So I put the motor in yesterday, ran it like any other rebuilt should be in the very beginning, and now am experiencing pinging, a lot. Fuel additives worked some, except it pings under heavy acceleration still. My guess is that it is caused by the higher compression in the cylinders, I measured it at about 15psi above standard after 4 strokes (185psi). The timing is at specs, and the carb mixture hasn't been tinkered with...

Do you guys have ANY suggestions? I've looked in the archives extensively but all I come up with are people with older engines that are pinging, but mine is brand spanking new..err "remanufactured" <img src="/forums/images/graemlins/zombie.gif" alt="" />

thanks a ton!

-Brian

Timing is prob advanced too much. Have you put a light on it?

Yeah the timing is at 7 degrees plus or minus 2 degrees. And I am using Normal length Spark plugs

During the last rebuild on mine, involving leveling the block, and shaving the head somewhat, to prevent out-of-normal-range compression ratios that would result from the reduction in volume of the combustion chamber, a `spacer gasket`was used, basically a steel plate with gasket on each side to compensate for the material lost during the block head machining.
Not sure if this is your issue, maybe using higher octane gas should help (I think), but at a certain point the increased compression ratio will be difficult to live with...

I don't know the 2.6L engine, but I'd suggest that you check the cam timing and make sure it isn't one tooth advanced.

Frank

Did you just get gasoline with alcohol in it up your way? I have two cars that now ping that never did before.

Other than that check the advance curve in the distributor.

The above advice for ignition timing and CR increase due to possible head/deck milling is all good. I might be waaaay wrong, but here's why I'd check the valve timing:

Assuming the 185 number to be 15psi over standard - and I don't know what the standard spec is on that engine - I plugged the following numbers into the calculator linked below:

Bore = 3.587"
Stroke = 3.858"
Rod length = 5.906"
Static CR = 8.7:1
Inlet valve close = 59?ABDC

calculator

The calculator gives 141.33 psi as cranking pressure.

I don't know how many teeth are on the 2.6L sprocket, but if it's like the 3.0L, it has 40 teeth (how many on the 2.6L?) - which each represent 9? on the cam, but 18? on the crankshaft.

If you substitute 41? (59?-18? advanced = 41?ABDC) as the inlet valve closing point in the calculator, the cranking pressure increases to 159.75 psi - or about 18 psi.... which is close to the 15 psi amount stated as "above standard".

That said, 165 psi doesn't sound so high to me - and I may have some of the above measurements wrong which would throw off the calculations.

And as a final caveat: I don't know nothin' 'bout no 2.6L..... Charlie certainly does. <img src="/forums/images/graemlins/kewl.gif" alt="" />

Frank

I'd also check the egr for proper function. Especially if the vac lines may be messed up. And carb lean out from a partially clogged main jet. How is the power?

Power is about the same as before the rebuild, no surprise there. The whole Exhaust gas return system has me a little turned around, but if you could walk me through how to diagnose it, perhaps that could be part of the problem...

185 does not sound too high... And 2.6 motors are generaly tolerant to CR increases. I have run them at 9.5 to 1 with no issue with 92 octane fuel. That took a good head shave to get there, more than any shop would knowingly do.

I would make sure the vacum advance is conencted to the correct port and that the EGR is working. Also make sure the advance mechanisms in the dist works ok. No broken springs, worn shafts ect.

I have gotten a 185 PSI reading and still run 10 PSI boost and not gotten detonation.

Also make sure you dont have a lean cylinder or a hot spot.

Kevin