Car bogs and dies at WOT - Team Camaro Tech
Troubleshooting Diagnosing problems done here.

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post #1 of 12 (permalink) Old Oct 2nd, 19, 12:50 PM Thread Starter
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Boe
 
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Thumbs down Car bogs and dies at WOT

So, car starts and idles fine, and I can cruise around town and on the Freeway without a problem IF I ease into the throttle. However, if I stab it to WOT it bogs down completely and dies, starts right back up without issue and is fine as long as I donít get rowdy with it.

Car was running fine before I dropped the front sub frame out to repair body bushing mounts. At that time, I Installed some long tube headers, a new Pypes 2.5 system along with a new Dizzy cap/rotor and new plug wires. Car bogged on WOT from the start and even had some backfire issues. I thought at the time it was the new cap as it seemed to be moving around a bit too much. So, I tighten that up and the car ran ok for a few weeks although the power seemed off and it would randomly die after I came off the throttle after cruising on the Freeway for a while.

I have cleaned and been over the carb (650 Street avenger). I replaced the vacuum Diaphragm using a yellow spring. I changed Accel pump Diaphragm and adjusted the spring. I've looked for Vacuum leaks and added a new gasket. I went up 2 sizes on primary jets, double checked bowl levels even replaced the fuel pump and ran a new AN style fuel line from pump to carb and added a new in line filter.
So, after all that the engine seems to be running much better then before as far as throttle response and low-end power right up to when I go WOT and then it falls on its face and dies.

Starting to think itís been an ignition/timing problem rather than a Carb all along but I am not sure where to go from here, all I know at this point is I am running out of good weather am very frustrated that I havenít been able to figure this out yet.

350 SBC
Elgin E1065P cam
Holley 650 Street avenger electric choke, vacuum secondary
MSD 6A box
MSD MSD Pro-Billet Street Distributor

New plug wires
New cap and rotor.
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post #2 of 12 (permalink) Old Oct 2nd, 19, 01:17 PM
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Re: Car bogs and dies at WOT

If it was running fine before and you didn't let the carb sit too long so the ethanol shellacked your carb internals, I'd have to agree about looking towards the ignition. Recheck firing order first. 18436572. I'd pull the cap, rotor and wires and start from scratch if you haven't been able to find anything. Then timing. I've never had problems with a MSD 6AL box that I've run, but do you have a spare dizzy that you can throw in to take that out of the equation? Something is wrong, so take it one system at a time.
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'69 SS396 X66 L34 08D M21 BS
460ci Gen VI 9.75:1 AED 950 carb
241/249 @ .050" .625/.625 110 LSA

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post #3 of 12 (permalink) Old Oct 2nd, 19, 05:33 PM
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Re: Car bogs and dies at WOT

Everything above plus I wonder if you are running it out of gas when you jump on it due to vapor lock. Perhaps those new headers are heating up the fuel line more then it did prior to the change.

If you have sight windows look at the fuel level when it stalls before you start it back up to see if it is low. Also keep an eye on the fuel pressure.

Try getting on it before it gets too hot to see if it does it with the engine cold (when there is less chance of vapor lock).

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post #4 of 12 (permalink) Old Oct 2nd, 19, 06:05 PM
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Re: Car bogs and dies at WOT

What specific "MSD Pro-Billit distributor" did you "drop in"? With, or, without vacuum advance fitted to it?

What are the various timing particulars, please?
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post #5 of 12 (permalink) Old Oct 2nd, 19, 09:02 PM Thread Starter
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Re: Car bogs and dies at WOT

Quote:
Originally Posted by dave ray View Post
What specific "MSD Pro-Billit distributor" did you "drop in"? With, or, without vacuum advance fitted to it?

What are the various timing particulars, please?
Not sure on the Distributors actual model as it was in the car when I got it 2 years ago. I can tell you it has to be 6 -7 years old based on the info that did come with the car.

It does have the vacuum advance fitted to it.

I am not sure what the timing is set at currently, I've never messed with it.
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post #6 of 12 (permalink) Old Oct 2nd, 19, 09:03 PM Thread Starter
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Re: Car bogs and dies at WOT

Quote:
Originally Posted by 1969SS454 View Post
Everything above plus I wonder if you are running it out of gas when you jump on it due to vapor lock. Perhaps those new headers are heating up the fuel line more then it did prior to the change.

If you have sight windows look at the fuel level when it stalls before you start it back up to see if it is low. Also keep an eye on the fuel pressure.

