerator pump may need to be replaced or adjusted too.

30 HP on a carb rebuild? WOW!

CFM is the expert on that stuff so hopefully he will get back to this thread. :)
Click to expand...
Hold on for a split second, no carb expert here. I know the basics of a carb, so more than many, but way less than many too.

Anyway, yes, a sneeze out the carb is typically lean. It can also be caused by a stuck choke, and by other things.

So, we know the carb worked fine and the other carb works fine, so, let's just make it normal, back top normal.

You could very well have a transition problem from idle circuit to main circuit, so let's clean some of it out.

Take the idle mixture screws out, don't lose the cork o-rings.

Spray in each mixture screw hole with carb clean can's red tube pushed in it until the carb clean mists out of the top air bleed consistently. Watch your eyes, carb clean in eyes hurts real bad. Note the bleed hole that the carb clean comes out. Spray into this hole (push the red tube onto it) and make sure the cleaner comes out the idle mizture screw hole well.

Do the other side the same way. While your there, spray carb clean down the other pair of bleed holes too.

Bleed holes are super important and very easy to get dirty, especially with PCV systems and flame arrestors not designed to filter air.

Put mixture screws back in and reset to best idle. Either by vacuum guage, rpm, or by ear if it's 'trained.' :bigsmile:

That concluded my 'Holley Tune Up In A CAN' speech. I'll add more in a bit.
 
#8 ·
Listen to CFM here!!
I went through my carb and did what he said, but found 'other' problems along the way.

CFM's tuneup in a can I know de-crudded my carb, after all the screwed up stuff was fixed.

I sure hope that your carb was not gone through by the same idiot that did mine before....
===
Oh, and CFM's tuneup in a can worked PERFECTLY for my lawn tractor!!! It wouldn't idle, and hesitated, running very lean when running. So, I pulled the carb and =CFM CANNED= it!! Now it runs perfectly, without buying a carb kit!!!

Thanks, CFM!! You da man!!
 
#9 ·
Carb clean should be used this way atleast once a year, especially when boat is brought out of storage. :bigsmile:

Mud, glad it saved you $$ by not having to send it in for repairs.

You know where to send the check. :bigsmile: :laugher: :laugher:
 
#11 ·
If you stay this basic, you can do it on, however, if you are going to try to pull the choke blade out or you want to pull the bowl and metering plate to spray thru those orifices you may want to do it off.

BTW: With the J tube vent, the choke blade can be a beatch to try to pull out. You may want to look into just disconnecting the rod from the choke mechanism and tying it up to domething to keep it totally open.
 
Discussion starter · #12 ·
cfm said:
If you stay this basic, you can do it on, however, if you are going to try to pull the choke blade out or you want to pull the bowl and metering plate to spray thru those orifices you may want to do it off.

BTW: With the J tube vent, the choke blade can be a beatch to try to pull out. You may want to look into just disconnecting the rod from the choke mechanism and tying it up to domething to keep it totally open.
Click to expand...

Ok, I will give that a try for this weekend. Have the pics of the themostat housing, Just having a hard time putting them in. My have the computer genius (wife) put them in tonight for me.
 
Discussion starter · #14 ·
CFM,
I didnt get to the carbs yet. I had a chance to get out on Sunday in between the rain showers. I am hoping to do the work to the carb this week and test it next weekend.Working 6 days a week 10-12 hrs aday, it takes me alittle while to get things done that I need to do, plus it has rained here everyday since last Wed and its raining today.
 
#18 ·
cfm said:

BTW: With the J tube vent, the choke blade can be a beatch to try to pull out. You may want to look into just disconnecting the rod from the choke mechanism and tying it up to domething to keep it totally open.
Click to expand...
Yep, the J tube is a BEAR to get out!! I could not remove the choke with it in there. I used heat on the carb to get it out...

Before I removed the choke completely, I just turned the electric choke housing until the choke was always open. Very easy.
Kent
 
1 - 18 of 18 Posts
About this Discussion
17 Replies
7 Participants
Last post:
Mudball
Powerboat Forums at SpeedWake
posts
921K
members
19K
Since
2002
A forum community dedicated to Powerboat owners and enthusiasts. Come join the discussion about performance, modifications, classifieds, troubleshooting, maintenance, and more!
Full Forum Listing
Explore Our Forums
General Boating Discussions Powerquest News Articles