Crossflow build

[Fastbass88]

Hi all, been browsing the forum and seen lots of great info, wondering if someone could lend some advice.

Boat is a 15.5ft hydrasport veestar 90, does have a pad.

Current engine is a '87 Johnson 88. I also have a '73 Evinrude 115 and '76 Evinrude 135 (no lower or power pack on 135).

Want more ponies out of the 88, one cylinder is a bit low so was going to open it up anyway. Not sure of the condition of the 135 block but options right now are to port the 88 using the 135 specs, or swap power heads if the 135 is usable.

What would my best options be with the parts I have? Anyone have porting measurements? Don't want a full 9 page motor but a lake runner that could ideally get me to 60mph+ at 6000rpm.

[powerabout]

the powerhead wont bolt up due to 2 of the front studs being in a different place
the 135 has great heads but you will need good fuel

[Dave S]

Best Bet.... save ya self lots of work.....get a V6 150 merc ....Cheep .... common..... and ya can get parts for them....And they will blow the old stuff ya have out of the water.....I see ya up North.....and things may be harder to find....go for a ride....JMO........

[Fastbass88]

Thanks. I've been doing a ton of research and always find conflicting info. For example 115 and 135 crossflow have the same porting (different heads/exhaust/etc). My 88 is the old 115 since it's post prop rated hp. Guess I won't know until I open them up. Plan is to run 91oct.

Plan so far
-use 135 heads, carbs, bubble exhaust on 88.
-port and widen with 5/8 corners the 88 to the 135 specs
-keep the 88 coils
-throw a 23p prop on and see what it does after getting Jetting dialed.

Any better way to do it with what I have? Is dropping the bottom of the exhaust port advisable, such as in the 9 pages?

Boat parts are scarce here. Also a v6 Merc would weigh almost 100lbs more then the 88. I'm keeping this on a diet, also thought about a looper but similar weight penalty.

[FMP]

Looper 140, then start the game.

[powerabout]

Looper 140, then start the game.

Same weight as a v6 merc

[FMP]

I'll take your word for it but thought less by enough.
So a looper v4 is about a hundred more than an X flow?

Wow , big bore with big lu 368. Must have been thinking earlier version.

[Fastbass88]

I originally was thinking 140 looper if I could find one until I found out how heavy it was. I'm thinking if an old 90hp can push it low 50s, a massaged 135(130ish prop) could be in the 60s setup right. Not to mention higher cruising speed which would be used often heading to fishing spots.

[Forkin' Crazy]

Same weight as a v6 merc

A V4 looper is 400#s? Hell an old school 235 is lighter than that. And as fast or faster than a Merc 200.

[Forkin' Crazy]

Hi all, been browsing the forum and seen lots of great info, wondering if someone could lend some advice.

Boat is a 15.5ft hydrasport veestar 90, does have a pad.

Current engine is a '87 Johnson 88. I also have a '73 Evinrude 115 and '76 Evinrude 135 (no lower or power pack on 135).

Want more ponies out of the 88, one cylinder is a bit low so was going to open it up anyway. Not sure of the condition of the 135 block but options right now are to port the 88 using the 135 specs, or swap power heads if the 135 is usable.

What would my best options be with the parts I have? Anyone have porting measurements? Don't want a full 9 page motor but a lake runner that could ideally get me to 60mph+ at 6000rpm.

Find a 79 or newer 140 and build a drop on. Keep the 88 for a spare for when you blow it up. ;)

79 up has the same linkage. 78 down no.

In 87 they started rating HP at the prop instead of the flywheel. So you really have a low compression 115 or 100. I think the 87 up 115s were the old 140 with looser heads.

Some one will be along in a minute to tell me how wrong I am or agree with me, one or the other!!! LMAO!!! :D

The heads in 79 and 80 will probably be good enough. Premium fuel ONLY!!! I am more of a V6 Xflow guy. But I assume they were like that because right after 80 on the V6s they started loosening the heads or adding thicker head gaskets because of the crappy gas. No one wanted to pay for premium.

