SoCal Jet Boats
Tech Talk => Engine Mechanical / Electrical => Topic started by: Legal Chemistry on December 12, 2007, 06:22:25 PM
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I'll open up a new thread (yeah, I jacked the other one.)
Question for you folks... I'm ditching my Q-jet and bought a Holley 800dp (4150, 9022). I'm a newb on this so bear with me. To make this change I'll need the spreed bore/square bore adapter, new gasket, and fuel log. Anything else? What about the carb spacers... any advantage to these? Holley says this should work out of the box, is this true? Any tuning needed? If it needs tuning what really needs to be done except adjusting idle? Any takers to help a brotha out O0???? Free beer and stripers (well the beer at least.)
Thanks!
beerjet, thanks for the feedback.
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I'll open up a new thread (yeah, I jacked the other one.)
Question for you folks... I'm ditching my Q-jet and bought a Holley 800dp (4150, 9022). I'm a newb on this so bear with me. To make this change I'll need the spreed bore/square bore adapter, new gasket, and fuel log. Anything else? What about the carb spacers... any advantage to these? Holley says this should work out of the box, is this true? Any tuning needed? If it needs tuning what really needs to be done except adjusting idle? Any takers to help a brotha out O0???? Free beer and stripers (well the beer at least.)
Thanks!
beerjet, thanks for the feedback.
Where do you take it out to tune it?
OK, this is what will probably happen when you put it on. When you goose it with a Jet, you probably will have a hesitation / bog for a second. This is becuase a jet boat needs very little acc pump, but most carbs DP's are designed to hit some kind of limiter (IE the torque convertor or prop). No big deal if you have this happen (try it first, it may already have a mellow pump cam) just get an Acc pump tuning kit and put in the pink cam to the primaries, and the green in the secondaries and see where that gets you.
You will need more acc pump the higher the carb sits. Open spacers will help top end, 4 hole will help the bottom end.
What manifold are you using?
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Where do you take it out to tune it?
OK, this is what will probably happen when you put it on. When you goose it with a Jet, you probably will have a hesitation / bog for a second. This is becuase a jet boat needs very little acc pump, but most carbs DP's are designed to hit some kind of limiter (IE the torque convertor or prop). No big deal if you have this happen (try it first, it may already have a mellow pump cam) just get an Acc pump tuning kit and put in the pink cam to the primaries, and the green in the secondaries and see where that gets you.
Thanks for this bit of info. Mine kinda has a bog from idle to WOT...always thought it was from not enough acc. pump. But it makes more sense that it would be too much pump, which ends up flooding the motor for a second...since the "limiter" on a jet boat is the pump itself reaching max RPM, unlike a torque converter or a prop which unloads as the boat gains forward speed. Now I know where to go when I start playin' with my carb this spring.
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The acc pump covers up the fact the engine can't rev to WOT potential and the fuel takes a while to get flowing from the mains. With the engine effectively unloaded due to the jet's design, the pump shot can rev the engine quite high, high enough to pull on the pri/sec mains almost immediately.
In a car, the lower the stall, the bigger the pump shot for a given carb. My 12 second van with 1800 stall, needs a decent size pump and squirter in the primaries, and a HUGE shot in the secondaries so it doesn't bog off the line.
My 9 second duster with a 4500 stall has about 1/2 the pump shot volume the van needs.
The single carb I have setup for my jet, has the smallest cam available, backed off a bit on the adjustment, with a std size 31 squirter.
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I believe it is the Edelbrock Performer. I'll probably go to San V or El Cap to test it out (east San Diego.)
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It probably goes without sayin but I'm going to anyway, thats the same carb I put on first of the year, the only issue I had was the chock fell shut. When you open it manually it feels like it takes enougph force to open I didn't expect it to fall shut with the motor runnin.(but it did instantly) There's probably a better way, but I just took the butterfly completly off.
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Speedy, out of curiosity, since on a jet the motor can rev to max RPM at WOT and pull on the pri/sec mains almost immediately, would it be a good idea also to increase the squirter size to shorten the duration of the pump shot?
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If you do that, you decrease the pump duration, but the CC's stay the same. With an aggressive initial shot, the engine will rev quicker, however too much will bog it too. You have to find that balance between enough fuel and too much.
If it sputters then goes - squirter size
If it goes, sputters, then goes again - pump shot.
