225 Promax Smoked Piston Need Advice

**TNRoostertail** · 10-24-2019, 10:08 AM

And just clarify we are just going to hang the black max as is while we rebuild the promax.

**LakeFever** · 10-24-2019, 01:03 PM

I’m pretty sure the pin connector is the same. I haven’t swapped from carb to fuelly on the same hull yet but I have worked on both and the key wires are the same color and config from what I can recall it all looked the same

**TNRoostertail** · 10-24-2019, 08:08 PM

Originally Posted by LakeFever

I’m pretty sure the pin connector is the same. I haven’t swapped from carb to fuelly on the same hull yet but I have worked on both and the key wires are the same color and config from what I can recall it all looked the same

Right on, thanks fever. We are going to grab the black max tomorrow and try to hang it saturday after our tourney. So far we have planned to do a .030 overbore build, shave the heads, performance reeds and maybe some exhaust work. Then put her back together. Will also ditch the stabilizer, what exactly does the stabilizer do? This is a pre mix engine, does it have something to do with the auto oiler?

**tux974** · 10-25-2019, 05:27 AM

Your swap should be fine. EFI and carb difference are in the engine harness to run ECU etc, not pin connector.
Normally I do not comment on this stuff but...be careful shaving heads if sleeving because sometimes they deck the block after sleeving so take that into consideration.
Stabilizer bumps idle timing, one more thing that could go wrong, not necessary and that box in particular has nothing to do with oil IMPO.

**Merc 2.5** · 10-25-2019, 06:01 AM

Idle stabilizer, it moves timing around , if it was to tear up timin will spike and burn a slug. I would tell my machine shop guy , .015 over instead of .030 , and sleeve bad cyl

**bullet123** · 10-25-2019, 06:06 AM

. If you cant get away with .015 over, get new sleeve

**TNRoostertail** · 10-25-2019, 06:58 AM

Right on thanks guys. Will try the .015 route and see where were at there. Is there a process to removing the idle stabilizer?

**TEXAS20225** · 10-25-2019, 08:07 AM

Just a FYI seeing the deposit of aluminum on the sleeve what happens here as piston goes up and down in that hole clearance is decreased because of aluminum deposit being left on sleeve. register( i call it holder because it holds the sleeve ) gets pushed away from the actual sleeve and creates a gap between the sleeve and holder causing that hole to not transfer heat and that hole will probably blow again in short order( but not always inspection will reveal how much out of round it is ) if James does the work he most likely wont bore it but recommend a new sleeve . he is the man who alerted me as to why i was getting blown hole again in same hole!!!! lots of people say oh it was injector but that is normally not the culprit i clean injectors also Ive never found a injector to be the cause of blown cylinders most of the time it is heat or detonation . at the far end of my motor building adventures i started not having any blocks bored but replaced sleeves because of this problem just my .02

**mrichartz** · 10-25-2019, 09:34 AM

I would re-sleeve any in doubt (like texas said above cooling problems etc) seems like alot but cheap if you do all that and ends up blowing up/melting another piston..
But if you can get James Perry to do it he will tell you exactly what you need to do even if you have to wait..
There are other great mechanics/machinists on here too.
If James is that far out and can't do it.

**rock** · 10-25-2019, 12:52 PM

Bobby is 100% correct. That sleeve needs to be removed and the block welded up or you'll get to do it again later.

Rock

**LakeFever** · 10-25-2019, 03:17 PM

Is it ever safe to overbore a lean burned mota or is boring only for worn out/weak engine freshens?

**mrichartz** · 10-25-2019, 03:26 PM

Originally Posted by LakeFever

Is it ever safe to overbore a lean burned mota or is boring only for worn out/weak engine freshens?

Yes Depends on damage..if you have piston melt and have aluminum on the sleeve that can cause it to be out of round... re-sleeve
Or if it doesn't cause sleeve to be out of round kind of damage likely can just bore it all depends on how/what the damage is.

**TNRoostertail** · 10-25-2019, 05:26 PM

There you are rock, how yah been buddy. You used to help me all the time with my old norris craft on here. You got any 2.0 heads.

**rock** · 10-25-2019, 07:41 PM

I've been doing good. Hope you are as well. I think I have a couple sets but they are 2 piece. Make sure you get that Promax done right. Easily one of the best motors Mercury ever made.

Rock

**TNRoostertail** · 10-25-2019, 08:23 PM

Originally Posted by rock

I've been doing good. Hope you are as well. I think I have a couple sets but they are 2 piece. Make sure you get that Promax done right. Easily one of the best motors Mercury ever made.

Rock

Yeah they are imo the best ever made with the 2.4 bridgeport a close second, but what do I know lol. I just think their mean and sound really cool. Right on on the heads, I need a shaved set for my 2.0 build.