Carburator issues

[chiefshocker]

I have a Holley 600cfm 4160 on my 83 turbo.. i fixed all the exhaust leaks and while it was down.. i rebuilt the carb cause it had flooding issues in the secondary and looked like it might have been sitting for a while. Now I'm have major flooding issues. At first after the rebuild it wouldn't start, dumping a ton of fuel into cylinder six and generally fouling all the plugs. I've swapped the needle and seats out twice.. and now have the spring loaded version. It runs now, with a very rough idle but still floods out, even with the float bowls dialed all the way down and the fuel pressure dialed down to as low as 1/2lb. I know its not the stock carb.. but was hoping for some help either with the holley or recomendations for a new performance carb that runs good with these buick beauts..
thanks
Fred

 

[charlief1]

You may have another issue here. What jets are you using? You've checked the float level I'm sure. You really need to go with a spread bore carb instead of a square bore. It will work much better than the square bore and you will be able to use a 750 instead of the 600.

 

[ek02]

You may have bad floats. If they are brass, it's easy to tell if there is fuel in them. Just shake them. If they are phenolic floats, they may be saturated with fuel making them heavy. You would have to compare them to a new float. The other problem I have had with Holleys flooding after a rebuild is the threads in the float bowl. They tend to crumble and small pieces of the casting will get in the needle and seats. Look at them closely when you take them out.

 

[chiefshocker]

The jets are 64, which I believe are the correct size for my altitude, power valve a 6.5. I've messed with the float level up and all the way down, it only runs if they are all the way down. I can get it to run & run as long as i want.. but its rough and once i shut it down i can't get it restarted until i pull all the plugs (which are wet and carbon covered). I checked the compression and its 105-115 across the cylinders. I took the whole carb apart again, rechecked the plastic floats (ok) and sprayed out every passage.

There is standing fuel in the intake, I also have fuel in my oil.

I'm at a loss. Maybe the timing is off? What is the stock setting.. i'll go back to baseline and work up.

 

[charlief1]

Base timing should be 15 degrees if I remember right. You might want to add some dye to the fuel. If there's a crack in the body or metering block you may be able to find it that way. You'll need a black light of course, so you can see any issues.

 

[chiefshocker]

Base timing should be 15 degrees if I remember right. You might want to add some dye to the fuel. If there's a crack in the body or metering block you may be able to find it that way. You'll need a black light of course, so you can see any issues.

Thats a good thought.. little crack sounds about right. Is that 15 degrees at idle?

 

[charlief1]

Set it at idle. I don't remember if it's an auto or stick though. If it's stick then normal idle if auto you want it in gear at idle.

For some reason 18 degrees is coming to mind but I think it should be 15 degrees. I'm sure Rich or someone else will correct me if I'm wrong.

 

[chiefshocker]

Timing looks fine.. I'm going to try and replace the floats just in case they have become saturated. If that doesn't work i'm going to buy a new carb for it. I'd appreciate some recomendations, as i have a big trip planned for thanksgiving and i want to get her running ASAP.

Thanks
Fred

 

[charlief1]

A spread bore Hollley will work the best in the application. What most guys don't realize is that a spread bore gives a high velocity for the primaries so you develope better torque on the bottom and when the secondaries open you'll get the top end you want.

 

[chiefshocker]

A spread bore Hollley will work the best in the application. What most guys don't realize is that a spread bore gives a high velocity for the primaries so you develope better torque on the bottom and when the secondaries open you'll get the top end you want.

I could use the low end tourque. I'm always confused when it comes to the CFM calculations. The current one is 600cfm is that what has worked well on the turbo buicks?

 

[charlief1]

There's a lot of math involved in the VE calulations for a carb size. The one thing that a lot of those calculators don't take in is the way the engine works. It's a general sizing that works ok in most cases. With the spread bore vacuum secondary carb you can run a bigger carb because the secondaries don't kick in until the vaccum signal is at the right place and progresses as the signal changes.

A 650 will work ok but a 750 would give you more top end, and since the stock C/T system used a 730 CFM carb that was slightly de-tuned either would work fine.

 

[chiefshocker]

There's a lot of math involved in the VE calulations for a carb size. The one thing that a lot of those calculators don't take in is the way the engine works. It's a general sizing that works ok in most cases. With the spread bore vacuum secondary carb you can run a bigger carb because the secondaries don't kick in until the vaccum signal is at the right place and progresses as the signal changes.

A 650 will work ok but a 750 would give you more top end, and since the stock C/T system used a 730 CFM carb that was slightly de-tuned either would work fine.

Yes the simple calculators based on RPM and Cubic inches of the engine show only 300-470cfm. Crazy stuff!

 

[usetaboost]

if you didn't change the distributor that could be your problem

 

[mikemcvaney]

Its probably a float would not put a spredbore holley onit had one runs way better with a squarebore spools way faster on my car.

 

[chiefshocker]

After countless hours of screwing with it. I finally took it to the hotrod shop. They fixed it, it purrs like a kitten now. He told me i had blocked airway passages, the wrong gasket on the primary metering block and my powervalve diaphragm was ruptured. I guess i'll keep my day job.

 

[charlief1]

Had a feeling that was part of the issue you were having with it. Have you tried seeing how well it's accerating now?

 

[chiefshocker]

Had a feeling that was part of the issue you were having with it. Have you tried seeing how well it's accerating now?

Thanks for your help, not sure how it accelerates yet, I was running it this morning and the alternator mounting bolt snapped before i could go anywhere.. Strange.

 

[mat231v6]

Thanks for your help, not sure how it accelerates yet, I was running it this morning and the alternator mounting bolt snapped before i could go anywhere.. Strange.

wow are you having bad luck. hope everything get better