Corsa 31

I have searched though old posts related to changing from V8-24 to a V6-14 module with TB IV, but have not seen anyone due this on Merc 800SC's (572 tall decks,420 megablower, 7.5 CR, flat tappet hyd cam). I have read that other fellow blower owners and bulders have done it, but has anyone done this with reliable success on the Merc 800SC. I do not need more power or speed, just a little more dockability, in and out of gear. 32 Skater, twin 800SC's, # 6's 1.24 gears, 34" pitch props,top end 125-130mph. Thanks, Paul

Corsa 31

Any module change on an 800sc?

asmith

iTrader: (2)

it will work ok and give you more initial timeing which helped my idle. i have two for sale if you need them. i used the crane ignition which has every mercury advance including the v6, but also has one that gives even more advance than the v6. all are available by turning a rotory switch. thats the one that works best on my blown 540,s. they also give multipal spark discharge like the msd boxes and built in adjustable rev limiter. i killed two birds with one stone.

ratman

im running the same crane hi6 boxes i got them from randy at cobra. he has crane do a few things to the ones they sell him that are different from the regular off the shelf units. i bought mine to run on my blown 588's. good luck wif it, ratman

Griff

All this info is out of a Merc HP manual

Base timing at idle is set at 8*
The module on the 800SC has 20* of advance.
12* of that is in by 2500rpms
The other 8* comes in slowly between 2500 and 5000rpms.
Total timing at 5000rpms is 28*.

I would think a V6 module would work well for you. The base timing of 8* seems way low. With the V6 module, you should be able to set base timing somewhere in the 20* range. The V6 module gives from 6-10* advance on a V8.

You could always just bump your base timing up to 18-20* while at the dock and give it a try idling around to see if it helps. Just don't run it except at idle.

Corsa 31

Thanks guys. Griff that is a good idea, I may do that.

Linster

I have used the V6 on blower motors. It woks well but its advance usually starts below the idle of a blower motor. Need to set the timing at 3000 rpm for total and not worry about the bottom. It will be somewhere in the 16 range.

It will be vulnerable to surging. The way I got it out was to install a Crane ignition. MSD will also do the same, I did the Crane so I would not need the V6 module.

Edward R. Cozzi

You guys are bigger risk-takers with those big expensive, blower motors than we are here in SE Florida.

Doesn't it stand to reason that if Mercruiser KNEW those engines were better off with the V-6 module that they would come with it? Hell, the part is in their inventory and wouldn't cost them a nickel more.

If you get some poor fuel isn't that engine more susceptible with that more aggressive advance curve?

I would think that just adding the MSD box would help that docking without jeopardizing that engine.

Just my .02. Just tell me to shut-up.

Strip Poker 388

iTrader: (6)

Total timing at 28 seems real Conservative to me.

I have always run the MSD stuff and you can do what you want to with the timing.I one of my blower motors the 460ci I built I put the base at 18 and total at 35 on 93 oct . Dynoed the best there and at at 762hp . Most big cam motors I have seen like a lot of timing at idle .

Ya got to figure that when Merc built the 800sc's they built them with a little fail safe in them.

10x

Rob..... you are correct, but, I think what Mercury is doing is..... they're building an engine that is supposed to be turn key with a warranty on it also.
28* is very conservative total advance. But also the 800 SC has iron heads too, therefor you need to be shy a few degrees from those of us that run aluminum heads.
By running the most advance you can at idle, will help eliminate that blower surge.

We generally lock the timing in at 30-31* for steel hds, and 32-33* for aluminum hds. That's on the big hp stuff, and not for everyone. Some people just need to be more conservative.