thezigman

Hi everyone, I am new here, and need some help.

I have a 91 Larson with a 305Volvo penta
has a GM block. The stock carburator, and distributor was replaced with MSD equipment, and an MSD 6AL ignition, and MSD BlasterII coil was installed as well. Running stock compression, and stock plugs gapped at .055"

Running the stock set up on the distributor (we made no changes to the curve)

The boat has no pick up, and a lousy hole shot. initial timing was set at 21degrees BTC as I interpreted the instructions to say;however, I am not sure if this is correct.

My main question is where should the initial timing be set?
The book for the distributir says 21degrees crank timing. is that initial timing or total timing?
as determined by the advance stop bushing...

When accelerating from a dead stop, the boat bogs and sounds like it is backfiring through the carb, or missing badly, I cant tell which. it will eventually plane out, and then seems to do ok as it approaches 4000 RPM

this is my brothers boat, and we have been beating our heads on the wall trying to get this set up right.

ANY help would be appreciated.

Edelbrock 1409 Marine carb 600CFM
MSD 6AL Ignition
MSD Billit marine distributer
MSD Pro plug wires
MSD Blaster II coil

Initial timing at 700RPM is 21 degrees

Thanks for the help, and happy Boating!!

picklenjim

When they say 21 degrees crank you have to add your initial to that which is 8 degrees for a total of 29 degrees. This means total above 3000 RPM. I have the Mercury Manual which also uses the 305 Chevy motor. It says in it total should be 30-34 degrees. Set up at 8 degrees at 700 idle. Then use the correct stop to give you 30-34 degrees total by 3500 RPM's. Watch with a timing light as the motor is accelerated to see when the mark stops advancing. You may need to put a timing tape on your balancer if it is not marked in degrees that high.They can be purchased at speed shops.You will need to know the diameter of your balancer. Remember you need to set at 8 degrees idle and should stop advancing at 30-34 by 3500 RPM.

initial degrees (8) + crank degrees (21) = total timing

Rockfish71

Hello,
You need to verfiy that you installed the distributor in right. From what you are saying it sounds like the distributor was installed 180' degrees out from top dead center that puts the number one plug to fire when the camshaft is in over lap. and yes it will run just like what you are claiming it's doing. When you get it right set the base timming to 12 degrees you want 32 degree's total @ 3500 rpm. pull the valve cover and rotate the engine over till you see 1# exhaust valve close and the go to the zero mark on the crank degree mark. you need to make sure all the plug wire where on right.

picklenjim

There is no way the engine would even start if it was 180 degrees off. Having timing at 21 degrees initial is way to high.The plugs are firing so early it's popping through the carb because the intake valves aren't fully closed yet .Engine probably was "pinging" a lot also.Initial timing for that engine is 8 degrees at 700 RPM idle. Total timing is 30-34 degrees by 3500 RPM. It should never go above 34 degrees.

Xray50

Make sure you don't have the 2 wires going to the distributer crossed. I did and it gave me symptoms like that.

KAAMA

iTrader: (1)

Not sure if this is your problem, but it is something worth noting---you mentioned .050" plug gap. That sounds like a bit too much...??? I gapped mine .045" and was experiencing pops and misses even though the Crane (HI-6M) manuel said I could gap to .045". I remember checking the gaps as the plugs came out of the box from the factory and they were right around .030" or so before I changed the gaps to .045". I took the same plugs and closed the gaps back to about .030", reinstalled back in the engines and the occassional pop/miss disappeared.