New to timing?

[Lerch1145]

Have a 1972 GMC 350, just purchased a Petronix igniter, flame thrower coil, new cap, rotor, wires, and spark plugs. Plan to install tomorrow, set plugs at .045, and recheck timing.

Here is the question: when checking what my timing currently is (12) I was going to move down to 8-10 and see how she reacts. The manual states "adjust timing by loosening distributor clamp and rotating the distributor body" is this the clamp holding the distributor? I loosened this to the point of removal and still nothing moved.

What is a stupid guy missing here?

[itstheDRE4M]

Loosen the bolt/clamp at the base of the distributor where it meets with the intake. Then rotate the distributor by hand to adjust timing.

It does not move on its own.

[frankslagoon]

I think ya got the right bolt. you don,t have to loosen it very much.
remember to warm it up, keep the idle down below 800 or the dist weights will start to advance the timing and unhook and plug vacuum line to dist hose at the manifold/carb.

[Lerch1145]

That is the one I loosened? Will be taking her out tomorrow and pass on how it goes. Wish me luck.

[frankslagoon]

Kool every time I pull my dist. it never wants to go back in like it was. if I make sure I'm on TBC and put a mark on the engine inline with the rotor when its pointen at number 1 I can eventually get back close. the darn oil pump rod moves alittle when I lift the dist and it wants to set down one tooth off when I put it back in. I just put a accel conversion in my trk. runs good.

[mechanicalman]

Originally Posted by Lerch1145

Have a 1972 GMC 350, just purchased a Petronix igniter, flame thrower coil, new cap, rotor, wires, and spark plugs. Plan to install tomorrow, set plugs at .045, and recheck timing.

Here is the question: when checking what my timing currently is (12) I was going to move down to 8-10 and see how she reacts.

Why do you want to retard the timing? Is the engine stock?

[NC_John]

Originally Posted by frankslagoon

Kool every time I pull my dist. it never wants to go back in like it was. if I make sure I'm on TBC and put a mark on the engine inline with the rotor when its pointen at number 1 I can eventually get back close. the darn oil pump rod moves alittle when I lift the dist and it wants to set down one tooth off when I put it back in. I just put a accel conversion in my trk. runs good.

You can (carefully) use a long screwdriver to realign the oil pump driveshaft. I installed my own Pertronix setup yesterday and had a bit of a fight getting the distributor to seat fully on the intake until I had my "doh!" moment and remembered to realign mine to match up.

I bet if you can't turn your distributor, your hold-down clamp is way too tight- the diameter of the distributor base might be wider than the inside diameter of the hold-down clamp. The base on my cast flamethrower was even bigger than the one on the MSD I removed and I had to dremel some clearance to make it fit properly.

[Daman]

How long has the distributor been in there?

Mine was almost completely stock when I picked it up. I had to use a BFH to break it loose and 2 pry bars to lift it out

[frankslagoon]

Originally Posted by NC_John

You can (carefully) use a long screwdriver to realign the oil pump driveshaft. I installed my own Pertronix setup yesterday and had a bit of a fight getting the distributor to seat fully on the intake until I had my "doh!" moment and remembered to realign mine to match up.

I bet if you can't turn your distributor, your hold-down clamp is way too tight- the diameter of the distributor base might be wider than the inside diameter of the hold-down clamp. The base on my cast flamethrower was even bigger than the one on the MSD I removed and I had to dremel some clearance to make it fit properly.

I built a tool probably 45 yrs ago to get in there and turn the oil pump, but it's almost impossible to see down in there with the hood on. The (correct ) way. if there is such a thing, ha. is to put the rotor inline and then hold it while ya turn the crank two full turns till the dist. falls in.

[frankslagoon]

Originally Posted by frankslagoon

I built a tool probably 45 yrs ago to get in there and turn the oil pump, but it's almost impossible to see down in there with the hood on. The (correct ) way. if there is such a thing, ha. is to put the rotor inline and then hold it while ya turn the crank two full turns till the dist. falls in.

That doesn't sound right?? duh.
no. 1 to TDC
Position rotor to point to front of engine
turn rotor appx. 1/8 turn ccw towards left bank and push dist. down to camshaft
While pressing firmly down on dist. housing kick or turn engine over until oil pump shaft is engaged
make sure rotor is pointed at no. 1 on dist and crank is at TDC snug down the hold down clamp and it should be close enough to get started.
Looks like stock for your truck is around 6 but with this gas we got now seems better around 10
Does that sound better guys?

[Lerch1145]

Well day went well thanks to the advice of everyone. I think everything has been there from the factory. It took some time to free the distributor (that is why she wouldn't turn), putting on the points eliminator required me to remove the gear and add a spacer, screwdriver trick worked great getting everything back lined up, she fired right up, timing was at 8 and I moved her back to 12 where she was stock. Runs great! 8 is in the manual but is 12 okay?

I still have every spark plug wire clamp, plug heat shield, etc from factory in great condition. Getting everything back routed correctly was time consuming but worth it. I also replaced the vacuum advance as the arm was bent. Thanks for a great day in the garage.

[mechanicalman]

Originally Posted by Lerch1145

Well timing was at 8 and I moved her back to 12 where she was stock. Runs great! 8 is in the manual but is 12 okay?

The factory specs in the manual are but a crutch for the lack of technology regarding emissions control in the day.

Try 15.

Or better yet, if you have a degreed balancer or a nice timing light with a dial, set the total advance at 36' and see where the base timing falls. With the vacuum pod dis-connected, rev it till it quits advancing and set the 36'. Record where it stops advancing with a tach if you can.

If it cranks the same, does not ping and you don't exceed 36' total timing, it's all good; better power, mileage, and cold drivability.