[FMP]

Chrysler ! Ha!!! Didn't expect that, did you!

[MattGreen]

Please update your location so Canadian S&F members can perhaps help more. Crossflow V4 parts are plentiful in Canada if you look in the right places.

The 135 heads are the tightest non-race V4 heads available and will work great if you use enough octane but I caution that 91 with proper timing is probably NOT enough; try Sunoco or Chevron 93/94.

To to make the ‘88 work well you actually need the bubble-back exhaust housing from the old 140s/later 115s. The turtle-back 135 is not the same. Overall Forkin is pointing you in the right direction.

Matt

[FMP]

I would think fresh 91 Shell will do the job with lots of good oil and proper tuning.

[Dave S]

I saw a 140 bubbaback in the scrappy yard.....too lazy to pull it out.......

[Fastbass88]

Thanks for the info guys, been scouring the net enough to make my head spin.

I'm from southern MB. I'll keep my eyes open for an old 140 but will also buy a lottery ticket. Im all for someone nearby that has stuff laying around!

Can I adapt the 135 carbs on the 88? As in swap the carbs but use the newer linkage system from the 88? Was hoping the ports wouldn't be to far off the 135 and use the 135 exhaust. I read it's not as good as the 140(smaller channels?) but still could be used? Thanks again for the help!

[FMP]

1980 Johnson 140 in Kenora , comes with a boat
https://www.kijiji.ca/v-powerboat-motorboat/winnipeg/1980-140-johnson-18-ft-starcraft/1456239276?enableSearchNavigationFlag=true
Build two, the StarCraft for shiit weather.

But I'd redo the StarCraft and keep the 140 on it. Good boat.

[powerabout]

140 looper and nic bore v6 merc within 20lbs

[FMP]

Okay , the looper big bore sounds better:D

[perfmarine1]

Find a 79 or newer 140 and build a drop on. Keep the 88 for a spare for when you blow it up. ;)

79 up has the same linkage. 78 down no.

In 87 they started rating HP at the prop instead of the flywheel. So you really have a low compression 115 or 100. I think the 87 up 115s were the old 140 with looser heads.

Some one will be along in a minute to tell me how wrong I am or agree with me, one or the other!!! LMAO!!! :D

The heads in 79 and 80 will probably be good enough. Premium fuel ONLY!!! I am more of a V6 Xflow guy. But I assume they were like that because right after 80 on the V6s they started loosening the heads or adding thicker head gaskets because of the crappy gas. No one wanted to pay for premium.


THIS 100% correct! They are all over the place for cheap. Hell I have had people give them to me. Got one on my G3 1860 duck boat.

[Fastbass88]

I'll keep an eye out, to busy till Dec to work on it. Just want to have all my ducks in a row before I started tearing into it. I also found a blown xp 200 that weighs 380lbs. But that'd either rip the transom off or give a spectacular wipe out.

I still like the idea of a light weight massaged v4. Relatively light package, getting on plane isn't an issue. Gonna aim for that first.

Just a question, been looking at boat hp ratings. Seems like it's a calculation rather then actual strength capacity on smaller boats? Wondering if going over the boat spec plate will cause any issues other then just over powering the vessel.

[Forkin' Crazy]

140 looper and nic bore v6 merc within 20lbs

With a light single ram bass mid? W/O the trim pump, etc? Light cowl, flywheel too, etc? I bet I could trim some fat off a 140 looper! ;) BTW, how much is a good nic block ready to assemble? And the damn ring$$$$$$$!!! :D Hey, I like the nic motors too. I have 3 of them so far.

[Forkin' Crazy]

I'll keep an eye out, to busy till Dec to work on it. Just want to have all my ducks in a row before I started tearing into it. I also found a blown xp 200 that weighs 380lbs. But that'd either rip the transom off or give a spectacular wipe out.

