Swapout

[berdes]

Will a late '90's promax powerhead bolt onto a 2.4 mid without too much trouble. If it fit's would there be any real drawback of doing such a swap ?

[Merc 2.5]

Everyone says dont run a 2.5 on 2.4 adapter plates buttt....
I did just that. installed a 2.5 on a 2.4 mid with 2.4 adapter plates and got little over 50hrs on it. lots of wot runs. Perfect water pressure great cooling , no issues for me. Just make sure u use the 2.4 gaskets. u will run hot with 2.5 gaskets. Mite have to trim exhaust dump holes to make em match

[KIRCHNER]

Will a late '90's promax powerhead bolt onto a 2.4 mid without too much trouble. If it fit's would there be any real drawback of doing such a swap ?
WHICH adoptor plate are u going to use?

[KIRCHNER]

Everyone says dont run a 2.5 on 2.4 adapter plates buttt....
I did just that. installed a 2.5 on a 2.4 mid with 2.4 adapter plates and got little over 50hrs on it. lots of wot runs. Perfect water pressure great cooling , no issues for me. Just make sure u use the 2.4 gaskets. u will run hot with 2.5 gaskets. Mite have to trim exhaust dump holes to make em match
are u using a 2.4 1pc, my plan is the opposite 2.4 on a ported 2.4 1 pc 1pc has BIG exhaust ports.

[berdes]

Thanks, but I thought all promax were 3.0 ?


Everyone says dont run a 2.5 on 2.4 adapter plates buttt....
I did just that. installed a 2.5 on a 2.4 mid with 2.4 adapter plates and got little over 50hrs on it. lots of wot runs. Perfect water pressure great cooling , no issues for me. Just make sure u use the 2.4 gaskets. u will run hot with 2.5 gaskets. Mite have to trim exhaust dump holes to make em match

[berdes]

Don't know. Haven't taken anything apart yet. Should I assume bolt pattern, shaft spline, geometry are universal ?


WHICH adoptor plate are u going to use?

[Merc 2.5]

Promax make 2.5 and 3.0. U got 225 or a 300?
A 3.0 will not swap

[berdes]

Neither one yet. Just a thought experiment at this point. There seem to a few of both available.


Promax make 2.5 and 3.0. U got 225 or a 300?
A 3.0 will not swap

[Merc 2.5]

Ya the 3.0 promax is one of it's own. the 2.5 (200,225) different story. more can b swapped around
Other words anything over 225 pm is a 3.0

[berdes]

OK, thanks.

[Capt.Insane-o]

Will a late '90's promax powerhead bolt onto a 2.4 mid without too much trouble. If it fit's would there be any real drawback of doing such a swap ?

One piece yes..two piece no.

[Merc 2.5]

One piece yes..two piece no.

So you cant run any 2.5 on 2.4 200 adap plates? 2 piece ?

I have one aet up just like that with 0 issues ever so far. Now I no u know exactly what ur doin also. Not being disrespectful at all. With that said. Reason I set mine up like this is because a builder here (well known) has set up many with no issues and it's the parts I had and everything has came out perfect. but everyone says cant b done. So I'm still kinda stumped by this. I do know cant mix the plates or gaskets again I am talking bout 2.4 200 with 2.5 200 powehead

[nitro_rat]

I looked at using the 2.4 plate when I did my 2.5 clamshell swap but I couldn't find a reason not to use the 2.5 plate since I had it...

[Merc 2.5]

Ya I tried finding 2.5 plates but ended up no so easy come by and was told bout this , so I went with it. Truth b told I didnt no if it would work or not. I was goin on his experiences and word. But it worked flawlessly still workin great. I'm not tryin down grade or start chit in any way. Just conversation

[tlwjkw]

I've run justa 'bout ever combination possible with 2.0's, 2.4's and 2.5's.. always use metal infused ph gaskets that fit tha "block" exhaust.. did tha "grindin' ta match exhaust on some and some not.. couldn't tell any difference... never a problem.. one piece and two piece present they're own problems with tha coolin' differences... jmo

[tux974]

I personally like to run the 2.5 plate if running a 2.5 PH.
I also like to match the exhaust port to block ports.....but I trust tlwjkw he knows his z*** and has done plenty of testing so if he says it works I'm sure it does!
You can use a 2.5 200 for the 2.5 225PM just open exhaust to match, done plenty or as Tommy stated run the smaller ports......MPO!

[tlwjkw]

ya right Tux.. always best ta run matchin' stuff.. wasn't so much as experimentin' jus 'cause, it was back then sometimes ya had ta do with whats "on hand" and hope for tha best if ya wanted ta go to tha water....

