Batmobile66

The problem is the car pings and detonates too much to drive. The car has not been running for about 3 years. This is what ive done to this point. I have a freshly rebuilt quadrajet, new delco spark plugs, 8mm wires, brand new hei distributor with vacuum advanced, fuel pump, and hoses. I tried my best to drain most of the crap gas and put fresh 87 in it.

Ive done some research and found to set timing with advanced off to +-20*BTDC. The numbers on my timing plate are worn off so i assume it is the first mark of the three, from top to bottom. I set it to the mark at around 1100 RPM. I let the car back down to 780 RPM and plug the advanced in and the engine runs smooth. I checked the timing mark to assume total time around 50* would just be right outside the plate. But when i checked it, the mark was way off almost at 12 oclock of the balancer. Ive tried adjusting it every which way i can think of. The car will idle good, crack the throttle and revs up but when you get to about 30-35 mph the car acts like it wants to die.

Idk i just want this car to run well enough to drive it home from work.

Jaybird

I have a '67 with a 425. I would suggest you use Sunoco 93 octaine. You might even consider adding a bottle of octaine booster as well. These beasts weren't made to run on today's gasoline. I'm in the process of having my engine rebuilt with low compression pistons and I will probably still have to use premium.

Jaybird

Oldsmaniac

The factory timing tab on the 66 425 is 0 5 10 and these are the only numbers on the tab. That 87 octane is not enough for a HC engine. The HC was a premium fuel engine. Just back down the timing some from factory specs and see.

65Delta88J-Scril

what is the correct timing for the Olds 425??

oldcutlass

Here are some reference sites:


http://www.tpocr.com/olds1.html


http://www.oldsmobility.com/old/tuneup.htm

R-body_mopar

The correct timing for a 425 or any engine is what was correct for the time that it was built! I have had two 425's and two 455's years ago, and they were very sensitive to fuel at stock settings.

But you need to keep in mind that these engines were HIGH COMPRESSION, and designed for fuel MUCH better than anything available today. Sunoco 260 LEADED fuel at the time was 103.5 octane at the pump, and today's fuel are totally lacking in anything NEAR that!

I gave up driving my 1970 442's back then (early-mid'70's) because I got tired of running to the speed shops for leaded racing fuel, or the local airport for leaded AVGAS!

The older engines were designed for "ultra premium" LEADED fuel, which is virtually unavailable today, except for racing fuel, and they are NOT for highway use.