Try getting on it before it gets too hot to see if it does it with the engine cold (when there is less chance of vapor lock).
It does it cold as well as warmed up. I have been thinking about adding a fuel pressure gage to see what the pump is pushing so I may go ahead and get that ordered.
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post #7 of 12 (permalink) Old Oct 3rd, 19, 07:42 AM
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Re: Car bogs and dies at WOT

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Originally Posted by Boedy View Post
It does it cold as well as warmed up. I have been thinking about adding a fuel pressure gauge to see what the pump is pushing so I may go ahead and get that ordered.
Assuming you are getting a mechanical gauge mount it close to the carb. After you go for a long highway cruise stop in a parking lot and let it idle for a couple minutes and watch the fuel pressure to see if its low.

If you still have the fuel lines running on the inside of the frame then some headers get really close to it and it doesn't take much for newer fuel blends to boil. Since you have a mechanical fuel pump the fuel line before the pump isn't under pressure so it can start to boil at just 100į. Newer cars have the pump in the tank and are fuel injected so the entire line is at a higher pressure which prevents boiling.
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post #8 of 12 (permalink) Old Oct 6th, 19, 11:45 AM
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Re: Car bogs and dies at WOT

Another thing, how was the engine grounded before the work? How is it grounded now?

The engine should be the buss bar for all grounds to the various places like body, etc, with the battery ground cable affixed to the engine itself.
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post #9 of 12 (permalink) Old Oct 7th, 19, 10:00 AM
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Re: Car bogs and dies at WOT

You may have to replace the diaphragm spring with a stronger one because secondaries may be opening too quickly
Ignition timing may be retarded also, use vacuum gauge on manifold and adjust for best reading.
Once carb/engine adjusted, sitting in driveway at operating temperature, by hand, you should be able to go from hot idle to WOT and engine should rev from 550 RPM to infinity in about three microseconds without failure and secondaries should be starting to open.

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post #10 of 12 (permalink) Old Oct 7th, 19, 12:04 PM
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Re: Car bogs and dies at WOT

Respectfully to Everett, please do not set timing with a vacuum gauge, timing is a collection of specific settings, and needs to be set that way.

If possible, might you do a rudimentary timing assessment for us, please?

If so, please mark the balancer and do not use any "dial back" feature on the timing light.

Disconnect the distributor vacuum advance hose, and plug the end.

At idle, please record the timing.

Then, slowly rev the engine until the timing stops going up, record. This should be no higher than about 3,200 or so RPM's.

Back at idle, reconnect the vacuum advance hose, and re-read the engine idling timing, record, and post for us, please.

We can help with the timing then, if need be.
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post #11 of 12 (permalink) Old Oct 17th, 19, 02:51 PM Thread Starter
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Re: Car bogs and dies at WOT

UPDATE- I went ahead and replaced the Carb with a reconditioned one from Holley. Car had a 670 Street Avenger on it that was pretty old and I just couldn't get it running right no matter what I tried. Found the same model but newer one on eBay and figured for $299 it was worth a shot. New one has 4 corner idle and window for float level so what the heck I thought. Took it for a quick test drive in between rain storms just now and the stumble is gone.

Still need to tune the carb to the car as it wasn't perfect, but seeing how I have all the jets. springs and cams already that shouldn't be to hard. Thinking I will up the jets and put a yellow vacuum spring in the secondary as that gave me the best results as far as power and throttle response when I was troubleshooting. Not sure on the Pump cam though, is there a good way to land on the right Color Cam?
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post #12 of 12 (permalink) Old Oct 18th, 19, 06:29 AM
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Re: Car bogs and dies at WOT

Quote:
Originally Posted by Boedy View Post
UPDATE- I went ahead and replaced the Carb with a reconditioned one from Holley. Car had a 670 Street Avenger on it that was pretty old and I just couldn't get it running right no matter what I tried. Found the same model but newer one on eBay and figured for $299 it was worth a shot. New one has 4 corner idle and window for float level so what the heck I thought. Took it for a quick test drive in between rain storms just now and the stumble is gone.

Still need to tune the carb to the car as it wasn't perfect, but seeing how I have all the jets. springs and cams already that shouldn't be to hard. Thinking I will up the jets and put a yellow vacuum spring in the secondary as that gave me the best results as far as power and throttle response when I was troubleshooting. Not sure on the Pump cam though, is there a good way to land on the right Color Cam?
Glad to hear it ended up being a relatively easy fix for you. The accelerator pump cams go in order from lightest shot to heaviest as follows: Black, Pink, White, Red, Green, Orange, Blue, Brown, Yellow. Just like jetting, you need to see what you have in there, see if you're rich or lean on that circuit and adjust as appropriate.
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'69 SS396 X66 L34 08D M21 BS
460ci Gen VI 9.75:1 AED 950 carb
241/249 @ .050" .625/.625 110 LSA

Semper Fi!

"The galleries are full of critics. They play no ball, they fight no fights. They make no mistakes because they attempt nothing."
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