f_inscreenname

Built a O.K. radical 496 stroker for my boat last year and have been dealing with a starting issue for a while now. Crank 4.25, 496 stroker. Scat 26385P - 6.385 in. Connecting Rods - Bushed -I Beam Forged 4340 steel. Howards Cams 120255 - Max Torque Retrofit Hydraulic Roller Camshafts, Hydraulic Roller Tappet, Advertised Duration 288/294, Lift .585/.610, 112 L/S. Should be about 10.25 to 1
Everything was checked and rechecked with this motor when I put it together last year and besides this issue it runs perfect. Never anything less then 50psi oil press. No knocks or pings..ever. Probably has about 25/30 hours on it now.
This is the deal. Take the boat out, run it hard (to get it hot), slow down and put up to the dock (at least 3 to 4 min running cool down period as I get to dock), shut it off. Now if I go to start it right away it does with no issue. If I let is sit for 5 mins it cranks like its a dead battery or the timing is to far advanced but the 2 Bats are fine (wires and ends are also new) and the timing is base set at 10*. So I thought it was the starter. Get a new 1.5hp mini starter and when I would go to use it in the same situation it would spin over the teeth of the flywheel. Tried to shim it every way I could upside down in the bilge but no matter what it would do it. There is a opening in the bell housing to see the flywheel and the ring gear looks fine all the way around and the the flywheel relatively new. So I just replaced it again with a 3hp 4 gear reduction starter. No more skipping over the teeth but it works hard in the same way the first one did when I thought it may be bad.
This only happens if I run it on the water. If I run it in the driveway it wont do it
Any ideas? I'm thinking at some point I may break something or is that the way it is with motor like this?

c_deezy

iTrader: (1)

Heat soak on the starter after sitting for a few minutes and engine room/engine heating up due to no cooling water coming through perhaps?

How long until it goes back to normal after the engine cools down?

Ted G

iTrader: (1)

I would bet it's too much compression/timing. Get it hot till it slow cranks and then disable the ignition, see if it spins well then. If it does you will probably need a retarder for starting or more octane. I would also worry about detonation at high speeds if it is slow cranking like that.

stevesxm

this sounds really right. remember all your 454 duallies your couldn't start after you parked them until you poured cold water on the starter ?

sounds like the same thing...

f_inscreenname

10 or 15 mins

mcollinstn

Yep, pull the kill switch when it's cranking slow - if it speeds up, you need to retard your ignition timing at startup. If not, then grab the starter. If your skin melts, then it is heat soak on the starter.

If killing the spark doesn't help and the starter is at normal temperature, then pull the plugs and crank it and see if you get any water spraying out.

MC

f_inscreenname

No water thats for sure. I'm always super paranoid about that.
You all got me thinking and I will try your suggestions the next time out. Also just picked up a heat wrap for the starter just for sh!ts and giggles.

FIXX

iTrader: (2)

for starters!! im funny, having a 153 tooth flywheel dont help..i know you mark and i know you did not degree the cam,,it may be off 2 * and if thats the case you are most likely 4* advanced on the cam..dont trust the marks on the harmonic ballancer,,when degreeing the cam i always make sure when the @ one piston is at TDC no 1* - or + i mean rite on TDC i always check the timing mark and as always its way off.to correct you have to move the marks on the timing cover or buy a adjustable timing marker.install a starter button,,push the button and let the engine turn over a few times then turn the ignition on..
cured!

FIXX

iTrader: (2)

Tttttttttttttt

f_inscreenname

Hey fixx
No I didn't degree the cam but did use a dial indicator to make sure #1 was at the top of its stroke before went on putting the motor together and the timing mark was on 0*. With the cam I used there was no reason to advance or retard the timing set so everything went in straight up. A bit crude but it works. I also tried dropping the timing back to the point the motor would stumble and always had the same results.
The new 3hp 4 gear reduction starter seems to be doing the trick at the moment. Went up to Baltimore tonight. A good 25 miles round trip. Ran up hard, did some 6mph for a couple miles, shut it off, give it 5 or 10 mins and hit the key. Started right up. Ran harder coming home. Blasted right up to the ramp. Tie up, shut down, unlock gates and back the truck up (now i want it to do it so I can try a couple of the suggestions) maybe 5mins and it started right up again. The only difference then the times before is that it was cooler (80's) compared to the 100*+ weather that seems to have been here all summer.
Now to get my confidence back in the boat. It's never left me stranded. Maybe with a total piece of useless junk under the motor box cover when I got to the ramp but it would give it dieing breath getting me there.