I still like the idea of a light weight massaged v4. Relatively light package, getting on plane isn't an issue. Gonna aim for that first.

Just a question, been looking at boat hp ratings. Seems like it's a calculation rather then actual strength capacity on smaller boats? Wondering if going over the boat spec plate will cause any issues other then just over powering the vessel.

No such animal. Unless if that is shipping weight less gearcase.

BIA rated HP is calculated by a formula. Ignore it unless you have to have full coverage insurance, or if your boat police are pricks up there? Why not run the 88 cowl. My bet is they are too lazy to get the model number to look it up.

[Fastbass88]

I was going off Nada guides for weight. Looked up the model and said 380lbs.

Id be all for a lightweight exotic looper if funds permitted, but they don't.

We do have some authority roaming around. That's why I thought I could crank up the 88 and use the same hood. Insurance doesn't care, let alone would know what to look for mechanically.

[powerabout]

With a light single ram bass mid? W/O the trim pump, etc? Light cowl, flywheel too, etc? I bet I could trim some fat off a 140 looper! ;) BTW, how much is a good nic block ready to assemble? And the damn ring$$$$$$$!!! :D Hey, I like the nic motors too. I have 3 of them so far.

I prefer steel bores and if i had a HP merc i would fit steel sleeves.
Yes you can take weight out of a looper, silencer and base has some weight.
Cowl and trays could be carbon

Sure you can make more horsepower with v4 or v6 looper but weight is weight
You can have lots of fun with a v4 xflow on a light boat

[spybot]

As powerabout has just said you can have a LOT of fun with a light boat and a v4.
I have a 620lb Dateline Bikini (Sidewinder clone) She had an Johnson xflow V4 85 (300lbs) 447869
This would fly along the loch at 40+ knts was no rocket but was great fun. I Took the 85 of her and have built a 140 xflow ported and tuned still to go on to her.
But in the short term i have 120hp looper on another Bikini but the weight is a killer. I know the 140 Xflow will be the same as the 85 was. The boat handle great but putting the 120 looper on the other boat was a big mistake.
It flies along but no where near a nimble as the xflow. The weight is only like 80lbs but thats 10% of the boats weight.
Just mind if you get a looper you will have all that extra to lug around.
If you find a Xflow and want to tweak it there is tons of great folks on here who have done the same and wiull gladly help out.

[Fastbass88]

That's been my thoughts. The 88 sit pretty deep in the water as is, while running the anti cav plate is 1in above pad. That's with a 20in mid. Might add some exhaust relief holes after I test vented props, idling is hard with all the water pressure.

So as is, can I throw everything from the 135 on the 88(exhaust,carbs mainly)? I know a 140 drop on or 140 exhaust would be ideal, will see if I find anything. I still want a strong lake setup not a full race motor ready to burn down.

Would just need best bang for labor, I would widen the ports and match the 135 block. Port match everything. Not doing fingerporrs but does scalloping the pistons and intake be worth it? Will be putting new rings and honing at the least if everything checks out inside. Hoping the crank set will be in spec.

[Fastbass88]

Had time to pull the intake covers off both 88 and 135. 88 defiantly has the smaller ports. Internals from what I could see look great, but I'm assuming some work has been done to the 88 since there were some markings on inside of intake cover and port housing.

88
448053

135
448054

88 inside of port cover
448055

[Fastbass88]

Did some more digging, found some numbers of several threads that correspond. V4 90hp ports IN 2.170 EX 1.805, 140hp IN 2.100 EX 1.76 (measured from top of cylinder). Barbaric measurements i know but are helpful. Found measurements from a v6 but thats a different animal. There seems to be no porting templates in existence so looks like im stuck using stock heights. Also debating minor scalloping on the block/piston. Is it worth the hassle? It will be disassembled so thats the time to do it. Ill be cleaning up all the casting imperfections as well.

I picked up a decent raked and vented 13.25 x 23p that i want to try and get a baseline from the current setup. I think all said and done hitting 60+mph with a rig that will be 1200lbs leaving the dock sounds attainable.

