Siver century direct drive problems

[Arbian]

Hi,I acquired a supposedly non running silver century 1973 direct drive a while ago and after fitting a new plug and putting in fresh fuel and new throttle cable got it going no prob. After running for a good while on boat it lost power and died. I managed to re start with a little difficulty but only gunning it would stop it dying. After reading Johns FAQs I was concerned that it was a leaky head gasket but was advised to first try cleaning out fuel line carb etc before the dreaded head removal. I did this and turned the float on the Amal twin jet back to it's correct position (it had been moved to the tank side of carb body). Now when I have gone to tank test the motor I had serious bother getting it started (although water very cold .... Scotland! After I finally got it going it really was not happy and when I gave it revs it was backfiring and cut out. After changing my underwear I then tried re starting without success any ideas? Cheers
P.S. I took prop off to run in tank, carb is converted to 25:1

[Stelios_Rjk]

I believe that in case it was a leaking head gasket you would have face that problem when you first attempted to start the engine. In addition in case your problem is that you will be able to see water or oil coming out of the joints, where the gasket is located.

It looks like an ignition issue to me. What about resetting the points and measuring the resistance of the coil? Or it could be the condenser. Add a condenser to see what is going to happen at first and then continue to anything else. It is easy.

There is a screw where the lead of the condenser I am holding ends. Connect over there the lead from a condenser, then bolt the cond. somewhere that it won't interfere with the flywheel. Cond should be around 0.25uF.

[Arbian]

Thanks for the reply Stelios. I went out to try another (new)HT lead and found the metal cap on end of plug loose. I tightened this and fitted new lead and got engine going again however ...... bad news is I looked at head seal and you were right I could see tiny water bubbles. I wiped the seal with washing up liquid and this confirmed the bubbling so I guess it's now time to try and get those head bolts off .... oh dear!Any tips? Do I heat the ends of bolts with blow torch (after removing tank)?

[Stelios_Rjk]

Yes I almost get the head of the bolts glowing red. It is no need to heat it so much but some heat would do good. Don't apply enormous torque to avoid breaking a screw. In case they don't come off, heat them more. Patience and luck!

[Collector Inspector]

"Bad news is I looked at head seal and you were right I could see tiny water bubbles"

Take the block from the cases. Mount solidly said block in a bench vise.

Head has to come off but do not sweat that, is really no big deal as you may have to accept a broken thing or two worst case .

Yep, heat and cooling cycles each fastener. I say cycles as expansion contraction between bits is a powerful friend without you actually seeing anything happening. It is like Zen.

Bubbles of stuff will come out of the gasket area as you repeat.

When you have enough and totally over this process use an impact driver set to undo. Hit smartly but not over the top each. One may break but even broken fastening can be fixed later on the rebuild.

Basically it is a case of being firm, resolute with patience and seeing what happens with absolutely NO FEAR.

Yeh, stuff may break and be a pain later but in that you have progressed.

All can be rectified at a later date and satisfaction will be a dead cert.

Enjoy

B

[Arbian]

Well, either this head has been off before or I am guessing this motor has seen mostly freshwater running as all studs came out no prob. Cleaned up both faces and got new gasket and sealant. Managed to borrow a torque wrench from a friend ("bench experience" ..... about none .... what does 18ft/lb feel like? ... not a clue) and got it all back together. Gave the sealant the recommended 4 hours then torqued up .... engine running again and no leaks evident. Will keep my fingers crossed it endures ............ I think it will need to wait till spring for a boat test ..... had to clear the ice from my test bin! Cheers for all the advice, much appreciated.

[Stelios_Rjk]

Good news! Nice to hear it, clean the ice and run it in gear if you are in the mood.

[headdownarseup]

good news that the head came away without any upset.
yep these motors respond quite well to a bit of cleaning , just make sure the entire fuel system is good and clean everywhere, points are set up right and the right plug gap and the motor will repay you with years of noise and smoke. btw when you had the head off what where the water jackets like?
rust and crud will build up quite quick if its been out of action for a while. and water will cease to flow from the outlet, which eventually leads to a cooked head gasket?