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coors909

  • Karma: +6/-0
454 carb question
« on: January 21, 2014, 02:36:18 pm »
I have 18ft Tahiti with a 454 that has a comp cam and some internal work done to it from what my friends dad told me he sole it to me. it also has a 12jc berley on it I'm pretty sure.  I have a edlebrock performer I want to know which carb should I get for it?  I was thinking a 750 edlebrock or 850 holley?
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jyeager

  • Karma: +62/-0
Re: 454 carb question
« Reply #1 on: January 21, 2014, 03:08:13 pm »
I have 18ft Tahiti with a 454 that has a comp cam and some internal work done to it from what my friends dad told me he sole it to me. it also has a 12jc berley on it I'm pretty sure.  I have a edlebrock performer I want to know which carb should I get for it?  I was thinking a 750 edlebrock or 850 holley?

Holley hands down! Ive never been a fan of edlebrock carbs. i would put a 850 on it. My 30 over ford had a 750 on it. Put the 850 on her and really woke it up.  :thumbup: :thumbup:
  • Boat #1: Southwind Tunnel Dragster 19
  • Boat #2: DiMarco18 V-Bottom
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GoinBrokeBahner

  • Karma: +6/-0
Re: 454 carb question
« Reply #2 on: January 21, 2014, 03:24:51 pm »
I have a stock 454, it came with a holley 750 vac sec... That carb wasn't working well and someone suggested I get an 800 dbl pumper. I put that on and it ran started and ran much better but not so much with my foot in it. I just got done working with a local engine builder on some machine work and explained to him my carb issues and he said I would be dialed with a holley 650 dbl pumper. I'll be seeing him again tomorrow to possibly trade both my carbs for one of his 650's... If that doesn't work out I'll have the 800 on here for sale by the end of the week, freshly rebuilt. If your interested look into the 800 specs and let me know...


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coors909

  • Karma: +6/-0
Re: 454 carb question
« Reply #3 on: January 21, 2014, 03:29:47 pm »
I have a stock 454, it came with a holley 750 vac sec... That carb wasn't working well and someone suggested I get an 800 dbl pumper. I put that on and it ran started and ran much better but not so much with my foot in it. I just got done working with a local engine builder on some machine work and explained to him my carb issues and he said I would be dialed with a holley 650 dbl pumper. I'll be seeing him again tomorrow to possibly trade both my carbs for one of his 650's... If that doesn't work out I'll have the 800 on here for sale by the end of the week, freshly rebuilt. If your interested look into the 800 specs and let me know...


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I thought a 650 double was to small for a 454?
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ka0tyk

  • Karma: +30/-0
Re: 454 carb question
« Reply #4 on: January 21, 2014, 03:49:49 pm »
I thought a 650 double was to small for a 454?

im running a demon 650 here with vac secondaries.  relatively stock/mild 454. 


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ka0tyk

  • Karma: +30/-0
Re: 454 carb question
« Reply #5 on: January 21, 2014, 03:54:48 pm »
I have a stock 454, it came with a holley 750 vac sec... That carb wasn't working well and someone suggested I get an 800 dbl pumper. I put that on and it ran started and ran much better but not so much with my foot in it. I just got done working with a local engine builder on some machine work and explained to him my carb issues and he said I would be dialed with a holley 650 dbl pumper. I'll be seeing him again tomorrow to possibly trade both my carbs for one of his 650's... If that doesn't work out I'll have the 800 on here for sale by the end of the week, freshly rebuilt. If your interested look into the 800 specs and let me know...


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theres no reason either of those carbs didnt work out.  stop throwing parts at it, and just get the carb tuned by a shop that knows what they're doing.
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GoinBrokeBahner

  • Karma: +6/-0
Re: 454 carb question
« Reply #6 on: January 21, 2014, 03:58:06 pm »

I thought a 650 double was to small for a 454?
Me too!! I can say that I've seen boats at the lake and up for sale w/ 454's and 460's running Holley 650's. I was told that for my all stock setup I need the smaller ports. I know very little about this stuff but I've seen both this engine builders boats run and they RUN!


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GoinBrokeBahner

  • Karma: +6/-0
Re: 454 carb question
« Reply #7 on: January 21, 2014, 04:14:49 pm »

theres no reason either of those carbs didnt work out.  stop throwing parts at it, and just get the carb tuned by a shop that knows what they're doing.

