304 Why so sluggish?

[stocky]

So I've recently installed a wade cam into my VR 304. it makes power at 2500rpm to 6000rpm, and i can definately feel it kick it around then. the problem is before 2500rpm its just too much of a slug and i dont think its due to bad cam choice. i think the problem is elsewhere.

if i try to stall it up and launch, say stall to 4000rpm or so, then slowly let the clutch out. no matter what i try, it just seems to bog down way too much and go off real slow. only sometimes can i get a bit of chirp from the tyres.

even when crusing along, the car seems to jolt about a bit. if im driving along and the revs are between 1100 and 1500 or so, the car seems to lurch back and forward while driving. its hard to describe, but it doesnt feel right.

along with this, its using a fair bit of fuel. before the cam, i could get about 13L/100km average, but after the install, the best i can get is around 22L/100km. this definately doesnt seem right. what are the chances that the spark plugs, or the oxygen sensor could bugger up the same time i did this install? would it be worth looking into replacing any of these bits? the current plugs are around 7000km old, and i recently had one of them fail for some reason.

im not sure what else i can do, except adjust the tune, get some diff gears and a new manifold, however i dont see the manifold fixing up my low rpm problems. the heads have been shaved 60 thou, to raise the compression up around 9.2:1, and the exhaust consists of pacemakers, twin cats, crossover, twin 2.5 merging into a single 2.5 out back. the exhaust will be a full twin system soon

 

[betts]

even when crusing along, the car seems to jolt about a bit. if im driving along and the revs are between 1100 and 1500 or so, the car seems to lurch back and forward while driving. its hard to describe, but it doesnt feel right.

I had a similar problem to this last week. The insulation on one of my ignition leads had worn out because of the heat from the engine, and the spark was shorting straight onto the extractors, which made it quite rough and lurchy at around 2000rpm, especially when cruising. This might not be the same problem as what you are experiencing, but I would recommend you check your ignition system anyway, something else could be wrong.

 

[v8commy]

chuck in an auto with 3000 hi stall

 

[shiftySLE]

theres no such thing as stall it up and let the clutch out slowly, that's called 'riding' the clutch, it defeats the purpose of stalling it up in the first place, you have to hold 4000 revs then dump the clutch, I realize you wont get traction like that but even dumping a standard clutch has some slip otherwise you'll start breaking bits in the box. Cams only move the power curve up, if you want more power, start doing head work.

 

[HSV472]

how did you get it tuned for the cam?

 

[shiftySLE]

Sorry, didnt read the post properly, head work is done, up the diff gears for a bit more acceleration, be careful going to high in ratio or you'll never get off the line, you shouldn't be using that much more petrol unless you are testing the car and revving out a lot more, sensors can throw the thing out of wack, how long has it been since you put the cam in, the computers do adjust after a few drives.

 

[cjazzavy]

i have a similar problem in my VY SS i just did head a cam work last week and it really slugish down bottom but up top its crazy and it drinkin the fuel on hwy its sitin at 22l/100 can awyone suggest anythin for me

 

[96SEN8R]

The jolting is normal for a lumpier cam at low rpm. When you hear it at idle and it lumps over, picture connecting the clutch up with that, the wheels will jolt when the revs go up then down, even though its a little bit, that wot makes it jolt at low rpm if that makes sence. My cam is 230/230 and i alway keep it above 1800 when cruising, otherwise your going to start damaging you drivetrain. Thats why people start talking bout driveability when going bigger cams. I changed my manifold from a starr (which is a glorified banana manifold) to a torque power dual plane highrise and my driveability when up alot. When company suggest diff ratio changes with a cam change, it is to get the car out of the "sluggish" range quicker and it get it into its power making range. So I dont think there is anything drastically wrong with yours, you just need to make a few upgrades with the cam..

 

[NZVK308]

Firstly.. you may want to do a complete ignition check.. Leads/plugs timing etc..

mayjust need a Tune up

 

[stocky]

The jolting is normal for a lumpier cam at low rpm. When you hear it at idle and it lumps over, picture connecting the clutch up with that, the wheels will jolt when the revs go up then down, even though its a little bit, that wot makes it jolt at low rpm if that makes sence. My cam is 230/230 and i alway keep it above 1800 when cruising, otherwise your going to start damaging you drivetrain. Thats why people start talking bout driveability when going bigger cams. I changed my manifold from a starr (which is a glorified banana manifold) to a torque power dual plane highrise and my driveability when up alot. When company suggest diff ratio changes with a cam change, it is to get the car out of the "sluggish" range quicker and it get it into its power making range. So I dont think there is anything drastically wrong with yours, you just need to make a few upgrades with the cam..

yeah thats what i was thinking too. the jolting caused by the lumpyness of the cam. ill try to avoid lower revs while crusing then.

i think im going to have a look at leads/plugs, since one of the plugs failed a couple of months ago so the others might not be that great anymore. the tune is a 284 based tune, with a few changes to suit the cam, so that shouldnt be the problem, although i might try fiddling with the timing a bit.

how did the drivability improve when doing the manifold swap? did you lose much bottom end power or economy with the TP manifold?