phragle

iTrader: (3)

You may be a bit overambitious with a 28 b1. I dont remember what springs Al set my heads up with for the 731, but on the first outing with a 24 p 4blade, it was instantly at 6000 rpm and 80 mph or so... Even on the dyno at 5800 it was pulling strong and hadnt started to nose over (though my heads and valves are different that what you are running)

SCARAB.23.SCS

I talked to a guy with a 22 scarab ( I know it's a different hull, 400 lbs lighter) with a 525SC and he said he runs a 28p bravo 1 and does 78mph. The place I bought the prop from said I can exchange it for a different prop if it doesn't work for me so we will see. On my test run with this motor before it blew up I was running my labbed 23p merc revolution 4 and hit 67mph @5100 rpm

phragle

iTrader: (3)

gps speed???

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Yeah GPS. 67mph and then both head gaskets let go and she hydrolocked !

Griff

Isky 8005 or Comp 929's would be the valve springs to use with a 731. You will also need a different timing chain and different pushrods to run a 731. By the time you are done, swapping to a roller cam will run about $1500 more.

The 731 gives better midrange acceleration and will add about 30-40 hp / 200rpms on the top end.

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Couldnt find JEs on summit racing, but found the same part number in SRP and read that they are the same company? Just want to confirm these will work.

https://www.summitracing.com/parts/srp-139477-8

There's also a couple other brands with the same part number that look the same. ( ICON / Ross ) I'm guessing they would also work for me as well. Thanks!

Griff

SRP is JE's Sportsman Racing Piston

mike tkach

iTrader: (3)

several years ago i built a pair of sc525 clones for a oso member,i don,t remember how far we bored them but i don,t think it was much,i had some 9.1 to 1 custom pistons made for it,had bob madera get me some mild hyd roller cams,used afr 305 heads and the merc distributors and if i remember correctly total advance was 34.they made 690 hp on the dyno with good dyno headers and with his not so good exhaust system i would guess he lost 50 hp in the boat.he ran them trouble free for several years before he sold the boat.maybe he will see this thread and offer more information.

mike tkach

iTrader: (3)

i have used the icon pistons in a few 502 builds with good results,nice piston at a decent price.

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Could someone post a summit racing link for head gaskets?

4.280 bore. (.30 over)

I've been recommended Cometic MLS but there's alot of options