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jcmmcote 04-26-2006 09:33 PM

Help on a 305's timing
 
I am rebuilding my 305 and the timing is killing me. I have the #1 piston up on the compression stroke. The dots on crank (up) and cam (down) are lined up. rotor button is facing the #1 spark plug and then I started my firing order. When I try to start it up, it blows out the carb like its 180 deg. out on the timing. I bumped the motor till I got the #1 on compression stroke again and the dots changed crank (up) and the cam (up). WHY????????
please if anyone has the answer I need it bad. Been dealing with this problem for about 4 weeks now. Thanks

Alf P 04-26-2006 11:43 PM

I can't tell you why the dots are changing positions but i might be able to help you on something else. when you drop in the distributor bring #1 to TDC, then point the rotor (the flat part not the springy part) at number #1 on the cap, not to the number one cylinder.

docvette 04-26-2006 11:57 PM

Doc here, :pimp:

Number 1 cylinder TDC, compression, Timing marks aligned, --->Both intake and exhaust valves closed <----, no pressure on the lifters (not too much slack either..) ---->If you can't co~ordinate these, you have timing chain/gear issues..<----

Drop the dizzy in, and watch the rotor, It will advance clockwise a bit, this is because the gear teeth are diagonal cut, It will go about a tower in a half in some cases..Note the amount of change and then withdraw the dizzy.

Line the oil pump shaft up to that location with a large screw driver, and reset the dizzy, for number one plug tower, allowing for advancing as the gears seat..

The easy way to do this is make magic marker lines on the base of the dizzy, for exact #1 plug tower, and the difference of rotor movement as it seats..due to the cut of the gears..(I.E...#1 and the amount of distance BACK required to make it sit on #1 plug tower when bottomed out..)

#1 plug tower in the stock location for SBC's is 5 to 7 O'clock, (depends on year, and obstructions) 7 is usually good.

Direction of rotation is clockwise.

The F.O. is 1 8 4 3 6 5 7 2..

Put on your hold down just tight enough to hold it but enough to forcibly move it by hand, and start it up..set your static and total timing..

Static 10 to 12 is a good starting point advance defeated and vacuum line plugged.

Total around 34 to 36 is usual on a stocker with advance hooked back up..

Tighten down the hold down, set your idle for 650 Manual trans, 950 Automatic, and drive it .. hammer it on the freeway, If it pings or runs hotter than usual, retard it a few degrees..If it dogs, advance it..Try also lugging it up a steep hill highest gear as slow as it will pull, If it pings check the timing again.

That's it.

Doc :pimp:

SouthernRodder 04-27-2006 06:01 AM

did you happen to change harmonic balancers or timing chain covers while building the motor. I had this happen to me last year and it just about drove me crazy. The older 305's timing mark is in the center of the timing cover and on newer models its off to the side. I had an aftermarket timing cover with the tab on the side and an older balancer which would have matched up with the older style timing covers. I was off one wire b/c of this. Run that through your head and think about what you are working with.

Frisco 04-27-2006 08:09 AM

Quote:

Originally Posted by jcmmcote
I am rebuilding my 305 and the timing is killing me. I have the #1 piston up on the compression stroke. The dots on crank (up) and cam (down) are lined up. rotor button is facing the #1 spark plug and then I started my firing order. When I try to start it up, it blows out the carb like its 180 deg. out on the timing. I bumped the motor till I got the #1 on compression stroke again and the dots changed crank (up) and the cam (up). WHY????????
please if anyone has the answer I need it bad. Been dealing with this problem for about 4 weeks now. Thanks

Actually when the dot on the crank is in the up position and the cam sprocket is in the down position the #6 piston is at TDC.

You have the distributor 180 degrees out.

When you bump the engine over and see the dots no longer lined up that is because this is when the #1 piston is ready to fire.

Lining the dots up is for the cam installation not for setting the distributor.

I'm not sure that I have explained this clearly. Try this.

Remove the #1 sparkplug. Disable the ignition so that the engine will not start. Place you finger (or a piece of tissue paper) over the #1 spark plug hole. Bump the engine over slowly until the paper blows out or your finger gets pushed away because of the engine compression. Stop at this point. Look at the timing pointer and timing mark. They should be very close to being lined up. Now re-install the distributor so that the rotor is pointing to the post on the cap where the #1 spark plug wire is located. Replace the sparkplug. Enable the ignition. Start the engine and set the timing with a good timing light. Be sure to dis-connect and plug the vacuum advance hose when setting the timing. Re-connect it after the timing has been set.

jcmmcote 04-27-2006 08:20 PM

thanks
 
thanks Frisco, That is exactly what i needed to know. It fired up tonight. Got another Q. for you if you don't mind. What would make the spark plugs have oil on them when you pull them out and look. Do you think my intake gaskets haven't sealed yet? Definetly appreciate the other answer.

jcmmcote 04-27-2006 08:27 PM

timing cover
 
My timing cover is an aftermarket and yes it is off to the side. Don't make sense to me why they would do such a thing when the orig. was in the center. Appreciate the help

killerformula 04-27-2006 08:27 PM

Quote:

Originally Posted by jcmmcote
thanks Frisco, That is exactly what i needed to know. It fired up tonight. Got another Q. for you if you don't mind. What would make the spark plugs have oil on them when you pull them out and look. Do you think my intake gaskets haven't sealed yet? Definetly appreciate the other answer.

depends on how much oil, but that's common until the motor has a few miles on it. Rings should seat in the first few minutes of running with molly rings, but I find that most motors take a couple hundred miles to start feeling just right.

K

Frisco 04-28-2006 06:56 AM

Quote:

Originally Posted by jcmmcote
thanks Frisco, That is exactly what i needed to know. It fired up tonight. Got another Q. for you if you don't mind. What would make the spark plugs have oil on them when you pull them out and look. Do you think my intake gaskets haven't sealed yet? Definetly appreciate the other answer.

Killerformula answered this question very well.

I would add that it would depend on a few other points as well. Are you talking about oil on the threads of the plugs or on the electrodes? What kind of oil are you using? You should not be using a synthetic oil yet. I would suggest a good 30 weight sulphur based oil for the first 2000 miles. Change the oil and filter immediately after the cam break-in and again around 100 miles, 500 miles, 1000 miles and then every 3000 miles. You can safely use a synthetic oil after about 2000 miles.

As to the intake gaskets being sealed. They are either sealed at installation or not. They do not take run time to seal. I have seen where the intake and heads do not line up very well (caused by machining of the block / heads or poor manufacturing of the intake) and then there can be a lack of sealing between them from the lifter valley area. This can enable oil to be sucked into the cylinders causing oil fowling/burning. Use of good gaskets and a small amount of RTV on the lower edge of the gaskets and around the water port sections of the gasket can eliminate this leakage if the mis-alignment is minor.


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