The Stovebolt Site Forums The Shop Area Engine Shop 3100 216 Timing? 10/28 Update pg2

Hello all,
I have a 1950 3100 with a 216. Just rebuilt Rochester model b, new plugs, wires, cap, rotor, condenser. Rebuild fuel pump. Vacuum advance works. Starts easy. Idles like a purring kitten. Give it high RPM in gear or in neutral it sounds horrible. My wife describes its sound like a "barfing dinosaur". I can hear a back fire every once in a while in the tailpipes. I did the timing twice. Ballbearing at point. Cylinder #1 at firing position. Any help or direction is appreciated. Yes vacuum advance moves distributor upon acceleration.///I will re check points gap after work & wires// Thank you.///Update. Vacuum advance working.....points set @.016. wires all correct 153624...Will check Carb after work. Thank you All for your input.

Check the firing order, did you replace the points if so check the gap or read the dwell. Check the mechanical advance too.

Does the vacuum advance work when you rev the engine up (in neutral, hood open, and watching the distributor)?

Starts easy
Idles smoothly
Increase RPMs and it barfs like a dinosaur

Carburetor? (wait to hear from an expert mechanic, or from a paleontologist)

Retrace your plug wires. You've probably already done it but look again. Sstock has offered a good suggestion. Double/triple check the point gap.

Mine was similar, idled great,but as soon as rpm came up it puked....it was the Carb.

JAHacker, Rochester model b carb? Also did your backfire in the exhaust? Thank you.

Could be fuel or advance timing, a couple easy checks to isolate.

1) with the engine idling, open the throttle by hand and verify the whole distributor rotates. If it does you're vacuum line is tight and the vacuum advance unit is good. If not troubleshoot the vacuum line and advance unit.

2) if #1 works, check the carbs accelerator circuit. Make sure the little accelerator rod is connected to the throttle linkage. With the engine OFF, remove the air cleaner, shine a flashlight down the carb and manually work the throttle to wide open, you should see a squirt of fuel. If not, either the linkage is off or the pump inside the carb wasn't installed correctly or damaged. disassemble and troubleshoot accordingly.

Good luck

UPDATE///// Pulled the spark plugs (R45) All 6 had black(Soot??)on them like burned fuel???? Also pumped accelerator , looked with a bright flashlight and I DO NOT see any gas squirts at all. Carb for sure????

That would explain the lean pop when you blip the throtte but at sustained higher speeds you are on the main metering jet. If it is a rochester carb, I had to run a jet size richer because of the 10 percent alcohol that they are putting in the gasoline these days. It would buck at highway speeds otherwise.

We just rebuilt the carb on our truck because it wasn't starting well, and wasn't squirting fuel. Someone had recently gone into the carb and left out a few pieces - ball valve for the accelerator, also another ball valve, spring and T clip. Starts and accelerates better now, quite rich but I'll get to that.... It squirts a noticeable amount of fuel for sure now. Did it seem to run well before rebuild? Likely something was left out or stuck now?

I have the carburetor off and all apart. Prior to running it sat 43+ years.... Since I did not see any gas "squirt" I am going to check the power piston and pump. Must be semi or blocked somewhere. I do have a second carburetor (Rochester model b) and might go through that one and run it to see if problem gets eliminated.////

I have the carburetor off and all apart. Prior to running it sat 43+ years.... Since I did not see any gas "squirt" I am going to check the power piston and pump. Must be semi or blocked somewhere. I do have a second carburetor (Rochester model b) and might go through that one and run it to see if problem gets eliminated.//// It should be noted I cleaned and rebuilt the carburetor after it sat for 43 years.***** All parts were in carburetor when I took apart, both T& ball including the 2nd ball for needle on power piston. With gas in bowl I manually pumped and gas did come out the T area. Going to clean & re assemble. Then test with mineral spirits.

Reading up on the Rochesters, for some reason it's not uncommon for people to leave out the ball check valves, so on the accelerator pump all you do is pump fuel back into the bowl.

///Weekend update: Carburetor cleaned all parts were inside. Back on . Engine off throttle down CAN SEE squirt of gasoline now. Starts right up.....Purrrss like a 216 should. Give it higher Rpm's and its doing the same as before. (I did confirm fuel pump & how much was pumping out before remounting carb.) I'm scratching my head... Stuck valve? Would or could that make it horrible at higher Rpm's? But idle perfect? A bit frustrated but keep moving forward. @@@ will remove valve cover after work and start there.

Valves might be the next logical check.🛠

My truck ran like a top for 25 years, then one day it started running weird, popping sometimes gas would pour out of the carburetor, sometimes not, I did everything from new gas tank, new lines, new points, condensor plugs, wires, three different carburetors, propped the heat riser in the opposite position it was in previously, (don't do that !) nothing helped. Then one day it started up and as ran like it always has. Still no idea.

You might want to check for a broken or weak valve spring.

Try his easy check.
With engine idling, slowly increase rpm until it starts missing then manually start to slowly close the choke to see if it evens up or if you have an automatic choke use your hand to slowly partially to fully covering over the carb to see if it evens up.
If it does you have a carb problem, probably blocked main jet, power jet or internal passage.
If it doesn't you probably don't have a fuel delivery problem and need to pull the valve cover and check valve adjustment and operation.

Good luck