Normally with a car, you start small and work your way up from the stock settings.
With a Jet, Start at stock and work your way down. If a problem appears or engine acceleration gets worse, only then start going up. Most jets are not going to have a problem of not enough pump shot. YMMV
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If you guys start to tune your carbs, I'm here to help you out. Most of the time, if you have a carb that is unknown, take the time to find the list number, go to Holley's site, and find out what parts your carb originally came with. Make sure you are starting from there, if things get too far from stock, it can seem like you are getting nowhere.
http://www.jason.fletcher.net/tech/carbtuning/carbtuning.htm
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:o Speedy !! A Blue Oval site ??? Are you starting to see the light >:D
jk ;D thanks for the link, cool info.
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:o Speedy !! A Blue Oval site ??? Are you starting to see the light >:D
jk ;D thanks for the link, cool info.
Don't get your hopes up...
Then again, I'm starting to realize why you run dial-up. After all, it takes a lot of cash to keep that BBF runnin'! ;D ;D
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Don't get your hopes up...
Then again, I'm starting to realize why you run dial-up. After all, it takes a lot of cash to keep that BBF runnin'! ;D ;D
Shut up Jetaholic !!! Grown-ups are talking !!! [attachimg=1]
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Shut up Jetaholic !!! Grown-ups are talking !!! (Attachment Link)
Can't handle the fact that it takes a real man to wear a bowtie? What a bitch!!! O0
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Can't handle the fact that it takes a real man to wear a bowtie? What a bitch!!! O0
?? Did you forget who your talking to ??
http://www.socaljetboats.com/index.php/topic,1946.0.html
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Oh shit...you just reminded me...
The guy running the piece of shit smog motor that didn't have enough horsepower to take what the oil pump was throwing at it...thus breaking the oil pump in half and costing that smogger its life. ;D ;D
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:o Speedy !! A Blue Oval site ??? Are you starting to see the light >:D
jk ;D thanks for the link, cool info.
heh heh - if you only knew.... it's the other way around....
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I believe it is the Edelbrock Performer. I'll probably go to San V or El Cap to test it out (east San Diego.)
Want to pull it north to elsinore?
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It probably goes without sayin but I'm going to anyway, thats the same carb I put on first of the year, the only issue I had was the chock fell shut. When you open it manually it feels like it takes enougph force to open I didn't expect it to fall shut with the motor runnin.(but it did instantly) There's probably a better way, but I just took the butterfly completly off.
A jet really doesn't need a choke, esp if you have a hand throttle.
There is an adjustment for the mixture on the side (on electrics you loosen and turn the entire black canister), as well as an idle screw for the choke (bottom access 5/16 screw, only visible at WOT when mounted with electric choke). If you leave the choke on a carb, play with the mixture setting, but back off the idle speed. No one needs to be idling at 1700 rpm at the docks waiting for the choke to come off.
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Want to pull it north to elsinore?
Sure... the swampland is only 45 minutes or so from my house. I'm still waiting for the carb and fuel lines in the mail, hopefully they'll go on this week. As for the choke, I didn't run the choke on the the Q-jet -never really needed it, and probably won't with the Holley.
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His carb, if it's like mine is a manual. and when you opened it it gave me the "fantasy" it wasn't goin no where. I was wrong :-[
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On manual chokes, if you don't want to physically remove it, you can put a piece of coathanger / wire in the cable slot and have it wired (locked) open.
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Finally in. Ain't she purdy ;D Just waiting for the fuel lines....
(https://www.socaljetboats.com/cpg/albums/userpics/10520/IMG_7964.jpg)
(https://www.socaljetboats.com/cpg/albums/userpics/10520/normal_IMG_7965.jpg)
since 1903
(https://www.socaljetboats.com/cpg/albums/userpics/10520/normal_IMG_7966.jpg)
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What's the number on that carb?
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... bought a Holley 800dp (4150, 9022)...
::)
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Opps.. Sorry about that. I must have just scanned over that and it didn't sink in. :-\
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Legal ,just nosey , about what did that new Holley set you back if its OK to ask ? Tom
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under 3 bills ;D ;D ;D
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under 3 bills ;D ;D ;D
Then, want one too!! :D
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hmmm, direct from Holley for under $300... that ain't bad.
why would you say that's cheesy? got somethin' better in mind?