[dpoltzer]

Thanks for the good info SD455DJ, The cam is a stock equivalent 068 style. I do have have 17 inches of vacuum at idle and the needle in the gauge is very still, so I don't think there is a vacuum leak. I will richen the carb 1/2 turn and see what happens. I can still set the timing down tp 9 BTDC to see if these two adjustments helps. If these two adjustments don't help, I will try and find
someone in the Daytona Beach, FL area that can tune/curve the distributor as I have no idea on the total advance. Is 35-36 degrees a good target? Thanks again.

[SD455DJ]

Dave, Your ultimate total maximum mechanical advance will be unique for your engine, but 35-36 degrees may work if there is no detonation or audible pinging. I like the initial set at 9 degrees (factory setting for all the '70 4-bbl d-port engines 330 hp to 366 hp) and calibrating for 36 degrees max if your engine is 93 octane tolerant and you can keep water temps under 190. The 9 degrees initial will help with hot starts vs. the 12 degrees if you have around 10.0 compression.

Dennis

[steve25]

Here's another few things I need to ask,did the car ever run right without this issue happening?

Has the car sat for a few months without running?

If so then I would pull the top off of the Carb and look for signs of today's fuel turning into a jell that is either hanging up the primary metering Rods, the power piston or both.

[Formulajones]

You should be able to lug a RAIII all the way down to idle if you want to without complaint. Those 068 cams are baby smooth, not big at all, make tons of vacuum, and don't complain at all at low rpm. I have pretty healthy camshafts here with stick shifts behind them that will idle down all day in high gear and creep along at 30 mph, even in 5th gear, but it takes some tuning and quite a bit of time spent to find what the engine likes. But it's worth the time and effort because it makes driving the car much more pleasurable with no need to hunt for the right gear all the time when putting around town.

On my RAIII I have 14 initial timing in mine, and 34 total. I daily drive it and it's just as happy as can be right there on 91 octane and 10.13:1 compression. I don't have the total all come in until 26 or 2800 rpm if I remember correctly.

What took some fiddling was the idle circuit in the carb, and the vacuum advance on the distributor to make it behave nicely in all idle and very low rpm conditions.

I ended up drilling the idle feeds in the carb with a set of long bits I have just for that purpose on a Q-jet, way back decades ago before I knew I could get those idle tubes from Cliff and just replace them.
Since you put a Cliff kit in it, I'll ask if you pulled those idle tubes out of the main body and replaced them with a set Cliff supplies?? If not, that's likely going to need to be done on todays fuels, because with ethanol the stock calibration is just too lean. If you did, it might be worth a call to Cliff to see what he may have sold you, my guess is if he sold you a set and you replaced them then they are probably fine since Cliff does take into account todays fuels with his calibrations. Wouldn't hurt to ask.

The other area I spent a bunch of time on with mine is vacuum advance. On the 70 RAIII carb, there is no ported source for the vacuum advance. I think the factory may have ran it to a thermal switch on the intake but I don't do that. So this car is running manifold vacuum. To do that I had to weld and modify the vacuum advance and this particular combo liked 11 degrees additional from the can, and I have that start working at 6 inches of vacuum and all done at about 10 inches. So it's working at it's peak most all the time at light throttle and idle conditions but will pull timing out with moderate blips of the throttle. So at light throttle cruise the engine is actually running with 45 degrees of "all in" timing if I'm running down the highway at 2800 rpm.

The result is baby smooth running at any rpm, and 17 mpg highway driving.

Hope that helps.

[dpoltzer]

Thanks again for the great information. I will dig in to this weekend. BTW. Cliff himself did all of the carb work and I also test ran this same carb on my other car and it performed flawlessly. I really think the problem is with the vacuum advance.

[Kenth]

Did you set the initial 9° with vacuum advance disconnected and plugged?

[dpoltzer]

I disconnected the VA hose from the intake manifold port and plugged the hose and capped the port. I then set timing at 10-11 btdc. I have about 17" of vacuum. If I retard the timing a bit more my vacuum drops a bit too much. The motor was professionally built with under 100 miles on it.

[Kenth]

I would advice against using the vacuum port om #1 intake runner since the vacuum signal in this port is weak and fluctuates. Not what the ignition vacuum advance wants..
Better to split and put a T on choke pull-off hose for the vacuum advance if full vacuum advance at idle speeds is desired.
Best however is to get the TCS system working as intended.

[kenelder]

I had a very similar issue with my '64 GTO clone, went nuts trying to find it. Tried almost everything suggested in this thread. I thought the carb had a problem.

Turns out the distributor had the "uni-point" set in it (points and condenser on a single plate, one screw to install) and after reading a lot about points and condensers decided to change them to standard set. The uni-point set looked new, there was no arcing on the points, etc. Went ahead and got the NAPA Echlin brand separate points and condenser and installed.

Presto, no more lugging issue. So it was not carb or timing but likely a bad condenser.

[Schurkey]

Originally Posted by kenelder

I had a very similar issue with my '64 GTO clone, went nuts trying to find it. Tried almost everything suggested in this thread. I thought the carb had a problem.

Turns out the distributor had the "uni-point" set in it (points and condenser on a single plate, one screw to install) and after reading a lot about points and condensers decided to change them to standard set. The uni-point set looked new, there was no arcing on the points, etc. Went ahead and got the NAPA Echlin brand separate points and condenser and installed.

Presto, no more lugging issue. So it was not carb or timing but likely a bad condenser.

For every problem, there's one or two "typical" or "common" causes. We tend to forget how inter-connected/inter-related our automotive systems are. If there's one or two common solutions to each problem...there's probably twenty five possible but less-likely repairs that could be needed.

"When you hear hoofbeats, think horses not zebras." Except, sometimes it really is a zebra.

[Greg Reid]

Originally Posted by dpoltzer

Stock distributor is new from Napa as is the coil, plugs, wires, points, cap rotor etc....

These guys know way, way more than I ever will about this stuff but I wouldn't be real surprised if some of that new stuff was crap, especially the distributor. Hard to get anything but junk over the parts-counter any more for these cars, especially something as critical as a distributor.

["QUICK-SILVER"]

Originally Posted by Greg Reid

These guys know way, way more than I ever will about this stuff but I wouldn't be real surprised if some of that new stuff was crap, especially the distributor. Hard to get anything but junk over the parts-counter any more for these cars, especially something as critical as a distributor.

Wonder if "new" to the OP is a factory reman or china repop?

Clay

[dpoltzer]

Bought it from Napa but it was a Cardone re-man unit. I did richen up the carb and set timing to 9 BTDC. Will test drive soon to see if that helps as suggested here earlier.

[dpoltzer]

Took a test drive last night and making those adjustments made improvements to the "bucking" and "lugging". I think I can live with it now. Thanks everyone for the input.