202 Idle problem and intake manifold question

[bang_chong]

Hi guys, i just currently put a set of extractors on my carbied 202 in my VK. I noticed once i had fitted the new exhaust the car wouldnt hold idle. The car runs fine but i have to rev it to keep it going. I was thinking do i need to tune the carby or when i removed the old exhaust there were 2 ports on the bottom of the intake manifold that bolt into the top of the old exhaust manifold that are now freely open with the new system. I believe the 2 ports are for helping the car when its cold to help run. I bought the exhaust of a guy who had it on his carbied 202 and he said that it ran fine on his when the 2 ports were open like mine. So im just wondering if anyone would have any advice for this

I just wanna know is it fine that the 2 ports are open or should i block them off? and does anyone have any advice on my idling problem

[soop]

Trying to scrape my memory, the ports your talking about are the heat risers from the original manifold no?
That was to aid with cold starts and the like by heating the intake manifold. So i don't think they matter all that much. (Could be wrong, been along time since i fiddled with a 202)

Have alook for broken vacuum lines you may have forgoten to replace and the like, that sounds like whats going on here. Just a vacuum leak.

[bang_chong]

well now that you mention it theres a vacuum line that i dont know what to do with as it was attached to an actuator or valve that help these exhaust gases to help the car on cold. what do you propose i do with that? block it or run it into one of the trees?

[project commy]

try both and see what happens check the pcv valve on top of the rocker cover it may be loose or faulty. but its definetly a vacume leak.

[soop]

Guranteed that wont be helping the cause. Test it by banging a screw in the end of it and see what happens.

[bang_chong]

appreciate all the advice guys. cheers

[Drewie]

We have had extractors on our VC 202 for many years, those holes or ports you are talking about on ours we have one blanked off and one open, don't ask why that is what the exhaust fitter did, maybe after doing one he thought it was not needed, not sure, so I don't think it matters that they are open as it is just a cavity within the manifold for the hot exhaust gases to go into to warm the manifold. The only problem we have is in the warmer months the car runs faultlessly but come the winter because it does not have a heated manifold it tends to stall a lot until it has been driven quite a few kms and the motor is right up to temp. Our VC according to the gauge does run very cold if the gauge is right, thinking of partially blanking off part of the radiator for winter to see if that helps with the stalling.

[VK SL 3800]

Your two ports are for the EGR system on the car, the standard varejet carbie has been tuned to run with them connected and will have the idle problems your experiencing and can be a dog at low revs and sometimes light throttle without them connected as it gets to much oxygen instead of exhaust gases. Its a very simply thing often overlooked. Just connect both up if possible but it should be fine with just one pipe as it should have enough volume to carry the amount of air needed and block off the other.

[Not_An_Abba_Fan]

The butterfly on the original manifold was operated by vacuum, make sure the vacuum port that fed it is blanked off.

The two ports on the bottom of the intake manifold are not open to the air so they don't need to be blanked off. If they were open, the engine would not run at all as there would be two gaping big holes feeding straight into the bottom of the intake manifold.

The only straight Holden 6 that had EGR was the EFI VK, all carby 6's never had EGR.

[codfishface]

The only straight Holden 6 that had EGR was the EFI VK, all carby 6's never had EGR.

Incorrect.

Carby VK black motors also have/had EGR.

[BoNeZ-01]

The only straight Holden 6 that had EGR was the EFI VK, all carby 6's never had EGR.

One of, one other was also the 2.85 (173) Blue motor in the VH, I owned one once.

[VK SL 3800]

The butterfly on the original manifold was operated by vacuum, make sure the vacuum port that fed it is blanked off.

The two ports on the bottom of the intake manifold are not open to the air so they don't need to be blanked off. If they were open, the engine would not run at all as there would be two gaping big holes feeding straight into the bottom of the intake manifold.

The only straight Holden 6 that had EGR was the EFI VK, all carby 6's never had EGR.

The two ports run up to the EGR valve located on the side of the manifold, which is always open slightly and opens fully under acceleration and cruise. Look on the manifold its a round thing with a bolt head on it and the vacuum hose running to it, you can also pull it on manually to test, from there it runs up two the bottom of the intake manifold where the carbie sits. from there it passes into the intake directly under the carbie around two sleeves with the fuel coming through the center of the sleeve ie. the two holes you see when the carbie is off.

Refer Injectronics for cleaning procedure as mine was stuffed full of carbon and was causing detonantion problems.

Injectronics Automotive Electronics Parts Melbourne Australia - 3) Pinging (VK EST Commodore)

[BoNeZ-01]

I'm wondering if there may be some confusion here, between EGR, and a Heated Intake Manifold.
These are actually two completely different systems, which perform two completely different operations.
In a factory Heated Intake Manifold set-up, the Intake and Exhaust Manifolds are join by chambers where the exhaust gases are diverted slightly from the Exhaust Manifold into the sealed chambers under the Intake Manifold, to heat the Intake on cold starts.
A vacuum valve closes off this chamber when the engine reaches normal running temps.
This is the set-up 'bang_chong' is referring to.
EGR is Exhaust Gas Recirculation, where a pump driven by a fan belt, recirculates some of the exhaust gases back in to the cylinders, to be 're-burnt'.

[strgas]

''EGR is Exhaust Gas Recirculation, where a pump driven by a fan belt, recirculates some of the exhaust gases back in to the cylinders, to be 're-burnt'.''


The belt driven pump is in fact a air pump for air injection into the exhaust manifold to lower emissions of NOX , EGR is a simple valve between the inlet and exhaust manifolds to allow a recirculation of some exhaust gases for a second and complete burn

[VK SL 3800]

Ok To clear up, the stock VK Black six has all three system in place as mentioned above.
-EGR system
-Heated intake for cold start
-Air Pump

The air pump just pumps air into the exhaust manifold as strgas said to lower nox so the engine could meet emissions requirements.

The heated intake is the just a pipe that connects to a little flange on the manifold that draws air up around the exhaust manifold to warm it up before it get sucked down the carbie, which get closed off by a TVS in the air filter housing once the engine is warm, but most cars have jammed or inoperative flaps now so they just draw in cold air form the word go.

The EGR system becomes fully operative once the engine is warm, but a small amount of exhaust gases are always allowed to flow through the valve as it never fully closes unless it is full of carbon. This just sucks exhaust gases up through the two ports on the bottom of the intake manifold which are bolted to the two ports on the stock exhaust manifold.