The original carb, 750 w/ vac secondaries, has a worn out throttle plate and leaked all down my intake manifold. Also, I never truly found out how to hook up secondaries properly. I ran into a retired NHRA engine/carb tuning guru on the water and he said my carb was junk and I should run the 800 dbl pumper. I found the 800 freshly rebuilt online for a good price and bought it. Immediately the boat started and ran better! The only thing I noticed was it was actually less responsive in the higher rpm's. I pulled my logs to be machined and noticed color change in different ports. I then pulled plugs and took everything to engine guy. He suggested more appropriate plugs that don't burn so hot and said that a 650 carb would make that motor twist bitchin because right now I'm dumping more air and fuel into a stock, low pro intake manifold than it needs. He said I can at with jetting all I want but really need smaller ports coming out of the bottom of the carb into manifold.

Sorry if this is too dumb sounding, it's all new to me! I think I've found a good engine guy, I've seen his work and I've seen his personal toys run.


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GoinBrokeBahner

  • Karma: +6/-0
Re: 454 carb question
« Reply #8 on: January 21, 2014, 04:48:59 pm »

im running a demon 650 here with vac secondaries.  relatively stock/mild 454. 


Just for future knowledge can you please tell me how you hook the secondaries up? I still have that Holley 750 vac secondaries that I may buy a throttle plate for and use in the future, maybe another boat.... I was getting away with a small machine screw in the slot where the arm moves back and forth as the primaries are opening to twist the secondaries open. Totally rigged!! Haha

Thank you!


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Six-Oh-Nine

  • Karma: +28/-0
Re: 454 carb question
« Reply #9 on: January 21, 2014, 09:35:25 pm »
750 Holley DP will get it done... 850 DP will not hurt it, and may get you a little better cruise gas mileage.


« Last Edit: January 21, 2014, 09:47:25 pm by Six-Oh-Nine »
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The Bostick ®

Some people play hard to get, I play hard to want.

Jet Boat Maloney

  • Karma: +9/-0
Re: 454 carb question
« Reply #10 on: January 21, 2014, 09:41:10 pm »
That 750 wasn't made to run with a screw in throttle shaft. Get a 850 and be more than happy with it. IMO


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rush1

  • Karma: +18/-0
Re: 454 carb question
« Reply #11 on: January 21, 2014, 10:29:43 pm »
The reason he says go with the smaller carb is because it speeds up the air moving through the carb for better throttle response if your running the stock intake he's right , I'm sure you've got oval port heads if you put on a high rise intake that 750 vacuum secondary will run like a champ plus you can keep your foot out of it and conserve a little fuel that 850 mechanical secondary will slow the air down to much and bog the motor it will only work at high rpm's but your not making enough hp to spin the motor up to high enough rpm's  for that carb to work 

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Squirrel Master

  • Karma: +7/-0
Re: 454 carb question
« Reply #12 on: January 22, 2014, 03:25:15 am »
im running a demon 650 here with vac secondaries.  relatively stock/mild 454. 




nice ka0tyk you are doing a fine job on that boat, BUT isn't this a jet boat forum ijs  >:D
  • Boat #1: 1976 Sleekcraft Kauia
  • Boat #2: 1979 Tahiti Super Tiger
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"most important... WHEN IN DOUBT, THROTTLE OUT!!!"  Crewchief22

GoinBrokeBahner

  • Karma: +6/-0
Re: 454 carb question
« Reply #13 on: January 22, 2014, 05:16:58 am »

The reason he says go with the smaller carb is because it speeds up the air moving through the carb for better throttle response if your running the stock intake he's right , I'm sure you've got oval port heads if you put on a high rise intake that 750 vacuum secondary will run like a champ plus you can keep your foot out of it and conserve a little fuel that 850 mechanical secondary will slow the air down to much and bog the motor it will only work at high rpm's but your not making enough hp to spin the motor up to high enough rpm's  for that carb to work 

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Thanks. That's really clarifies what I was thinking that I've been told about these carbs. I started out listening to the wrong people this last season when I bought this boat and learned a few things the hard way. This is why, stupid or not, I'm asking most my questions on this site and am happy to have found a local mech that I believe I can trust.


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rush1

  • Karma: +18/-0
Re: 454 carb question
« Reply #14 on: January 22, 2014, 06:10:48 am »
Yeah this site is great ,people don't judge they just give you a hand.

