Could me engine timing be inaccurate
 

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?

Re: Could me engine timing be inaccurate
 

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

Re: Could me engine timing be inaccurate
 

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...

Re: Could me engine timing be inaccurate
 

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.

Re: Could me engine timing be inaccurate
 

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?

Re: Could me engine timing be inaccurate
 

36 at 2500 could likely produce a lot of detonation!

What’s your initial timing?

Re: Could me engine timing be inaccurate
 

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?

Re: Could me engine timing be inaccurate
 

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

Re: Could me engine timing be inaccurate
 

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

Re: Could me engine timing be inaccurate
 

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.

Re: Could me engine timing be inaccurate
 

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

Re: Could me engine timing be inaccurate
 

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

Re: Could me engine timing be inaccurate
 

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

Re: Could me engine timing be inaccurate
 

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

Re: Could me engine timing be inaccurate
 

Oh you're absolutely right. Thanks.

Re: Could me engine timing be inaccurate
 

Total 32 but at what rpm?

Re: Could me engine timing be inaccurate
 

Found that info I'm my paperwork :)

Re: Could me engine timing be inaccurate
 

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?

Re: Could me engine timing be inaccurate
 

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

Re: Could me engine timing be inaccurate
 

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

Re: Could me engine timing be inaccurate
 

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.

Re: Could me engine timing be inaccurate
 

I read in my documentation that there is a mark on the distributor for the perfect adjustment set by Blueprint. I found the mark and turned the distributor so the chisel marks line up. I'm going to start it up this weekend and check the timing but what do you think? It's probably right on the money now right?

Re: Could me engine timing be inaccurate
 

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!

Re: Could me engine timing be inaccurate
 

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.

Re: Could me engine timing be inaccurate
 

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?

Re: Could me engine timing be inaccurate
 

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.

Re: Could me engine timing be inaccurate
 

Your best bet is to set your initial timing at 12 degrees.
Leave it there!
Lock it down and leave it there!
If you keep setting your timing at high numbers like 35 at 2000 rpm you’ll cause damage to your pistons!

Re: Could me engine timing be inaccurate
 

My plan is not to set it at 35 at 2000 RPMs.

Blueprints directions do not say to set it at 12 and leave it there.

I'm just trying to get advice on following their specs. Not create new specs.

Re: Could me engine timing be inaccurate
 

If you follow their specs you will end up with 12-14 degrees initial.

Re: Could me engine timing be inaccurate
 

Oh thanks. Does this mean that at idle it would show 12-14?

Re: Could me engine timing be inaccurate
 

Yes!
That’s what initial timing means.
Timing at idle.
Idle needs to be below 750 rpm though.

Re: Could me engine timing be inaccurate
 

Oh thanks, it's going to be great having this thing run right. :)

Re: Could me engine timing be inaccurate
 

It seems You didn't. mention lining up the rotor to #1 terminal on the dist cap.

George

Re: Could me engine timing be inaccurate
 

Running 13 degrees advanced at 700 RMP and 32 degrees advanced total possible not going any higher no matter how high the ROMs,,,,, that's all with the vacuum advanced plugged right?

Re: Could me engine timing be inaccurate
 

Usually the initial is with the vacuum disconnected.

BTW, I'm more a fan of experimenting with timing. The specs are just suggestions. As long as you can hear the knock (pinging, marbles in the coffee can, or whatever it sounds like to you), I'd advance the timing and see how it runs. If you have loud exhausts then stick to the specs. I had a Chevy S-10 pickup through the 1980s and 1990s didn't own a timing light. I just adjusted timing to get very light knock at wide open throttle. It ran much better when advanced from the factory/dealer tune-up settings.
(I did some laboratory work with a Chevy 350 in the late 1980s also: https://www.sae.org/publications/tec...ontent/890161/)

Re: Could me engine timing be inaccurate
 

Am I the only one that reads this title in a pirate voice?

Re: Could me engine timing be inaccurate
 

Lol, oh cr@p,,, I never even noticed I had a typo in there. :)

Re: Could me engine timing be inaccurate
 

I do now🤣 thanks for the chuckle

Re: Could me engine timing be inaccurate
 

Set timing as said then double check advance at 3500-4000 rpm. This guarantees that the distributer springs let all that timing in. SbC usually like 29-36 degrees total timing not including vac advance. I set to 36 degrees at high rpm then test drive and back it down from there. Many aftermarket distributors will have base timing at idle around 16 or 17 degrees. Honestly you don't need a tach. Set over all timing at a high rpm then note what it is at idle for future reference
This is the only way to do it unless you are recurving the distributer. The curve is dependent on the distributer wieghts and springs and on some distributors, the bushings

Re: Could me engine timing be inaccurate
 

Yar.