Mercury 2.5 OptiMaxx conversion

[Sam1cats]

Has anyone converted an OptiMaxx 2.5 to a carburettor motor I have put a set of carbs On the front and changed the heads And changed the top bearing carrier to receive a Stater And trigger I have left the original OptiMaxx pistons in And they seem to clear on 2.5 heads With normal head gaskets Everything looks to be the same Has anyone done this and does it work . Probably wondering why I'm doing this I need to build a 200 2.5 And this block come up for not a lots of money So I fought I would give it a go As the OptiMaxx was designed around the OptiMaxx block Will it run okay?????????

[Hydrostream]

Yeah, You will also need to make a new electrics plate or adapt a way of mounting the old style with switch boxes. Same for coils. And you may need to cut a few lugs off but it'll certainly work. Used after market pistons though not opti ones.

[Sam1cats]

Originally Posted by Hydrostream

Yeah, You will also need to make a new electrics plate or adapt a way of mounting the old style with switch boxes. Same for coils. And you may need to cut a few lugs off but it'll certainly work. Used after market pistons though not opti ones.

Was there a reason that I cannot use OptiMaxx Pistons

[Hydrostream]

I dont know, its a whole different charging system so hard to say what if any effect the dished pistons would have!

[Sam1cats]

Thanks really appreciate the information I guess I will just have to run it and see what it does. Been great speaking to you

[Sam1cats]

Hi just to let you know I have run it With OptiMaxx piston and seems to be okay But I am going to skim the top Of the piston It is very very responsive on the stand Running two-stage Boystuns read

[Techteam]

What cc heads are you running and what combustion chamber. I take it you mean just machine off the di chamber on the crown. I'd be careful you don't increase the compression too much with the domed piston.

[Sam1cats]

Hi thanks for your reply I have run the engine with the standard OptiMaxx pistons With the dome on top With standard 2.5 carburettor cylinder heads It seems to run okay but haven't done a water test yet She ran with 130 PSI compression But not sure if the OptiMaxx Pistons needs the extra port in the side To get 200 hp I have Taken the raised dome off the top of the piston Will try and then it again next week The compressions should be about 120psi Can you shed any light on the extra port needed As the OptiMaxx Pistons don't have any ports in the sides

[Techteam]

I think you will do well to get 200hp from a bitzer without a lot of work. I've sent you some info by PM. Hope it helps.