Pinto bucking / no power in the corners

[redcar9]

Back at this again. Got some fresh parts.

The pegasus mechanical pump runs about 1psi lower overall.

I changed to the DaveW jets. However the car would stall when coming off full throttle.

DaveW’s jets in 2006 were:

JET PRI SEC
AIR 200 140
FUEL 135 165
(FOR AVGAS, ~55F)

So I changed the idle jets from 55 Primary and 50 secondary to 65 Primary and 60 Secondary solved this issue.

Does anyone know what idle jets DaveW ran with those Air/Fuel jets?

Also, I added a wire to the distributor base to solve the ground issue. That didn't improve the timing stability. Just wanting for the parts to show up from PerTronix.

[DaveW]

That was a long time ago - all I know is that they were what was in the carburetor when i got it from QS or Stimola. I did have to clean dirt out of them a few times - when they were blocked it wouldn't idle.

[DaveW]

Bucking/no power or stalling off power, considering your fix, may have meant that one or both of the idle jets were blocked, causing the idle mixture to be way too lean. I say that because a small change in idle jet size should not, IMO, have resulted in this big a change in stalling/throttle response.

To confirm or refute this theory, check both idle jets you removed to see if they WERE blocked.

[DaveW]

Back at this again. Got some fresh parts.

The pegasus mechanical pump runs about 1psi lower overall.

I changed to the DaveW jets. However the car would stall when coming off full throttle.

DaveW’s jets in 2006 were:

JET PRI SEC
AIR 200 140
FUEL 135 165
(FOR AVGAS, ~55F)

So I changed the idle jets from 55 Primary and 50 secondary to 65 Primary and 60 Secondary solved this issue.

Does anyone know what idle jets DaveW ran with those Air/Fuel jets?

Also, I added a wire to the distributor base to solve the ground issue. That didn't improve the timing stability. Just wanting for the parts to show up from PerTronix.

See my post above...

[redcar9]

Bucking/no power or stalling off power, considering your fix, may have meant that one or both of the idle jets were blocked, causing the idle mixture to be way too lean. I say that because a small change in idle jet size should not, IMO, have resulted in this big a change in stalling/throttle response.

To confirm or refute this theory, check both idle jets you removed to see if they WERE blocked.

Thanks for this info it's very helpful. I did check and both idle jets were clean. I just left the new ones in for the dyno test.

I think I have an ignition problem on top of a fuel one.

[Offcamber1]

Years ago (50? 55?) I read either a article or a book by the above author about British sports cars. I remember only two things about it:

1. It was extremely amusing

2. In it was the observation: Carburetor problems is usually spelled, "Check ignition."

Just out of curiosity, have you replaced the ignition wires? Just because they look new doesn't mean they'll function well above 3500 RPM. (I made my own and replaced once a season when I ran CFF, quality ones are available from Averill, Pegasus...)

Kip

[billtebbutt]

2. In it was the observation: Carburetor problems is usually spelled, "Check ignition."


Check your battery. No, am not kidding. Two weeks ago at Shannonville, mid session, right after turn-in to the hairpin, my RF 90 started to hesitate for a second or two, then would clear itself up and be fine. This went on for any number of laps until the car just stopped running. My first instinct on track was fuel (did I break a float, forget to top up the tank, etc?). But when the car eventually stopped running period, I discounted that. Had to be the Pertronix, or the coil, right, as they can fail.

By the time I got it towed back to the paddock, I realized that the Aim dash had been flickering a bit as well. Master switch then, right? Battery cable connection maybe?

In an uncharacteristically (for me) bout of calm, I decided to check the voltage at battery in the paddock before riping into the ignition system: it was 12.5 volts. Put a high quality load tester on the battery (thank you for the recommendation some years ago, Eric/EPix!), and the battery showed a smashing 4.5 volts. Had David Clubine double check it with his super fancy tester, and all he said was "Oh, that's not good" .

Clearly, on track, a plate in the battery had become dislodged that caused an intermittent short when the car was thrown in to the hairpin, that corrected a second later when the side load was reduced post apex. Eventually the plate decided it had had enough of this, and completely trashed the battery. Slipped in the new spare, and all good

good luck

bt

[DaveW]

Minimizing the probability of battery issues is one of the reasons why I'm using a DEKA ETX-18L AGM in my Citation F2000/FC. DEKA is reputed to be one of the best for resisting vibration, etc., failures. It also has enough reserve power that I never use a jumper battery, even for multiple starts w/o recharging. DEKA ETX specs from about 10 years ago below: