Merging a pair of V4s - 1979 140 with a 1978 115

[drumz2129]

I have a 1979 Evinrude 140 (140943R) on my 15.5' Stott Craft Bass Boat. First, a little history on the boat/motor. I purchased the combo from an acquaintance who had a ice bag wrap around the foot while on the river and smoked the head. He had it bored .030" over, and a new impeller installed (according to the receipt he gave me). He had never put it in the water after having the work done. He had three kids back to back and had no time. I followed the break in procedure with a 25:1 mix. The boat has always been very hard to start, and would not idle unless fully warmed up. I have fought it for 5 years.

This past weekend I decided to get it running after sitting for 1.5 years. I noticed the starboard cylinders were over 200deg while the right side was still under 100. First thought was stuck thermostats. I pulled the t-stat cover and found nothing. Not good.

Next I ran the engine with the cover and hoses disconnected. I had a steady stream of water out of the port side and a erratic stream out of the starboard. Blown head gasket.

After pulling the heads I determined that the block was bored .030" like the previous owner claimed, But the 'mechanic', and I use that term loosely, Installed the starboard head gasket upside down.

Which you can see, toasted the head and pistons.

The port side had a little moisture in the bottom cylinder, but the head gasket seemed to be intact.

The heads were clean

Here is my plan, I have a '78 115 (115ETL78C) flat back that was given to me in good running condition but has a lot of corrosion on the foot (it sat in a freshwater boat slip most of it's life). It seems to have been properly maintained by a local marine shop. It's only owner was my friend's grandpa who has since passed away. The tale-tell mod where you tap each side of the block for water has been done. The port head gasket has been changed, while the starboard has never been opened.

After a compression check on the 115, I will pull the powerhead and put it on my 140. I will reuse the 140's carbs, reed blocks/reeds, exhaust manifold, power packs(both new), and coils (all are new). Are there any other items I should swap from the 140?

I have read that the '79 140's heads are high compression, but one of mine is fried so I will have to go with the 115 heads, will this create much difference? I will now be able to use regular pump gas instead of premium.

I will also be changing the impeller and getting the proper thermostats and pressure relief valves.

I plan to pull the heads on the 115, check all the water passages and change the tubes. I will go ahead and get a full powerhead gasket kit and change all the one I get to.

Is there anything I am missing, anything else I should look for?

 

[drumz2129]

Re: Merging a pair of V4s - 1979 140 with a 1978 115

Also, Should the timer base and stator be swapped from the 140 to the 115?

And is it normal for a set of heads to be as clean as the set without the blown head gasket? The spark plug in that cylinder was clean, as in looked brand new.


Thanks for any help.

 

[emdsapmgr]

Re: Merging a pair of V4s - 1979 140 with a 1978 115

Why not reuse the 115 carbs on the 115? The 140 is considered a high performance engine. If you swap the 140 carbs onto the 115, it is possible they will overfuel the powerhead. Those 140 carbs are jetted for a high port block, high compression heads, with bubble back exhaust. That's not what the 115 is. You may have running issues with the 140 carb swap without some modifications. You probably can rejet them to work, but it may take some fiddling to rejet them. Try them and see how they work out, then decide. The intakes are the same, so no need to swap them along with the reed boxes. The ignitions sytems are nearly identical, so no need to swap them unless you want all the new parts. The 140 exhaust manifolds will not work on a 115 unless you transfer the exhaust filler blocks, then deck (machine) the exhaust flat on a mill. A lot of work for little gain. I'd check your factory service manual regarding the required octane for the fuel. Possible all those engines of this vintage were rated to run on 89 octane fuel, not today's 87. You may have to run midgrade fuel. 3 of the 4 heads appear to be washed-water cleaned. Only one looks "normal" with carbon residue on the head face. You know one of the head gasket rings was bad, so you may have water getting into that cylinder through the bad head seal ring. On the other head, both look water washed. You may have something else going on, like a water leak in the exhaust area. Something else is wrong. You appear to have one original head on that 140 engine and one replacement head. The pitted head may be original to the engine, the other is a later (bathtub) head which is low compression. That will result in a significant compresson mismatch in between the two cyl banks. You may well solve a few other internal issues with the 140 powerhead when you replace it with the 115 block. Lucky that you have that other powerhead. It should bolt right up.

 

[drumz2129]

Re: Merging a pair of V4s - 1979 140 with a 1978 115

Thanks for the great info emd.

