Max speed 45mph [or so] ????

[George Zeck]

Hello All -

Finishing up the delayed start for the winter projects as it gets warmer in my area. In the installation of the new header - removed the SU's and then "adjusted" them a bit.

Also - my friend played around with the linkages (dual SU's).

I think my problem resides in

a) linkage adjustments (choke has never been right)
b) accelerator cable adjust

Have had run on problems and don't think the timing is off (at least I'd feel better if I were confident the SU's are OK before I start tinkering).

Anyone else have experience or therories or $.02 they'd like to share ??

Tx-

George Zeck

 

[Thor]

George,

Look at the butterfly in the chokes. Have someone push the pedal to the floor or pull on the accelerator cable and see if they open all the way.

I had a similar experience and at about 50 mph the car just had no power to go much faster. Everything was tuned, etc but the linkage wasn't setup correctly by me. Once corrected things went a whole bunch faster. Go luck.

 

[zimmy]

should go at least 70...the "power" should kick in at 40 or so........keep tinkering :wink: ...z

 

[Pythias]

evrything i've ever read about adjusting the carbs is that is the LAST thing you do. that is after its timed, after the valves are adjusted, after the oil is changed, after the car is warmed up, then and only then start to adjust the carbs.

 

[Jim_Gruber]

Run on, had that issue with Bugsy my '68 until I realized Premium Fuel only. Suncoco 240 is minimum. I get run on and dieseling with 93 octane. Played with timing didn't make much difference. We forget they had "good" gasoline 40 years ago when these engines were built and designed.

 

[Morris]

Sounds like a manifold leak to me. That would definitely give you a low stop speed.

 

[George Zeck]

Morris -

Just replaced it. I don't see any exhaust fumes leaking. Should I - if that were the problem - or would a very small amount (trace) be enough to cause the problem????

Tx-

George

 

[dklawson]

If you have an intake manifold leak it's typically difficult to achieve a good idle. The additional air often requires you to apply choke just to keep it running.

George, just for fun, get the engine to operating temp, then remove the air filters and take the car on a VERY short drive to see if you can better your top speed. Two years ago a friend of mine had a very similar problem to yours and it turned out he was running a used, dirty, K&N air filter that simply wouldn't breath. The car was great at idle and OK right up to 45 MPH. A new air filter restored his top end.

 

[Morris]

The time that I had the symptoms you have, the leak was between the carb and the manifold.

Someone smarter than me may correct me, but I doubt carb or choke adjustment alone would limit you to 45mph. It would make your car run like crap and get poor MPG, but you would be able to beat 45mph. My guess is that your issue is a vacuum leak, an improperly timed cam, a stuck valve, or a bad ignition system.

I would pull your air filters and rev the engine up to about 3000 rpm or so and observe the pistons in the carbs. They should rise smoothly to the same height and hold that height until you let off the gas. If this happens, you can probably count out vacuum leaks or a stuck valve and start looking elsewhere.

 

[Jim_Gruber]

Sure you've got the linkages connected properly? Couldn't figure out why Bugsy had no power when I started first time and took him around the block only to discover 2 days of swearing later that choke and throttle were reversed. Now since I was working from a MOSS Catalog trying to figure things out and where cables were supposed to go, surprised it didn't take me longer than that to diagnose the porblem.

 

[jcatnite]

I had a old pickup with the motorcraft 2100 carb that the choke shaft would actually suck half shut on WOT causing the truck to have a limited top speed. It was a problem in the auto choke but this could be something a bit similar.
JC