olysan

Going to LOTO Friday.

Just got the engine finished and in the boat, and I'm trying to get it fired up. All I get is a bunch of backfiring. What would cause this? I've checked my plug wires, and they seem correct. When I installed the distributor I pointed the rotor directly at the #1 wire. Is that correct for start up? I was planning to set the timing later. Help????

Monty

You''ve probably got your ignition timing 180 degrees off. Even though you have the distributor rotor pointed towards #1, doesn't mean you're on the #1 power stroke. Double check that #1 is at TDC, you're probably at #6 TDC. If you've got the valve covers off, rotate the engine until you approach the TDC mark on the damper and look at the #1 intake and exhaust rockers, if neither one is moving as you approach the TDC mark on the damper, #1 is approaching TDC and you can orient your distributor cap and rotor towards #1. If either of the #1 rockers are moving as you approach TDC, #6 piston is appraoching TDC and you need to rotate 180 degrees.

formula31

And then, put your timing light on #1 and set the timing by cranking. It will get you close before you start it.

blue thunder

And if you cannot see the rockers because the valve covers are on, remove spark plug one (first on port side of engine) and insert finger. Rotate engine until you get pressure on finger. Then bump starter until the timing line is on 10*btdc. Install the cap with the number 1 plug terminal point at the end of the rotor. If you already know all this then never mind....

BT

US1 Fountain

iTrader: (1)

That's not saying to insert your fingure THROUGH the spark plug hole, just cover it.

Gotta be careful these days Dave

olysan

Thanks for the speedy response. I was 180 degrees out. I would have sworn that I had the #1 piston at tdc when I put the heads on, but I guess somewhere along the line I rotated it 180.

Mike

mcollinstn

There's TWO tdc's. One is on the exhaust stroke, one is on the compression stroke. You had it on the exhaust stroke.

blue thunder

Thanks for the disclaimer Jerry. I actually thought the same thing after I re read my post

Yep, two tdc and two bdc per cycle, hence the term 4 cycle engine. Hopefully it is running properly for you now. You are very lucky. I never have fixes that easy. They usually require many, many man hours labor and thousands of dollars........ but that's another saga. Good luck.

BT

olysan

yes i remember that (2Xtdc etc) now, and the engine is running well, but I'm still high and dry because my transom leaks. Oh well.

robyw1

you're distributer rotor is pointing this way < it needs to be pointing this way >

In short you're 180-deg off.

Roby