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mphatc
09-16-2003, 06:18 PM
During a phone converstaion with the resident student of boats and Donzi's today the question came up;
"Why are you maintaining the reverse rotation of the original Holman & Moody 302 when you build a new engine ?"

For me it's because that's the way it was first built and it's unique . . but after thinking about it a while , and that CDMA didn't know :confused: :p I started to wonder . . Why did Donzi originally build these boats that way??

Is it because the seating is on the left?

Anyone really know why?

MPHATC

BillG
09-16-2003, 09:28 PM
Why do you think it is a reverse rotation? The Volvo drive, if that is what you have will rotate either way by just changing the linkage.
Bill G

MOP
09-16-2003, 09:54 PM
We got into this rotation thing with the Volvo drives awhile back, I will leave it as this! One direction the drive is damn near Invincible! One direction will if supplied with enough HP eventually drive the vertical shaft through the top cap of the drive blowing it to Smithereens when the keepers let go. Lets see how many can figure out which direction is which!

My libation tid bit!

DonCig
09-16-2003, 11:08 PM
M.O.P.. Great answer!

Don

BigGrizzly
09-17-2003, 05:50 AM
Wake up, there was never a reverse rotation H&M engine in a Donzi classic. The outdrive, was a left rotation NOT the engine. I can tell you this because I currently have Two H&M Donzi clasics. MOP I checled with All Island Marine and it is the right hand rotation and it takes over 500HP and an abrusivre driver and no matainance to cause the problem.

BillG
09-17-2003, 06:47 AM
The normal rotation for engines is left hand as viewed from the rear of the engine. The drive direction does not have to reflect that. Right hand rotation engines are reverse rotation.
Bill G

MOP
09-17-2003, 05:27 PM
I figured that was a pretty fair post coming in late and loaded with Libations! Yeah if you pump the horses it pays to follow Petes guidence on rotation, so it coats a prop or two. I had one old boy shove the shaft jumping wakes!

mattyboy
09-17-2003, 09:50 PM
MOP
is that your left or my left, sounds like someone is ambitexturous with the libations :D

Matty

mphatc
09-17-2003, 09:51 PM
OK, If there was never a reverse rotation engine from Holman Moody why was I able to buy the last two cams like this from them?? Yesterday! they just found the billets for these while moving to new facilities! Why did they have them, why do other cam grinding shops* know of these engines?

I'm really confused now!

*Comp Cams and Lunati

MPHATC

Moody Blu'
09-17-2003, 11:11 PM
BigGrizzly:
Wake up, there was never a reverse rotation H&M engine in a Donzi classic. The outdrive, was a left rotation NOT the engine. I can tell you this because I currently have Two H&M Donzi clasics. MOP I checled with All Island Marine and it is the right hand rotation and it takes over 500HP and an abrusivre driver and no matainance to cause the problem. thank you! wink

I said this in a thread before. My motor is not reverse rotation and all i did was take the h/m motor out and put in a standard rotation motor with a custom ground lunati cam. To even further verify this, my msd distributor was installed after rotating the motor till it hit TDC on #1. It was rotating standard.

I also have a left hand drive.

Now that you sorta know :confused: wink

how bout checkin out that ford motorsport 6500 cam :D

Craig
09-18-2003, 06:14 AM
I had a friend who had a friend whose kid could bat left handed OR right handed; he said he was "amphibious" but I'm not sure that will help here.

BUIZILLA
09-18-2003, 07:13 AM
Here's the scoop as I know it being a local... :)

The Donzi HM spec'd motors were ALL std. rotation, in single engine applications.

That is to say, the engine turns clockwise, when looking towards the front. Grizz would be correct.

HM had reverse rotation cam blanks for TWIN engine applications, where reverse rotation would be a necessity. I am 99% positive they had 289, 390, and 427 cam blanks in each rotation configuration.

J

J&K SHAHBAS
09-18-2003, 09:19 AM
Your correct Im also having H&M grind my 600 cid
cam for my 1967 28' that is based on a 460 camshaft. also older GM based motors were build
with righthand rotation for use in cruisers and
inboard ski boats. Holman Moody was the only supplier that I could find that had the ford blanks. or I would have the put outdrives on my boat in stead of v-drives.

BUIZILLA
09-18-2003, 09:42 AM
I'm pretty sure the original blanks came from Crane. Not positive though...
Crane still makes a TON of blanks for several other cam grind company's, who don't have the tooling. I bought 2 blanks from them for roller cams in my V6 and V8 Buicks and had 2 other company's grind them with their master lobes to my spec's. I have bought even fire and odd fire V6 Buick blanks from Crane, and had COMP or Cam Motion grind them. My Mighty Mouse 392" engine is a Crane roller blank ground by Cam Motion.

J

CDMA
09-18-2003, 11:18 AM
Jim,

I think you are on the money. Mario I would be really suprised if your engine is in fact reverse roation.

Chris

Wake up...friendly aren't we...Back to bed for me :)

DonziDave
09-19-2003, 09:16 PM
OK - Here's the skinny. You are all partially correct. Donzi did not spec. reverse running engines, but I know of at least two that had them installed by HM. I knew John Holman and many of his engine builders. Lake Wylie, where I live, was just a couple of miles from their shop and they would test run boats every day. Holman liked to experiment and would combine various combinations of engines, drives, and setups in his test boats. Many times after they were done with testing, these boats would be sold by HM. I know of at least two Donzi's, two Champ's, a Rayson Craft, and a Super Nova with reverse engines.
In fact, the Super Nova was a 19' boat that was custom built by Brownie for John Holman. It had a reverse running HM 427 hooked to "vee" drive. I bought the boat from John. It was a great boat that I regret selling to this day. However the reverse setup was a major pain in the ass. Try finding a reverse running starter in the backwaters of Florida on a Sunday. When I rebuilt the engine, I coverted everything to conventional running.

Dave