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ka0tyk

  • Karma: +30/-0
Re: 454 carb question
« Reply #15 on: January 22, 2014, 08:21:40 am »

nice ka0tyk you are doing a fine job on that boat, BUT isn't this a jet boat forum ijs  >:D

I had the same motor in my 18 Tahiti with a jet.  Heh.  Don't hate me because my boat has a big black thing hanging off the back!
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RockyCapone

  • Karma: +0/-0
Re: 454 carb question
« Reply #16 on: January 22, 2014, 09:55:32 am »
750 Demon w mech secondaries. Love this carb.
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1978 Southwind Formula 1 T body
454 Berkley
IF I GET BORED AND HAVE NOTHING TO DO I'M CALLING GTJETS AND ASKING HIM IF I SHOULD RUN A T-STAT IN MY JETBOAT--THAT SHOULD BURN OFF 8 HOURS EASY
....it would have been cheaper to spend our money on cocaine and hookers

Jet Boat Maloney

  • Karma: +9/-0
Re: 454 carb question
« Reply #17 on: January 22, 2014, 10:50:56 am »

I had the same motor in my 18 Tahiti with a jet.  Heh.  Don't hate me because my boat has a big black thing hanging off the back!
Nobody's hating.  You  just drive on the wrong side. But you sure do some nice work!!!


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coors909

  • Karma: +6/-0
Re: 454 carb question
« Reply #18 on: January 23, 2014, 01:14:00 pm »
So im thinking I might go with the marine 850 holley.  are the marine carbs a good idea?
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74hondo

  • Karma: +8/-0
Re: 454 carb question
« Reply #19 on: January 23, 2014, 02:22:25 pm »
Short answer is yes, go  with the marine version  if you can

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ka0tyk

  • Karma: +30/-0
Re: 454 carb question
« Reply #20 on: January 23, 2014, 02:27:41 pm »
So im thinking I might go with the marine 850 holley.  are the marine carbs a good idea?

the differences between an auto and marine carb are the shafts are sealed, and the vent tubes on top from the bowls are turned downwards (called j tubes) to direct the vapors down into the carb rather than open.  this minimizes the chance of a fire when an engine is covered by a hatch in a boat. 

if it were up to me i would get a marine carb, mechanical secondaries, and no choke/choke horn. 

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GoinBrokeBahner

  • Karma: +6/-0
Re: 454 carb question
« Reply #21 on: January 24, 2014, 06:58:54 am »

theres no reason either of those carbs didnt work out.  stop throwing parts at it, and just get the carb tuned by a shop that knows what they're doing.
Well my mechanic and you seem to be on the same page... I took him my carbs and he said the 800 dbl pumper marine carb I have is a good one and I already have money in it so he wants to launch with me and see what we can do to tune it up. After I install the pan he just sold me I'll be taking him up on that.


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ka0tyk

  • Karma: +30/-0
Re: 454 carb question
« Reply #22 on: January 24, 2014, 10:24:14 am »
Well my mechanic and you seem to be on the same page... I took him my carbs and he said the 800 dbl pumper marine carb I have is a good one and I already have money in it so he wants to launch with me and see what we can do to tune it up. After I install the pan he just sold me I'll be taking him up on that.


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yeah i just bring a jetting plate, a couple tools to drop the bowls and metering blocks, a towel or two to catch the fuel, and a spark plug socket/wrench to check the plugs to see how she's running with the changes.  now is a good time to check the timing on the motor too.  and a few beers for when you're done.  :beer:
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GoinBrokeBahner

  • Karma: +6/-0
Re: 454 carb question
« Reply #23 on: January 24, 2014, 10:38:40 am »

yeah i just bring a jetting plate, a couple tools to drop the bowls and metering blocks, a towel or two to catch the fuel, and a spark plug socket/wrench to check the plugs to see how she's running with the changes.  now is a good time to check the timing on the motor too.  and a few beers for when you're done.  :beer:
Cool, thanks! Beer and a crescent wrench!! Hahaha

Another thing I want to do is build two small interior boxes to hold speakers and cup holders up next to front seats... Can you tell me what type of ply wood would be best? I have a small amount of sanded oak laying around but thought it wasn't necessary, also some OSB but thinking that's too cheap....


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