Carb bogging
#1
I replaced my engine in my 73 mach with a 351W crate back around 2001 or 02. She was running great, but after 4 cross country moves and sitting for 7 years the gas became bad and I had other issues to contend with (electrical etc.) Anyway, one step at a time I replaced the fuel filters, spark plugs, rebuilt the carb (edelbrock #1411 750cfm electric choke...I know probably too big), fuel pump (b/c fuel wasn't going to carb) and just recently I've replaced the fuel tank (rusted, old varnished fuel & leaking). Clean fuel is now showing up into the carb with good pressure.

The problem I'm having is bogging mainly when I have it in drive and put a load on it. She wants to sputter and bogs down, so I have to slowly press on the accelerator and wait for her to catch up. Once I get moving it's fine, but I'd rather not stop b/c the process starts again.

I've set the linkage for the accelerator pump as close to the shaft as it can go. The further away, the worse it seems. I've also bent the linkage a bit, but nothing helps. It looks like plenty of fuel is sprayed when I rev it up. Measurements on the floats are according to edelbrocks specs-7/16" upside down & 15/16" with floats hanging down. I've also turned the distributor c/w and cc/w thinking it was timing but that doesn't seem to have an effect. I don't seem to have any vacuum leaks. (I've sprayed carb cleaner around the carb while running but she doesn't rev up)

I've taken the carb apart a couple times now. BTW The drivers side idle screw has no effect when I turn it. Blew it out a couple times, but nothing. Passenger side works fine. To me the problem points to the accelerator pump, but anything I do doesn't have any affect. The new spring that came in the rebuild kit was much softer, so I put the old one back in. It didn't matter...

I'd rather not buy another carb even if 750 cfm is too large. I would greatly appreciate any thoughts or advice here...I can take pictures if needed.
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#2
Well you have got a plugged idle circut in the carb. As evidenced by the DS. idle screw not having any effect. An important thing to know about carbuerators is that you must have flow through passages, jets, etc. Not just being able to blow air through them. You must have a liquid flow. Take a cheap can of carb cleaner, $1.97 at walmart
trim the end of the plastic straw to a pencil point. I do this on a grinder. It takes a few tries to get a good tip. Now insert the tip into the passage you want to clean if you get fluid comming out of a hole somewhere else that means the passage is clear. if it pops the straw out of the hole or sprays back in your face that passage is plugged. Which could mean disassembly and more cleaning. I would try pulling out the Idle screws and squirting carb cleaner through the holes where the needle screws were. While holding the throttle open there are tiny little slots just below where the butterflies close that are your idle circut bleeds and the carb cleaner should be comming through them. Be careful not to use an excessive amount of carb cleaner, as a lot of it can do nasty things inside an engine. JTS 71 Mach1
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#3
I believe that Jack has hit the issue squarely on the head. Once that passage is clean I think the performance will return.
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#4
I'll take the carb off and try to do another meticulous cleaning. I feel like I'm spinning my wheels with this carb. I'm guessing it's pointless to try and figure out the bogging issue if one of the idle screws isn't working properly?
Thanks for the advice, once I'm done cleaning and testing I'll repost.
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#5
Just an update, I took the carb off tonight and in the process of cleaning. I took off the drivers side primary venturi booster and it's completely clogged in two of the 'needle-like' ports. Plus I'm finding more gunk coming out when I spray/blow out other ports. So it definitely looks like you guy's got me pointed in the right direction. Hopefully I'll finish cleaning the carb up tonight and can start her up in the a.m. I would do it tonight but I would wake up the neighborhood...hmmm I'll update tomorrow. thanks again!
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#6
Definetly let us know how it goes. JTS 71 Mach1
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#7
Cleaning out the carb really did the trick! I had forgotten I had started her up a couple of times between fuel system repairs. Sucked up way too much junk. She's running great now! I haven't heard that motor sound so nice since my buddy and I put it in. Thanks for pushing me in that direction! I had spent a lot of time to get her back to this point. feels great! Now onto that recurring electrical problem, sagging suspension, the list goes on...
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#8
Sounds like JTS knows what he is talking about. Glad it's up and running right.
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#9
I can't take all the credit. I had a guy that was a real A hole, he was the bosses son. He told me about having to have liquid flow not just air going thru the passages. Just goes to show you can learn something form anybody. You just have to be smart enough to listen. Even if they are an A hole. Did I mention I love carbeuration! JTS 71 Mach1
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#10
I really appreciate it JTS 71! It's really nice to be able to go to a forum and get that extra help. My mach was originally supposed to be a father/son project but I lost him almost 9 years ago. He had all the knowledge and I sure learned a lot from him. I miss being able to pick up the phone and getting car advice (and other advice) from him. (he was a mopar guy) I'm learning more and more everyday that I work on her. I swear he's there with me every time I'm under the hood. And I always throw the 'oldies' on the radio when I'm in the garage!
Anyway, thanks again! I will definitely have more questions as there are a ton of projects on this mach.
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