81 Crusaders 350 cid 270 hp, timing help

[bshillam]

I set my base timing as the manufacturer recommends at 10 degrees BTDC. However in the owners manual there is nothing about TA most of my reading says I should be all in at 3200 rpms and about 22 degrees, not to even worry about base timing - let that fall where it will after setting it at the higher RPM setting. First time I have adjusted timing and would like to do it properly. Thanks for the help.

 

[Ski in NC]

Set at 22deg at 3200 or above. That is what matters. Back to idle if advance is working, it should settle around 10deg.

 

[DavidM]

Well, let me go back a few decades to the olden days when ignition consisted of a coil and a distributer with points.

Almost all ignition systems advanced timing based on engine vacuum (via a diaphragm) and rpm (based on spring loaded weights like a governor).

So I believe that the proper procedure is to disconnect the vacuum hose and adjust the base timing at idle using a strobe light.

David

 

[OFB]

I have always set timing on marine gas engines using a vacuum gage. dockside under load.
Secure boat to dock , bring RPM up in forward gear and adjust for high vacuum reading at like 1800 , 2000 rpm. You might have to back off adjustment a bit after a test starting of the engine.
Sorry my written word sucks. But it is very simple and effective.

Works for me any way on the older power plants.

 

[Capt Kangeroo]

Probably already know this but if you have counter rotating props remember the port engine turns backwards and is set opposite at ATDC. I had the Crusader V6 229cid's once and made this mistake. Amazing how well they idle so far out of time. Starboard has timing gears, port has timing chain.

 

[River Cruiser]

Well, let me go back a few decades to the olden days when ignition consisted of a coil and a distributer with points. Almost all ignition systems advanced timing based on engine vacuum (via a diaphragm) and rpm (based on spring loaded weights like a governor). So I believe that the proper procedure is to disconnect the vacuum hose and adjust the base timing at idle using a strobe light. David

All marine gas engines I've worked on had mechanical timing advance not vacuum. I always thought that was part of the marination of a automobile engine. Even electronic ignitions I've used had the same type of advance, you used different springs to set the advance curve. You have to make sure the linkage is free of rust & can move smoothly, a bit of lubricant helps.

 

[High Wire]

Make sure the weights move. My old boat had Crusaders and both advance mechs were frozen. I should have just replaced the distributors with new, electronic units.

 

[capt jerry]

All marine gas engines I've worked on had mechanical timing advance not vacuum. I always thought that was part of the marination of a automobile engine. Even electronic ignitions I've used had the same type of advance, you used different springs to set the advance curve. You have to make sure the linkage is free of rust & can move smoothly, a bit of lubricant helps.

all the newer ones are advanced by the computer now days. I liked the old way better

 

[River Cruiser]

all the newer ones are advanced by the computer now days. I liked the old way better

I'am not very hi-tech, I liked the old type.

 

[Ski in NC]

Ha! High tech indeed. A boat on my dock is an old Harker's island skiff with computer EFI GM 5.7. One day it would not start, just fart and sputter. Tech called down and plugged in computer. Said something was wrong with ECU or something. Ignition failed some tests, crank position sensor doing something strange. I came down a week later to help out.

Fiddled with it a bit. Boat was out of gas.

 

[bshillam]

When I checked both motors the advance was 10 degrees at 700 RPM which is what factory spec was. I also checked at 2600 RPM and it was 26 degrees which is what factory specs were on my distributor. So I am assuming the weights/springs are in good shape being the advance was w/i spec. Yes?

 

[Bob Cofer]

Yes. The only way you will get a completely accurate picture of the advance curve is to remove them and have them tested and the curve plotted. Total overkill for your application.

 

[RT Firefly]

Greetings,
Mr. b. Best not to assume anything. Not a big deal to check to see of the weights and springs are fairly rust free and free to move. Remove cap and rotor take off the plate holding the points and the weights will be exposed. Wiggle the weights about with a small screwdriver. A SMALL drop of lubricant wouldn't hurt on the weight shafts. IF you decide to take off the weights and springs, make sure the parts go back on in exactly the same position-very important.

 

[Ski in NC]

BSh- Definitely lube advance mechanism as per above. That's an often neglected maintenance step. But if 10deg at 700 and 26 at 2600, advance mechanism is working. Should be good to go. What about at 3500? Check that too as it might not be on the stops at 2600. Not sure of the spec for your engine, have no idea where to find that.

 

[bshillam]

Max degrees were at 2600 rpms between 26-29 per the manufacturer. But I will add some oil to the weights to make sure they are free.

 

[Bob Cofer]

Not sure oil is the correct choice, light grease may be better.