I've run into a few situations with Holley carbs and pump gas[now with ethonal] that going up about 2 jet sizes fixed a simular issue.My concern would stem from the air leak in the rear carb's mixture[lean at that point] might just be your culprit.
409 Questions
- Thread starter 409acoupe
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409acoupe
Active Member
Yes i don't want to go swapping a bunch or stuff or making changes until i seal up the carbs for good. I did bump up the psi from 3 to 4. We can get 94 octane from chevron here that has zero ethanol so that's what i run in both the camaro and now the coupe. costs 7 million dollars a gallon but hey you can't take it with you!!! ha ha
I absolutely love your hot rod .........that’s bad ass..!!!!!!.......The color .....the wheels...... the power plant .......your spot on.....!!!!!
Camaro...Shamaro, who cares!!!!!!........( just kidding beautiful car )...... i’ve never been interested in main stream hot rods ..... Camaros and mustangs the tri-5’s...... shit everyone builds ...... it’s all you ever see in the rags ........The model A rocks.......
What are the carbs jetted now? As far as the pump shot, I drilled my cluster out for more volume because of Bogg when I dumped the throttle. I can walk you through that procedure. Also there is a power valve in the center carb, spring loaded, vacuum actuated, make sure you have enough vacuum to keep that closed at idle and light cruise conditions. The spring in the accelerator pump can be manipulated to customize the pump shot. Pay attention to that. As for the throttle blades not sealing your on the right track. I had to use the DAG on my Pontiac GTO trips, worked very good.
409acoupe
Active Member
Thanks man. An almost three year build (work, family, budget) but i'm happy with the outcome for sure. had a clear vision in my head and had done a ton of homework before and during the build. Have a build thread on the HAMB site which has been a great resource for this early stuff.
409acoupe
Active Member
All good info, thanks man. I have read and heard of everything you are saying and i might definitely pick your brain if needed. The secondary carbs are 55's for jets. I can't quite remember what the primary is as i rebuilt them a while ago. Gonna pull it off and check when i do the bases on the sec's. Like i said it's not really a bog, it's just not clean for the first second you get on the throttle then it clears right up and goes. My instincts say it's the whole set up off idle with the sec's messing things up like it's a little too lean with the air bleeds. Will get it solved i know. Appreciate the offer to help, that's what the hobby is all about to me!!
Can you block off the rear carburetor and try it?
What do the spark plugs look like?
Is the advance in the distributor working correct?
What do the spark plugs look like?
Is the advance in the distributor working correct?
The 55 jets are waaaay to lean. The stock jets are from .061 to.063. I ran .061 front to rear with no issues. My suggestion to you is front and rear carbs .060 and the center carb .061. The stock jetting was, with the turbo glide tranny, front .060, Center .060 and rear, .061. With the standard tranny, front, .060, Center .063 and rear .061.
Yup, what Dream’n said. It’s the perfect hot rod. Thank you for not choppin’ It. You’re one of the few who don’t. It looks perfect with the stock greenhouse.
As far as your fuel issues, I would highly recommend a wide band a/f meter. That is by far the best mod I’ve ever made to a carbureted, street/strip car. I have the auto meter one, analog with a full sweep. Weld a bung in one collector, 12 volts to the gauge and you’re in business. I have mine in the glovebox to conceal it. It’ll help you pinpoint every throttle position and you can get a car tuned razor sharp. My 61 gets 15-16 mpg on the highway because of that gauge. 10.75:1, dual quads, no overdrive, and 3.70 rear. 3900# with me in it.
As far as your fuel issues, I would highly recommend a wide band a/f meter. That is by far the best mod I’ve ever made to a carbureted, street/strip car. I have the auto meter one, analog with a full sweep. Weld a bung in one collector, 12 volts to the gauge and you’re in business. I have mine in the glovebox to conceal it. It’ll help you pinpoint every throttle position and you can get a car tuned razor sharp. My 61 gets 15-16 mpg on the highway because of that gauge. 10.75:1, dual quads, no overdrive, and 3.70 rear. 3900# with me in it.
409acoupe
Active Member
i can block the carbs off but i have the new bases arriving start of next week so i'll just do the swap (as long as the blades are set right) and go from there. Plugs look good, not perfect but it's been a lot of little in town driving and garage tuning so they always blacken up like that. advance is working correct. Dizzy is a new pertronix stock look unit
409acoupe
Active Member
good to know. I'll play with them and jet it up and see what happens
409acoupe
Active Member
ha thanks man, i've been preparing myself for all the guys who DON'T have cars saying you shoulda chopped it!
and all the guys who will just assume it's a 348 with the tri power being on there. I did and have thought about an AF meter. I have tried to keep the interior as ultra clean as possible. All switches are hidden and it's just bare bones for guages so i was struggling with where to put it. no glove box option so would have to be perhaps tucked under the dash. Been pretty decent at tuning carbs like my QFT on my Camaro but of course you are never gonna get it as deadly vs an AF guage. The old school in me says no, the intelligence in me say why not make life easier. I'm also one of those guys who stares at guages too much so i don't really want to add another viewing option to the mix! ha ha We shall see
If you get a AF gauge, just use it to get it dialed in then remove it and plug the O2 sensor hole.
409acoupe
Active Member
yes good point. I do remember when i have looked at them before, they are a little pricey. oh well
That's why I don't have one, just to old school I guess.
If your not drag racing and want to squeeze out every ounce of performance reading plugs has won tons of street races.
I'm with Kevin! I would definitely have an air-fuel gauge on that engine.You could switch it between both cars.You may THINK that the Camero's "right on",but you just can't be sure without checking.Plug readings at WOT aren't hard to figure out,but when you spend 99 percent of your time at a part throttle cruise,it gets trickier.Tuning for the best part throttle usually results in longer engine life.
409acoupe
Active Member
Why is everyone pressuring me?! 
It’s true. My friends who own a body shop in town who did the paint on my coupe just bought an AF tester system I’m gonna weld in a bung and we will do some tuning once I get these bases replaced. Then I’ll just plug the bung afterwords. Don’t tell anyone though, can’t admit to o2 sensing on a traditional hot rod!! Ha ha
It’s true. My friends who own a body shop in town who did the paint on my coupe just bought an AF tester system I’m gonna weld in a bung and we will do some tuning once I get these bases replaced. Then I’ll just plug the bung afterwords. Don’t tell anyone though, can’t admit to o2 sensing on a traditional hot rod!! Ha ha