N12 Engine Sounds like a Diesel

sgs · Post by **sgs** » Sun Jan 09, 2011 3:22 pm

If the tops of the valves are dished out your pretty fucked (for accurate adjustment) when this happens its impossible to do with the feeler gauges!

TurboZ.Dude · Post by **TurboZ.Dude** » Thu Jan 13, 2011 9:44 am

sgs wrote:If the tops of the valves are dished out your pretty fucked (for accurate adjustment) when this happens its impossible to do with the feeler gauges!

That's exactly the problem I have... I adjust the tappet clearances regularly but I can't get the noise down.

sgs · Post by **sgs** » Thu Jan 13, 2011 2:49 pm

Yeh it was funny when I set mine, tappa tappa tappa. oh shit.
was worse than when I started!!

I thought maybe if you could rig a DTI up somehow you could pull it off thought

Post by **tassuperkart** » Thu Jan 13, 2011 5:20 pm

sgs wrote:If the tops of the valves are dished out your pretty fucked (for accurate adjustment) when this happens its impossible to do with the feeler gauges!

Nope! No imagination at all! You have 2 clearances you can check you know!
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Old hands to the rescue!!!

Here you go you young pups, some more (free) pearls from the old time mechanics experience vault!

You divide the tappet clearance by the rocker ratio and measure between the cam lobe and the follower. Its easier than measuring the tappets gaps themselves with bent feeler guages, accurate, repeatable and allows for rooted tappet faces due to overrev abuse!

There you go ladies..............Damn Im good!!!

L8r
E

Kimmo · Post by **Kimmo** » Thu Jan 13, 2011 9:31 pm

Cool, what's our rocker ratio?

TurboZ.Dude · Post by **TurboZ.Dude** » Thu Jan 13, 2011 10:33 pm

Hey, thanks E! It's good having you around...

Yeah, it would be good to know the ratio... is it easily measurable or do you have some factory value for it?

Kimmo · Post by **Kimmo** » Fri Jan 14, 2011 9:07 am

You shouldn't have to measure it; I seem to recall seeing that spec somewhere...

It's not often mentioned, but it is occasionally listed in engine specs.

TurboZ.Dude · Post by **TurboZ.Dude** » Fri Jan 14, 2011 10:02 am

Besides, doing measurements by hand would give highly inaccurate values anyway, now that I think of it.

*sigh* Not my day today...

paul w · Post by **paul w** » Fri Jan 14, 2011 12:15 pm

Having been on the end of tassuprkarts' whip from saying exactly the same thing, I have to say that once correctly adjusted, the engine sounds fine.
Nothing like a diesel, although it did somewhat on low revs/higher load until I swapped to higher-octane fuel (to remove the pinging).

Post by **tassuperkart** » Fri Jan 14, 2011 7:30 pm

Was I an arsehole again paul?.......................................

paul w · Post by **paul w** » Fri Jan 14, 2011 8:16 pm

No, not at all...far from it.
You just made it abundantly clear that the N12 engine SHOULD NOT MAKE ANY NOISE IF THE TAPPETS ARE CORRECTLY ADJUSTED!
Righto...got that!

Post by **tassuperkart** » Fri Jan 14, 2011 8:39 pm

Sheesh...Im always an arsehole...............................

Kimmo · Post by **Kimmo** » Sat Jan 15, 2011 11:54 am

Yeah, but you're our arsehole.

Almost a mascot : )

sgs · Post by **sgs** » Sat Jan 15, 2011 1:19 pm

paul w wrote:Having been on the end of tassuprkarts' whip from saying exactly the same thing, I have to say that once correctly adjusted, the engine sounds fine.
Nothing like a diesel, although it did somewhat on low revs/higher load until I swapped to higher-octane fuel (to remove the pinging).

These motors run just fine on low octane, maybe check your ignition timing?

paul w · Post by **paul w** » Sat Jan 15, 2011 2:45 pm

I'm always concerned about adjust the timing to other than that supplied by the factory. It's there for a reason - to get the best of both worlds.
Any change has its pros and cons, so if I make to the timing, what is it, and what's the downside?
I presume by lower octane, you mean E10?
I tried out Premium Unleaded on a recent trip to the Snowy Mtns, and it seems to run smoother, with a bit more power.
Who knows if this is just perception, but it certainly seemed to have a bit more go. And, at $4 more per tank, it's not that much of an issue.