Intake choice

[ericcarr]

Ok…I finally got an engine to drop in my 1990 sundancer. I’m looking at changing the intake from the stock one to a different one…the one that WAS on it, I already pulled it off of it yo inspect some internals & get the casting numbers off of the heads. The intake tgat was on it had just the standard quadrajet 4 barrel carb with what looks like some sort of a choke rid that goes down into the intake. Anyone have any clue to what that is called & some insight to a good choice for an intake manifold?
Casting numbers on the heads are pictured.

 

[achris]

That style of choke is called 'heat stove', and I'd convert it to an electric choke.

As for intake, stay with a dual plane.

Chris...

 

[Lou C]

I have the well type choke on mine and as long as the spring is in good shape (you can get them and many other Quadrajet parts from Cliff's High Performance Q-Jets and Quadrajetparts.com) and the exhaust crossover passage is not clogged with carbon they can work OK. They open slower than an electric choke but they follow engine temp, not the timer on the electric heating element. The electric choke needs a constant 12V at the heater element to stay open. Sometimes you can have problems with them, if you have a bad electrical connection. There is a conversion kit to convert to electric, (carburatorparts.com) that I have but never actually installed. I think they work well as long as you have a good power source.

 

[ericcarr]

That style of choke is called 'heat stove', and I'd convert it to an electric choke.

As for intake, stay with a dual plane.

Chris...

Could I just go with any type of dual plane or does it have to be a marine manifold?

 

[Scott Danforth]

Are heads stock 1990? Or other?

Yes on the marine manifold.

 

[ericcarr]

Are heads stock 1990? Or other?

Yes on the marine manifold.

I’m not sure of the heads, I picked this motor up from a guy who was going to put it in his amberjack. If I’m not mistaken according to the numbers off of the heads these are up to an 85 GEN four

 

[ericcarr]

Will I have to switch carbs?

 

[Scott Danforth]

Perimeter bolt is 85 and older
What is full casting number?
Do you have the correct intake that matches the heads?

 

[ericcarr]

When I look up the casting numbers, 336781, it says 73-85

 

[Lou C]

Not sure that’s a marine QJet because I don’t see the nipple for the mechanical overflow hose. If you use a mechanical fuel pump that safety feature should be included; in case the diaphragm leaks. If you use the old manifold make sure that it’s not rotted out under the thermostat housing; that will put water right into the cam valley & into the motor oil.

 

[Scott Danforth]

336781.....73-85...oval...OPEN...454, 118cc chamber, 256/114cc ports

its a BBC not an SBC like I thought.

Perimeter bolts are all that was available on BBC

these are some of the better open chamber heads from back then. 2.06/1.72 valves. I would do a bowl blend and casting flash removal on the heads which allows the heads to breath a whole lot more (making more power)

hope the motor is 1978 and later and the heads have hardened seats (yes, GM changed in 75, however some boats built up to 78 had old stock)

its a generic Mark 4 motor - depending on the pistons that are in there, it can have a compression ratio of between 7.4:1 to 9.4:1

 

[achris]

Not sure that’s a marine QJet because I don’t see the nipple for the mechanical overflow hose. If you use a mechanical fuel pump that safety feature should be included; in case the diaphragm leaks. ....

Not all the marine fuel pumps have a sight tube, and hence a fitting in the carb for said tube. Some fuel pumps used a dual diaphram, so didn't need a tube to the carb. It appears as if Eric's is one such...

Chris.......

 

[ericcarr]

So do you guys suggest I just rebuild the carburetor and reuse the intake?

 

[Scott Danforth]

So do you guys suggest I just rebuild the carburetor and reuse the intake?

pretty much. unless you intend to pull the motor apart and go thru it.

did you do a compression test on the motor before buying it?

 

[Lou C]

take a look at Cliff's high performance q-jet site, his rebuild kits are very nice plus he has the better accel pumps, and other better quality parts. Fast shipping and good customer service. Quadrajetparts.com is also good for whatever you can't get from Cliff's.
A clean and properly rebuilt Q-jet will work great on that engine.
Just make sure that the water passage in the intake isn't rotted and the mating surfaces are flat & level.

 

[ericcarr]

pretty much. unless you intend to pull the motor apart and go thru it.

did you do a compression test on the motor before buying it?

I didn’t but I was told it was rebuilt 10 hours ago by his Marina mechanic….i did put my bore scope in the spark plug holes to see if what he told me that it was bored .30 over was true or not & all 8 pistons had the 0.30 stamped on top & the cylinders did still have the cross hatches on the cylinder walls..

 

[ericcarr]

take a look at Cliff's high performance q-jet site, his rebuild kits are very nice plus he has the better accel pumps, and other better quality parts. Fast shipping and good customer service. Quadrajetparts.com is also good for whatever you can't get from Cliff's.
A clean and properly rebuilt Q-jet will work great on that engine.
Just make sure that the water passage in the intake isn't rotted and the mating surfaces are flat & level.

What’s his site?

 

[ericcarr]

pretty much. unless you intend to pull the motor apart and go thru it.

did you do a compression test on the motor before buying it?

Also, is it ok to bypass that stove choke opening on the intake or will it have a vacuum leak or anything like that?

 

[todhunter]

What’s his site?

Cliffs High Performance Quadrajets – Quadrajet Rebuild Kits, Cabruretor Parts, Quadrajet Rebuilding, Quadrajet Parts, Bushing Kits, Carb Tuning

I just rebuilt my qjet with his kit and his book. Runs really well.

 

[ericcarr]

Cliffs High Performance Quadrajets – Quadrajet Rebuild Kits, Cabruretor Parts, Quadrajet Rebuilding, Quadrajet Parts, Bushing Kits, Carb Tuning

I just rebuilt my qjet with his kit and his book. Runs really well.

Where do I find the numbers on the carb to order the right kit?