HEI Distributor, '69 V6 Dauntless

[Hedgehog]

This isn't my vehicle, I'm asking for a friend.

The Jeep:

1969

CJ5

Compression ~165 (Can't exactly remember, it was checked just before the HEI swap and was good then)

Carborator rebuilt at the same time as the HEI swap. By a well known and respected carb. shop here in Tucson

Fuel Pump is a new electric holly

Motor this is a low mileage motor in great shape

1 - The motor will rev. freely when not under a load
2 - The jeep has an over drive Transmission
3 - When accelerating up to highway speeds, something he never had trouble with before, between 55 and 60 the motor will start popping and blowing back through the Carberator. The trouble seems to be when the Jeep is under load.

What has been done:
There was a question about his advance setting. He fooled around with about every combination you can think of. 0 advance, 3, 4, 5, -8 with no change. The vacuum lines have been inspected. The fuel pump was old so it was replaced with the recomended Electric Holly. He took the Jeep to the Carborator rebuilder and they went through it with a fine toothed comb and found nothing wrong with it.

I have suggested:
Running a wire straight from the battery to the distributer. Change the ingition module.

He believes that he should check the voltage while driving the jeep.

 

[JR74CJ5]

Fuel pressure regulator in the system? If the carb is a holly too, they like certain PSI's only... Too much or too little they run like :down:

Just my first thought... I'm not sure which carb he has though...

I'm not too good with those engines or the trouble shooting of them. Hopefully another person will chime in...

I think you both may be onto something though that it could be in the wiring... I would think it would be affected though the RPM range though and not just in freeway acceleration?

~ Jr

 

[Torxhead]

Setting up an electric fuel pump can be tricky, so I would consider the pressure also. Like install a gauge, a tee fitting on the fuel inlet line which can be blocked off after testing. Hopefully the timing chain is good. The distributor should advance to around 28 degrees.

 

[Hedgehog]

The Jeep has the original carb. but completely rebuilt, it's nice and tight like a new carb. The carb has served him well for a very long time, so I doubt it's a problem. Especially sinc the carb. shop pulled it and functoin tested it again for him.

The Fuel pump was the one recommended by the Carberator shop so the pressure is supposed to be correct. The crux of the matter is, the new pump made absolutely no differance. The problem acts the very same.

I suppose it might be possible for it to be electrical. Higher RPM especially under load can require more electricity or a more consistent flow. Honestly I think he needs to try a new module, the one he has could be iffy or hmmmmm maybe he should pull the module and clean the connection points.

 

[Barry2]

Mike:
Same distributor you've had all along right? In which case under the backing plate in the distributor there is a small coil that can create the problem for one and make sure the rotor is actually very close to pointing to number one at TDC. One tooth off on the dist will cause higher RPM cross fire. I have experienced these in years past.


In order to get that coil out requires removing the dist. gear and pulling out the shaft.

 

[Hedgehog]

Barry - not my Jeep, this is for a friend having troubles with his 225 V6.

Actually it's a new dist. While he was at it he rebuilt the carb. Yep, two major changes at one time, not the wisest of moves, but it seem like the thing to do.

 

[mtnwhlr]

3 - When accelerating up to highway speeds, something he never had trouble with before, between 55 and 60 the motor will start popping and blowing back through the Carberator. The trouble seems to be when the Jeep is under load.

When you are getting a backfire thru the carb it's your timming is not set right

 

[mstar]

Could be a couple things going on.Lets eliminate a few.
Holly elect pump is 7# does not need regulator.(a Weber carb. does)
HEI dist needs full battery voltage ( by pass ignition resistor.)
Check total mechanical advance with a timing retard timing light or mark harmonic balancer and check that way. Total advance should be about 32-34* with vac adv. disconnected @ 3,000 rpm or when it looks like the advance is all in.
Test vacuum advance. The vacuum source on the Dauntless Buick 225 V6 with Rochester 2g carb will be ported vac.Same spot as the other dist used.
Double check to make sure all the parts are for a odd-fire engine.There is plenty of info about odd-fire/even-fire HEI's on the net.
Back firing could be lack of timing advance or lack of fuel.To much fuel will bogg or be sluggish .To little fuel will miss fire / back fire.
As you stated your friend broke Rule No. 1. never change 2 things at once.
Of course politicians do it all the time and we know how that works out.
Overall it sounds like lack of timing advance or lean fuel condition.Wouldn't hurt to change module if you suspect that just to rule it out. mike s.

 

[Hedgehog]

And the final story is:

Jim and I did a bunch of reading. Information on the odd fire V6 frequently conflicts, especially where it comes to which spark plug post is used for #1. He used what appeared to be very well thought out instructions to install the HEI, then noticed that other write ups used a different #1 post. He also read that truly excellent power was required. He used his original Distributor wire, excluding the resistor for a full 12+ volts. Unfortunately the wire is fairly small. So he upgraded the wire to a 10ga and moved the plug wires around on the posts .... naturally he retimed the Dist. as well. ....... I admit to pushing him toward investigating the plug wire placement, yes I'm a hero, but I'm modest about my heroness so I'll give Jim all the credit ...... The result is a V6 Dauntless Buick 225 V6 that runs very well. I honestly wish he had done one change at a time, at this time we don't really know which change actually fixed the problem.