Minor mods to V8
Discussion
Evening all.
I have been given some advice by another member of this forum on how to improve the drivability of my Chim through some small modifications to the engine.
I asked him to elaborate on what the best products to use to enable these mods are but never got a response so I'm hoping someone can help. I've put my questions below each of the suggestions he's made.
First suggestion:
"Fit a simple check valve in the small bore pipe that goes from the crankcase breather "T" to the plenum so it can now only suck, this will also help with drivability. The next step would be to separate the throttle butterfly from the crankcase and plenum (larger 90 degree pipe) at idle by using a proper PCV valve, this also helps with low speed drivability."
First question:
Which check valve, size, make etc? Where can I get one? Same for the PCV valve, which one, where etc?
Second suggestion:
"Disconnect the stepper motor feed hose at the rear facing steel pipe at the throttle body, seal the steel pipe so there are no vacuum leaks, this is actually the venturi effect rather than true vacuum as the pipe goes to the atmosphere side of the throttle butterfly not engine side. Fit a small breather filter to the stepper motor feed hose to stop any dirt entering the stepper motor and engine."
Second question:
How best to seal the steel pipe?
Which breather filter is best to use for stepper motor feed hose? Where can I get one?
If anyone has anything else to add about the above I'd be interested to hear it!
Many thanks
I have been given some advice by another member of this forum on how to improve the drivability of my Chim through some small modifications to the engine.
I asked him to elaborate on what the best products to use to enable these mods are but never got a response so I'm hoping someone can help. I've put my questions below each of the suggestions he's made.
First suggestion:
"Fit a simple check valve in the small bore pipe that goes from the crankcase breather "T" to the plenum so it can now only suck, this will also help with drivability. The next step would be to separate the throttle butterfly from the crankcase and plenum (larger 90 degree pipe) at idle by using a proper PCV valve, this also helps with low speed drivability."
First question:
Which check valve, size, make etc? Where can I get one? Same for the PCV valve, which one, where etc?
Second suggestion:
"Disconnect the stepper motor feed hose at the rear facing steel pipe at the throttle body, seal the steel pipe so there are no vacuum leaks, this is actually the venturi effect rather than true vacuum as the pipe goes to the atmosphere side of the throttle butterfly not engine side. Fit a small breather filter to the stepper motor feed hose to stop any dirt entering the stepper motor and engine."
Second question:
How best to seal the steel pipe?
Which breather filter is best to use for stepper motor feed hose? Where can I get one?
If anyone has anything else to add about the above I'd be interested to hear it!
Many thanks
Chimaera27 said:
Evening all.
I have been given some advice by another member of this forum on how to improve the drivability of my Chim through some small modifications to the engine.
I asked him to elaborate on what the best products to use to enable these mods are but never got a response so I'm hoping someone can help. I've put my questions below each of the suggestions he's made.
First suggestion:
"Fit a simple check valve in the small bore pipe that goes from the crankcase breather "T" to the plenum so it can now only suck, this will also help with drivability. The next step would be to separate the throttle butterfly from the crankcase and plenum (larger 90 degree pipe) at idle by using a proper PCV valve, this also helps with low speed drivability."
I don't see why you would need a check valve unless you have FI
First question:
Which check valve, size, make etc? Where can I get one? Same for the PCV valve, which one, where etc?
Second suggestion:
"Disconnect the stepper motor feed hose at the rear facing steel pipe at the throttle body, seal the steel pipe so there are no vacuum leaks, this is actually the venturi effect rather than true vacuum as the pipe goes to the atmosphere side of the throttle butterfly not engine side. Fit a small breather filter to the stepper motor feed hose to stop any dirt entering the stepper motor and engine."
That pipe is there to seal that part of the system so why remove it?there are no vacuum leaks if the stepper motor is connected and working correctly. the Stepper motor helps control idle
Second question:
How best to seal the steel pipe?
Which breather filter is best to use for stepper motor feed hose? Where can I get one?
16mm vacuum blanking plug from Ebay
If anyone has anything else to add about the above I'd be interested to hear it!
Many thanks
I have been given some advice by another member of this forum on how to improve the drivability of my Chim through some small modifications to the engine.
