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1965 buick special 300 v8 cant get it running right please help (timing,idle,points etc.)


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hey guys im pretty new to the forum i have a 65 buick special with a 300 in it (v8) and she feels like shes got no power and kinda skips or chokes when i try to accelerate and this also makes it so she doesnt really accelerate past 35 without a hell of a struggle an plenty of noise lol, i rebuilt the carb, put new pluggs in it new plug wires and headers with a dual exhaust, today i tried putting a new set of points in the car, i then adjusted the gap to .016 with a feeler gauge and reassembled the distributor, after this i installed a tach so i could check the rpms, i then set the idle with the choke off, vacuum advance disconnected and plugged up to prevent vacuum leak to 550 rpms with the screw connected to the throttle, after this i put the timing gun on and adjusted the timing to 2.5 degrees on the scale with vacuum advance still disconnected and plugged, after all this i tightened the distributor down plugged the vacuum line back into the vacuum advance and took it for a spin and needless to say she still feels about the same, i haven't adjusted the mixture screws yet because it was getting dark on me but i dont think they single handedly would make it run the way it is although i could be wrong, when setting the ignition timing do i do that at the 550 rpms or lower then set it to 550 afterwords? and what should the idle speed be set at after all this is that the 550 rpms? any other ideas ?? im a 21 year old floorman and learning as i go so this isnt my territory any advice would be greatly appreciated lol

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If the specs call for 550rpm as "base idle", that's fine. Optimizing the idle mixture (screw) adjustments might increase it a little, but hopefully not too much, although you can see the speed increase as the mixture gets to what the engine "likes", at idle. The mixture screws affect ONLY the idle mixture.

I tend to concur about the plug wires being on the appropriate spark plug/distributor cap locations. ONE plug wire not where it is supposed to be can really make a BIG difference in how things work!

As I recall, the points adjust with an Allen wrench via the "sliding window" on the side of the distributor cap? On an aged distributor, the cam lobes the points "ride on" can become worn, making the point gap and dwell reading not correlate too well on ALL of the cam lobes. I also hope you used some "point grease" on the point set's rubbing block when you changed the points?

In some of the service manual illustrations, you can see how the distributor's supposed to be "angled" (or where the vacuum nipple on the vacuum advance is "clocked" in the engine) and where #1 plug and #1 plug wire are supposed to be.

I hope you checked the gap on the new spark plugs? Verified and adjusted them to .035" gap, rather than just putting a drop of oil on the threads and installing the plugs? Will the vacuum advance unit hold vacuum?

Something else might be a clogged exhaust system, due to a muffler baffle that's come loose internally and is blocking exhaust flow through the muffler? Or possibly a collapsed (internally) exhaust pipe? Back when GM used "bead-style" catalytic converters, they could be prone to clogging. When that happened, the car would not run much past 35mph, if that fast. Taking the exhaust y-pipe loose from the exhaust manifolds was a quick check (other than feeling the flow out of the rear tailpipe). Usually, once the exhaust was unhooked from the manifolds, the engine responded normally to throttle input (without having to drive it, just running it in "Park"). Once the new converter was installed, everything was "right" again.

In the 1990s, we sold lots of Chevy HD2500 pickups. Many of our customers were in the horse hobby, so they pulled long trailers all over the countryside going to shows and competitions. Under continued long pulls, the exhaust would get hot enough to cause the bead converter to overheat (enough to cook the carpets on the rh front seat side through 3 full inches of heat insulation!). When the bead converter failed, the beads then went through the muffler and stopped at the honeycomb monolith (NOx) converter behind the rear axle. When that converter became sufficiently clogged with beads, the truck would slow down and (soon) stop, regardless of how much throttle was used. ONLY way to fix it was a complete new system from the y-pipe to the rear tailpipe area. Plus some new factory carpet/insulation. Some suggested shaking the beads out of the muffler, but any residual beads would eventually find their way to the rear converter (new) and then cause another failure, so we put the whole system in and then made sure the fuel system was operating correctly after that.

Please keep us posted on your progress.

Just some thoughts,

NTX5467

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