I just bought a Holley carb to put on my 351m because I could never tune the older carb and it was really really bad shape....(and I got a really good deal on a brand new one)...

Well here is my problem, I first put it on but it ran like crap so I set it up abit checked the float and it was high so I set it and than I played with the mixture screws and I had it running really smooth, but when I step on the gas............IT STILL STINKS LIKE GAS

Is there something I might not be doing right, I have never been very good at setting carbs......

this is how I did it

-set up the idle at about 700 rpm
-turned the screws all the way in then out about 1-1/4 turns
-adjusted slowly the same amount on each side till I got the highest idle
-re-adjusted the idle to 700 rpm in park and about 4-500 in drive

If there is a better or easier way or something I am missing please fill me in..............thanx..............


I just thought I might add that when I put the brakes on and give it a fair amount of gas that I get some black smoke out of the pipes and if I burp the gas a few times and let off it will usually die on me.....

 

Did it backfire? It could have a blown powervalve. But it sounds like it may need smaller jets in it. I would try about 3 sizes smaller to start.

 

I agree with LxMan1, it sounds like a bad power valve. It is unlikely that you could blow the power valve(PV) on a new carb with a backfire. The new carbs have pv protection. The stock jets should be #61(List 7448?). I have seen some carbs that sat too long with dried out gaskets that can plug passages, ports, etc.

 

When I blew the motor last year and put in a motor I found here, I had to change the fuel pump so I checked the timing chain through the fuel pump hole and found that it was very loose.

Could this have any thing to do with the whole gas smell thing because I really does not idle bad or smell under normal driving but only when I hammer on it????????????

 

A loose timing chain will make it run poorly, but it won't cause a gas smell. You might have too big of an accelerator pump shooter on there. It would cause the stall after "burping" the throttle a few times. What is your carb list number?? it will help with what should be in it.

 

I got the Holley 2300, 350CFM with a 30cc acc. pump

I also noticed that there is a small plate just to the passenger side of the carb on the intake (about 1 inch by 2 inch) with 2 holes that look like there was 2 tubes that have been ripped off flush with the plate ( I think it is for the EGR sys) but if thies are left open will this be a problem??????

Sorry for alll the posts,,,,,,,,not too good with carb stuff and just trying to throw all the things that might be of some good info that will help trouble shoot the prob......

I also just noticed that when I leave the truck off for a bit the fuel flows back down the fuel line.......First time having a clear fuel filter never noticed it befor with the stock filter on the old carb...

 

Is the fuel running back into the pump or is the carb letting fuel drip into the intake from a high float level or a small piece of debris in the needle and seat.

The two holes on the passenger side of the intake were for the factory hot air choke. They will not cause any problems being unhooked except that the factory hot air part of the choke would not work.

 

> but if thies are left open will this be a problem??????

Yes, it will be a big problem, if this is the factory spacer you are talking about that goes between the carb and manifold, there should be two 1/4x20 holes where you bolt on the EGR adapter.

If you take off the carb. you should have a hole under the adapter that matches up to the adapter (not to the carb), Basically, hot exhaust goes through the adapter, then to the EGR, then from there out down the other side of the adapter, and into the air intake.

On my 2 BBL 390 when I replaced it with a 4 BBL Holley, here is what I did. Not recommended for anyone else because I can not warranty the long term results.

Sanded the holes and made sure bare metal showed and got rid of all the carbon. Put some loosely packed wads of newspaper under the holes. Filled the holes with JB Weld. Let it cure 24 hours, sanded it smooth so the gasket would seal well, then used a thin gasket along with an 1" aluminum adapter/spacer under the carb that also covered the hole. Put a thick carb spacer (1/4") on and then the Holley 650 CFM Street Avenger. Hooked the electric choke to the starter relay (use a 15 amp fuse), made sure the choke worked, away I went. No tuning needed.

You can put a 10" Edelbrock cleaner on with a 3" element (I think the Advance Auto number is 360047). This is the old one I put on that worked with my 2150. Probably a 14"x3" would be best.