My car knocks at WOT, so I'm gonna play with the timing to see if it does anything.

I've already tried 110 race gas in 20 % proportion with 80 % of 91 gas giving me around a 95 octane rating and it still knocks and pulls 7 degrees of timing. It smells really good too.

It also knocks and pulls timing with no load in neutral.

I am not sure if it's false or real cuz the car feels like it's under a load when it isn't. It feels like I'm always fighting something.

Is there a chance that the timing indicator could be off and what the mechanic thought was 6 degrees was not actually 6 degrees?

What would the symptoms be of timing being off? I also experience hard starting, is that a symptom?

I'm gonna try 4 degrees, do a scan run, then 2 degrees and another scan run to see if it eliminates knock. It's really frustrating!

I've already upgraded the knock sensor last year to a less sensitive one. I read about the knock sensor should only be tightened to 15 #'s and no more. I told my mechanic and he said "That doesn't sound like much, it'll probably fall out if it's only 15 #" which leads me to believe it's in there tight.

The car shows very few knock counts under normal conditions, but at WOT, it knocks and pulls 7 degrees verified by DataMaster.

 

For the hot starts put and ohm meter on the injectors and make sure they all fall around the same voltage. Below 16 is unexeptable. As for the timing problem. How noisey is your valve train? If it is actually retarding timing without a load on the car, something is deffinately wrong. It is very possible that the balancer slipped or the timing tab is off. Do you have a custom chip? Maybe it isn't set at 6, or maybe your combustion chambers don't like the amount of advance the motor is seeing. If you have access to tuning software I would pull some timing out at the rpm you are seeing most retard.

 

The knock counts in neutral are likely a symptom of "false knock", the knock sensor reacting to noises other than detonation or "real" knock. I am not familiar with a less sensitive knock sensor. There IS a more discriminating ESC module that cuts down on false counts. I believe it is written up in the "Tech Tips" section. Also, I have heard of people using pipe fittings, like a 45* elbow between the block and the sensor, to reduce the transmittal of some of the "noise".

It sounds like one thing you are going to have to do, is verify your timing marks. There seems to be enough doubt in your mind, at this point, that further diagnosis would be a waste of time, if you can't have faith in your readings. Remember, "GICO". Garbage in garbage out.

What do you mean, exactly, by "hard starts". If it cranks more slowly, or cranks slow and then fast, when hot, only, THAT is a symptom of too much initial advance.

RACE ON!!!

 

When setting the initial timing with a timing light you're using two reference points that should have been verified when the engine was built. The first is the TDC mark on the damper/balancer and the second is the timing tab on the timing chain cover. If either is off, the timing you set using the timing light will be off too.

On a new build, I always verify the damper TDC mark using the positive stop method and verify the timing tab using a degree wheel.

You can try to verify the marks using a dial-back timing light if you use a good, accurate one.

Jake

 

I'm guessing the outer ring on his damper may have moved. *I* think it needs to be verified via the "positive stop" method.
Can you please explain verifying the timing marks with a dial back timing light?

RACE ON!!!

 

I borrowed one at the track and it's a slick little unit. This one only advanced from 0 though. This is a total shot in the dark, but for verification I can only surmize you have let's say 12 degrees of advance at idle. Retarding the dial 12 degrees should flash the light precisely at 0. If your actual timing was 14 degrees and you retarded 12, you'd get a flash at 2.

Again, just a guess........

 

" borrowed one at the track and it's a slick little unit. This one only advanced from 0 though. This is a total shot in the dark, but for verification I can only surmize you have let's say 12 degrees of advance at idle. Retarding the dial 12 degrees should flash the light precisely at 0. If your actual timing was 14 degrees and you retarded 12, you'd get a flash at 2."

Yes thats how they work...sort of...

You use the timing light to dial in your advance. To see what you have you turn the dial while looking at the dampner marks. When the dampner marks line up with Top Dead Center(0*) then where you stop turning the dial is the timming that the engine is set at. The other way is to, say you are looking for 6* advanced. Then you would set the dail on the timing light at 6* advanced. Using the timing light and watching the dampner marks turn the distributor until the TDC(0*) marks line up. Then you are set at 6* advanced.

 

Maybe you could use that timing light and datamaster to check timing marks. For instance my car idles at 26* advance according to the scan. Run datamaster and see what it says and dial that # of degrees into the timing light at the same time and you should get 0* . Just a thought.

 

Others beat me to it.

Jake

 

Jake,
Not really. At least not in a way *I* understand. I know how a dial back timing light works. I have one and use it all the time. What I DON'T understand, is how to use it to verify the accuracy of the timing marks.

RACE ON!!!

 

See, if you set your timing at, let's say. 6 degrees using the marks on the balancer and the timing tab, then use the dial back feature and turn the **** to 6 degrees, the mark on the balancer should then move to Zero on the tab.

