Stumped by a 5 1/2

Okay, back to old Evinrudes. I bought a basket case 1958 5 1/2 Fisherman, it came in two milk crates, but I was told it did run. Well, I reassembled it enough to try it, and it did run, but badly. Okay, new coils, new points, new wires and plugs. Did a carb rebuild, cleaned the tank, new lines, new everything, tore the gear case apart, replaced gears and bearings and seals, new impeller.

Tried to fire it yesterday, after the new paint had dried enough to be handled. Long story short, nothing!!!!!! I set the timing with an ohmmeter, so I know thats ok. Great spark, jumps a 1/4 inch gap with a loud zap, on both wires. The carb is getting fuel, the float bowl and filter are full, and there is fuel in the carb throat. All I got out of about an hour of pulling was a couple of backfires from the carb. I even tried reversing the plug wires, thinking I might have switched them. That got me one backfire out of the exhaust. I sprayed ether into the carb throat with the throttle wide open. Nothing. Tried ether into the clyinders direct. Nothing. I started with the low speed needle 1 1/2 turns open, and the high 1 turn open. Adjusting them did nothing. The plugs aren't wet with fuel after all the pulling. The compression is a bit on the down side, about 80 lbs each. If it ran with all the old stuff in it, including a carb float that was broken in two, why won't it even kick now???

If you have spark, compression, and fuel....... what is left is the flywheel key (timimg).

Possibly the key slipped out of place?

You are using Champion J6C plugs, gapped at .030 ? If not, do so.

The key is there, I have re-checked the timing using the timing marks and an ohmeter, and I do have new Champion J6C's at 30 thou. Could the lower compression have something to do with it? But why aren't the plugs wet after pulling over for 15 min with the choke on? Why won't it fire on ether? Why did it run on old junk parts, a fouled carb, but not on new ones? Why oh why lol.

Oh Oh...just re-checked comp. Now have about 10 lbs on the top cyl, about 70 on the bottom. Maybe a broke/stuck reed valve? I didn't pull the powerhead apart during the rebuild, so I shouldn't have messed anything up in there. I still would think it should have at least tried to run on one cyl with the ether.

No reed plate in that model, it has a "leaf valve plate". This has nothing to do with compression.

Remove the cylinder head.... hopefully you simply have a bad head gasket.

Reed valves have nothing to do with compression in the cylinder !!----------Check for a blown head gasket.

One part I did pull was the head. It had a stripped plug thread. Had it helicoiled, and replaced it with a new gasket.

Gasket is good. Re-checked comp, the guage wasn't sealing in the top cyl. Now have 70 psi in both. Is that enough to fire it? Should I be looking for another powerhead?

Just thinking here....like I said, it ran when I got it. As part of the rebuild, I did take the carbon off the pistons with a fine wire wheel. I'm wondering if by taking off the carbon, I decreased the compression enough so that it won't fire. I can fill the clys with ether, or gas, and barely get a kick out of it. I'm going out tomorrow to buy a gallon of fresh premium gas, and try that.

What gas to oil ratio are you using??? If you need to prime the engine, use a squirt oiler filled with a 25 to 1 gas oil mix...too much ether can reduce compression and damage the engine parts

30:1 ratio. I know it calls for 24:1, but I figured for a quick run in the test barrel it wouldn't hurt. It hasn't hurt it, cause it hasn't fired yet. I tried priming it using gas and a squirt bottle, first through the carb, then directly into the plug holes. Still no kick, gas just runs out the exhaust ports. After that, I tried ether, through the carb first, then directly into the cylinders. I tried opening up the plug gaps to 40 thou...still nothing. I'm still thinking the 70 psi compression has a lot (or all) to do with it.

Bill W.
When I first revived My 55' CD12 It had sat for about 20yrs. and was stuck. The compression
was 55lbs and it started, didnt run so good at first. But after a tank of gas with a bunch of
Sea Foam, The compression is 85lbs on both cylinders.It runs real good now.
Sounds like it's time to stand back, Have a beverage of choice, Then check all the basics again.
Good Luck
Steve A W

Okay Steve, I followed your advice. Sat back, and thought about it. What did I take apart that I might have screwed up? So, I took it back to where I tore it down to, and sucess. One of the leaf valves was misaligned, and staying open. I fixed that, refilled the tank with fresh premium gas at 30:1 (with some seafoam), and got it running. New problem now. It won't idle, anything below about 1/2 throttle, and it dies. It seems to go to running on one cyl, and even at full throttle, it stays on one cyl. Left long enough, it either dies, or the other cyl kicks in, and off it goes. I know that it really needs to be on a boat to set the carb needles, but the best I can do right now is a 50 gal drum. The high speed needle is at about 3/4 turn open, and the low is at about 1 turn open. The carb seems to be really sensitive to adjustments. Any suggestions??

IT LIVES. Bought a timing light, used it to track down an intermittent spark on the bottom cyl. I switched coils, that didn't cure it, filed the points, that didn't cure it. Finally just let it run, and the miss started to go away, until it finally went away all together. Now it purrs at both high and low speed, and keeps getting better with time. Thanks to all for your help, and to Racerone for letting me know that you can time these things with a light. By the way, my final point gap wound up at about 23 thou. Now its on to my 18, time to bring it back to life, its had about a 15 year nap.