Why not reuse the 115 carbs on the 115? The 140 is considered a high performance engine. If you swap the 140 carbs onto the 115, it is possible they will overfuel the powerhead. Those 140 carbs are jetted for a high port block, high compression heads, with bubble back exhaust. That's not what the 115 is. You may have running issues with the 140 carb swap without some modifications. You probably can rejet them to work, but it may take some fiddling to rejet them. Try them and see how they work out, then decide.

My experience with carbs (some 2stroke but mainly 4 stroke) is that larger does not always mean more fuel. While capable of delivering more fuel, larger carbs are less sensitive to small changes since the air velocity through the venturi is lower. I will most likely start with 140 carbs (1 3/8") and if I do not have luck with jetting them, I will swap on the 115 (1 5/16") set.

I was under the assumption that the blocks were the same. I did not realize the porting was different. Is it only the exhaust porting or both the intake and exhaust. I assume stripping the block down to a bare bore is required to have the block ported to that of my 140. Is the power difference worth that?

The intakes are the same, so no need to swap them along with the reed boxes.

So the reeds and boxes are the same, so I will use which ever is in better condition.

The ignitions sytems are nearly identical, so no need to swap them unless you want all the new parts.

I will definitely use the new power packs and coils off of my 140, I am not sure if the stator and timer base are new or not. I will save all the old ignition parts for spares.

The 140 exhaust manifolds will not work on a 115 unless you transfer the exhaust filler blocks, then deck (machine) the exhaust flat on a mill. A lot of work for little gain

So running the flat back exhaust will not be much difference in preformance from the bubble back unless I have the intake/exhaust porting done. I have read that you should not swap exhaust filler blocks from one block to another, only new ones should be used. I guess I will decide on this after I have it apart and see what all is involved. I have access to a full machine shop if needed.

3 of the 4 heads appear to be washed-water cleaned. Only one looks "normal" with carbon residue on the head face. You know one of the head gasket rings was bad, so you may have water getting into that cylinder through the bad head seal ring. On the other head, both look water washed. You may have something else going on, like a water leak in the exhaust area. Something else is wrong.

I am ordering a full power head gasket kit, will this include the gaskets/seals that would correct a water leak in the exhaust area or are there others I will also need to order?

You appear to have one original head on that 140 engine and one replacement head. The pitted head may be original to the engine, the other is a later (bathtub) head which is low compression. That will result in a significant compresson mismatch in between the two cyl banks.

I did not even notice that! Thanks for pointing that out, I was blown away by the fact that the head gasket was installed upside down and how bad off the original head was to even notice that. I'm sure that was from the rebuild right before I purchased the boat. Only someone who would mount an head gasket upside down, and leave thermostats / bypass valves out would mismatch a set of heads. :facepalm:

Will the '78 115 have the same low compression 'bath tub' heads or will it be somewhere between the high compression used on the '79 140 and the low compression post '79 heads?

You may well solve a few other internal issues with the 140 powerhead when you replace it with the 115 block. Lucky that you have that other powerhead. It should bolt right up.

How much difference in power should I notice if i just swap the blocks out without moving any performance parts? Were these engines really that different? I know the Johnnyrude V4s were all over rated back then, was the 140 more so than the others?

Again, thanks for the help.

 

[drumz2129]

Re: Merging a pair of V4s - 1979 140 with a 1978 115

I did some more research, and according to Chinewalker in this thread:

http://forums.iboats.com/showthread.php?t=258737

Nope. Last year for powerhead rated was 1984 on Johnrudes. 1985 was first year for prop rated.
1984 was also the last year of the crossflow 140 and flat back 115. They became 1985's 115 and 100 respectively, and that also made 1985 as the first year with the bubbleback on the 115.
Prior to that, the "old" 115 was kind of a cross between the 90 and the 140, using the 90's exhaust plate (flat) and the 140s intake and exhaust porting (larger than the 90).
- Scott

and

The 115 and 140 (c. 1984 & prior) have the same porting. The 90's are considerably smaller. A couple years back I picked up several crossflow V4s from that era and was able to really get a handle on what went where and why. Getting a 90 and 140 block side by side was rather enlightening. The ports on a 140 block are HUGE compared to the 90. I saved parts to build up a 140, and ended up using a 1988 GT100 block as my starting point. Only thing I need to do to it is to machine out a bit of the webbing between the cylinder banks to accept the inner manifold. I also have a set of the 1 5/16" carbs for it. It'll be a true Johnrude, as it has at least four source motors for the parts so far.

