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Hi All,

I recently installed a Holley Street Warrior 600 CFM with Vacuum Secondaries and an Electric Choke. Once I got a trans kickdown that fit properly (or seems to). The fast idle was set very high around 1500 RPM (which is the factory setting according to the manual). I looked in the car manual and saw that the suggested RPMs for my set-up (351 4V Auto trans) is 625/500 (I assume that's 625- fast idle and 500- curb idle). After futzing with the Fast idle bolt, it seemed like the engine was idling around 625, but it sounded like it was struggling a little. I called it a day, and came back the next day to try adjusting the idle mixture screws and I think I might have gotten a little overzealous going back and forth between carb adjustments and starting the engine up. I could not keep the engine idling, heard a loud pop. I waited a while, tried again and the carb backfired, shooting a flame out the top. I waited a while, and got the engine to idle just enough to back the car into the garage for the night. The next day, i tried cranking the engine and heard a grinding noise and smoke coming from the battery. I tried jumping the battery and it seemed to start fine. Then I noticed a smell. I shut the car off and noticed the vinyl covering the ground cable which connected the frame of the car to the negative battery terminal had begun melting. I took the battery (Autocraft Silver) to Advance Autoparts to run a diagnostic on the battery. "Bad sale" was what the cashier said once the diagnostic completed (which only took one or two minutes), and they gave me a new Diehard Silver under warranty. I haven't put the new battery in yet, but I wanted to ask the vets on here what I'm doing wrong before I venture to try and "fix" anymore issues. 

P.S. What does rank FNG stand for? I assume "friggin' new guy" because that's how I feel right now.

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Hello and Welcome from Michigan. For a 351 Cleveland with an auto transmission the cold/fast idle should be around 1500 and the hot or curb idle should be around 700-800. Not sure what manual you are looking at but the numbers you posted are too low. And the hot or idle at 700-800 rpms is with the car in gear and all accessories and lights on. If you have a larger than stock camshaft, then you might need a little more idle than that. I have a pretty decent size cam and I need 850-900 to idle good.

As far as the carb settings go, I would put the idle mixture screws back to the factory settings. Usually you turn them clockwise till they are just seated and then back them out 1/12 turns. Then tune from there with a vacuum gauge and timing light. Not sure why you only went with a 600 cfm carb, 715 cfm was stock from factory for Q code engines. 

The cable getting fried looks like it was just getting old, not grounded good and a lot of cranking the engine over. With a new battery and cable, clean all contacts you should be fine.

And finally, fng is what you said. Lol

Edited by jpaz
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John - 72 Q Code

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Thanks for the feedback jpaz! The reason I went with the 600 CFM was because I was replacing an old Holley that had been on the engine since it's previous owner and was also a 600 CFM. I called Holley Customer Support and gave them the part number (80457-2) on my old 4160 and the guy informed me that the 600 CFM was in fact the correct replacement for that part. On the Holley website, I don't see a 715 CFM, but I do see a 750 CFM. Do you think it's worth swapping for a 750 CFM? In addition to the battery cable, I plan to get some new terminal connectors because my old one's are pretty worn looking. When I was reading online that the battery issues could also stem from a bad ground. The old carb's electric choke was grounded to the Intake Manifold, while the new one is grounded onto one of the choke housing screws right out of the box. I had to use the old cruddy nuts and bolts to accomodate for the thicker holley base gasket (which was on with the old carb) because I thought vapor lock might have been another issue I was experiencing (also ordered a new one of those, but they're on backorder. Part # 108-12).

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No one makes a 715 cfm, was just saying that was what was on from the factory. Not sure what to tell you about going to a 750, but I don’t know why the P.O. went down in cfm. Doesn’t make sense but I don’t know what exactly has been done to your engine. If the heads were changed to 2v, then I could see why it was downsized. A 700-750 vacuum secondary carb would be better if you have the 4v heads. 

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John - 72 Q Code

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Well, hopefully I can get it working with the 600 CFM, unfortunately I think it might be too late to make an exchange with Holley. This just seems to be another one of the previous owner's many eyebrow-raising decisions. These issues all started when the car broke down as a result of the rotor in my distributor snapping. The mechanic it got towed to informed me that the previous owner had put an optical distributor in as if they intended to do a digital conversion, but stopped with the distributor. Very confusing. Even so, your advice is extremely helpful. I'd be completely lost with this thing if it wasn't for all you great people on this site. Hopefully one of these days I will no longer be a FNG. Thank you again!

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The previous owner either installed the smaller carburetor in an effort to improve gas mileage or he found an online carburetor size calculator and that is what it showed. 4V Clevelands like more carburetor than those online calculators show.

A 750cfm will work fine on your engine.

However, it should also run good on a 600cfm, just not realize it's full power potential.

Backfiring through the carburetor can be timing or carburetor too lean.

Check your timing, start with 12° to 16° BTDC, with the vacuum advance disconnected and plugged.

Check the spark plugs for carbon and the gaps.

Check the electrical connections inside the distributor and at the coil. There should be a small bare braided wire that connects the breaker plate to the inside of the distributor body. This is necessary even for aftermarket electronic conversions. 

Check all vacuum lines, make sure there are no uncapped ports on the intake manifold or carburetor. Make sure the PCV valve is in place and functioning.

If the base configuration on your new carburetor does not match the old one you may have a vacuum leak there, with the old gasket.

Make sure your fuel pump is supplying adequate fuel, make sure the fuel filter is not clogged.

Good luck on getting it to run.

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“If you can't explain it simply, you don't understand it well enough.”

--Albert Einstein

 

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Thanks Don,

I will say that the shop I had the car towed to in Connecticut replaced some spark plugs that needed to be replaced, installed a new analog Distributor and ignition coil. When they took the car for a test drive it broke down. They discovered the vacuum advance plate had come off and was spinning around inside the housing, so then they had to replace that. The shop owner told me it would run well enough to get it home (which it did), but I should definitely take it to a local mechanic because it seemed to have carburetion issues (which was later confirmed by a local mechanic who then directed me to install the new carb). Being that that shop in CT had just replaced all that, do you still think it's necessary to adjust the timing? Or do you think my futzing with the carburetor might have thrown the timing off? You are correct, though both the old carb and the new carb are Holley 4160s, there are some deviations in the grooves on the base, so that could definitely be a factor. I also just replaced the fuel filter with a clearview mr. gasket before installing the new carb. I didn't find any sediment in the old filter. Like a dope, I actually did forget to clamp the vacuum line that leads into the temperature sensor on my air filter when I was working, so I'm thinking that may be the cause for the backfire issue. One more thing to note: I also noticed the CT shop had re-routed the vacuum advance line to the vacuum splitter on the intake manifold, not the timed spark on the old carb (I assume to prevent another vacuum advance failure) 

@jpaz I've attached the manual I had mentioned and the page I got the idle speeds from. The screwdriver is underlining what I had thought to be the correct idle speeds for my engine. Am I just reading this wrong? Sidenote, you said to back out the mixture screws 1/12 turns. Did you mean 1 1/2 (1.5)? 1.5 turns is what the Holley manual advised, which I did do.

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I would check the timing, you don't know what they set it to. I would also move the vacuum advance back to the timed port on the carburetor, see if that makes a difference. 1 1/2 turns out on the idle mixture screws is just the initial setting, you then adjust them to maximum RPM or vacuum while keeping the idle speed within the recommended idle speed range. 

  • Like 1

 

 

“If you can't explain it simply, you don't understand it well enough.”

--Albert Einstein

 

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