VP 4.3 GL conversion to Holley Sniper 2 efi

[Donald0039]

Send it out to be rebuilt. There is more to rebuilding than just slapping in a rebuild kit.

 

[Lou C]

Holley's website also has a pretty good forum where you can post up questions.
I too am a fan of carbed engines on older boats. EFI gets very expensive to repair and the OEMs have a lousy habit of leaving you high and dry with NLA parts. Whereas I can get any part I need for a Quadrajet that hasn't been made in over 30 years.

 

[stresspoint]

i was looking to go the sniper on my 4.3 , after lots of research "most mentioned above" it was filed in the too hard basket , the benefits are IMHO not worth the cost nor the effort to get it set up for marine application.

i ended up going with the 4bbl Rochester , it sips fuel when cruising and was easy to tune to suit my mods ,fwiw , i was going to go with a 4bbl 600 vac secondary holley as i was skeptical about getting a Rochester to work on a modded 4.3 engine . however, there was no room with my AM distributor so i also canned that idea..

any info you need on the Rochester you could reach out to Lou C, he is the man when it comes to those things on 4.3s , i am sure he wont mind ??? , he helped me a lot with my set up to get it rebuilt and set up ..

 

[Lou C]

With any carb rebuild the cleaning is about 90% of the job. It is not easy to get it 100% clean, but important to get it as close as you can. That and using high quality parts in the rebuild. On the 4.3 OMC & Volvo used Rochester 2bbls and 4bbls till Rochester quit making carbs, then switched over to Holley about 1990-1991 or so. The 4bbl works well for a 4.3, the Quadrajet has smaller primaries and the adjustable air doors for the secondary system which allows for the 4.3's smaller displacement. A 2bbl will work fine too but runs out of breath over about 4000 rpm.
The Holley 4160 will fit the 4.3, but it has to have the style with the fuel inlet on the side of the bowl not in front, or else it will interfere with the thermostat housing. I believe the 4150 style Holley might be too long to fit a 4.3. But an Edelbrock 1409 will also fit fine.
Holleys and Holley parts are very easy to find, as are Edelbrock. The issue with Quadrajets as much as I like them is finding a good core that has not been put together from several different carbs. I was lucky the one on my boat was an original marine Qjet, unmolested and in pretty good shape. The parts are out there because of the classic car aftermarket, they were used on nearly everything GM sold between 1966 and 1986 or so.

 

[Mi_fiveo]

Power valve requirement varies from motor to motor. I would run a 45 on the 4.3

Hey Scott, I took my carb apart and it has a 2.5 in it. The kit I bought has a 4.5. I’m going to try the 4.5 like you recommended, just wondering if you can explain what the difference is?

 

[Scott Danforth]

The 2.5 opens at 2.5 " of vacuum or below. The 4.5 opens at 4.5" and below.

As the PV opens the PVCR jets add fuel. About 6-7 jet sizes worth. The 4.3 will use that extra fuel just before WOT. The 3.0 won't need the extra fuel until WOT.

Running the 2.5 vs a 4.5 just richens up the mix slightly sooner.

It's just tuning

 

[Lou C]

OK Scott since we are talking 4.3s and Holleys, I got a riddle for you. When the Quad went out of production, Holley built a special spec 4160 for the 4.3 which does not have a power valve, as unusual as this seems. I know this for a fact because I tried one on my engine (still have it but preferred the Q Jet). Why was this done, and what are the pros/cons? I hear they made the main jets bigger to compensate for the lack of a PV. Thoughts? It is still sold on Holley's website.

 

[Lou C]

Holley 0-80492 600 CFM Marine Carburetor-Aluminum

All Holley Marine Carburetors are designed to meet Coast Guard specifications. A marine carburetors fuel metering system is calibrated to compensate for unique engine loads found on boats. The J-style vent tubes direct fuel/fumes back into the carburetor for safe operation while on rough...

www.holley.com

this one was used by OMC and Volvo on the 4.3:
always wondered about that, must be a reason for no power valve
perhaps with a 600 cfm carb the little 4.3 does not need the extra enrichment of the power valve
I also wondered why they didn't use the 450 cfm version on these, as they did on the Ford 5.0.
this one was used on the Ford 5.0:

Holley 0-80364 450 CFM Marine Carburetor

All Holley Marine Carburetors are designed to meet Coast Guard specifications. A marine carburetors fuel metering system is calibrated to compensate for unique engine loads found on boats. The J-style vent tubes direct fuel/fumes back into the carburetor for safe operation while on rough...

www.holley.com

 

[Scott Danforth]

The 4160 was originally an economy carb. I'm not a big fan personally

Some people like to block off the PV and increase jet sizes on the secondaries by 6 or 7 sizes. This is usually done by the quarter mile crowd. However you loose mid-range drivability.

