Hi guys,

I have a 2001 C5 in Australia and I have recently replaced the 383 with an LS7 427.

The 383 with a cam was a bit of a pig to drive and I wanted something smoother, without losing power so I went bigger of course.

The 427 has ported heads, ported inlet manifold, cam 115 238 244, 1 7/8 headers, 3 inch twin exhaust, basically just about all the available bolt ons, upgraded fuel system,etc.

I also replaced the Textralia clutch that was with the 383, which I did not like due to some shudder, with a twin plate carbon clutch and flywheel - the one recommended by Tony Mamo for drivability on the street. I am pretty sure it has a light weight flywheel (I have not been able to speak to Tony yet but will ASAP).

This combination of engine was supposed to be quite smooth and not jerky when you are driving around in 1st and 2nd gear at 1000-2000 rpm, but it is heaps worse than before with the 383. It is incredibly jerky and I hate it. The clutch also has an annoying rattle/vibration.

The funny thing is the people who have built and installed the engine here have used this cam in a number of other 427s (in commodores, which are your GTOs) and this cam is considered a baby cam that is very smooth - no problems at all. They agree that something is drastically wrong and that it should be much better. They have tried everything with the tune and it is definitely not that as they have tuned many of these.

I have read some posts about light aluminium flywheels causing problems in 427 but there was not much detail given. Does anyone have any experience here?

Could something not be balanced properly?

Could something have been damaged during the install?

Is the clutch just too light for a 427 with this cam, even though it is mild? I would have thought that it should be okay as it is the same one that Tony has tried in his 427 and he said it was great.

would the standard LS7 clutch do the trick?

I cant complain about the power though - the thing is a monster.
The tuners here who have driven it and also race here, expect it to run in the 10s over the quarter if this helps.


Any help here would be greatly appreciated. I may have to put the Textralia one back in but who knows, what could be worse.

I dont drive that hard and dont go to the track (I may once just to see what it will run). I do sometimes flog the pisser out of it, but only when I am 'off the mark'.

Any help will be greatly appreciated.

 

lightweight flywheel.

 

the recommendation from RAM for my Mopar HEMI [528/650FWHP], was to stay away from a lite wheel for a street application.
Thier reasoning points were exactly what you are seeing.
As for the noise, that could be the nature of a multi-disc clutch. We have that same problem w/ a twin in my buds Camaro..