Ignition question?

[FUN4ME]

What should the timing be on a BBC in a jet boat?
I have a 79 Southwind with a BBC. Last time I took it
out I got water in the oil. What is the most common
source of a water leak? A head gasket or an intake
gasket? Any way I bought it about a year ago and have
no idea what type of cam it has in it (does the cam
make a difference in timing?). Here is what I know
about the engine BBC rectangle port heads, tunnel ram
intake, Holley carb, stock dist with electronic
conversion, Bassett headers. Other than that it has a
Berkeley JG (don't know what impeller it has) the
engine will spin to about 4750 RPM and reach about 65
MPH. Thanks in advance Erich.

[Squirtcha?]

More often than not, your headers will cause the water in the oil thing.
Couple questions.
Do you have steam/water to your headers at less than 1500 rpm?
Are you running a Bassett T valve with those headers?
If so, have you checked it lately?
Make sure it's clear of obstructions that could hold the ball open. Check to make sure the spring inside isn't broken, and when you reassemble it, spray a little WD-40 on the ball and inside the valve prior to putting it back together. Also the spring inside the valve has two different sized ends on it. Make sure the small end is the one the ball sits on. The ball should not fall inside the spring but be perched up on top of it.
Are you running a valve for the cooling water from the pump to the motor? What is your engine temp at idle and while cruising?
Have you ever had this problem before, or is it a recent development?
My take on the timing thing would be to check with the cam manufacturer to see what they recommend (if you know the grind # and cam maker).
Otherwise a pretty good rule of thumb would be 10 degrees BTDC static (idling at about 900 rpm)
Total would be around 34-36 BTDC when all the mechanical advance is in (3000 rpm or so).

[squirt]

Yep everything that Dan said. Just one more thing to check on water in the oil stuff. It could come from the intake so you should at least check the torque on the manifold. Most al manifolds should be around 25 ft/lbs. You might also want to check the water pressure your engine is seeing.

[Moneypitt]

Sounds like you're really close to perfect!! IF your speed is truly what you say, at that RPM, you must have some kinda pump on that boat......But, if your looking for real speed, I mean really 65 MPH, not just what feels like 65, then you should get a total advance of about 30 to 35 degrees. Like 14 initial, and 16 in the dist. for a total of 30, run the boat in a controlled test,(GPS) and advance from there until the top end starts to fall off, OR the motor starts to detonate. Remember, this engine isn't in a car, with a factory set recomendation for timing, there is no book to go to for this info, so you're going to have to learn by trial/error what works the best for your set up. Just like we all have to do. Also, the "curve" of the dist. is VERY important in a jet boat, how much advance at how many Rs, etc. Just be careful not to "ping" the motor to death while experimenting.....Good luck...Moneypitt

[FUN4ME]

Thanks
Squirtcha?,
They are water injected and they do steam arroud 1000 RPM. Ill check the T valve. It also has a gate valve between the pump and motor which is fully open. Ill have to look at the temp gage later at idle I dont know what the temp is but at speed the needle is at rest on the cold side of the gage. This was the first time I ever got water in the oil (new problem)
squirt,
Thanks Ill retorque the manifold sounds easier than replacing gaskets (Ill do that if I have to)
Moneypitt,
GPS 65.?MPH going up river near Park Moabi.
one last question how do you know if it is pinging (detonating) I cant hear much over the exhaust.
Thanks again for all your help Erich

[squirt]

sounds like too much water pressure ya need to close the valve alot. Idle around 160-180 might spike up after hard pass but will recover quick. I run mine a bit cooler and run around 20lbs at wot. You might have blown by your gaskets with alot of pressure and it just might not reseal after retorque but it's worth a try.

[Squirtcha?]

one last question how do you know if it is pinging (detonating) I cant hear much over the exhaust.
This is a very good question and why I would caution about trying to run too much timing. By the time you hear it, it could be too late. In my mind, a mph or two is not worth frying my motor. I'd tend to be a little more cautious with it.
They are water injected and they do steam arroud 1000 RPM
Yup, good idea to check that valve. If it's working properly, they shouldn't steam below 1500 rpm or so. You may want to close off that cooling water valve some too. Just keep a close eye on the temperature. It should be around 150-180 degrees at idle like Squirt said.

[Jake W]

Moneypit not trying to be a know it all but my heavy ass Tahiti that I just sold would run 69 GPs at 4700 it had a feul problem (would start to run out of gas and fall on its self)that I never fixed to see what the top rpms would be.Though this was a(flat) shoed pump with a ride plate and droop that had just been rebuilt the year befor last..
Jake

[RD Express]

I would run the timing at 38 total. You can check the plugs to see if timing is slow, fast, or just right. On the electrode (The flat bar with the bend) find the line where it changes colors (The heat line). This should be in the middle of the bend. I think if the heat line out towards the center timing is to fast, if it is down towards the treads it is to slow. I my be backwards on the slow/fast, but I will double check this and let you know. You definately went the heat line in the center. Also check for peppering on the porsulien.

[Havasu47]

91 octane......32 deg. total
Keep the Bassett's dry below 1800