Could me engine timing be inaccurate

[K10-Kansas]

Thanks for looking to help me out. I really appreciate it. I have a crate blueprint 350 https://blueprintengines.com/product...ed-front-drive

I'm worried I have not done the timing process correctly.

1. I pulled all the plugs and put a paper towel ball in plug hole 1.
2. I turned the engine with a socket wrench and after a few turns the ball shot out.
3. I saw on the harmonic balancer this was top dead zero per the marking.
4. I dropped the distributer and as it lowered it turned ~50 degrees clockwise. I was worried this was too much of a rotation because I have never done this before.
5. I raised the distributer, rotated it ~55 degrees counter clockwise. I lowered the distributor in the exact same degree orientation I have seen in a dozen mechanic videos and it rotated itself ~55 degrees clockwise again just like last time.
6. I started the engine. At ~2500 RPM with my timing light I rotated the distribuer to show 36 degrees advanced on the harmonic balancer which is the value in my documentation.

Is there anyway possible that my engine is not actually at 36 degrees advanced?

[AcampoDave]

My does that when I lower it too. I just account for it when I'm dropping it in. Probably normal.

[RustyPile]

As you lowered the distributor into position, the rotor rotated a bit because the gears on the shaft are spiral cut.. This rotation is normal.. If the vacuum canister on the distributor is in a "comfortable" position after the timing is set, you're good to go.. Wanna see something that will fascinate and puzzle you a little more?? Put the timing light pickup on the #6 plug wire. Start the engine and check the timing as before...

[67 twins]

Originally Posted by RustyPile

As you lowered the distributor into position, the rotor rotated a bit because the gears on the shaft are spiral cut.. This rotation is normal.. If the vacuum canister on the distributor is in a "comfortable" position after the timing is set, you're good to go.. Wanna see something that will fascinate and puzzle you a little more?? Put the timing light pickup on the #6 plug wire. Start the engine and check the timing as before...

This should not puzzle you at all. Cylinders 1 and 6 are at TDC at the same time. When 1 is on the power stroke 6 is on the intake stroke.

[K10-Kansas]

Thanks all. So it sounds like I have nothing to worry about and since the timing light is showing 36 degrees advanced on the harmonic balance at 2500 RPMs then it is infact 36 degrees advanced and could not be another value based on the correctness of completing the steps in the process?

[RustyPile]

Originally Posted by 67 twins

This should not puzzle you at all. Cylinders 1 and 6 are at TDC at the same time. When 1 is on the power stroke 6 is on the intake stroke.

AAWWWW... Why'd you have to go and let the cat outa the bag???

[geezer#99]

36 at 2500 could likely produce a lot of detonation!

What’s your initial timing?

[K10-Kansas]

Originally Posted by geezer#99

36 at 2500 could likely produce a lot of detonation!

What’s your initial timing?

Does this mean, when I first started the engine, at idle, what was the timing?

Initially, my idle screw was not adjusted well and the idle was too high, and I did not yet have a tachometer. At idle, the timing was around 16 degrees, but I may not be remembering correctly.

Now that I have a tachometer, should I redo the process?

[RustyPile]

Originally Posted by K10-Kansas

Does this mean, when I first started the engine, at idle, what was the timing?

Initially, my idle screw was not adjusted well and the idle was too high, and I did not yet have a tachometer. At idle, the timing was around 16 degrees, but I may not be remembering correctly.

Now that I have a tachometer, should I redo the process?

Aluminum heads and 9.2 C/R will allow you to run a bit more advance above "normal".. According to the manufacturer's specs, 36* will give you the best power production, but you might have to run 90-91 octane gas.. The flame travel is faster with 87-89 octane than with 90-91 octane.. Also, as compression goes up, so does the flame travel.. To answer your last question --- No, you don't have to "redo the process"... With the engine at correct idle speed, using your timing light, just back the timing down 2 - 3 degrees if you experience detonation.

[K10-Kansas]

Originally Posted by RustyPile

Aluminum heads and 9.2 C/R will allow you to run a bit more advance above "normal".. According to the manufacturer's specs, 36* will give you the best power production, but you might have to run 90-91 octane gas.. The flame travel is faster with 87-89 octane than with 90-91 octane.. Also, as compression goes up, so does the flame travel.. To answer your last question --- No, you don't have to "redo the process"... With the engine at correct idle speed, using your timing light, just back the timing down 2 - 3 degrees if you experience detonation.

This may be a really dumb question. But how does one know if they are experiencing detonation?

[RustyPile]

Originally Posted by K10-Kansas

This may be a really dumb question. But how does one know if they are experiencing detonation?

If your exhaust isn't too loud, you'll be able to hear the sound... Sounds like hand full of marbles rattling around in a shaken coffee can... Most prominent when lightly accelerating or under load. Disappears when you lift the throttle.

[geezer#99]

Warm the motor up, plug off the vacuum advance, lower the idle to 750 rpm and then check your timing at idle.

[geezer#99]

Listen for it!
It’ll sound like a small rock rattling in a tin can.

[Wrenchbender Ret]

Does the timing go up farther if you rev it up over 2500?
36 degrees is a bit too high using a street cam. 34 degrees is safer. Its better to err on low side. If you had access to a dyno & other equipment you could get it perfect. Rest of us just have to settle for best.

George

[68 P.O.S.]

Your engine calls for 32 degrees,, you need to lower it.

[K10-Kansas]

Originally Posted by 68 P.O.S.

Your engine calls for 32 degrees,, you need to lower it.

Oh you're absolutely right. Thanks.

[geezer#99]

Total 32 but at what rpm?

[K10-Kansas]

Originally Posted by geezer#99

Total 32 but at what rpm?

Found that info I'm my paperwork

[K10-Kansas]

So if at 3500 RPMs and 34 degrees, if I raise the RPM to 4,000 and the timing advances further, I would then turn the distributor back down to 34 correct?

[Wrenchbender Ret]

Originally Posted by K10-Kansas

So if at 3500 RPMs and 34 degrees, if I raise the RPM to 4,000 and the timing advances further, I would then turn the distributor back down to 34 correct?

Correct. You don't want the total advance to go over the recommended 34 degrees. (Vacuum advance not included). You want it all in about 3500 RPM.

George

[geezer#99]

Follow those instructions and then come back and let us know what your initial timing is.

[geezer#99]

Maybe!
If you put the distributor and rotor in in exactly the same place as original then it could.
My monies on you didn’t!

[K10-Kansas]

Originally Posted by geezer#99

Maybe!
If you put the distributor and rotor in in exactly the same place as original then it could.
My monies on you didn’t!

Oh. What can be different? I turned the engine until the paper towels was blown out of spark plug hole 1, saw on the harmonic balancer that this had the needle on 0. I dropped the distributor so that the tack & 12v connectors we pointing at 3pm, i.e. the distributor was perpendicular to the engine.

What can go wrong I'm new to this so I genuinely don't know.

[geezer#99]

When you found the ‘mark’ and turned the distributor so the mark lined up, how far did you turn the distributor and which direction did you turn the distributor?

[K10-Kansas]

Originally Posted by geezer#99

When you found the ‘mark’ and turned the distributor so the mark lined up, how far did you turn the distributor and which direction did you turn the distributor?

Clockwise about 15-20 degrees.

I previously did put it at 35 degrees advanced at approximately 2000 RPMs. I didn't have a tachometer though. What I found out Sunday though was that it is supposed to be adjusted to 32-34 degrees advanced at 3500 RPMs.