Check distributor vacuum advance with a vacuum pump connected to the diaphragm , watch to see it move. Also check points with dwell meter. Installing new parts with factory settings is just a start, you must fine tune them for maximum performance or economy.
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pontiax- (canadian pontiac X frame)1964 Parisienne 2dr. Hardtop ,lagoon aqua metallic (Q) ,421 cid Dart Industries block and heads. 550 hp. 575 ft lb of torque.
I am running a six in my Beaumont and I think sometimes the comparison is made with the newer cars as far as a smooth running engine. I wouldn't call mine smooth running but it idles fine and smooths right out when you require it to work. It is the smoothest when you are cruising and it will cruise all day at 70 mph if you want it to. I find the carbs are fairly sensitive with them but they seem to run better the more you drive them. Pretty basic, points set right, time it ( I usually get it close with the light and then tweak it just by feel when I drive it) and make sure that carb is functioning right.
Like Pete (Pontiax) said, fine tuning. Is the point gap set right?, Is the timing set to factory spec?, Was the distributor ever taken out and put back in? If it is off by a tooth, it will run but not run right. As mentioned before the vacuum advance, the rubber could be cracked and causing a vacuum leak. Vacuum leaks in general, especially at the carb base. Check all the vacuum hoses going in to the carb and replace cracked hoses that might cause leaks. The push rods were changed and my question is. Were the lifters properly adjusted? They could be too tightly adjusted or too loose. Either way this would effect the running. Even thought you did replace all the tune up parts, how do you know they are all in good working shape. You could have some bad wires or a bad plug. The PCV valve hose could be causing a vacuum leak. Put a vacuum gauge on your motor and see what it tells you. You could have late valve timing or late ignition timing and the worst culprit of all is a worn out motor. Another thing to look at is leaks at the intake manifold. Check the intake by spraying WD40 around the intake runners, while the engine is running. If your motor suddenly starts running better when you spray, then you know you have to replace the intake manifold gaskets. These are some that i can think of off hand, someone else here knows more. Good luck with the fine tuning of that fine 250 engine, i have had those engines and i love them. Cheers. George.
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1957 Pontiac Pathfinder Deluxe sedan restored 261 six
1974 Chevrolet Caprice Estate wagon low mileage original 400 V-8
I notice you said you changed the pushrods. Do you know that you have the adjustment correct when you did that? Valves that are adjusted too tight (rocker arm nuts were tightened too much) would certainly cause a miss.
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1966 Strato Chief 2 door, 427 4 speed, 45,000 original miles
1966 Grande Parisienne, 396 1 of 23 factory air cars (now converted to a "factory" 4 speed)
An awful lot of possibilities here. That's the joy of playing with these old cars. You get to be a detective, slowly eliminating all the various issues.
I'd like to know how it ran before you changed the push rods. These aren't something I would normally change on a car. I might do one if it was bent.
Did you get it to run smooth yet?
Tony i would make another recommendation for your inline six. Get rid if those silly points and condenser and replace them with a PERTRONIX electronic conversion kit. For about $120.00 you will never have to replace stupid points and condensers again and never have to worry about proper dwell. The installation is as easy as two screws, the screws that normally hold the points down. I have converted all my oldies in the last 15 years or so and would never use silly points again. This may not cure the shake but once you get your motor running right, it will run ever better with the PERTRONIX conversion. Also everything is hidden inside the distributor cap, so it still looks stock. Good luck with your motor. Cheers. George.
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1957 Pontiac Pathfinder Deluxe sedan restored 261 six
1974 Chevrolet Caprice Estate wagon low mileage original 400 V-8
Hello, you need to check your timing with a timing light and if it's off, set it to correct advance (plug the vacuum line hose to the distributor with a screw while checking, the distributor will be difficult to turn(twist) try tapping after you've loosened the tightening bolt......also your new carb. has an idling screw to adjust the lean/rich mixture at an idle...for a test, turn the screw, usually at the front lower part of the carb with a spring on it, inward (clockwise) until the motor almost stalls, then go reverse one full rotation and see if it improves....good luck...TDM (4 speed)
Thanks for all the advice guys. I started off by taking the valve cover off and see if any of the rockers were sticking.
It turns out that I had them on waay too tight! So I loosened them until they rattled then tightened them up plus half a turn,I did this to all of them and what a difference it made. Almost no shake now.
Next is the timing.and a pertronix kit.
Much appreciated
I don't feel like I'm riding in a blender anymore!
Tony
Good for you. Glad to see you got it worked out. And now you know how to set your rockers . I bet some day some one is going to have the same problem and you will be telling him how to do it.
Well done
Ian
-- Edited by Beaumont4008 on Saturday 28th of June 2014 11:44:08 AM