Another note, everyone harps about crossflow harmonics at around 6200-6500rpm. While i aim for 6000rpm, some people say that only the v6's are affected by this?

[powerabout]

Did some more digging, found some numbers of several threads that correspond. V4 90hp ports IN 2.170 EX 1.805, 140hp IN 2.100 EX 1.76 (measured from top of cylinder). Barbaric measurements i know but are helpful. Found measurements from a v6 but thats a different animal. There seems to be no porting templates in existence so looks like im stuck using stock heights. Also debating minor scalloping on the block/piston. Is it worth the hassle? It will be disassembled so thats the time to do it. Ill be cleaning up all the casting imperfections as well.

I picked up a decent raked and vented 13.25 x 23p that i want to try and get a baseline from the current setup. I think all said and done hitting 60+mph with a rig that will be 1200lbs leaving the dock sounds attainable.

Another note, everyone harps about crossflow harmonics at around 6200-6500rpm. While i aim for 6000rpm, some people say that only the v6's are affected by this?
no problem with a v4 harmonics its even fire
yes v6 xflow has an issue around 6200-6400 or something

[Freddie Webb]

Fastbass88 don't raise the porting any higher unless you are putting it on a boat that weighs less than 400 pounds. If you are going to scallop the Pistons don't raise the skirts over .375". I don't remember what my crossflow race engine weighs but I know for sure what my race v4 looper weighs because I weighed it recently. The complete v4 looper flywheel but to prop nut is 295lbs. The loop charged engine has the capability of making much more power. The crossflow does weigh less the parts are cheaper usually and they are much easier to port. If you plan on using those 135 heads you should at least run AV gas. My crossflow race heads are tighter than that, but they require 112 or methanol. Don't thin the bridges between the ports unless you won't to decrease ring life. If you decide to "D" shape the ports leave at least an 1/8" radius in the corners of the ports. I hope this helps. Find some 1 3/8" carbs. I gave Chris Carson the template to cut reeds for the crossflow reed block. This allows for better reed block flow and still use the reed block stuffers. This helps keep the bottom end and it helps with flow in the higher rpm range.

[powerabout]

Hi Freddie how do your modded reed blocks compare with ficht 60 degree ones?

[Freddie Webb]

I should be at the shop tomorrow I will try and get you pictures of the reed block I sent to Chris.

[ssv170]

Curious, what block would be better to mod? Early small bearing or late model big bearing. Longevity not being an issue.

TIA

[Fastbass88]

Thanks for the help Freddie. I picked up some boyesen reeds and intake stuffers as well. Does porting the reed blocks pay off for the work involved?

Tore open the 135 bubble back, exhaust blocks not warped which is good. I'll machine the assembly a bit the match the porting and get as close to the size of a 140 bubble back as possible. The 135 has higher ports then the 88 so I'll copy them to the 88 and open em up some.

Can I swap the stator and regulator to the 88? Found out the 135 is a silver star flight with 12amp charging system. If it's all apart might be worth it over the 6amp on the 88.

I put a 23p prop on and got 47mph GPS with stock 88 (15gal fuel and 2 people). Hoping I can exceed that baseline with a large margin.

[Fastbass88]

One other thing although will be done at the end, I'm assuming timing is around 28bdc on the 88 currently. With everything ported and 76 135 heads, I'm seeing I should set timing at 22 deg at 4800rpm? Will be running 93oct and 32-40:1 oil.

From my research the 73 heads should run some av/race gas mixed in but 76 are safe enough to run on fresh premium with no ethanol.

[powerabout]

Perhaps someone has the bulletin on how to run a 135 on 80"s gas

[Fastbass88]

So this winter didn't pan out so great time wise, ended up not touching the 88. Decarbbed it this spring and worked to good plugging a bunch of things.

One plug is heli coiled on 88 and letting go, also gasket needs replacing on flat exhaust cover. So going to put 135 heads on and bubble back exhaust minus the stuffers for now.

