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Carburetor issue

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docmorg

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"I am new to boats and just bo

"I am new to boats and just bought a 1995 Reinell with the 5.0 mercruiser and aplha one. I took it out last week and noticed that it did not have much power. It ran and sounded alright, but could not get it much past 30 MPH at full throttle. I took it home and thought it was a throttle cable issue. With the engine off, I noticed that I was getting full throttle, however; the small throttle plate was not opening until about 2/3 throttle. Also, when the throttle was wide open, the small throttle plate was only open about 1/3 at most. The rear large throttle plate was not moving at all.

Forgive my ignorance if my terminology is off. I am by no means knowledgeable with carburetors. I believe this is wrong, but am not sure. Does this sound right, if not can it be adjusted easily?

Thanks,
Steve"
 
It sounds like you have not en

It sounds like you have not enough throttle cable travel

Is there any adjustment on the throttle bellcrank arm on the carb whereby you can get more throttle action with the cable travel that you have?
Years ago I had to modify my old 898 in just this fashion so as to get full throttle.

There may be a series of holes on the throttle arm of your throttle quadrant. If so you can move the cable connector farther out to get more travel.

Rod
 
"Thanks Rod,

I took another

"Thanks Rod,

I took another look after reading your post. It appears that when I am full throttle, the throttle bell crank stop is hitting the stop plate. I think that someone has rebuilt the carburetor and possibly reassemble wrong. The rod assembly that opens the main plate to allow air in is not being activated at all when put in full throtte mode. I think I am going to have someone take a quick look at all the linkage to make sure it is assembled properly.

Thanks for the info, I am going to tinker with it some more.

Steve"
 
If its a Quadrajet there is a

If its a Quadrajet there is a belllcrank and peg affair that opens the secondaries quickly once the primaries are about 2/3 open. This mechanism is easy to watch and see if its working properly while someone opens the throttle slowly.
Its on the outside of the carb body on the other side of the carb from where the cable hooks up.

Rod
 
"Thanks Rod,

Does this need

"Thanks Rod,

Does this need to be checked while the engine is running?

I have done that with the engine off and the throttle valve (air valve) near the front of the carb only opens 1/3. The rear air valve never moves even at full throttle. I have received info that I might have a linkage problem. I think that the previous owner might have taken the carb apart and not assembled the linkage correctly.

When I manually push the vacuum linkage all the way in on the other side, it does move the bellcrank, but does not activate and open the valve."
 
"Something sure sounds wrong.

"Something sure sounds wrong.
You may have to get your hands on a detailed blowup parts drawing to troubleshoot it. You may be better off to buy a rebuilt carb. Then it is someone else's problem.

Carbs are something that a lot of shade tree mechanics, myself included, likely should not touch. They are fiddely and easy to mess up. My first Quadrajets were on a Firebird 400 4 speed and a 396 Chevelle some 40 years ago. That was when I was young and had lots of patience. Then along came the HOlley spreadbore carb. Direct replacement for the Q'jet but much easier to work on and trick up.

It was fun messing with trick metering rods, quick opening linkages and air valves, CDI ignitions, and lighter advance springs and weights. Man did those cars make power! Gas and tires were a lot cheaper in those days!
Enough rambling.

Rod"
 
"Steve
I kind of came in here

"Steve
I kind of came in here late. The upper secondary plates are opened by air pressure on the quadra jet. The lower secondary throttle plates are opened manually by the linkage. When the lower throttle plates are opening the air pressure begins to enter into the secondaries thus feeding the rear two. The upper plates are held closed by a spring on the outside of the carb body on the shaft. This gives a smooth transition to the secondaries coming on and not a hard hit. When the throttle is wide open, both primary and secondary lower throttle plates should be vertical in the bore.
Bert"
 
"Just hold the upper secondary

"Just hold the upper secondary air valves open to see down to lower throttle to verify secondary (rear) operation. Asuming you have mechanical secondaries. Also for primaries (front), are you speaking of the choke plate above primary throttle plates? just want to be clear.

Kurt"
 
Steve;
Check out fig 72 of Jo

Steve;
Check out fig 72 of Joe's manual attachment.
It shows what the secondary throtle plate linkage looks like.
Kurt and Bert are correct; you have to hold the upper secondary air valve open to see down to the bottom to see what the throttle butterfly is doing.
The upper air valve will not open without the engine running and air flow past it.
Rod
 
"Rod, Kurt, Bert,

Thanks fo

"Rod, Kurt, Bert,

Thanks for info. I am going to play with it this afternoon and will get back with you."
 
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