Pro Max Mid section swap question

[ypbullet]

Hey Guys,

I'm swapping the (20")mid section on a stock 1995 promax 200 to a 20" offshore mid complete with clamp bracket and one piece exaust plate. Are the studs in the motor gonna work and what gaskets do I need. Also am I good as far as cooling ETC?

[Merc 2.5]

Ur gonna wanna use 2 piece plate for coolin purposes, I wouldnt modify coolin unless u just gotta

[tux974]

Depending on the plate and can most will work.
Late 2.5 plate has thicker flange especially in the rear area so the 4 will need to be a bit longer 2 1/2"-2 3/4" to get a proper bite on nuts.
Also the 2-7" may need to be shorter 5 3/4". I have cut and rethreaded the 7" to work.

Yes, the cooling will need attention/modding so will the block drain holes near exhaust ports.

If you do not plan on spinning 7K and above, running in the rough most times or do not want to tweak the initial setup like suggested by above post run a 2pc plate with good and properly installed solid mounts and leave stock cooling alone......all is MPO!

PS; if you decide to run the 1pc.....I strongly suggest visiting US1 (John Marles) on here web site and follow step by step!

[TEXAS20225]

yes x2 i did everthing your listing above only to find all sorts of new problems on my 20' Bullet

[ypbullet]

Ok, sounds good. ill stick with the 2 piece. Thanks for the help guys!

[ypbullet]

one more thing, will the 2 piece plate work with the HD single ram clamp bracket or am i just swapping cans?

[tux974]

one more thing, will the 2 piece plate work with the HD single ram clamp bracket or am i just swapping cans?

Yes!
Most likely your tiller arm/swivel pin mounting holes are 1/2” so just drill your solid mounts 1/2” from the 7/16” and get 2-1/2” grade 8 bolts or it will have play and feel loose.

[Mrzip]

I have used a 1 piece plate many time's. No problems

[tlwjkw]

Yes!
Most likely your tiller arm/swivel pin mounting holes are 1/2” so just drill your solid mounts 1/2” from the 7/16” and get 2-1/2” grade 8 bolts or it will have play and feel loose.

drill ona lathe or drill press if possible.. gotta make sure tha holes stay straight.. if even justa "tad" off will make tha two piece piece not set right around tha mounts..


I have used a 1 piece plate many time's. No problems

you're one of tha few "lucky" ones if ya didn't hafta make changes...…….

[tux974]

drill ona lathe or drill press if possible.. gotta make sure tha holes stay straight.. if even justa "tad" off will make tha two piece piece not set right around tha mounts..

Yes, sir and before a few beers.....LOL....:D
We even clean the outside of the new mount (in lathe) a thou or so bolt both halves together without gasket with a feeler gauge inside and see if we can pull it out. This is to assure a good sealed fit.



you're one of tha few "lucky" ones if ya didn't hafta make changes...…….

I agree Tommy. Also like to know what changes he made if any to get things to work. Like to learn something everyday.
I have my own personal motors and some other ones I have done for class 7 racing on the 1pc plate but it has taken a bit of tweaking especially here in the colder waters.
I have stopped selling the complete motors with 1pc due to not many having the time, knowledge or patience to get things right.

[tux974]

I have used a 1 piece plate many time's. No problems

Very glad to hear that!
Please, elaborate on what you have done if anything to get your setup to work well for you. Your provided info may help others!
My guess the warmer waters has helped you.
BTW, I do not disagree that it can be done but I have found it takes time and work, not something that is plug and play....JMPF

[ypbullet]

Ok great! As usual thanks for the input guys. I appreciate it!

[Mrzip]

Tux974. I took the 2 piece off. Put the 1 piece on. New gaskets off course. Hit the water :cheers:

[Merc 2.5]

Tux974. I took the 2 piece off. Put the 1 piece on. New gaskets off course. Hit the water :cheers:

How often did u hold it.down and turn high rpm for long ways?

[tux974]

Tux974. I took the 2 piece off. Put the 1 piece on. New gaskets off course. Hit the water :cheers:

You are a lucky guy.....:thumbsup:
If you do not mind me asking.
What plate did you use and did you do anything to it? 2.4BP, 245/260 or 280?
What is your water temp and pressure idle, running?
How long have you been running the swap?

[Mrzip]

Merc 2.5... From the time i get in it :).. Tux974. I use a Land & Sea. I have no idea of the water Temp. Several lbs @ idle. Double digits on top. I have NEVER had a Hot engine. NEVER:rolleyes:

[Merc 2.5]

Well lucky u. I have heard all kinds crap people tryin use em
Steel bore motors?

[Mrzip]

How am i Lucky ?

[tlwjkw]

How am i Lucky ?

'cause most everyone else has ta make changes to tha coolin' stuff ta get temps and pressure where it operates tha "steel sleeve" motor right...………..

[tux974]

Merc 2.5... From the time i get in it :).. Tux974. I use a Land & Sea. I have no idea of the water Temp. Several lbs @ idle. Double digits on top. I have NEVER had a Hot engine. NEVER:rolleyes:

Water temp in a steel sleeve motor is important. Not about running hot which is also important to keep an eye on but to have the block build proper heat. Having the motor run nice and warm will probably help in longevity.
The L&S plate is a bit different but I would still be very concerned about obtaining proper heat.
3 most important basic gauges to me....Temp, Water pressure and Tach.

[TEXAS20225]

X2!!!!! amen Tony thats the gospel concerning 2.5 steel sleeve motas !!!!! as a person who has rebuilt 100s of steel sleeve motas and not just a well one time i had A and thats that statement, my best luck with a one piece plate was using a bridgeport one piece on my promax as bolts were 7/16 not 1/2 it seemed to work ok after water was being controlled on how much it was restricted by closing off pisser hoses with brass fuel hose barbs (reducing is diam.) but the off shore mid caused me to go into find a prop mode the can exchange would not allow me to run the thru hub props i did before just my .02

[tux974]

Bobby, yes I have found the BP plate works well because the 4 small holes which allows the water to exit nicely thru out the plate, I like that.
As for the 7/16 bolts. I end up tapping them to 1/2" because I usually run the newer single ram saddle that has the fat HP arm which are 1/2" holes, more work....:eek::D
Yes, the water tweaking takes a bit of work to obtain the proper running temp especially in the water temp one runs.
Here (north) if you really want to be on top of things the tweaking is a couple of times a year. Spring water is colder, fall the water is warmer. The good thing once you do it you get to know you swaps/mods....;)
Also agree the heavier, wider housing changes the dynamic back there....:D