My concern is the head gasket didn't seal enough on cyl 4 or there was some water intrusion. Ended up scoring some on the head mating surface
467519
How many thou can I shave them? I know 73 heads are the tightest, these 76 heads not far behind. Will be running fresh non ethanol 91 for sure.

[Fastbass88]

Also found the 88 block is stamped 90 and the 135 11. So the 88 is definitely a low/small port block. I'll rectify that when the season is over.

[perfmarine1]

So this winter didn't pan out so great time wise, ended up not touching the 88. Decarbbed it this spring and worked to good plugging a bunch of things.

One plug is heli coiled on 88 and letting go, also gasket needs replacing on flat exhaust cover. So going to put 135 heads on and bubble back exhaust minus the stuffers for now.

My concern is the head gasket didn't seal enough on cyl 4 or there was some water intrusion. Ended up scoring some on the head mating surface
467519
How many thou can I shave them? I know 73 heads are the tightest, these 76 heads not far behind. Will be running fresh non ethanol 91 for sure.

Take that down by hand. Get a piece of bullet proof glass from a bank installation co. 3'x3' is ideal from the drive through.They tear them out all the time when remodeling a bank. They are laminated with 5 -1/4" pieces of glass, Or a real thick piece of glass and go to a abrasive co. or a floor sanding co. and get a piece of 120 grit sand paper or screen paper 2'x2'or 1'x2' and duct tape it to the glass, and sand that down moving it back and forth the long way and finish in a figure 8 motion,no side to side that will roll it. You will know when it is flat by looking at it and no chance of going to far,you should do this with all cases on a crossflow including the block.and reed blocks. The only surface you don't surface is the 2 surface's between the crank

[FMP]

Do both heads.

[Fastbass88]

Thanks for the input, had seen that done before on small engines. Cheap to try for sure. And I would try to get both heads close to the same. Biggest issue was thinking of a medium flat/true that was big enough.

Would I have to turn timing down to 20deg like the original 135 with the tight heads on the 88? Had seen in my manual the 140 xflows were 28deg exactly like the 88 is currently. Was planning on backing down if I don't find any info on it and tuning from there.

[Fastbass88]

Sanded heads flat and removed the gouges, took couple hours but surprising how quick I did it. Measured before and both heads were a couple thou out from flush, each were recessed in the middle of the head between the cylinders. Not sure if that was a factory tolerance or not.

[Fastbass88]

Found some interesting info on brp parts fiche. The 88 block is also used for the 110 of the same year. 110 has 1 5/16 carbs, bubble back, and maybe slightly different heads. My engine will have that now but with the 135 heads, intake stuffers and boyesen reeds. Hopefully have at least 110 prop hp if not closer to 125. Added fuel nipples to 135 carbs for solenoid system and rigged brackets to hold coil packs on the head. Almost ready for the water. Will retard timing to 20deg to get a baseline since I cannot find any info on timing with the head swap. 140 xflows were 28deg so thinking ill be back around there when finalized. I'll likely port it over winter unless it spins the 23 prop then I may leave it.

Continuing this thread to help others if they want to do the same. Not a ton of info on this for outboard newbies.

[powerabout]

Found some interesting info on brp parts fiche. The 88 block is also used for the 110 of the same year. 110 has 1 5/16 carbs, bubble back, and maybe slightly different heads. My engine will have that now but with the 135 heads, intake stuffers and boyesen reeds. Hopefully have at least 110 prop hp if not closer to 125. Added fuel nipples to 135 carbs for solenoid system and rigged brackets to hold coil packs on the head. Almost ready for the water. Will retard timing to 20deg to get a baseline since I cannot find any info on timing with the head swap. 140 xflows were 28deg so thinking ill be back around there when finalized. I'll likely port it over winter unless it spins the 23 prop then I may leave it.

