Holley 390 setup

martin_t · Post by **martin_t** » Tue Dec 06, 2011 12:58 pm

Hi

I am struggling to find anyone in the Lincoln\Newark on Trent area who I can get to set up my Rover 3.5 V8 with a Holley 390 on top (GD Cobra). Although I bought the carb jetted up for a Rover 3.5, I built the engine with a Hurricane Cam and have Stage 3 heads on from V8 Developments. There are a couple of guys around Lincoln but they have said they can't get hold of jets etc etc to carry out any work.

I have set up the carb as best I can from advice and books, but I still feel it is running too rich. It starts OK and runs OK although the exhaust is always black and sooty, with a trickle of smoke on tick over.

Any help, or anyone who could point me in the right direction would be appreciated.

regards

Martin

kiwicar · Post by **kiwicar** » Tue Dec 06, 2011 1:42 pm

Hi
I can only give general advice here but I think your best aproach (well cost wise anyway) would be to get a wide band O2 sensor like the Inovate LC1, a jetting kit from Real Steel, or similar and a book like the david Vizard one on carb tuning http://www.amazon.co.uk/How-Build-Horsepower-Carburetors-Manifolds/dp/1884089143/ref=sr_1_12?s=books&ie=UTF8&qid=1323178587&sr=1-12
and ask advice on here. After logging the engine using the LC1 it is a process of making small changes to the jetting of the carb in line with reading about what the various parts of the carb does and logging it again. It is far cheeper than a rolling road to get you set upand close to ideal, then the final stage is to log times around a circute, or on the drag strip (depending on what floats your boat) and looking for the final small improvments there.
Best regards
Mike

mgbv8 · Post by **mgbv8** » Tue Dec 06, 2011 7:56 pm

Maybe put the car on a dyno first to get a log of AFR's. Then you have a starting point.
If it starts and runs fine but seems a little rich at idle it may just be some minor tweaks required on the idle screws or an adjustment of the throttle flaps as they may have been set a bit wide to get idle speed up and may be exposing a little of the transition slots at idle?

Whats it like on MPG ?

martin_t · Post by **martin_t** » Tue Dec 06, 2011 8:21 pm

mgbv8 wrote:Maybe put the car on a dyno first to get a log of AFR's. Then you have a starting point.
If it starts and runs fine but seems a little rich at idle it may just be some minor tweaks required on the idle screws or an adjustment of the throttle flaps as they may have been set a bit wide to get idle speed up and may be exposing a little of the transition slots at idle?

Whats it like on MPG ?

Hi

I reckon I am getting about 25 mpg overall, and I generally drive it hard!!

Martin

mgbv8 · Post by **mgbv8** » Tue Dec 06, 2011 8:27 pm

martin_t wrote:
mgbv8 wrote:Maybe put the car on a dyno first to get a log of AFR's. Then you have a starting point.
If it starts and runs fine but seems a little rich at idle it may just be some minor tweaks required on the idle screws or an adjustment of the throttle flaps as they may have been set a bit wide to get idle speed up and may be exposing a little of the transition slots at idle?

Whats it like on MPG ?
Hi

I reckon I am getting about 25 mpg overall, and I generally drive it hard!!

Martin

Thats pretty good Martin

Cant be too much wrong with the carb then ??

sidecar · Post by **sidecar** » Tue Dec 06, 2011 8:39 pm

I 'second' using an LC1 and doing it yourself, I have no faith in rolling road operators! (Well the two that I've dealt with anyway!)

I also don't think that a rolling road can replicate what the engine goes through when its being used on the road, especially at cruise.

All just my humble of course!

martin_t · Post by **martin_t** » Tue Dec 06, 2011 8:50 pm

mgbv8 wrote:
martin_t wrote:
mgbv8 wrote:Maybe put the car on a dyno first to get a log of AFR's. Then you have a starting point.
If it starts and runs fine but seems a little rich at idle it may just be some minor tweaks required on the idle screws or an adjustment of the throttle flaps as they may have been set a bit wide to get idle speed up and may be exposing a little of the transition slots at idle?

Whats it like on MPG ?
Hi

I reckon I am getting about 25 mpg overall, and I generally drive it hard!!

Martin

Thats pretty good Martin

Cant be too much wrong with the carb then ??

May not be an exact figure, but not far off I guess!! Roll on some better weather when I can do a bit more driving\testing\setting up!!!!

Thanks

mgbv8 · Post by **mgbv8** » Tue Dec 06, 2011 9:10 pm

sidecar wrote:I 'second' using an LC1 and doing it yourself, I have no faith in rolling road operators! (Well the two that I've dealt with anyway!)

I also don't think that a rolling road can replicate what the engine goes through when its being used on the road, especially at cruise.

All just my humble of course!

The main problems with rolling roads from my racing point of view is that they cant replicate forces of acceleration, and neither can they replicate prolonged cruise mode as Pete says. But they still give you a baseline to work from

However! You can always ask the dyno operator to run the car as you want?? I do...

If you want the operator to do a full power pull then do it. But then ask him to run the car up to an MPH barrier and hold it there etc...

I tell my guy what I want him to do and he does it. I even sit in with him and give him instructions ?? If I'm paying for my dyno time I get my moneys worth