You will notice that most of the VP Holley carbs do run a PV.

@Lou C , on your 4160 with the blocked PV, is it just a plug or the blocked metering block?

 

[Lou C]

The 4160 was originally an economy carb. I'm not a big fan personally

Some people like to block off the PV and increase jet sizes on the secondaries by 6 or 7 sizes. This is usually done by the quarter mile crowd. However you loose mid-range drivability.

You will notice that most of the VP Holley carbs do run a PV.

@Lou C , on your 4160 with the blocked PV, is it just a plug or the blocked metering block?

It's a blocked metering block, no way you could install a PV in it.
I would have thought that given the 4.3 only being 262 cu in, they would have used the 450 cfm unit, but I'm just guessing.

 

[Scott Danforth]

VP used 715/750 cfm on a 5.7, 650cfm on the 5.0 and 600 cfm carbs on the 4.3 and a 500cfm 2-barrel on a 3.0

They tend to over carb vs under carb

 

[Dillusion808]

Just throwing this out there but I have a Rochester on the way. See if I can get a little bit better mpg. If not oh well.

But I'm taking a Holley off once I get the Rochester in the mail. You can have it for free just pay shipping. I rebuilt it last year maybe has 100 hours since then.

The only thing I did not change was the floats. They were at the right position according to what I could see and I didn't order them with my rebuild kit so I left it.

 

[Scott Danforth]

Rochester hasn't made a carburetor since 1989.. Volvo Penta has t used a non-holley carb since 1988. So what did you buy?

If you want fuel economy, get a sail boat

 

[Dillusion808]

MARINE CARBURETOR 4 BARREL QUADRAJET 262 CID 4.3LX 1347-804623R02 ELECTRIC CHOKE

4 BARREL ROCHESTER QUADRAJET MARINE CARBURETOR 262 CID 4.3 LX V6 ENGINE Rochester 4 Barrel Quadrajet With ELECTRIC CHOKE For 6 Cylinder 262 CID 4.3 LX Mercury Marine Engine Applications. These carburetors where assembled using only the highest quality components, They feature: All new parts and...

www.marinecarburetors.com

Rebuilt who knows better than my Holley that has seen better days. Doesn't hurt to try.

Never said I wanted great fuel economy. If its .1 better I'll take it. If its the same I could care less.

 

[Mi_fiveo]

I’m finishing up on the carb rebuild. I ran it through an ultrasonic cleaner and chased all the passages with carb cleaner and then fishing line. The choke was adjusted all the way to the right when I took it apart. According to that chart it is supposed to be 5 notches lean. Should I leave it where it was or adjust it? Is 5 notches lean counting from the left or the right side?

 

[Dillusion808]

I would adjust by where you live and not just stick to the notches.

Mine is somewhere in the middle. I live in Hawaii so I don't have crazy weather swings to deal with.

 

[Scott Danforth]

Should I leave it where it was or adjust it? Is 5 notches lean counting from the left or the right side?

You should adjust it where it needs to be. Every motor is slightly different

 

[Mi_fiveo]

So 5 marks in from the left side or 5 marks in from the right?

 

[Dillusion808]

When you turn it the choke flap should move. I think turned all the way to the right the choke is going to be stuck open when cold which isn't what you want.

 

[Lou C]

One of the best sources of Quadrajet information and parts is
Cliff's High Performance Quadrajets
they have a forum where you can ask questions and also sell parts.
I hope that carb is not a "frankencarb"! that's what Cliff calls some of them that were pieced together from several different carbs but they don't work well like ones that have all the originally spec'd parts. The one on my boat was an original un-molested marine carb, so it was easy to put it back in good shape. Good cleaning, better quality parts

About the choke adjustment, forget the hash marks. What you want is to adjust it so it just barely closes with a cold engine and also so it opens fully vertical when the engine warms up. If you're not going to install it you can just set it like that, so the choke flap just closes lightly.