I asked him to elaborate on what the best products to use to enable these mods are but never got a response so I'm hoping someone can help. I've put my questions below each of the suggestions he's made.
First suggestion:
"Fit a simple check valve in the small bore pipe that goes from the crankcase breather "T" to the plenum so it can now only suck, this will also help with drivability. The next step would be to separate the throttle butterfly from the crankcase and plenum (larger 90 degree pipe) at idle by using a proper PCV valve, this also helps with low speed drivability."
I don't see why you would need a check valve unless you have FI
First question:
Which check valve, size, make etc? Where can I get one? Same for the PCV valve, which one, where etc?
Second suggestion:
"Disconnect the stepper motor feed hose at the rear facing steel pipe at the throttle body, seal the steel pipe so there are no vacuum leaks, this is actually the venturi effect rather than true vacuum as the pipe goes to the atmosphere side of the throttle butterfly not engine side. Fit a small breather filter to the stepper motor feed hose to stop any dirt entering the stepper motor and engine."
That pipe is there to seal that part of the system so why remove it?there are no vacuum leaks if the stepper motor is connected and working correctly. the Stepper motor helps control idle
Second question:
How best to seal the steel pipe?
Which breather filter is best to use for stepper motor feed hose? Where can I get one?
16mm vacuum blanking plug from Ebay
If anyone has anything else to add about the above I'd be interested to hear it!
Many thanks
The stepper air feed passes through the AFM from its current take off point, so the total air is correctly metered with the required fuel being added against airflow. If you feed the stepper from atmosphere, and bypass the AFM feed I cant see how the car would ever idle correctly as there is now a big mismatch between the AFM airflow and what the engine is getting. This would also screw the long term fuel trim settings. If it does work, its by good luck and nothing more.
pjac67 said:
Hi Ronan - whereabouts in Glos. are you - there's a few of us in N.Bristol/S.Glos if you fancy joining us on a run ?? ATB Paul.
Hi Paul.I'm in central Bristol, and would love to come join in on the odd run. Are you with TVRCC? Ever go to the monthly meets?
The car is currently off the road until April while I iron out the kinks!
Thanks all, appreciate the feedback. Got tbh I had a feeling someone may pipe up and say why bother with these mods, the car runs fine as it is and its not like this will make an enormous difference in power output!
Does anybody advocate adjusting the idle to 1100 (16 degrees) on the dissy and then turning base idle screw in until.you get 950rpm? Supposedly this gives a steadier idle and makes the engine more responsive?
Does anybody advocate adjusting the idle to 1100 (16 degrees) on the dissy and then turning base idle screw in until.you get 950rpm? Supposedly this gives a steadier idle and makes the engine more responsive?
Wont work- the ECU control the idle with the stepper, the base idle is only a setting that the stepper adds air to. 16'is too much advance at idle, it will mean the addition advance will be added at peak advance and that could damage the engine. Basically dont mess with it, there is no golden bullet you can use in the stock set up to improve things.
Edited by blitzracing on Friday 3rd February 12:13
If everything is in good order on the ignition, the cars run well. Good quality parts are not always new ones unfortunately.
Plug extenders can be problematic as well.
If you have a problem then finding local known spares to test is a good way. If you are looking for general improvements, it could work out expensive!
Plug extenders can be problematic as well.
If you have a problem then finding local known spares to test is a good way. If you are looking for general improvements, it could work out expensive!
One thing you might like to try is removing the vacuum advance valve (if it is still fitted) and replacing it with suitable length of open pipe. Try running like this and if you don’t get pinking then leave it out, obviously put it back in if you do. It will not make a dramatic difference but I think it is slightly smoother when driving at low speed and small throttle openings. All the value does is delay the vacuum advance taking effect; with it removed, the advance is applied as soon as you crack open the throttle.
It looks like this;
It looks like this;
Chimaera27 said:
pjac67 said:
Hi Ronan - whereabouts in Glos. are you - there's a few of us in N.Bristol/S.Glos if you fancy joining us on a run ?? ATB Paul.
Hi Paul.I'm in central Bristol, and would love to come join in on the odd run. Are you with TVRCC? Ever go to the monthly meets?
The car is currently off the road until April while I iron out the kinks!
https://www.facebook.com/groups/539155626100231/
Hope to see you out but always around for coffee/natter..
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