Flywheel Forward Engine Page
 

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283 V8 Flywheel Forward Engine
 

The original Paragon 1.5:1 reduction transmission was replaced by a Velvet Drive 71C 1:1 ratio transmission. (05-APR-2011)

Installation angle is 15 degrees.

 

 

 

 

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The following photos are of a Chris-Craft flywheel forward 283 HO that we rebuilt for a Glen-L Monaco builder.   Transmission is a Paragon HF7 1:1 ratio.

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4.3L V6 Flywheel Forward Engine
 

A 1993 Chevy 4.3L TBI V6 was fitted between the front and rear plates to check for fit.  Note the front engine mount tab which was used to mount the V8.  The V6 is 6" shorter than the V8. (07-APR-2011)

Installation angle is 15 degrees.

 

 

A custom oil pan will be required for this application.

 

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Increasing engine power level

Before costing out performance engine parts for your 283, check out the pricing for 350 crate engine performance long blocks.  You'll need better flowing cylinder heads and a more aggressive camshaft to increase power levels.

Here are a few issues you'll have to resolve if you're not using the stock engine :

  • Water outlets

    Your cylinder heads will require machining to fit the water outlet elbows, or you can substitute an Edelbrock Performer or RPM Air Gap intake manifold equiped with four corner water outlets.



    More details and photos can be found on this thread on Glen-L's BoatBuilder Forum : Marinising 350 Chev


  • 283 Flywheel Forward Water Cooling System Flow Diagram (02-FEB-2013)

       

    Click photo for a high resolution 1024x359 image.



  • Drive plate

    The drive plate is a press-fit on the 283's crankshaft snout.  The transmission's splined input shaft mates to the drive plate hub.

       

       

    The 6.18" dia. damper for 26 spline transmissions as used on flywheel forward Flagship, Chris Craft & Perkins engines are hard to find.  A source is www.partman.com under Part Number  BJMDA102



  • Distributor

    The Chris-craft distributor is driven by a spur gear mounted to the front of the camshaft.  You can plug the hole and use the stock Chevy distributor location and retain the more modern HEI ignition system.


  • Transmission

    A rebuilt Paragon will get the job done on a stock engine, but the Velvet Drive 71C would be a better choice for higher power levels.

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Installation Dimensions - Velvet Drive 71C transmission
 
  4.3 V6 283 CID V8
Engine & trans overall length 33-1/4" 40-1/4"
Bellhousing to front engine mount 22-1/2" 28"
Bellhousing to to front face 17-12" 22-1/4"
Crankshaft centerline - Front 12" 12"
Trans output flange centerline 3-1/2" 3-1/2"
71C transmission length 15-1/4"

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Shaft Layout Diagram - Flywheel-Forward V8 with Velvet Drive 71C transmission (14-MAR-2012)

We've had several requests from Glen-L builders wishing to extend the hull length and pondering where to locate the engine, or adding a transmission to a design that was never intended to have one (direct drive) such as the 15' LOA Glen-L Cracker Box.

We needed to find some answers, so frame offsets from the Glen-L plans were loaded into an ASCII file and imported into HullForm95 hull modelling software.  The hull was balanced and the hull CB (Center of Buoyancy) was noted after the hull hydrostatics report was run.  The HullForm input file was converted and imported into DelftShip.  The CB was confirmed by running the hull hydrostatics report.

The hull weight, hull CB, engine, transmission, passenger and fuel tank weights and locations were loaded into our Excel Hull CG Locator spreadsheet to derive the hull CG.  The spreadsheet calculates the hull CG for a single driver and hull CG for a driver & co-pilot.  The hull CG-to-CB distance is included in the drawings below :

Click image to enlarge.

Notes :

Modelling the stock length (15') Cracker Box Hull reveals that the hull CB is located at 58" from the transom.  The boat is usually fitted with a direct-drive flywheel-forward V8 (no transmission is used) with the propeller shaft coupled directly to the front of the crankshaft snout via a chain coupler.  The 600 pound engine CG is located at 70" from the transom.  Hull CG is located at 68 1/8" from the transom and 9 3/4" forward of the CB.

Substituting a flywheel forward V8 equipped with a Velvet Drive 71C inline transmission will increase the engine/transmission weight to 700 pounds.  The engine/transmission CG is located at 70" from the transom.  Hull CG is located at 68 1/4" from the transom and 9 7/8" forward of the CB.

The shaft angle in the drawing can be verified by using our Shaft Angle Table

  1. Take the length dimension from the aft end of the strut to the shaft entry point e.g. 30",
  2. Scroll down to 6.75" in the Drop column,
  3. Locate a value that is close to 30" in the Length column,
  4. The shaft angle for that length is listed in the Angle column.  Angle is between 12.5° and 13°.


The following shaft layout diagrams are for the same hull stretched 10%.

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The flywheel forward installation is the preferred installation as the engine CG is very close to the hull CB.  The shaft angle is lower which will ensure that the boat won't have any handling quirks associated with steep shaft angles.  For the same shaft angle, the flywheel aft engine is installed 8 inches further ahead than the flywheel forward engine.  In this installation, this places the engine CG 8 inches ahead of the hull CB.  As a general rule, the engine CG should be located on or aft of the hull CB.

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Hull Balance Spreadsheet (21-FEB-2015)

Here's partial ouput from the spreadsheet we developed to calculate the boat's CG :

Here's a link the spreadsheet :   Moment Study for the Glen-L Cracker Box (PDF)


Feel free to contact us if you are modifying the plans and wish to determine the optimum engine location without adversely affecting hull balance.

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Revised 02-FEB-2013
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