Carb tuning questions??

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Gus68
Posts: 77
Joined: Mon Oct 01, 2007 6:09 pm
Location: Minnesota

Re: Carb tuning questions??

#46 Post by Gus68 » Sun Jun 06, 2010 1:47 pm

Well, things went from bad to worse. After spending most of my weekend trying to figure this thing out, I think I have either a burnt or bent valve, I'm gonna bring my compresion test set home from work tomorrow to know for sure, I hope I'm wrong about this. I have switched carbs, installed a fuel press regulator and gauge, stuck on a stock fuel pump, and switched distribitors and changed my timing all over the place. The thing is REALY hard to start, it acts like it's flooded, and when I crank it over to try to start it, it will sometimes pop through the carb and sometimes lite on fire. When I do get it running it runs rough like its flooded but runs alittle better after it runs for a while, BUT if I rev it quick sometimes it will pop through the carb. Funny thing is, I drove it a little and it idled on its own and seemed to run ok, and even the pop in the carb was gone. But then I shut it off and tryied to start it again and I was back to the same ol same ol. So I will have to check all the cylinders tomorrow and find the culprit, and then I'll probably have to decapitate it!

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Speedster
Posts: 183
Joined: Mon Feb 08, 2010 2:35 pm
Location: Aloha, Oregon

Re: Carb tuning questions??

#47 Post by Speedster » Sun Jun 06, 2010 4:47 pm

I just went thru the same issues a couple weeks back. I dont know why but when i switched carbs and intake it was popping when i tryed to hit the gas quickly and even on start up. my engine builder said "your to lean" but i didnt think so so i spent money on a bunch of crap and played with timing and even rebuilt the carb. But once i started jetting up like the engine dude said it got better.
So i kept jetting up and got pretty good to where it was barely noticeable and then i changed the cam on the acc. pump arm and bingo it smoothed right up no popping and ran the quickest ET i have ever ran.
I went up a total of 10 jet sizes. the stock cam was kinda clear or white looking and i put the orange cam on and it was the fix.
I thought the same thing that i must of had a bad valve spring or bent or burnt valve.
Look what size jet you have in there now and make a big jet change and see if that works? It's quick and easy and dont cost you any money, if you have jets that is. I felt really stupid after i found it cause my guy told me what it was weeks earlier. :oops:

Gus68
Posts: 77
Joined: Mon Oct 01, 2007 6:09 pm
Location: Minnesota

Re: Carb tuning questions??

#48 Post by Gus68 » Mon Jun 14, 2010 8:29 pm

SPEEDSTER!!!! You were EXACTLY RIGHT!!!!!! I thought for sure that I had a bad valve, I checked compression and all that stuff. I finaly squirted a little oil in the cylinders (cause of all my flooding I thought the cylinders were washed clean) Put in new plugs. I took my carb apart and blew through eveything, jetted it up (79 in the front, 90 in the rear with no power valve) Put it all back together and fired it up! Ran it up and down the road and it didn't miss a beat!!! I let it cool down and tryed it later and it cracked right off!! I went from being pissed that i had a burnt valve, to a good runnin car, with just a major jet change!!! Thanks for all the advise guys!!!! I REALY apreciate it!!!

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Speedster
Posts: 183
Joined: Mon Feb 08, 2010 2:35 pm
Location: Aloha, Oregon

Re: Carb tuning questions??

#49 Post by Speedster » Mon Jun 14, 2010 9:04 pm

Cool. Glad it worked out for you.
I was just passing along what i found and others told me.

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