[bishir]

My car runs fine otherwise, but if I try to power brake, it will backfire out of the carb. What's up? Edelbrock 1405. Power-Braking is a Brake-Stand, same thing...

See my 69 convertible and the VMF parking lot at: http://www.geocities.com/Bishir1/FrontPage.html
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<P ID="edit"><FONT SIZE=-1>Edited by bishir on 04/14/01 06:45 PM (server time).</FONT></P>

 

[camachinist]

Describe the engine rpm and throttle opening where the backfires occur....

Usually, it occurs from a lean condition....

What happens with a WOT transition at low speeds in high gear?

What diameter converter are you running?

Pat
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[bishir]

Pat, everything else is fine. WOT transistion is great and it seems to have plenty of power. I have no idea what converter I have... My tranny is from a 75 LTD or something like that. It's a C-4 with a treaded dipstick tube. You or someone else said it's probably a "flared case" C-4. I assume the converter is stock. When it dies or stalls it's WOT with the Brake held down. WOT from a stop postition smokes the tires. WOT from any other speed snaps the head back a little. Nothing like your D coder probably does /forums/images/icons/smile.gif Do you think I'm too lean? or is it the converter? or should I stop standing on the brake? hehe

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[motorhead]

If your pushing your timing bring it back a couple degrees back to what stock would be.

Motorhead

 

[Guest]

I would think timing too, or at least try that first. I you've got lighter advance springs or have bumped up the timing it may be a smidge too far. If you haven't paid big $$$ to have your dizzie recurved there is a square opening in the breaker plates that allows adjustment of the posts that anchor the advance springs. You can get a long screwdriver down there and bend the post outward to put more tension on the springs (to slow the advance curve). This is for small adjustments only and Ford states that the minmum advance point should be checked after any changes. I would probably try to move the initial advance back as a test prior to any adjustments to see if you are on the right track but any improper bending can easily be corrected so go for it!

......Bill

 

[camachinist]

Sounds good James....I haven't seen timing cause this problem unless it's way off and that would affect other engine operations..

I ran the race car with no distributor advance at all (crank trigger) and used a fixed 34 degree pickup to run the car and a 15 degree pickup to start it. I could run the engine up against the converter to nearly 4000 rpm at WOT and never heard anything like what you're talking about...

Of course, that was with a high output coil, MSD, and crank trigger....you may be getting ignition anomolies under high cylinder pressure but that should show up elsewhere other than power-braking...

Head scratcher, yes?? *G*

Pat
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[bishir]

Pat, I adjusted my mixture (more rich) and the problem seems solved. Now I have tire smoking fun /forums/images/icons/smile.gif. I also retarded the timing about 2 degrees. It still happens if I just stomp the gas, but a gradual increase in throttle makes some nice tire smoke. Thanks for your help!

James

See my 69 convertible and the VMF parking lot at: http://www.geocities.com/Bishir1/FrontPage.html
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