off to the shop it goes!

[Speedman]

tore my promax down Sat, lost a piston, came apart and scored the cylinder a little, maybe .015. So its off to the shop. jury is still out on what to use for pistons. I have had several reliable people from this board and S&F (including Paul Nichols, Randy, Jay Smith etc) give me their opinions. Some said replace all pistons and if I use Merc, have them top pinned, some said promarine with spacers and others said vertex?? Paul said if I am only turning 6700 that he would use USED pistons top pinned, I don't think I want used so I am still out. I believe everyones experience and am now more confused :? If I understand this right, in order to top pin a piston you have to drill a hole in it, then weld it over? is that correct? how would that effect the piston tolerences, wouldn;t it create a hot spot? not sure on the process, keep in mind,I am no engine guy...small block chevy, I can do! Boat engines, just not learned enough yet...enlighten me!

 

[fishnfireman]

AS you said there are several DIFFERENT opinions on this subject.

John Marles has top pinned 2 sets of merc. pistons for me. the first set was a 280 bass and that was 2 yrs ago. the second set is in a 225 Pmax about 4 months ago, they are both running strong.
He has figured out how to weld the hole and not have an ignition point.
His web site has all the details.

For what it is worth, here is my opinion.........Knowing full well that..

"opinions are like A$$ holes :arrow: we ALL have one but some $tink"

IF you are going to be using this mtr extremly hard (like racing) spare no expence :!: New pistons, but not the same ones it has now... GPI has some good ones.
If you are on a budget and only going to fish or pleasure with an occasional top speed all out run.. I would not hesitate to to use my old pistons again and have John top pin them.

Thats my $melly opinion 8)

 

[varmint2002]

I have Marles Pinned Pistons..

That I put in 2 years ago from my 99 280 on my 02 comp pro. It was because of all the stuff I was reading on these sites about the side pinning causing engine failure. Some places I fish in Canada are a long way from anything. The posts about engine failures from side pins made me think of what kind of signal flares I need to have for float planes notice me when she seizes up in da bush eh? When I took down the engine it looked fine but I had John look/tell me whether to replace pistons or not.

We repinned the USED (yep I know how dumb I am, engine builders shake your head in disbelief :shock: ) pistons and put in new rings. His work for me has been great. I still have a strong motor that I spin up to 8300 rpm without a problem, sooo far.

But I am not a drag racer, nor an expert just a motorhead that likes to fish and go 110 mph from time to time and has faith in the advice of those who are experts.

Gary

 

[Speedman]

the rebuild continues

So, since I am getting a break on labor as the Merc mech is teaching me and I am working out some details on a mini- sponsorship, i have decided to go with all new pistons top pinned by marles racing, all new bearings and steel caged ones for the rods. also new DTR? reeds(not sure on the name). one question left is the balancing, thinning of the rods and possible angle cutting the pistons? saw on marles website and my guy talked to him about it some yesterday. he also suggested shaving the heads 34cc? what kind of real results will all this do? and how many RPM's will I be able to run? should I ditch the revlimiter? Now I have the go fast bug. remember it was a stock 225 promax, except for the Gforce tuner. Should I go for it? and yes I mostly fish and keep it under 75, but in a tourney take off, it's balls to the walls! and I have not been passed yet! before all this happened I was getting 93 for 2 guys and a light load with a reworked 29 SRX at the limitier. and 90 with full wells and a 28 ron hill chopper. its getting closer!

 

[fishnfireman]

With all the other mods your doing go ahead and do the heads.
It will help :!:
I had a set cut to 34cc on a 225 Pmax.. It helped a lot on the bottom end.

 

[chad202]

I would definetly have the limiter raised to at least 7250. The promax seems to like the 7000-7100 range. On mine, I raised the limiter, shaved the heads to 35cc(but used the thin gasket)(140 comp), relocated the water seperator to free up the air path to the butterflies, installed 2.4 Bell tuner, liteweight 40 amp flywheel, removed timing module and set at 25deg, adjusted my TPI to remove bog on holeshot, and installed sportjet reeds and cages. My motor would pull alot harder than a 225x and be a little faster on top. The heads you will like cause you will feel the difference.