It works the other way too. If you turn the **** to the 6 degree mark, you'd then turn the distributor until the balancer mark is at Zero on the tab. Then when you turn the **** back to Zero, the mark on the balancer should align with 6 degrees on the tab.

If they don't agree, then either the mark on the balancer or the tab is off.

Some SB Chevy balancers have the TDC mark off-set and the result is NOT an indication of the #1 piston being at TDC. I forgot exactly how many degrees the mark was off-set, but IT IS substantial.

That's why I always verify the balancer TDC mark with the #1 piston using the positive stop method. In fact, many after-market balancers don't have TDC marked at all and it's up to the installer to find and mark the balancer to indicate TRUE TDC.

Oh, I guess it's possible for the timing light itself to be off, that's why I recommended getting a quality light. Even if it is "off" I suspect it wouldn't be enough to work up a sweat over.

But as I've said before, I don't get locked in on 'numbers'; I let the engine tell me what it wants/likes. Dyno tuning works the same way; you'd tweak the base settings of fuel, timing, plug gap, valve lash, etc., until you get the best results and let the actual 'numbers' fall where they may.

The 'numbers' can be used, however, as a barometer. If any of the numbers are DRASTICALLY different from numbers known to work well on other similar engines, I'd start having a look-see elsewhere for the cause.

Also balancers and timing tabs are a mated pair; mated for life (not like so many marriages these days). So if the tab and/or balancer are changed to ones that are not the same as the ones they're replacing, the readings will be off as a result. That is, UNLESS the new balancer and tab as also a mated pair.

If the balancer is not the exact same diameter AND/OR it doesn't have the TDC mark in the exact same location OR if the timing tab has it's TDC location in a slightly different location OR if the tab has it's numbers spaced closer or farther away from each other than the one it's replacing, the reading will be off too.

There are a LOT of different timing tabs that will bolt the the timing chain cover of the SB Chevy but most of them will not be the correct one for the balancer being run because the numbers will be located differently.

Jake

 

I fully understand that different timing tabs and dampers are not necessarily compatible. And I DO time my engine by performance. Because my engine likes 14* btdc, I suspect the outer ring of my damper has turned in relation to the hub. I know and understand how to verify the marks with a piston stop. In fact that is the ONLY way, I am aware of. To me the explanation: To me, that only verifies that 6* on the damper ring is the same as 6* on the timing light dial. I don't see how that indicates whether zero on the damper (or any other number) is being indicated at TDC or not. Can you go a little deeper for a dummy, please?

RACE ON!!!

 

Drain your oil and fill in the thickest stuff you can find that is labeled as motor oil. See if that helps. With that much octane, I find it unlikely that it should be knocking. When mine did that, the engine was also blowing some smoke on hard accelerates. Also the leakdown test proved that the gas was going past the rings.

 

One other method use by some to find TDC on #1 is with a dial indicator. I don't prefer that method because the piston will dwell a couple of degrees on either side of true TDC and when it does, the pointer on the dial indicator won't move.

Some companies even make a magnetic bridge that fits across the cylinder and has a built in mount for the dial indicator.

"To me the explanation: To me, that only verifies that 6* on the damper ring is the same as 6* on the timing light dial. I don't see how that indicates whether zero on the damper (or any other number) is being indicated at TDC or not"

6* isn't on the "damper ring" and the damper does not indicate "zero". The groove cut into the dampner is only "supposed" to indicate that the #1 piston is at TDC WHEN that groove is aligned with ZERO on the timing tab. If the groove is aligned with 6 on the timing tab, the mark indicates that the #1 piston is 6 degrees BTDC, and so on. I'm guessing you already know that, but it just wasn't written that way.

I put "supposed" in quotation marks because many times it's not accurate.

Twice I started typing a long explanation on how the dial-back light can be used, but the more I wrote, the more I felt I needed to write. Kinda got out of hand.

Hopefully someone else will post the l o n g version to save me a lot of typing. Besides, I've got to hit the sack so I can get an early start to install my camber brace.

Jake

 

You are right. It wasn't written that way, and I DID write it "backward". I also agree that the dial indicator method, sucks. Let me re ask the question.

I suspect my damper ring has rotated and isn't giving a true timing reading. I would like to verify if it is correct, and if not, approximately how far off it is. I do not plan on pulling a head to put a dial indicator on a piston, or to attach a piston stop the the deck. I know how to screw a piston stop into a spark plug hole and mark the damper to find the correct point on the damper that aligns with the 0* mark on the timing tab at true TDC. IF there is a method of accomplishing the same, with a dial back timing light, it seems that would less work and simpler. And I wouldn't have to go buy or make a piston stop. I don't see how, what you originally explained, accomplishes that. Maybe when your not getting ready for bed and your camber brace is installed? Thanks.

RACE ON!!!