fuel system swap

[hawkman222]

A few weeks ago I posted a question about swapping out a blown 1985 Evinrude #E90TLCOS powerhead with a 1979 Johnson #J85TL79R. Responses to my question seemed to think the swap would work. I've since learned thatthe blown powerhead is a J90TLCUS (1987) that was apparently put on my 1985 Evinrude before I bought it. I still think the 1979 85hp will work. It was sugested that I use the newer fuel system off the blown motor. It has the primer system & VRO instead of the choke with conventional fuel pump. The problem is, I'd like to use the newer intake manifold with lube recirclation on the swap but the recirculation lines come together and combine into 1 line that goes to the crankcase to lube the crank center bearing. The old (1979) crancase cover doesn't allow for this, no nipple. So, where would I run this line? If I use the old intake,there is no crankcase tap for the flame arrestor fitting going to VRO pulse line. Could I use the hole which drives the old fuel pump? I'd have to retap it (YIKES!) or use a bunch of different fittings to get what I need. Could I use the old fuel pump, the old intake and install the primer system? Would the convetional fuel pump work with the primer system?<br />Or should I just throw in the towel and use all the old fuel system off the 1979 before I break something?

 

[tashasdaddy]

Re: fuel system swap

imho, throw the towel and premix, i still don't trust VRO's

 

[hawkman222]

Re: fuel system swap

I'd like to use the fuel primer set up and the bottom feed carbs from the newer motor and ditch the choke. I guess at this point the question is, will the conventional fuel pump provide adequate fuel and pressure to operate this setup? I know the VRO pump will, I'm just having trouble figuring out how to get all the newer stuff to work with the old.

 

[Dhadley]

Re: fuel system swap

You can actually drill the crankcase but you'll need to take it apart to do so. Rather than doing that I'd just run the single line to one of the by-pass covers. Better yet, run a line from each nipple on the manifold to a by-pass cover. They did it that way in the early 80's. The #1 intake to #2 by-pass, #2 intake to #3 by-pass, 3 to 4 and 4 to 1.<br /><br />If you want to use the oil injection just make sure you have the new style OMS pump. A very good system.

 

[hawkman222]

Re: fuel system swap

I like the idea of running a line from each intake to the by-pass covers as you suggested. Should I tap each by-pass cover and thread a nipple into it? Do you suggest staying toward the top of the by-pass cover, the bottom, or does it matter? Those lines are awful small, is it hard to find nipples to to fit them? I'd think you'd want everything to fit good and snug to preserve primary compression.

 

[Dhadley]

Re: fuel system swap

Rather than drill each cover it might be best to get 4 V4 covers that already have the nipples in them. If yours dont have the boss it might be better to get different covers. Some years they used no nipples, some had 2 nipples and some had 1 nipple. Thats the one you want.<br /><br />Be sure to get covers for a V4. The ones for a V6 are different.

 

[Dhadley]

Re: fuel system swap

As far as the flame arrestor, you'll use the same pulse line fitting and the flame arrestor is an in-line deal rather than one that screws in.

 

[hawkman222]

Re: fuel system swap

Thanks! One last question. If I'm shopping around for an OMS pump, how do I know it's really an OMS and not a VRO. It seems like everyone uses the term VRO anytime they're talking about a non-conventional fuel pump whether it is or not. I'm not real familiar with the OMS pumps. I guess I spend too much time working on old motors! I'm behind the times!