FF block?

[mercrazy]

What’s the difference in ff block and 225 pro max block other than paint?

[LakeFever]

Casting is the same. 225 promax has rod slots cut, exh dump hole larger, chamfer on the exhaust port, seven petal front half vs 4 on the FF. Promax supposed to have flashing removed and cleaner overall prep. The differences are minimal outside of the seven petal front. Easy to mod an FF up to promax spec. They share the same sleeves which is the biggest factor

[Glastron1987]

You lose and holeshot with the Promax spec?

[mercrazy]

Casting is the same. 225 promax has rod slots cut, exh dump hole larger, chamfer on the exhaust port, seven petal front half vs 4 on the FF. Promax supposed to have flashing removed and cleaner overall prep. The differences are minimal outside of the seven petal front. Easy to mod an FF up to promax spec. They share the same sleeves which is the biggest factor

Anybody else ever made a 7 petal out of a 4/5 petal?
I started cutting a damaged 5 petal front into a 7 petal. Don’t see why it wouldn’t work.

[LakeFever]

I don’t notice any difference down low after modding mine but I am still running the FF four petal which makes the biggest down low/up top difference. Most guys with laser 7 petals don’t seem to complain about lack of bottom end power running 7 petal set ups but carb guys say the difference is very noticeable. In order to turn a four or five petal motor into a seven petal you need to swap the front half. The four and five share the same front half it’s just the reed shape and size that is different. The seven petal is an entirely different animal and the reed plate is much wider which is why it won’t fit to a four/five front half

[XstreamVking]

Stock ff vs a stock promax seems to be fairly equal performance wise. I often ran my V-King with a bud and his Vector / 225 Pro max. Both spinning 28p props. The King was slightly faster. But, it may have been the blue printed bottom that made up some of the difference. Both engines are real performers and like to be modded.

[LakeFever]

There’s nothing disappointing about a 2.5 200 that’s for sure. Great motors. On the stock ecu I managed around 6500 rpm. I added a promax ecu that was chipped for 7600 and so far I’ve turned the four petal FF to 7300. I just ran out of room or it would have gone more I’m sure

[Aaronhl]

Did the 225 promax come in carb and which ones are they (or jets sizes for another carb) so I can turn an FF into a 225 promax

[DangerNewb]

Did the 225 promax come in carb and which ones are they (or jets sizes for another carb) so I can turn an FF into a 225 promax

225 Promax are FI. At least every one I've ever seen.

[LakeFever]

All pro max’s are laser. There is a 245 2.5L carb motor out there but I have no idea what the carbs on it are. Promax 225 is an overachiever it’s around 245hp according to most dyno reports I have seen. Here a good thread on hi perf carb builds

https://www.screamandfly.com/showthr...-WMH-carb-info

[johnmiffco]

the 2.5 carbed 245 was a 260 nic rotator with 7 pedal front and whm carbs
merc also made the 91-92 modvp motor which was a carbed 260 block but with steel sleeves to be legal cheater motor for the class
and sold as production and not racing division
these were screamer powerheads with no rev limiter being carbed
i had a modvp powerhead on 1 of my old drag boats with cut heads and wh carbs rest was stock
and it ran 8500+ for yrs and was a great fast motor
the 220 laser was the late 1980s 2.4 version till merc started the 91 2.5s and then called it the promax 225
so yes the promax 225 was always the laser style efi till they went to the 225x efi version

[skialot2]

There is a 2.5L Carb motor listed in Mercury's parts catalog that uses 7 petal reeds. I don't know what horsepower it is. It is just listed as 2.5L CARB in the parts catalog. The diagram shows 5 petals, but it's generic. If you search the part number, it comes up 7 petal. 34-815242A3 Reed. 87692--2 reed block

It lists carburetors part numbers as:

3311-818650A19 1 CARBURETOR (TOP)
3311-818650A20 1 CARBURETOR (CENTER)
3311-818650A21 1 CARBURETOR (BOTTOM)

[108]

1991 200

[skialot2]

1991 200

1991 200 2.5L has its own parts listing(highlighted). It uses 5 petal reeds. I am referring to the 2.5L Carb parts listing circled. It uses 7 petal reeds.

[JCSmile]

The 2.5 245 was usually called a "2.5 carb". The parts manual would likely include other hipo parts like 16a flywheel, hipo exhaust divider, lightweight cowl, etc