[tux974]

:iagree: Tommy on doing what ever it takes to get wet....:thumbsup:
I also find that the 2.5 plate cools better, not sure if it's just me......:D
Hands down using good and correct gaskets is a must!

[tlwjkw]

best I remember it does.. been away from "hands on" with this stuff for so long now tha brain cells are givin' up a big part of it.... lost my son back in august and that's seems ta have really taken its toll on tha ole noggin'...….

[tux974]

Can fully understand. Very sorry to hear that buddy.....:(

[tlwjkw]

appreciate it, thanks..……………………………………………..

[rock]

Really sorry to hear of your loss Tommy. Toll on the ole noggin is an understatement.

Rock

[tlwjkw]

pretty much... thanks bud.

[tunnelmike]

Sorry to hear of your loss Tommy.

I had to put a slight bevel on a 2.4 1piece plate to run a 2.5. The bottom cap assembly would contact with the plate and not allow the ph to sit down all the way. A bit of beveling of the driveshaft hole let the bottom seal fit into the plate and all was good.
That said I'm not sure what 2.4 plate it was. Mike

[tlwjkw]

thanks mike.. seems like I had one something like that at one time.. don't remember what plate it was though... mighta been a L&S?

[berdes]

Would using this tuner solve any/all problems with fit-up ? https://bobsmachine.com/product/mercury-exhaust-tuner/

[HStream1]

NO!! There was a 200 & 225 2.5L promax. The 3 L Pro max adapter plate will not work at all. Two completely different animals.


Thanks, but I thought all promax were 3.0 ?

[HStream1]

You are Right in Bayville NJ. Swing by Fullers marine and machine in Bayville 96 Atlantic City Blvd, I know George hangs on to alot of stuff. If you cant find what you really need Im sure he can help you out.


Would using this tuner solve any/all problems with fit-up ? https://bobsmachine.com/product/mercury-exhaust-tuner/

[tux974]

berdes, X2 on Fuller!
The Bob's tuner works pretty well! Currently setting up 2- 2.5 motors with them now.

Just to be clear!
1Stream is correct the 3.0 300PM will not fit on anything 2.5! They made 150/200/225 PM's most of us are responding thinking since you mentioned a 2.4 mid you were using a 2.5 PM.

[Merc 2.5]

Would using this tuner solve any/all problems with fit-up ? https://bobsmachine.com/product/mercury-exhaust-tuner/

Gotta pull can liner to run a Bob's I belive. But gud tuners

[KIRCHNER]

Everyone says dont run a 2.5 on 2.4 adapter plates buttt....
I did just that. installed a 2.5 on a 2.4 mid with 2.4 adapter plates and got little over 50hrs on it. lots of wot runs. Perfect water pressure great cooling , no issues for me. Just make sure u use the 2.4 gaskets. u will run hot with 2.5 gaskets. Mite have to trim exhaust dump holes to make em match
i read that the 2.4 1pc is the perfered plate to use , from a known race builder, so you got it right! be safe.

[nitro_rat]

i read that the 2.4 1pc is the perfered plate to use , from a known race builder, so you got it right! be safe.

I'm pretty sure that there's no problem swapping 1pc plates. The 2.4 is usually "preferred" because the dump holes in the 2.5 plate are oversized. Many restrict the dump holes when using a 2.5 1pc plate.

The difference is in the passages on a 2.4 and 2.5 2pc plate. They are different, I haven't spent enough time studying the differences because I've never needed to...

[KIRCHNER]

I'm pretty sure that there's no problem swapping 1pc plates. The 2.4 is usually "preferred" because the dump holes in the 2.5 plate are oversized. Many restrict the dump holes when using a 2.5 1pc plate.

The difference is in the passages on a 2.4 and 2.5 2pc plate. They are different, I haven't spent enough time studying the differences because I've never needed to... thats exactly what i read. once im up and runnin garage sale time, stuff im tired of lookin at!

[Merc 2.5]

I ended up with really good volume and pressure just rite up to 7k which ain't a whole lot rpm or nothin but it's done great. and I was very very nervous bout it , so theres just no signs for me that a 2.5 wont work on a 2.4 plates if rite gastes installed
O well maybe I should say this to. If u get the 2nd gen 2.0 gasket which is same as 2.4 but has the big exhaust dumps like the promax and 260. So.no trimming.
Again. It wasnt a experiment for me. i was told to do it. Works like stock I'm sure I'll get hammered bout this hahaha