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Old 11-19-2020, 05:47 PM   #1
Jrappl
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Join Date: Aug 2020
Posts: 29
Default Miss on newly rebuilt 292

Sorry this is so long, just trying to give all the info I can to get a solution.

I’ve got a miss I can’t figure out in a newly rebuilt 292 y-block, auto (aluminum case 2 speed) in a 59 Edsel. I’ve got it idling at about 575 in park and 480 in gear. The spec say idle in gear should be 450 but that’s too low right now. The idle is pretty good except every 3-4 seconds I get a miss. If I increase the engine speed quickly (in park) to about 2000 it goes up smoothly and strong without any problems but if I hold it at 2000 the miss is immediate and more apparent. I’ve run it for a couple hours total so far, including about 60 miles on the road around town. It accelerates strong (for a heavy 1959 2sp Edsel) and will run at 60 mph without problems but fuel usage seems to be very high – don’t know for sure but seems like around 8-10 mpg from gas gauge movement.

Engine was bored .030 over and crank cut 0.10 under by a trusted machine shop. I did the reassembly, I’ve done a few but this was my first y-block so I did use the factory shop manual for reference. I oil primed the engine using a drill. For the first startup I cranked it for about 5 seconds (nothing), waited a few seconds, cranked it again and it started right up (after 50 years!). It has never backfired. It starts and runs just not as good as it should. Oil pressure is running about 50 at idle and up to 80 as engine speed increases. I’m getting top end oil flow on both sides. Oil is running out of the overflow tubes on both rocker shafts.

I installed new main and rod bearings, new cam bearings (with original cam), new pistons, rings, and wrist pin bushings. New timing set (sprockets and chain) and I followed the shop manual for installation and counted pins several times! I did not have the valves machined but did clean and hand lap them and then installed new springs and retainers. Installed new rocker shafts also. The valve guides, rocker arms and push rods were good and reused. New oil pump, water pump, fuel pump. I’ve adjusted the valves using the shop manual and the 15 minute (90 degree) method, no difference.

I rebuilt the original 1959 Ford 2 bbl carb (48s for jets as called for in the shop manual), I also tried an early 70s Autolite 2100 (don’t know jetting) and it’s currently running on a new 2150 knockoff (Chinese) which is supposed to have 49s for jets. Seems to run best on the new carb but the miss is there on all carbs. I have it adjusted for max vacuum at idle and I’m getting 19-19.5”. The needle does jump a little between 19 and 19.5 but doesn’t drop below 19. There are no vacuum leaks that I can find and the high vacuum at idle seems to indicate there aren’t any.

I’m using the original distributor. I cleaned it up, checked for smooth movement and shaft play (none), checked vacuum advance for leaking (none) and installed a new condenser, points, rotor, cap, plug wires and plugs. I replaced the original coil with a 12v internal resistor Standard Motor UC15T and removed the external resistor from the circuit. I’ve tested the coil resistance and it’s within specs. I’ve also tested resistance of each plug wire and again they are in spec. I don’t see any cracks in the wires and no sparks watching it run in the dark.

Timing is set at 8 BTDC with the vacuum advance plugged at idle. The mechanical advance works and adds about 10-12 (could be 15, don’t remember) degrees as I increase speed. With the vacuum advance plugged in it looks like I get an additional 10-15 degrees and it moves smoothly. So with everything connected as I increase engine speed I get a total of about 35 degrees advance. It’s hard to tell exactly because the crank pulley only has marks for TDC, 10 BTDC and 20 BTDC. I did check the pulley for slipping but the pointer is right on TDC when the #1 piston is at the top.

Point dwell is at 28 at an idle but drops a little (22-24) as engine speed increases to about 2000 rpm.

After the last road run I pulled the plugs and did a compression test. Compression is good with 6 cylinders reading about 147 and 2 at 140. I don’t know why unless the rings on those two are taking longer to seat.
The plugs did not look good. They were darker than I thought they should be (too rich I guess) and 3 were wet with fuel. Funny thing is the porcelain tip on the plugs was only dark (carbon) on half the tip, the other half was tan. I’ve never seen that before and I’ve been messing with engines for 45 years!

I’m hoping someone has an idea why I’m getting this miss. Seems like my spark is not hot enough. I’m going to swap the coil for another just to rule out a bad brand new coil but I’m not holding my breath. Could it be the carb? But why would I get the same miss with 3 carbs I have tried?

Last edited by Jrappl; 11-19-2020 at 06:04 PM.
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