Pinging [newly rebuilt engine]

[Deleted member 8987]

Unplug the vacuum line to the EGR and tap the EGR with a brass hammer to make sure it's seated.
Plug the line with a bolt or golf tee.
That will disable it.

That said, is the distributor number correct for that car?

 

[Lucky_B]

It should be it was recurved to fit my needs. Problem was there before original 45DE4 distributor was replaced. I understand Canadian versions of this engine (18V883)came with the 45D4.

I am confident that the distributor is not the problem.

Weezer

 

[Deleted member 8987]

Not saying it is.
My LBC has a part number on the distributor housing, and a "code" on the advance, and they do, in fact, match the factory manual.

Your 22 degrees of mechanical advance at 3,000 rpm's sounds a bit high, and the only chart I could readily find shows it to be high for that vehicle, not necessarily that engine.

Not picking on you.
Don't go getting defensive.

If we want to get to the bottom of this without destroying your engine, we have to work together and keep the chips off the shoulders.

Are you telling me it did this before the distributor change, or before the engine change?

 

[Lucky_B]

Toc,

Thanks for help, don't mean to be defensive, just frustrated.

This all came about after engine change and before the distributor change. I have used original distributor, and does not matter. The original has some looseness in it which is why the change.

Weezer

 

[DrEntropy]

Isuspect this is NOT what ya wanna hear but I'm suggesting a different head, CC'd and chamber profiled. Sounds like head/block shave has put compression to a point where the detonation is compression driven.

Clive Trickey (a real guy, honestly) is author of a good book on chamber profiling, head mods in general. Amazon may have it used, likely out of print now.

 

[Lucky_B]

Ok. Here is what I did today and the results.

1. I changed the plugs to NGK BPR7ES (1 step Cooler than What I have been using)
2. Disconnected the EGR
3. Lightly sanded the last 1/3 of the carb needle. (to richen mixture) Really noticed this in the driving.

Result:
Pinging greatly reduced to point of barely hearing it.

This leads me to believe that the pinging is a mixture problem. not a combustion problem.

Any thoughts?

Weezer

I talked to an MG mechanic today and he told me that the Zenith?Stromberg carb does not do well with engines that have been bored as min is. His suggestion was to change to weber carb aand my problems (pinging) will vanish. I would just have to replace everything when time for smog test.

 

[DrEntropy]

Weber is frying pan to fire IMO. I maintain the needle can be changed for a more appropriate one. No good source for ZedS needles/charts here. Primarily an SU guy. Joe Curto may have inf/recommendations.

 

[Lucky_B]

Thanks Doc,

That is my next try before I go the weber route

weezer

 

[Deleted member 8987]

Like I said earlier, lean mixture will do it, advanced timing will do it, oil consumption will do it.

You had stated your color was good on the plugs.
You can "hide" a lot of pinging by going WAY rich.
BTDT.

If your goal is to stop the pinging, get more fuel.
If your goal is to fix the problem.......

You ain't lived until you've milled block and head so far the pistons lightly impact the aluminum cylinder head...now THAT'S a noise.

 

[DrEntropy]

You ain't lived until you've milled block and head so far the pistons lightly impact the aluminum cylinder head...now THAT'S a noise.

Even that occurred to me... but if some "less" pinking is occurring with a needle mod, seems interference is not the issue...

nevermind if it WERE. Wouldn't run long! :wink:

It may really be proper to find out how much meat has been scraped from block and head, methinks. What's compression after it's up to "normal" temp, fer instance?

 

[Lucky_B]

Compression was taken warm: 1-155, 2-155, 3-125, 4-155.

I don't think intereference is issue as the engine has 5000 miles on and still running

Did some further changes/measurements:
1. Fully retracted needle (enrichened) and pinging not heard.
2. Spark plugs are a light brown after run and removal
3. AFR measurements were made at:
Idle 12.8
1200 12.8
2000 13.0
2500 13.0
3000 13.1
3500 13.2
Does this mean (confirm) a richer needle required?

Weezer

 

[DrEntropy]

Pretty much.

 

[Lucky_B]

Well I guess I will be looking for a richer needle.

Thanks

Weezer

 

[DrEntropy]

At what point are you attaching EGA? Tailpipe or upstream? 12:1 would be on the edge of too fat, the pinking doesn't jibe with 13:1 and the compression numbers, IMO.

You've got SOMETHING weird goin' on in that mill. Dave said it with the "get more fuel, or fix the problem" comment. Seems as if you've covered everything but evidence suggests there's a missed detail someplace.

 

[Lucky_B]

EGA was connected at the tailpipe, all readings were while sitting engine reving only.

Drove 32 miles this morning combination of flat hilly drive no pinging with the above readings no changes made. I will check the plugs again when I go home

weezer

 

[DrEntropy]

The "no pinging" part sounds good!

 

[tr8todd]

The last engine I saw with a serious pinging problem, ended up being caused by the plugs. The standard plugs were not cooling enough between firing and the residual heat left in the electrodes was causing pre-ignition. This new fuel is crap once you start putting higher compression to it. Couple that with multiple spark ignitions, and the hotter plugs are too hot. I am seeing not only hotter plugs causing preignition, but also hot spots on exhaust valves in engines with long duration cams, or forced induction.

 

[Lucky_B]

I have been driving everyday (About 70 miles) since I did the above changes, even went to lower octane fuel and have not had the pinging problem.

I will try regular grade and see if it still runs well.

My shift range has improved to around 5000 rpm with good power.

Weezer

I am also going to try a smaller needle to see if adjustment range of AFR improves.

 

[tdskip]

Sounds like you are making some progress, no?

 

[Lucky_B]

Seems to be! Now to find a 45J needle

Weezer