Factory Cams?

[DRTDVL1345402287 0]

Lots of people have commented that my car must have non-standard cam's due to the lumpy idle.

 

I've finally gotten around to removing the rocker cover to replace the gasket and the only markings i can see are:

 

Intake: D2 and 320

Exhaust: J2 and 325

 

Anyone got any ideas?

[welshpug 1,657]

any paintt marks? aftermarket cams tend to have the markings on the end where the pulley is bolted on.

[cammmy 1]

Terry told me that it's the Bosch flapper unit. As they get older the contacts wear and they don't idle as well (or something along those lines). He knows what he's talking about though. Another suspect could be the idler stepper?

 

Alex's mint 16v idles like a pig and my 4bie doesn't idle too crash hot either (although that's probably more to do with air leaks). My 16v idle's like a champ though so I think it's luck of the draw really.

[JeffR 51]

The idle stepper motor is probably in need of a good clean out with carb cleaner. The valve inside should rotate freely (no longer gummed up with oil vapour, etc).

Another culprit to a lumpy idle is worn throttle shafts/spindles.

[JeffR 51]

I checked a pair of XU9J4Z cams today & the only identifying differences between them are-

 

Inlet-SA

Exh-SZ

 

These markings are stamped into the last casting furthest from the hex.

[DRTDVL1345402287 0]

From what i've been told, the engine was originally from a 4wd model and that it ran different cams than the 2wd to make up for the extra drivetrain loss...

 

It's paint on the cams not oil mayo...

 

I'll check the cam ends tonight or on the weekend.

Edited October 13, 2011 by DRTDVL

[JeffR 51]

According to ServiceBox, the 4 x 4 cams seem to be identical to the 2wd items on the DFW engine. Is yours a D6C?

 

This is where I found the stampings so you may have to rotate the cams.

 

[welshpug 1,657]

they look standard to me, but here's some pug data that may help http://forum.205gtidrivers.com/index.php?s...amp;hl=camshaft

[petert1345402284 0]

Lumpy idle could mean faulty AFM or blocked fuel return line. My Mi16x4 has a filthy idle at times. It use to be smooth, but a lumpiness comes and goes. I'm just about to transfer the engine to another Mi16 (fitted with a Haltech) whilst I restore the body. So that will confirm the AFM problem.

 

As for Mi16x4 cams being different, I always thought they were. Have a look at the attached screen shots. DC6 cams could be either C5/C6, or F1/F2 (early Mi16x4). The DFW cams can only be C5/C6. I've certainly measured DFW cams at 214 deg. @ 0.050" and Mi16x4 D6C cams at 218 deg. @ 0.050". Either way, they'd have a smooth idle.

[rodionski 3 1 Cars]

I have a set of aftermarket cams laying around with unknown specs. Could anyone help me measure their duration, etc?

I would assume that the lift is easy to calculate by measuring the tallest and shortest lenghts of the cam lobes and seeing the difference.

[petert1345402284 0]

Yes, lift is the difference between short and long axis. To measure duration you'll need to have the cam in a head with at least one inlet valve/bucket etc. Use a dial indicator with a long stem to measure the travel of the top of the lifter/bucket. It's difficult to get down past the cam lobe. You can put a degree wheel on the cam, but you need to double the readings (convert to crank degrees). The best degree wheel is a Motronic flywheel. Each tooth is 6 degrees, and being a larger diameter is more accurate.

[rodionski 3 1 Cars]

would one bucket/spring be enough? I imagine that the duration will be between the highest positions of the lifter supported by the spring - can't think of why the valve is important.

[petert1345402284 0]

You need the valve/spring to keep the bucket pushed up against the cam lobe.

[rodionski 3 1 Cars]

Oh silly me, yes I will indeed need the complete assembly.