The Stovebolt Site Forums The Shop Area Engine Shop Vacuum gauge reading / rebuild

Jist had my 216 rebuilt after cam gear problem. Engine timed to specs, points @ 22 thou, carb idle screw @ 2 turns out. Engine runs fine at idle - sluggish as far as pick up is concerned. Not as responsive as I would like. Vacuum guage reading shows "18" and falls in the slow ignition range. However when I advance the distributor, the readings do not change. What to check next? Thanks, BW

Where'd you hook up the vacuum gauge? Did you try over-retarding and over-advancing distributor while watching vacuum gauge? If you're not getting varying readings on gauge then something ain't right. Assuming your timing marks are correct, you might try bumping it up a couple degrees from spec. then bolt it down and start zeroing in on the carb. The carb rebuilt also? After setting timing, did you play with the mixture screw while checking vacuum readings? You wanna go as lean as possible without affecting performance. Well, I guess maybe answer a few of these questions and we'll all go from there.
-David

BW,

It has been a while since I worked on a 216 intake but my dim recollection is that it is similar to a 235/261.

Is there a chance you have the carb gasket and/or insulator on wrong? There is a notch/hole in the gasket and a notch in the insulator (between the carb and the intake) that is a vacuum "journal" (at least that's the case on a 235/261.

Maybe someone with more experience will reply.

Good luck,
Tim

To answer Mugsy's questions - vacuum gauge hooked up at intake manifold (wiper hose). Carb was rebuilt and idle screw adjusted 2 turns from seat. Advancing / retarding the timing has little effect on gauge reading = 18. Are points set too wide (.022)? Book says .018, but these points are new. BW

Set the points at 18, will probably make a big difference.

Yeah, .022 seems a bit wide. Try .018 and set your timing a couple degrees above spec. and leave it there. Now of course no two 216's are the same but, we advanced my neighbors 216 a few degrees from spec. and it seemed happier, more responsive.
Now with your engine fully warmed up and vacuum gauge connected are you getting the highest steady readings with mixture screw right where it is at 2 full turns off seat? Try leaning it out while viewing the gauge. Turn in small increments, 1/8 or 1/4 at a time and allow engine a couple seconds to react. What's the verdict? Points, timing and mixture make any difference?

Forget the vacuum gauge. Use a timeing light &
line up the ball in the flywheel with the vacuum
line disconnected.than kick it up about 5-7 degrees. Than hook the vacuum up. Turn
the idle mixture screw in slowely till the engine
starts to slow down. Than back it out a half turn
or were the engine runs smoothest. Road test it.
It should run like a top. If it pings under hard
acceleration drop the timeing back a little.

This is both a question and comment. How long have you run the engine to break it in, or does this matter. I had a similar problem but after some running time and adjusting like Wrenchbender reccommends,it went away. At some point Re-torquing the head and the valves is also required.

I looked closely at the "Octane" adjustment on the vacuum advance and found it locked down in the "retarded" side. Set it back to 0 with mark on the plate and tightened down the bolt. Engine runs much better now, as I also did advance the timing 2 degrees. Vacuum reading at a steady 20 now. Took the truck out for a several mile ride (63 degrees / drizzle here in WV) and found the engine responsive and very peppy! Thanks for all the input and suggestions. I am slowly "learning" these old trucks. BW

Good deal! 20 is a good vacuum read. Sounds like you've got a nice engine there. My neighbors 216 really surprised me. Good motor.
Happy New Year.
-David

Robert ;

Remember to check & re-adjust the valves as need in 500 , 1,000 , 2,000 & 3,000 mile increments as they will tighten up on a fresh engine .

If you can borrow / buy one of those nifty timing lights with the dial on the back , set the timing to 32* all in using the triangle as TDC referance .

If it doesn't ping when you stamp on the throttle in top gear @ 35 MPH , engine fully warmed up , it's not too much advance , be sure to test it this way no matter where you set it .