Convert 1985 E6RCO to E8RCO

[cprodave]

Looks like I need to swap 6hp Intake Manifold 390232 for 8hp 393733, plus 6hp LeafPlate Assy 390231 for 8hp 393959. I can't find a used (or new) 393733, but I found a 390232-2. Will the 390232-2 work Ok assuming I get/install the other correct p/n's?

Any other advice from someone who has successfully performed this conversion?

Thanks in advance.

Dave

 

[raczekp1]

only leaf plate is needed.
intake inlet you can rebore. i dont remember the hole size but can measure

 

[Vic.S]

Looks like I need to swap 6hp Intake Manifold 390232 for 8hp 393733, plus 6hp LeafPlate Assy 390231 for 8hp 393959. I can't find a used (or new) 393733, but I found a 390232-2. Will the 390232-2 work Ok assuming I get/install the other correct p/n's?

Any other advice from someone who has successfully performed this conversion?

Thanks in advance.

Dave

The crankcases are different too. I looked into up-rating an '84 model but decided it was not a viable proposition

IIRC a few other minor differences including cdi powerpack and carb jet

 

[jimmbo]

Until a line by line comparison of the Parts Lists of the 6 and of the 8, you can't say a carb/manifold change are the only differences.

 

[racerone]

A careful study or first hand look at the different motors may be required.-----Often it is not as easy as it seems to be.----Take a really good look at the intake gaskets for 1985 6 HP compared to the 8 HP model !!!!

 

[cprodave]

Thanks to all for the input--I will respond in order of my "thought process" undertaking this project.

Vic.S; the first thing I checked was Cylinder/Crankcase. For my 1985 the source document I am using shows 396257 or 396258 is used for both 6hp and 8hp. Same source shows that on your 1984 the 6hp and 8hp share usage of 393168 or 394449 Cylinder/Crankcase--what source document says the 1984 Cyl/Crank differs 6hp vs 8hp? On 1985 looks like CDI Powerpak Assy is 763798 or 396141 (6 models only) for both 6 and 8 hp. "Carb Jet" (I'm assuming this is Needle Valve) on 1985 is 432781 for both 6hp and 8 hp. So no changes are needed on Powerpack and Needle Valve.

jimmbo; 2nd thing I checked was line-by-line on Intake Manifold area. The 8hp uses fewer parts than 6hp ("restrictor "idea like on NASCAR?) This is how I concluded that I need to remove Intake Manifold 6hp 390232 and install 8hp 393733 (plus Leaf Plate and Gaskets). I have a seller offering a Used Intake Manifold embossed/molded with p/n "390232-2" which is the crux of my question. Is 390232-2 a bored-out 390232 which is then equivalent to 393733?

Racerone: as part of line-by-line compare I do see a couple differences in the Intake Gaskets and have planned accordingly.

Racekp1: Thanks for advising only Leaf Plate swapout is needed--this makes sense based on line-by-line compare. To rebore the Intake Inlet how would I know what dimension to achieve if I don't have the 8hp part in my hands to measure? Anybody got a drawing/"blueprint" for 393733 Intake Manifold?

Am I correct in assuming that OMC Help Desk at 844-345-4277 will not help me because this outboard is older than 1997? (that is what their website indicates).

Thanks again...

 

[racerone]

The gaskets between the crabkcase and reed plate are shown to be different.----I believe that should end this discussion.

 

[Scott Danforth]

Am I correct in assuming that OMC Help Desk at 844-345-4277 will not help me because this outboard is older than 1997? (that is what their website indicates).

Thanks again...

OMC went out of business in 1999. BRP picked up the outboard portion of the business in about 2001. the number you listed is for BRP, not OMC