Depending on the rate of the sweep, I think engines are tolerant to bad tuning in fast transients, basically they don’t spend enough time in the bad spots to hurt themselves. ON THE DYNO. And the amount of power gained/lossed is negligible to 90% or so of most engines going across the dyno so guys accept it. If more “street” engines went on a dyno I think this theory would play true more often than not.
Absolutely. In some combination 34 degrees at peak torque can be over timing the engine but if that were the case then why time it there? Why not time it where it is safe?
Because most Tom, Dick, or Harry paying customers want the big number on the screen and don’t want to do the work to put a curve in it. So lock it out, add timing till it stops making power, back it down a degree and send it. That’s the common MO. Then Tom blows his engine up in the car on a good weather day and blames the dyno tuner.
So, what your saying is if you overtime the engine somewhere in the rpm range to get a bigger number somewhere else in the rpm range the customers could blow up his engine if the weather changes and pushes what the engine will tolerate to the side of not tolerating it? I agree 100% that could happen. I don't recommend over timing an engine for that reason. Or leaning it out too much in the rpm somewhere in order to gain power somewhere else in the rpm range. In my opinion the motor was timed wrong. Wouldn't matter if it was locked or unlocked. Too much timing anywhere is too much timming. If the dyno operator properly communicated what the potential outcome of over timing it could be and the customer did it anyway the that's on the customer. If the dyno operator did not relay that information then thats on the dyno operator. In either case the fault is not the locked distributor. Even if the distributor had a curve and it was wrong, if all the dyno operator is looking at is one particular area the same blow up scenario is possible. The motor could have been tuned safely with a locked distributor. Somebody chose not to. If it we're me I and I saw that the motor wanted more timing at peak horsepower than what was safe at peak hp I would give my customer the option to put a curve in it for "x" power for "x" money or Time it safe and live with "x " power loss at "x" rpm. Their choice.
More often than not, the locked out distributor is the cause of the engine being overtimed. Because the person timing the engine doesn’t understand timing. I’d argue that because of what @Newbomb Turk has pointed out with his distributor machine and his testing that when there is a curve in the distributor, the engines are likely UNDERTIMED because of slew rate. And the opposite would be true with locked distributors. They’re more than likely OVERTIMED. I understand that you compromise timing at peak TQ and peak HP to be able to lock the distributor and make it safe. What I’m saying is I’m not comfortable with that compromise.
I’m saying what I think is the most common tuning technique from most dyno operators. They set timing at peak Hp (or tune the timing to make the most peak HP) with a locked out distributor. It’s not “somewhere else in the rpm range” typically. Watch any episode of Nicks garage and how he puts timing in an engine and “makes a test” (lol) and you’ll know what not to do. Curve or not.
I don't knowingly comprise by over timing anywhere that would put the motor in danger.
I say sometimes not always. And sometimes for some people the juice ain't worth the squeeze. And just because someone doesn't put a curve in it doesn't mean your car is going run like crap.
No, I meant a compromise on both ends to make it safe. To make it safe with a locked distributor you have to compromise at peak hp. Thats your statement, and you said it’s only a few percent so you’re ok with it. Thats the compromise I’m not ok with.
The reason for not using a locked distributor is because the timing requirements at peak torque and peak horsepower are different. Not because the dyno operator can’t develop a curve.
I don’t see that. I think with locked timing at idle they run cooler.
That's not always the case. Look at the charts I posted.
To do this fuel would have to be pretty close to where its going to end up. If its significantly leaner or richer then it will show best timing for that condition. Isn't this why we try to get a baseline timing established first? Then get best fuel mix for it, then try tweaking the timing a bit.
We agree. On my own stuff I usually am not ok with that either. But in some applications is isn't a compromise and in some applications it's not up to me.
I agree. Both need to be close in order to fine tune.
I felt the need to add the word "knowingly".
I definitely don’t like using definitives and rarely say “always” or “never” when talking about tuning stuff. We agree.
Yes, like you are completely aware, fuel and timing go hand in hand and it’s a constant back and forth to optimize both. They continually effect each other.
