1978 Evinrude 140 V4 Only firing on 2 cylinders

[snuggpot]

Hey everyone, I am new to outboards and boats in general but I picked up a project boat to tinker with and learn. I picked up this boat knowing it would need work and I have ordered a service manual from Ebay to arrive this weekend. She starts easily and runs but is not firing on the port side. I have a decent set of tools and am looking forward to solving but I would like to lean on your expertise to avoid spending money needlessly. Where should I start?

Model #140843C
Serial # J0003472
Compression (Harbor Freight) - 85-90lbs on all four

Problem: Only firing on starboard cylinders.
Symptoms: Idles rough and back fires. Starboard block is warm to touch not hot.

 

[snuggpot]

Also visual inspection it appears the the port cylinder and block is not the original. It is stamped 320370 which I googled and it seems to coincide
with the 115 engine?
Wiring appears to be in poor/average condition for its age. The coils do not appear to be in factory locations.

 

[jimmbo]

Welcome to iboats

There are considerable differences between the 140 heads and any crank rated 115 heads(pre 1985)

You compression numbers are poor. Could be the gauge, so try another.
You might have what is referred to as a Frankenrude(a cobbling together of a bunch of parts from several motors, sometimes of different years)

 

[snuggpot]

It certainly appears to be a frankenrude, but after thinking further I imagine it would be nearly impossible to swap blocks/heads due to the bore?

I agree about the Harbor Freight Compression Tester. Most likely will need to get a better one as I already suspected it was faulty,

 

[jimmbo]

The 140 and the 115 up till 1985 used the same bore and stroke, and in most cases, the same block(1977 and maybe in 78 there were some differences in the Block). In 85 the 140 became a looper and few, if any parts interchanged between it and the older crossflow block.

 

[snuggpot]

The 140 and the 115 up till 1985 used the same bore and stroke, and the same block. In 85 the 140 became a looper and few, if any parts interchanged between it and the older crossflow block.

Very interesting! How did they massage more power out of a 140? Bigger carbs/jets?

 

[jimmbo]

Very interesting! How did they massage more power out of a 140? Bigger carbs/jets?

Different jetting, some years not all, used larger Carbs, Crankcase Stuffers, different Heads, and Exhaust Tuning.
You can turn a pre 85 115hp(1979 -1984), into a 140hp, by changing/adding those parts. In fact a 1979 thru 1984 90 hp can be converted to a 115 by some Machining of the Block, and part changes. It can also be turned into a 140. After 1984, when Prop rating came along, the HP rating are a bit more muddled, but the old 140 survives as a 110, a 112, and a 115. If any of those engines have the Turtleback/Bubble Back Exhaust Cover, they shared a lot of the old 140s parts

 

[snuggpot]

Here is some, "eye candy"
Lots of wiring looks like it should/needs to be redone.
I am off to buy a better compression tester.

 

[racerone]

The 85 HP before 1979 had a 3-3/8" bore I believe.----The 88 / 90 /100 /115 /140 all had a 3.50" bore from 1974 to 1998 models.----Your compression numbers are not encouraging !

 

[snuggpot]

The 85 HP before 1979 had a 3-3/8" bore I believe.----The 88 / 90 /100 /115 /140 all had a 3.50" bore from 1974 to 1998 models.----Your compression numbers are not encouraging

Fingers crossed the tester was inaccurate.

 

[jimmbo]

In 1979 the 85 did become a 99.6 in engine, and a 100hp appeared. In 1981, the 85hp and the 100hp were dropped and the 90 appeared

 

[racerone]

The V-4 crossflow was a staple production engine.---The 100 HP was only offered in 79 and 1980.------All about marketing.-----Same pistons fit a 1974 and 1998 model 115 HP.----I do not understand why the design of top piston ring was not changed.

 

[saltchuckmatt]

With all that corrosion it could be a wire but after cleaning up the wiring swap the coils from one side to the other and see if your problem follows.

Your boat looks fast!

 

[snuggpot]

Got a higher quality compression tester and got these readers from a cold engine. I am thinking that compression isn't the main culprit at this time. Looking forward to getting my service manual in so I can start using my multimeter to go through the electrical.

Also will note that I trickle charged the battery overnight and the engine turned over much better this morning.

 

[racerone]

Some will argue.-----Pull the head off on the starboard side.-----I do not believe you will like what you see.---If I am wrong then a head gasket is cheap.

 

[Doh]

Only fires on the Port Side? What is in common to both Port Cylinders? I see 1 Coil/side. Quick try, swap the coils side to side and see if the Starboard side runs.

 

[snuggpot]

My service manual arrived today, so I am going to dive deep into this project this weekend. I ordered a new set of coils due to visual inspection showing that the housing was damaged on two coils. I also found a bullet connection that was not connected on the port side preventing any possibility of the lower port cylinder, cylinder 1, firing.

The manual is honestly a thing of beauty, very excited to learn how poor of a decision buying this boat was.

 

[racerone]

Upper cylinder on starboard is #1

 

[snuggpot]

Swapped in new coils and now I am running on all cylinders!

Does anyone have suggestions for good replacement control cables.

 

[jimmbo]

BRP comes to mind