valve adjustment on 6v92's

[hwginc]

I was wondering if anyone can tell me the proper clearances and adjustments on both the valves and injectors I had a complete head job done and replaced all the injectors as well.
Thanks

[captddis]

The valves are .016 and If you have the single turbo forward plan engine, the injectors should be 1.508. Check your Covington supplimental info as some of the 6V92s in those were TTA engines Covington converted over to the single turbo Forward plan style and they might be 1.484.

[Genesis]

I was wondering if anyone can tell me the proper clearances and adjustments on both the valves and injectors I had a complete head job done and replaced all the injectors as well.
Thanks

Valves are 0.016 cold.

Injector timing depends completely on the injectors and whether or not you have advanced timing. You must know this to get it right.

Common settings are 1.460, 1.484 and 1.508. Also, some combinations (e.g. injectors intended for an advanced timing motor in one that is not) have no documented correct setting - while you can "play with it" unless you're willing to risk cylinder damage I wouldn't - make sure your injectors match the engine's configuration.

Any Detroit dealer with the serial number can tell you if the timing is advanced AND what the proper timing is for the injectors in the engine (along with whether they match advanced -vs- standard timing)

("Advanced" means that the gear train timing is advanced one tooth from "standard". This makes the injector fire earler, which means that for the same timing as a "non-advanced" engine you need the injector height GREATER. All this must be correct for the engine to run properly.)

[captddis]

Don't count on the serial # always being accurate. The serial# tells them what the engine came with from the factory. If it was modified as was common before Penske bought DDC, The marinizer in this Covington would know. [maybe]. However a lot of the information was on paper and left with the mechanics. If you get the injector # then the chances for the correct setting are much better.

[Genesis]

You NEED the injector number.

However, you also need to know if the block has advanced timing or not. The only way to know how it came from Detroit is to get the serial number.

While its POSSIBLE that someone changed that at some point in the past, its highly unlikely.

[captddis]

IF THE TIMING WAS CHANGED BY THE MARINIZER , DETROIT WILL NOT KNOW THAT. UNLESS it was a factory engine. You just have to get the last word and give incorrect advice!!!!

[Genesis]

If Covington changed the gear train timing that would be extremely unusual.

That's not a trivial thing to do as it requires ripping the engine partially apart to get to the gear train so you can advance it (the term "advanced timing" is, literally, one tooth "advanced" from everything being aligned normally)

In any event there's no way to know if they did it other than asking the marinizer, and Covington has been, uh, less than easy to get information from in the past when I've needed to. I suspect (but can't prove) that their record-keeping just plain sucks.

As just one example of many, they were the marinizer on Gigabite's engines. When I bought the boat it had injectors in it that suggested that the timing was advanced.

However, not only was there no documentation of that in the original manuals from Covington (TAC-IIs), the injectors that Covington specified in that booklet were not the same ones that were in the boat and those injectors were not for an advanced-timing engine!

I went through quite literally two months bouncing back and forth as to exactly what correct injector timing was for those engines with the injectors that were in them. Everyone I asked gave me different answers, and one of the supposed "authorities" was the shop that rebuilt those motors (they were the ones that put the injectors in there!)

Finally, unable to get a straight answer I went back to what OEM spec was for them and reset the timing to the base specification. THEN they ran right. The gear train timing was in fact standard.

It appears that at some point before the engines were majored the previous owner had the injectors swapped and that person (who knows who it was) put advanced-timing injectors in the motor. The rebuilders did an inframe, didn't tear apart the gear train (since you DON'T during an inframe as the camshafts and gear train housing remains undisturbed), took what they had been given as "gospel" and put new injectors of the same number back in the motor.

Just because an injector is in the engine now does not mean that the CORRECT injectors are in the engine. If you think you have an advanced timing engine but in fact do not, and set the injectors (designed for advanced timing) to that spec, you will fire late, EGTs will be excessively high as the charge will still be burning when the valves open, you will have a hazing on the horizon at cruise power (due to incomplete combustion) and you won't like what it does to valve or turbo life. If you have no pyrometers you might not catch this before severe damage is done to the valves and/or turbocharger.

If you think you have STANDARD timing and in fact have advanced, you will fire early and the charge will "buck" the piston's travel at higher outputs, cylinder pressures will be extreme, fire deck temperatures will be through the roof and you may break a connecting rod, destroying the engine.

You have to start calling people (Detroit and/or Covington) but don't be surprised if you get contradictory answers. I would start with Detroit and your serial numbers, then I would call Covington (if they marinized the engines) and see if they have alleged records of what they did to those particular engines.

You may or may not get straight answers, but it sure as hell beats guessing!

[captddis]

This is my final round!
I will relate a few stories,
A few years ago the local distributor ordered and installed a V 12 longblock. It was built to the serial # of the engine that came out. At sea trial the engine would not make power and poured smoke. Guess what the timing had been advanced by the marinizer, in this case Key power. The longblock was standard timing.They lost their butt on that.
On a customers 60C with 840 HP 12V71s, the ser # says they are 650 HP.
On my 8V92s that Covington said were factory engines the ser# gives the wrong injectors and turbos. Plus Covington updated them in 1984 with different injectors and a modulator instead of the throttle delay and rack stops. None of this shows up on the build sheet.
I could go on and on. That is why Covington had a supplement that came with the boat noting the changes.
When Penske took over in 88, he ordered that the marinizers would no longer do their own conversions and all engines would come complete from the factory. A lot of marinizers used industrial blocks and did their own conversions. S+S and JT were famous for this. Order parts for one of those by ser# and see what you get.
As usual a simple question gets by a forum member turns into a debate! I am done. Dave

[Genesis]

Key Power advanced the timing. Ok, I buy that.

I've yet to see a Covington engine where that sort of thing was done. Its NOT a trivial thing to do. If you were building an engine from a block up its simple (since you have to assemble the gear train) but if you are buying an engine from Detroit and marinizing it (whether now or in the '80s) and want to change from standard to advanced timing its not as simple as remove a cover and move a thing here or there.

The key things to know for injector timing are:

1. What injectors are in the engine, and if they are supposed to be in an advanced timing engine or one with standard timing.

2. What the book spec height for that injector is.

3. What your engine's gear train is (advanced .vs. standard)

If the injector is intended for a different setup (advanced .vs. standard) than your engine it is not possible for you to get the correct injection profile from that injector for your motor. You can get the timing right (if you're willing to do the math and have all the angular measurements to go into it - I don't!) but you won't get the injection PROFILE correct. The only real fix for that is to remove those injectors and put in ones designed for the timing you have.

This error is made more often than people would think, as you've noted Dave. In the case of the V12 you had that poured smoke and would not make power, were there no appropriate injectors available for that motor and power level designed for the correct timing? If so, then while that's a fork-up its not all THAT expensive to fix ($1200 for the correct injectors plus a tune-up and all is well in the world.)

Anyway, my point is that you can't determine the injector timing without knowing (1) what injectors are in there and (2) if the engine is standard or advanced timing. If you discover that the engine and injectors are incompatable in terms of their timing the only correct course of action is to put the correct injectors in the motor to match the timing you have.

Its not as simple as "its 1.508" or "its 1.484". It is PROBABLY one of 1.460, 1.484 or 1.508, as those cover most settings, but first one must know what 'ya got.

'Nuff said.

[captddis]

Some people just don't get it. The 12V71s in the 60 referenced above were Covington! and they did not come that way from the factory. Got it?
Ps you are going to get carpal tunnel syndrome with those looong posts.