225 offenhauser/carb problem!!!

I have had my 56 CJ5 with a 225 for about 2 years now and I have had the hardest time getting it to run right. I have an offenhauser 4bbl intake manifold, a 4-2 bbl adapter plate, and a holley 350 cfm 2bbl.

To begin this, I have very little experience with carburetors and that may be the problem here. At the low end it loads up bad. The throttle response is terrible running extremely rich...that is until about 2500 rpm. My gas milage is horrific at best. I would estimate in the range of about 4-8 mpg. UGH!!! I had an edelbrock 500 cfm on it when I got it. I would like to know what carbs work the best on the 225 and perhapse some advice on carb tuning, or anything I am overlooking.

My first course of action to remedy the situation is to replace all of the gaskets and make sure there is not a vacuum leak. After that, if there is still a problem I am lost. I am doing a frame up on it and I DONT want to have this problem after all of that work to it. I am almost ready to scrap the whole engine and get a newer v6!!!! Thanks for your advice and your time.

Jason

 

A Holley 2V 350CFM should work fine on a 225; at least, it should work a lot better than what you describe.

Make sure you don't have any vacuum leaks.

First I'd make sure the idle is set right. Turn both the idle screws in all the way (finger tight) and back them both out the same amount, say 2.5 turns. Start the engine and adjust the idle screws in, bith the same amount, until the idle barely starts to stumble or roughen. Then back them out until the idle smooths. This is usually referred to as "best lean idle."

If you still have a rich condition, I'd suspect the power valve. The power valve is inside the float bowl. You don't have to remove the carburetor to get at it - remove the fuel line and the 4 bowl screws and the bowl and metering block will come off. You probably want to get new bowl gaskets before you do this, since they might be ruined by removing the metering block. The power valve is the big round thing in the middle of the metering block. Very often these are ruined by backfire through the carb.

You can get a new power valve at your local speed shop. They are cheap, say $3.50 or so. There'll be a number stamped into the side of the valve that you'll need to match.

How new is your Holley? Holley sells a kit that installs a new check valve to prevent the power valve from being ruined by a backfire. If your carb does not have this, I'd suggest you get it. Brand-new carburetors should already have it.

BTW welcome from Boston! Feel free to introduce yourself in the intro forum. Be prepared to be asked for pictures if you don't post them. Good luck with your CJ

 

Here's the Holley technical info site: http://www.holley.com/HiOctn/TechServ/TechInfo/FMCTech.html

Your carb is a 2300.

 

It is supposed to be a dual plane but when I took the manifold off, I found that there was only a separation from the left and right. I didnt see how that would affect the opperation but I may be wrong.

 

I dunno - I don't think you'd have any problems with a 2bbl on a 4bbl manifold. I've seen lots of folks do it. I plan to. As long as the barrells of the carb are positioned over both planes...seems like you'd really have to offset it to not have it positioned like that.

Sounds more like a carb rebuild and or adjustment is in order to me. How old is the carb?

 

I bought the carb bran new..right out of the box! I hope that the new gaskets would solve the problem...aka vacuum leak but im not sure. I am contemplating just going to 4 bbl after reading some of the other posts on this site. It just eliminates a possibility. If someone knows a good carb jetting for somewhere around 2000 feet, that would help some. I think that some of my problem may be jetting but, as I said before, I am not the greatest at carbs...looks like Im gonna have to get better though .

I really appreciate the response and the help by the way. This forum rocks!

 

Tim: Thanks for the site. The instructions there are better than come with the rebuild kit for the 2300.

 

Holy crap...thanks for the seal advice! I just used that on my intake manifold this morning!!! I will take it off before I install it again.

 

check your jets
stock 2G jets from factory were 51s
what's in your Holley?

 

I have no idea. The jetting is where my carb knowlege hits the wall. I know that I didnt change it when I got the carb...so if that will help, what should I go to?