Gas burner problems

[AWallace]

This is for any one out there that might know about upgrading a older car to electronic inc. My son has a 1972 mach I mustang he is doing some Mods to. change to alum. intake and Holly 4barrel. on the electronic Inc does he have to change the plug wires and plugs to. having trouble with backfire through carb. like there is something not right with fireing. Any sugg. would help in finding this problem.

 

[B.G. Smith]

Backfire through the carb when accelerating is usually caused by too lean a mixture or accelerator pump not working or not pumping enough fuel on acceleration. Depending on what 4 barrell carb you have, the second two barrells may be coming in too quick. Some are controlled by a lockout so they can't open until the engine is warmed up, others have a diaphram and usually have some type adjustment to control when they open. If it is just randomly backfiring then it is probably in the distributor. The wires, if they are in good condition should be ok. Look at them while the engine is running at night to see if they are lighting up(crossfiring). Check the plug firing gap also. If they were installed out of the box they need setting. bg

 

[AWallace]

This is a new Holly out of the box. the size is 670. he called Holley to find out what he could use on a 351 cleveland engine. The carb came with extra springs to change if need be to make the back 2 come in different. The carb came preset from the factory but I had to adjust the mixture to get it to run at all. It stalls on accelation from stop but after that it is find except at 50 or 60 it fills like there is a bad wire or plug. On these's later models you have to run the plug gap wider with electronic Inc. and use bigger wires could that be it. I have never had this problem before. I told him I could put the points and condenser back in and try that but I don't know if it would help. I have had a 600 on my old work truck for years and never had a problem. I am about to pull my hair out.

 

[B.G. Smith]

Try putting the strongest spring in the secondary (or the spring that causes the secondary to open latest) and if you have different cams for the accelerator pump, put one on that pumps more fuel, also make sure the cam is contacting the pump when the carb is at idle. Make sure the fuel level is right in the carb, it should have plugs in the bowls and adjustable needle and seat. If none of this helps, try advancing the timing a little. bg

 

[AWallace]

Thanks for the information. I told my son I have worked on them 2 or 3 weeks before getting them right. Sometime it is trial and error.



Andrew

 

[Mhannink]

well i would ditch the holley to tepremental go w/ edelbrock the best place to get all and any parts is summit racing for the ignition go w/ mallory or msd both are good w/ maybe msd be being a little better but that would be mostly opinion back to the card i had a cousin that could never get it dialed in right he rebuildt it accodring to the book read another book all about holley he knew all there was it seemed like and that thing would never get adjusted and when it was tuned it didn't stay long before it need to be retuned he then got edelbrock bolted it on changed the jets to run in the hills and never touched it again

 

[Nate]

Holy run-on sentence Batman!

 

[Mhannink]

yeah sry i just wright what im thinking and don't do all the grammer

 

[SBettencourt]

You really need to check the manifold and carb installation for vacuum leaks. A gasket may have slipped or you got the wrong one for the base of the carb. It happens. These things do not clear themselves up. If the timing is correct, then the electronic conversion should have no affect. I did not see what conversion you used. I like the Pertronix because they work well and have excellent customer service.

Make sure the firing order is right. I know Ford is different that Dodge and Chevy but I don't know what it is.

That Holley should work fine barring other problems. I like Edelbrock carbs, too but I've had good luck with Holleys.

 

[Hoefler]

Do you still have a condenser in the ignition system?? If so change it. After you have run it awhile, put your hand on the coil. Is it warm or is it hot. Warm coil OK, hot coil coil bad. Replace coil. Are you using suppressor plug wires?? Remove them and ohm them out. There should be no more than 2000 ohms per foot and no more than 4000 ohms per length ( from the coil to the plug, add the coil wire readings to the plug wire readings ) I have had brand new wires out of the box bad!! I use Accel 8mm copper core wires. About $30. The universal ones you have to install the distributer end. The tool is about $10.

 

[ToolManTimTaylor]

How is that Camshaft doin? Worn lobes on the exhaust side can cause this too ... especially on a solid lifter engine. Once any enhancements on the intake side is made it will make the problem more pronounce. A now less restrictive intake charge can now flow much easier into the cylinder. Without proper scavaging the cylinder"s fire can trace back up thru the intake port. ( Chased this exact scenereo down in shop class back in High school on a Nova)



Just thinkin' outside the box.