Replace a pre cross flow with OHC

[Roath]

Hi Guys

Looking at doing the same things as Chubs a while back with my boat. There is heaps of great advice on the old threads, my difference is that I have a hamilton jet.

Do the later motors (eg ED) have the same mounting for the gearbox as the pre cross flows (I can't see it!). My Hamilton Jet has a shattershield which bolts directly onto the motor.

Another concern is if the flywheel is the same? Can I use the one I have? (cause the whole system is balance on the current one)

The reason I am looking at ED is due to the torque figure being at such high revs (Torque: 348Nm at 3750rpm)

My WOT is about 3000 currently which is crap for the non cross flow XA motor (Torque: 325Nm at 1600rpm)
Problem is the engine cover is very narrow , I doubt there is enough room for an intake manifold. Are there any 'narrow' options?

TIA

 

[xctasy]

Any OHC intake will scupper your plans. Plan on regigging the seat. X-flows, ohc's and 202's and 265's have the exhast on the true left, just where we put our passangers in NZ. The only other option is getting into a good rebuild of your 250, and shove a direct mount or Offenhauser triple carb set-up on it. An engine rebuild is better, and one heck of a lot cheaper than doing an OHC.

The OHC's rev so much better than the old OHV's but have a different bellhousing pattern. The 1994 EF had 5 extra bolts on the standard four or five bolt bellhousing, and the ones after 1998 had alloy sumps. All OHC's have the starters mounted like the old 265 Valiants, nested up under the intake on the true left.

The industry is just catching up now, with a few boats getting them. Somewhere, there will be a full kit avaliable.

If not, the best bet is to use your ED, and try an convince some people to do an reworked 265 Hemi Hamilton jet adaptor. As stated, the starter motors are in the same place, both used the BW automatics and are pretty similar. Not that hard, and there would be more than a few takers.

Regards width, the ED multipoint is best because everything is mounted low down, and has a lot or grunt. The Link computer can be stuffed into the stock wire loom, and case, and all the hassles of tuning can be avoided with just one wide band oxy sensor.

A spare Ignition is cheap to get, and as long as you keep a back-up, you'll be sweet. Managed engines are a pain in the ar__ on the water as you've got to cull out quite a few of the Power steering, air con and cooling system parts, along with the EGR or emissions purge valves, idle steeper motors, yada yada yada.

PLus is that plenty of ruested out E-sereis Fords donate SOHC's to the scrap dealers every year, and your better off picking them up, and getting your head around the EFI management. Stock EA to EL cast iron exhasts are easy to turn into a heat exchanger.





Note Well

There isn't a better dollar per hp per pound power boat engine than the little ohv 202 Holden, 200/250 or 245/265 sixes. They are non electronic, have all parts avaialble, all the tricks are known. Stock, they are okay for a pleasure boat, but torque is at 1600 to 2500, which is too low for a more harded edged boat unless you fit the EI/XU1, aftermarket Crow or kelford or E38 cams.

Engines like lightweigth alloy Buicks and Rover's are very expensive, and Nissan L and R series sixes are suprisingly heavy.

The much better 1988 onwards OHC engines are another 50 pounds up on the X-flows and almost 140 pounds up on the old non x-flow. The packaging gets harder with each year.

 

[Roath]

Thanks Taxi , The Holden 6 doesn't have enough torque for a 3 stage hamilton jet. I would have to change the jet to a 2 stage and get the revs up higher. Too much work to swap it anyway.

It looks like a rebuild with the right cam might be the go then. I was liking the idea of the lighter motor with more grunt.. buying a good one off trademe seemed a cheap way to go.. but oh well.

I have another 250 non cross flow in the garage so I will go back to the old plan of rebuilding that.

Cheers