I've heard differing opinions on whether adding the bubbleback to the 90 was worth the effort with the smaller porting. DHadley is the expert on what works best with what...

 

[drumz2129]

Re: Merging a pair of V4s - 1979 140 with a 1978 115

EMD, after doing more reading I found some of your post on another site with pictures of your 135 build showing the machine work on the stuffers and block and now understand what has to be done. The machine work will be no problem, though I was not planning on doing a full tear down. I guess it will be good to go through the entire engine to know what I am working with.

Is there any concern over the smaller main bearings used on the '78 vs the larger ones use '79 and later?

Assuming my 115 has a good bore and good pistons, should I rehone the bore and install new rings or go back with what I pull out?

My 140 is already punched out to .030" is it even worth going bigger? Any chance that the block is weakened or warped from being ran hot for so long? The only difference is it already has the machining done for the exhaust though I would have to use the 115 heads.

I am looking to build this into something with good power, that starts easy, nothing too crazy and picky.

BTW, I'm running a 23pitch raker.

I'm sorry for so many questions, I just want to make sure I do it once and do it right.

 

[ezmobee]

Re: Merging a pair of V4s - 1979 140 with a 1978 115

Some previous owner put 140 carbs on my 90. My mechanic was able to get them jetted down to where my motor runs great. He recommended I look for some 115 carbs but I haven't bothered since it runs so well.

 

[drumz2129]

Re: Merging a pair of V4s - 1979 140 with a 1978 115

Some previous owner put 140 carbs on my 90. My mechanic was able to get them jetted down to where my motor runs great. He recommended I look for some 115 carbs but I haven't bothered since it runs so well.

Do you know if it was the 1 5/16" or the 1 3/8" carbs? From what I have read, the '78 and '79 140s were the only ones that came with the larger ones, my 115 has 1 5/16 carbs so I have a set of each to play with. Did the PO do any other modifications to the motor or just the carb replacement?

 

[ezmobee]

Re: Merging a pair of V4s - 1979 140 with a 1978 115

Do you know if it was the 1 5/16" or the 1 3/8" carbs? From what I have read, the '78 and '79 140s were the only ones that came with the larger ones, my 115 has 1 5/16 carbs so I have a set of each to play with. Did the PO do any other modifications to the motor or just the carb replacement?

I have no idea. I bought the boat, motor ran great in the driveway, however out on the water I couldn't get it into gear without stalling it. Took it to a mechanic to troubleshoot that and he found the incorrect carbs. I don't know any specifics. As far as know, the carbs were the only mod.

 

[emdsapmgr]

Re: Merging a pair of V4s - 1979 140 with a 1978 115

I put a set of 135 large 1 5/16" carbs on a small bore 85 years ago. The engine ran, but not exceptionally well. Too much fuel. I rejetted the mains downward. Took 4 tries to get it right. Wound up with mains that were just slightly over the original 85 main size. Engine hauled out of the hole. Gained about 200+ rpm's and went up one prop size. I was happy and that small bore engine ran fine for years. You will find the 1 3/8" carbs will start and run on your engine. You will want to test them for overfueling. You will waste fuel and not get the rpm's out of it unless you have the carbs dialed in correctly. Definitely worth a try! Your heads on the 115 are good heads. (Prior to the bathtub heads.) Very similar to the 140 heads, just a slightly larger volume. My guess is that you should be in the 125 compression range, vs 135+ for the original stock high compression 140 heads. Not sure you are ready to determine which block is best to salvage yet. Obviously the 140 would be the preferred block to get running again. Here's the thing: You seem to have some water issues in the 140 cylinders. That can originate from a powerhead that becomes warped due to severe overheat. You may have some issues on the exhaust side of the block. Probably good to remove the inner and outer exhaust manifolds and check the flatness of the exhaust chest with the exhaust filler blocks. They could all be warped, requiring mill work (deck the block) to flatten everything out again. Also check the manifolds for flatness.

 

[drumz2129]

Re: Merging a pair of V4s - 1979 140 with a 1978 115

I'm glad to hear that about the heads, maybe I will be able to get by on mid grade or regular gas now. I will be going back to the camp this weekend and will pull the boat w/ the 140 home to pull and inspect the power head. For now I will pull the 115 apart to check it's condition since I will at the very least need it's heads.
I am sure the water issues are from sever overheating which leads me to believe that I should not mess with the 140 block. Like I said I have had this motor for about 5 years, purchased on a fresh "rebuild" with a backwards headgasket that caused all the heating issues. I have learned quite a bit since then.