 

[Speedman]

when it is all done

what do think I should run for a prop? Gary

 

[Speedman]

what's a Bell tuner? is the the exhaust tuner?, where did you put the water spearator? when I bought the engine origianlly the previous guy had taken off the oil injection which included the sensor on the water separator . Also, in 8 years I never Decarbed the engine and always ran 89 mobil or citgo, and it looked very clean according to my mech?

 

[varmint2002]

What Prop

what do think I should run for a prop? Gary

ON my boat I use a 30 inch chopper 2 with an allison cut by performance props in sody daisy TN for all around use. If you have the same boat and with a promax you may get good results with that or a 28 inch. But there are others that have promaxes with the same boat that may give you good ideas too. I have a picture of the prop on the allison owners page link below.

http://allisonowners.com/garyr.html

Gary

 

[Speedman]

So Gary you are getting 110! holy speeding ticket, batman :shock: what do you think I should get with all those mods on my xb2002? and what is a comp pro? I don;t see many differences to mine in your pictures?

 

[varmint2002]

So Gary you are getting 110! holy speeding ticket, batman :shock: what do you think I should get with all those mods on my xb2002? and what is a comp pro? I don;t see many differences to mine in your pictures?

1) boat weight, 2) experience 3) boat set up 4) motor is different. if you want the speed spend your money on a bone stock 280.

 

[varmint2002]

Those are the first differences that come to mind.

 

[Speedman]

???

How Much lighter is the comp pro?, Don't have experience driving over 100, don't have a large amount of $$ to spend which is why I have to keep my indestructible 94, boat! Never got passed in a "T" so I don;t want a 280 that needs to be reringed every 50 hours, whats up with that? 18k for a motor that won't last??. I need the reliability factor and since I have to rebuild the 225, I thought I would hop it up a little, thanks for the input, If I shave the heads will I have to run super in it? I have been running 89 since I bought it in 97??

 

[GFinch]

If your on a tight budget, haven't been passed, can run mid grade gas, leave it stock. Once you cross the line theres no cure for this sickness.

 

[fishnfireman]

Speedman
I would say you got real lucky burning 89 in that mtr.

That was the main reason Merc recalled all the 225 pro maxs with a 20" mid section.

they said the poor quality of fuel was the main reason for the midrange, lean and pop that they experianced with those mtrs......

 

[Speedman]

my manual sais to burn 89!

 

[Jimxb02]

I agree that the ProMax will require less maintenance than the 280.

But you can get very good performance out of an internally stock ProMax with some bolt on mods. I have one with top pinned pistons, SPS rod bolts, Jay Smith light flywheel, Brocato SVS, modified ECU, 145 PSI heads and exhaust relieved. The motor pulls hard all the way to 7300 RPM and I have let it spin to 7900 for a few seconds. I am now in my second season with no problems.

Just to give you more to think about ---

Jim

 

[fishnfireman]

speedman,

All the manuals printed before the recall, still say 89 octane.

I believe the recall was in mid 2000 and included all 225 promax's with a 20" midsection back to 1997 models.

 

[Speedman]

My guy said the recall did not effect my motor? the 97

he had merc run the serial number and found that there were no recalls, that I didn't ever register it with Merc and that before I bought it, the previous owner filed a warranty claim against the stickers! weird huh? Well its in, we are going to ad the top pin standard Merc pistons, sending them to Marles and having the rods blalanced and lightened, going to shave the heads 34cc, replace all bearings, new reeds, not sure what brand, he told me but it was a 3 digit something, something, racing? all new gaskets, fuel filters, etc etc until it is almost like new! I can;t wait

 

[fishnfireman]

I think you will be impresed with those mods :shock:
Have fun with it, but be careful. They take on a whole new attitude over the 95 mark..