Porting a X Flow? Advice! Please.

[bobthebuilder]

175 X flow flat back motor? Oh boy, I took heads off today Planning to get em cut down some to raise comp. and found there has been a small piece of metal got into a cyl. It ruined a piston and a head! It didnt damage the cyl wall any at all.... Amazingly! I know I will buy 1 new piston and rings and a head and fix it.... I plan to finish taring it down to find out where the metal came from if possible to find out. But while I got it down it's tempting to square the ports. I havent a clue as whether or not to raise them any or what are the specs. I should follow? Or if I shouldn't do it at all just fix it and go! I plan to buy some old model 235 heads instead of buying just one to replace the damaged one. Want to get somewher like 115 to 120 on comp guage. I am gonna fix it either way. It is a great motor just cant figure out where that metal object came from? I been fishing tournaments for most of this year and using it very regular until 3 days ago when I heard something metalic sounding in there. I was very suspecious so I planned to remove heads today no matter what. I am not trying to built a super motor just a very strong one for what it is. Maybe 200 hp. On a 18ft ranger bass boat trying to make it run mid to upper 60's.......... What should I do with it? No one around here knows how to port them out right to make em go better. Can port heights be changed? How far from top down? Do we do only intakes or both int and exhaust? I suppose a bubble back ex. wont fitt on it huh?

[roadkill636]

what exactly was done and replaced during the rebuild 30 hours ago? just courious of what kind of break in procedure you did on a fresh rebuilt powerhead?
can you post some pics of the damage?

[bobthebuilder]

Right now dont have any pics of damage. After I built it first time I ran it under 300 rpm unitl it used 60 gallons of fuel or more. Then I ran it a little faster with short burst of speed now and then but no long runs WOT. There was absolutely no problem as I fished in the boat at least 15 fishing days and motor ran smooth and sweet just thought it should have a little more top end power. But about 3 days ago I heard a metal rattle in there as I was about finished with it for the day. So I eased back to the ramp running at slow speeds and loaded it up. I had to work a couple days until today I took heads off it.

[bobthebuilder]

Oh yes when I rebuilt it I had the block bored .020 os. New pistons and rings rod bearings, top and bottom cranck seals and gaskets. Also new t-stats and poppets. Boysen reeds and some smaller air bleeds. Oh yes and today I saw the bottom piston on port side was washed clean where intake ports are. I mean absolutely no dark material at all. I figure it is a bad fuel pupm flooding that cyl.... I plan to get a new fuel pump of some sort for it before I run it again. But the bad piston and damage is all contained in one cyl. #1 top starboard. With that low comp. and only running high test BP gas which has no ethanol in it so they say. I figure it had to be a small piece of metal. It isn't chewed up looking but it has little holes spiked into the piston and head. Mostly on intake side and just a few small ones on exhaust side. I figure it did that when it did it's exit into the exhaust chamber. When it was bored and honnd the machine shop who is a good friend also pressure washed it thoroughly or so he thought. That piece might have been hidden in there somewhere and we never saw it. Oh yes I also want to know what the exhaust stuffers look like. Are they the rubber strips in the reed plate??? No? Oh well I dont know exactly what to look for? I plan to fix it as it is too good to not fix even if I trade it or sell it I would never sell anyone it without it being fixed right...

[bobthebuilder]

Surely I can bump this ole motor up a little bit. It was 85% of all I need before it messed up. I mean I got a buddy who has a merc xr4 150 on 18ft bass boat about same thig I have and his will run 65mph GPS. I want and expect the Johnson to do same thing. Johnson is supposed ot be a 175 and I want ot help it out a little more if I can.

[Riverratt]

keep in mind that your 175 was powerhead hp not propshaft which makes it close to 150 propshaft hp. The exhaust fillers are in the exhaust back. the intake stuffers are the rubber you referred to. If you have pitting on the piston top it sounds like detonation. It is possible a ring also caught a port and pulled part of the piston top off. I would also count the number of screws left on the reed cages. A screw may be the piece of metal you heard.

[bobthebuilder]

Yea I checked reeds for all screws. They are all there none missing. All are in carbs too. There is not a chunk missing from piston either. I dont think it was detonation. I have seen one with that problem and it dont look like that. It seems more like a piece of metal came from somewhere. Also only 95 to 98 comp. and I only use best gas I can get for it. The other 5 pistons are still like new. Today I will disasemble the rest of it. After thinking about it for a while I am thinking about just a new piston rings on only the replaced one and a couple gaskets and put it back together. I have the plain stock heads Not the gt ones but some from another motor plain stock 150 heads. The comp then will be 90 unless I get em cut. Local shop gets 80 bucks to cut em? Probably not worth it huh? I can use them and get motor fixed back like new. I figure I might as well look for me a looper motor. When did they start rating motors from prop? I already have way more into this boat rig than I can sell it for! Oh well... I am looking for best solution? Might buy a boat with a looper and swap motors and sell it with the X flow on it. I can buy whole complete boats for about same as a as a motor. My ranger was rated for a 175 on the plate in it. Although I go more by what the motor weighs not HP. Thats where the merc's got em beat... A 200 merc is lighter than my X flow! All I was trying to do is get that ranger 18ft to run 65 or so.... I had it up to 61 once going with the wind on choppy water only me in it and not much else.... But 2 guys and full gear which isnt very much stuff I could only get 53 the day it messed up! I will post something soon as I find out more.

[bobthebuilder]

Yep it was detonation! I git it figured out! At WOT it was flooding the #6 cyl and starving out the #1 cyl. TOO LEAN! DARN FUEL PUMP CAUSED IT! I was using the old VRO which was disconected from oil and I mix my gas. But it was still being usd for the fuel pump.... Busted diaphram! Man it sure was what caused it!

[EMDSAPMGR]

It would be helpful to know the year. If you are looking for some mods for the engine, squaring off the tops of the intake and exhaust ports is relatively easy and worth the effort. The engine will breathe better at high rpm. Since it's a low port block to begin with, you won't suffer that much on the hole shot and it will raise the torque band perhaps 300 or more. I would also add the 200/235 hp rubber intake filler blocks, 322722. These are NLA, but you can find them around. The damaged head is trash. I'd look to replace the heads with some early 235 small bore heads. 323872/873. The heads should get you to 120 compression. Once you get these mods done, I'd spend some time rejetting the high speed jets. You will need to flow more fuel if you don't want to burn the powerhead up again. Run 92 octane fuel only. What size are the carb throats? They need to be 1 5/16". Depending on what year, you may find that your power pack has a rev limiter set at 5850. You'll want to replace it with an unlimited one if you want to get the potential out of the engine.