Why can a marine carburetor not be used on a street application?

Would it lead to the end of the world? To be serious now. The reason I ask is because Holley has the carburetor (850 CFM FOUR BARREL CARBURETOR PART #: 0-80443) with the exact features I want for the next carburator for my 72 GS 350. These features are

• Mechanical secondaries
• Automatic electric choke
• Dual fuel inlets
• 30cc primary pump
• 50cc secondary pump
• 5 airhorn.

Why cannot I it use it? Holley's warning could not be clearer: Marine Carburetors should never be used on street applications.

I really want this carb. If I cannot use it then why? I really want to understand the reasoning behind this warning!

 

Call Holley tech service @ 270 781-9741 and ask them! Let us know too....
John

 

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It has a manual choke.

---------- Post added at 06:54 PM ---------- Previous post was at 06:53 PM ----------

Biased source.

 

Get a manual choke Holley and convert it.

http://www.summitracing.com/parts/hly-45-224/overview/

---------- Post added at 08:10 PM ---------- Previous post was at 08:01 PM ----------

See if Ken G. still has my old Holley 850 DP for sale. That plus the conversion kit would put you way under the marine carburetor.

 

Durability and simplicity are of greater importance in the marine operating environment. That is a plus. Most of this source is why a nonmarine carb should not go in a boat, Does get a little closer as why not to put a marine carb in a car.

 

I think the only reason Holley says that is for liability reasons. The same as where they say a muffler or exhaust system is for "off road use only" so that they are not liable for people using a noisy exhaust on the street. There are EPA rules in each state as far as what is legal for aftermarket car parts. That is why they say 50 state legal for all the street carbs and the marine carbs obviously do not have to fit in the EPA guidelines. Most likely it is just jetted differently than the street carbs.

That being said I would be surprised if you could get better than about 12 MPG on the highway with the Holley carb.... I think with a well built Q jet you should be able to get 18-22 MPG on the highway. If you do not care about the fuel mileage then go with the Holley.

 

My thought exactly. The car is not a daily driver. We just take it out for fun. So not too worried about has mileage. I stumbled across this carb and thought "with a little out of the box thinking" this might be what I was looking for.

 

Get a properly sized and calibrated Q-Jet and never look back. If you use a Holley or an Edelbrock, you'll have to go through the whole gamut of tuning (I have experience with the E-Brock, its pretty simple, like the old Carters. You can rely on answers from people who don't have the engineering experience...or not.

 

I have to ask...

Do you even understand how a carb works?

Im not trying to be a jerk, and I respect your opinion, but I just don't get the Q-jet mind set.

Is it a misunderstanding of spread-bore vis--vis square-bore carbs?

Do you think %25 smaller primaries= %25 better MPG? (FYI %25 smaller primaries= %25 more throttle to do the same work, all the engine knows is how many CFMs its getting):Smarty:

Ive NEVER lost MPG by ditching a Q-jet, and usually gained MPG by going with a correctly sized and tuned Holley.

If you don't know how to tune a Holley carb then say so, but treating the Q-jet as a magic bullet is foolish.

You know exactly for a stone-cold-fact what it takes to have a Q-jet run right, and so do I.

That's why I NEVER recommend them to anyone.

Because not everyone wants to spend who knows how long looking for the ''correct'' core, then pray to GOD its rebuildable, then mail it to a guru to get it to run right, then if you ever change your setup, it wont be right anymore and you have to start over again...

I currently own dozens of Q-jets and have rebuild more than I can count, that's why I cant bring myself to recommend themou:

 

I think a Q-Jet can be a magic bullet for street cars where the tune will stay the same for a while. At least they have been for me. I will say Holleys are VERY easy to tune and are great carburetors. If your combo changes more than occasionally then the Hollley is the way to go. Can you imagine doing jet and rod changes on a Q-Jet at the track or on the dyno? No thanks! Each piece has their application.:3gears:

 

Qjets rock!
Get a Holley if you like staying under the hood

 

Build it, tune it, forget it: Quadrajet. Ideal if you want fuel economy and performance for a regularly driven and enjoyed Buick street engine.

Buy it, tune it, tune it, tune it, ...tune it... : Holley. Ideal if you're changing your setup regularly because the carb won't tune properly to your setup.

As far as gas mileage goes, smaller primaries tend to give better economy because of fluctuating throttle positions during street driving conditions, along with improved fuel/air charge delivery at lower RPM's and partial throttle. There is no magic, it's all science.

If the size of the barrel didn't matter, why does anyone make multiple barrel carbs? Why not just make it one huge barrel? Surely you could just touch the pedal slightly and get just as good of mileage as a Q-jet at partial throttle...

They both have their place in the market.

 

Funny:laugh:

More like, if your 40+ year old car dosnt still have its original carb if good rebuildable condition...

Buy one, buy one, buy one, buy one, buy one, finally find one that is still rebuildable.

Like I said, if you cant tune a carb then say so...

And if you cant tune a Holley, that's all the more reason to NOT buy a Q-jet.

Why would you want the hardest to tune carb everou:

That's just silly.

And a misunderstanding of how a carb works.

Like I said, I know for a fact a Holley can and will beat a Q-jet for MPG.

But I had to spend about a day test&tuning to get there.

If all you do is toss an out-of-the-box 850-DP on a stock 350...



I used to love Q-jets, that's why I have so many.

But I got fed up with trying to keep 40+ year old carbs working right and pretending nothing was wrong.

They are old, worn out and rebuildable ones are harder to find every year.

That's why I wont advise anyone to buy one without telling them what they are going to face.

I can go right now and buy a brand-new Holley at a parts store.

Can you say the same about a Q-jet?

 

That is what I thought I just did not want to say it.

 

Takes me 15 mins once a year to tune a qjet.
I will pay $2.00 for every qjet you have seriously do you have a couple 76 cores?

 

Back to the original question. I have a lot of experience with ski boats using 351 Fords. The boats must idle at 500 rpm in gear, and have a very smooth and instant acceleration curve. Then they have to be very steady at any pull rpm, 1300 to 3600 rpm. For barefoot skiing they will have to go to over 4000 rpm. Usually they top out at 4500 to 4800 rpm. The most common carb was a Holley 650 marine. That carb sucked. Serious skiers usually put a 750 DP on their boats. I knew a professional skier that got new boats every year and had a carb that he put on every boat. Never saw anything special about the marine carbs. 850 must have come off of a big block of some kind. I would not go out of my way to get a marine carb.