Continuing this thread to help others if they want to do the same. Not a ton of info on this for outboard newbies.
how much comp does it have at cranking and what fuel do you intend to run?
original 135's could be around 150psi+ pretty easily

[Fastbass88]

stock with bathtub heads was 125lbs I'm thinking it'll be 150ish but need to install exhaust before I torque down heads which will be later this week. Running 93, maybe 95 oct for the first tank. Would like to use 91 but will see.

[powerabout]

stock with bathtub heads was 125lbs I'm thinking it'll be 150ish but need to install exhaust before I torque down heads which will be later this week. Running 93, maybe 95 oct for the first tank. Would like to use 91 but will see.
use the primer when slowing down as thats when you can detonate a xflow engine thats close

[Fastbass88]

That's a good idea, was going to turn on the primer circuit manually about 50% for the first couple runs. Always start rich but I have no jets for these carbs. Think the 135 carbs have either 61 or 63c in them. Any aftermarket sources for jets?

[Fastbass88]

Got everything installed, had the first start up on the muffs and idles well. Hesitates when you hit the throttle but will see what it does under load. My engine only has the adjustable holes for the timer base shaft, not the threaded rod like most v4's. Was on the middle hole I moved it back to the most rearward hole to take off about 4deg timing. Forgot the timing light but will do an initial timing check with the reeves method.

Is there any other way to get more timing adjustment if needed? Only other thing I see is the eccentric screw on the linkage but I doubt that will make more then a 2deg change.

[powerabout]

Can you post a photo of that arm and throttle pickup

[mrichartz]

That's a good idea, was going to turn on the primer circuit manually about 50% for the first couple runs. Always start rich but I have no jets for these carbs. Think the 135 carbs have either 61 or 63c in them. Any aftermarket sources for jets?

What sizes are you looking for.

[Fastbass88]

469058
I'll grab a pic next time I'm at the boat, this is what the timer base rod linkage looks like.

I'm not sure yet, haven't taken the boat out to do plug chops and primer trick. Read some posts of carb swaps but no way of getting close to ideal range off forums with all the different year carb configs and motor mods. If anything I think it might be lean but who knows at this point.

If you just look percentage wise of high speed jet size to venturi, current 1 3/16 have 56c so increase the throats to 1 5/16 that's 25% bigger. That math comes to 70c jets which seems to large.

[powerabout]

The adjustment is on the thumbwheel on the curved throttle actuator
You are looking at the throttle cable side.
Think about when the timer base moves how does it move the carbs
Be aware that 88 system was designed to open the carbs and run with retarded throttle for emission reasons.
IMHO set it up so throttle closed at idle and then your idle timing is your idle speed adjustment

[Fastbass88]

469094
Thats what I'm working with. Where the thumb wheel usually is I have 3 holes to choose from. Then the eccentric screw in the cam fine tunes the timeing. Am thinking of 3d printing custom blocks so I have a wider range to tune from. I can probably get down to 22-24deg total advance as it stands.
I could back the thumb wheel off to the carbs and make the cam start earlier increasing timing but that does nothing to change my max advance. Just lowers the spread from start to finish.

[powerabout]

check if your 135 parts will fit??

[Fastbass88]

That's a good idea didnt think of that since it has the old style linkage but worth a shot. Plan was to transfer stator and rectifier from 135 since its 12amp system compared to 6 on the 88.

[Fastbass88]

Had boat out this weekend, worked advanced timing up to approx 24deg and may increase it some more. Jetting is perfect just a tad on the rich side on the high speed but thats where I want it anyway. No problem idling around scanning areas with the sonar.

Having problems with the tach, reads correct on the lower rpms but the higher it revs the more out of wack it is. Replaced the rectifier already didnt seem to help(old one melted itself down). Did manage the get 48mph @5000rpm which is what the 88 did stock so bit more timing should be in the cards. No sign of deto and plugs look really nice.

Fast idle lever is useless so have to take apart control box, also won't let me shift into reverse. All in all its coming together.