Mike
Thanks for the reply.
AF was measured using a short piece of pipe with a lmbda sensor attached and stuffed up the tail pipe.
The rolling road is 4 weks old and I would have thought that if there was a problem with AF measurements it would have been sorted.
Anyway Ill call in tomorrow and ask the guy.
The figures arent actually represented as a ratio.
1500rpm 15.7
2000rpm 20.0
2500rpm 18.5
3000rpm 18.3
3500rpm 18.2
4000rpm 20.0
4500rpm 18.3
5000rpm 20.0
5500rpm 20.0
6000rpm 19.3
Their machine didnt measure any higher than 20. it doesnt specify anywhere that these figures are " to 1 " as a ratio I just assumed that this was so?
I have limited experience, so do these numbers look odd.
Mark
Edelbrock 600 on a 4.6
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ihatesissycars
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The gas analyzer you stick up the end isn't for accurately measuring a/f ratios on a dyno run.
A wideband lamda sensor needs to be mounted in the exhaust quite near to the manifolds, mine is mounted where the two manifolds meet together.
I'd start questioning the ability of the RR if this is the way its being measured.
A wideband lamda sensor needs to be mounted in the exhaust quite near to the manifolds, mine is mounted where the two manifolds meet together.
I'd start questioning the ability of the RR if this is the way its being measured.
V8'less but a fountain of dorky knowledge ref v8's!
Right
The pipe that was measuring the AF had a lambda sensor. It was not the nomal MOT type thing but a sensor with electrical wires linked to the computer.
Got the Carb and just finished fitting. On inspection there isnt a great deal of difference. The venturies seem only ever so slightly bigger.
As far as jetting goes I decided to start lean on the chart So I went with #24.
It started on the button so I warmed her up and adjusted the idle mixture.
Went for a spin and it seemed to be pretty good but not quite right at the bottom end just off idle and when cruising.
Mid range I think was better than before and pulled strongly.
Top end seemed Ok but the car is so damned fast its very risky trying to test it on the road.
Seemed to be slightly fluffy rather than crisp.
Now I really need to know what happening with the fuelling so Ill book the RR and in the mean time play with different rods/jets/springs.
Mark
The pipe that was measuring the AF had a lambda sensor. It was not the nomal MOT type thing but a sensor with electrical wires linked to the computer.
Got the Carb and just finished fitting. On inspection there isnt a great deal of difference. The venturies seem only ever so slightly bigger.
As far as jetting goes I decided to start lean on the chart So I went with #24.
It started on the button so I warmed her up and adjusted the idle mixture.
Went for a spin and it seemed to be pretty good but not quite right at the bottom end just off idle and when cruising.
Mid range I think was better than before and pulled strongly.
Top end seemed Ok but the car is so damned fast its very risky trying to test it on the road.
Seemed to be slightly fluffy rather than crisp.
Now I really need to know what happening with the fuelling so Ill book the RR and in the mean time play with different rods/jets/springs.
Mark
The other thing to remember is that if you have any upstream leaks in the exhaust, this could impact on your afr reading.
I would consider getting an M18x1.5 bung added to your exhaust so it can be measured properly at the dyno. You may find that a dyno run is only any good for 'pulls' rather than tuning the the mid/part driveability.
Indeed having your own wideband as a tuning / diagnostic aid will pay dividends in the long term.
Innovate LC1 is a good choice.
I would consider getting an M18x1.5 bung added to your exhaust so it can be measured properly at the dyno. You may find that a dyno run is only any good for 'pulls' rather than tuning the the mid/part driveability.
Indeed having your own wideband as a tuning / diagnostic aid will pay dividends in the long term.
Innovate LC1 is a good choice.
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ihatesissycars
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Goes straight to Eliot's LC1 idea as it comes complete with logging software and or fit a gauge as well for general driving. There is some really good kit in the Innovate range, add an LMA-3 and you have MAP, EGT/CHT, RPM logging as well or whatever sensors you make up and plug into it.ihatesissycars wrote:A suggestion, instead of using a rr get a wideband lambda sensor, guage and some sort of ability to log runs and you could tune it to perfection yourself, a useful diagnostic tool also.
Who says you cant go high tech with a low tech carb.
and by you have bought the inovate kit and put the bung in the exhaust you will probably still have change from a rolling road session and be able to log it under real conditions on a track day, you will be able to compare tuning changes with times around the track. Much easier to see how to relate changes in the mixture to real performance and huge bragging points in the bar after a track day 
Best of luck
Mike
Best of luck
Mike
poppet valves rule!
A very interesting idea. Ill look into the wideband stuff.
Planning to go to 96mm bore next year and if poss the Merlin heads so it would make sense to get a wideband setup.
Tried a few rod changes and it seems my first setup was weak on the cruise mode. So gone 4% richer which has improved things but I think I need to go richer again which will take me to #5 on the 1405 calibration chart.
Im sure theres more in the mid range from 2500.
At the moment they are charging £50 hr for the RR which will soon be £65hr which is still very reasonable. On tuesday managed to do 4 runs in the hour.
Now my starter motor has packed up, Its a brand new high torque gear reduction nippon denzo.
It never stops
Mark
Planning to go to 96mm bore next year and if poss the Merlin heads so it would make sense to get a wideband setup.
Tried a few rod changes and it seems my first setup was weak on the cruise mode. So gone 4% richer which has improved things but I think I need to go richer again which will take me to #5 on the 1405 calibration chart.
Im sure theres more in the mid range from 2500.
At the moment they are charging £50 hr for the RR which will soon be £65hr which is still very reasonable. On tuesday managed to do 4 runs in the hour.
Now my starter motor has packed up, Its a brand new high torque gear reduction nippon denzo.
It never stops
Mark
It was after adding a lambda to my carb fed v8, that i quickly realised how difficult to balance each element to get a good all-round mixture that I went to fuel injection shortly afterwards.katanaman wrote:Who says you cant go high tech with a low tech carb.
The good news is that almost all aftermarket injection systems will use the same wideband. Widebands are a real no-brainer in my opinion.
For anyone interested.
Ive got the engine running really well. Throttle response is great. I seem to have more performance for less accelerator travel ( especially mid range ), which I suppose makes sense.
Gonna ring and book an hour on the rolling road hopefully this week if I can as I need an indication of what the AFR is.
The back to back figures should be interesting.
Mark
Ive got the engine running really well. Throttle response is great. I seem to have more performance for less accelerator travel ( especially mid range ), which I suppose makes sense.
Gonna ring and book an hour on the rolling road hopefully this week if I can as I need an indication of what the AFR is.
The back to back figures should be interesting.
Mark
#mgbloke wrote:Mike
Thanks for the reply.
AF was measured using a short piece of pipe with a lmbda sensor attached and stuffed up the tail pipe.
The rolling road is 4 weks old and I would have thought that if there was a problem with AF measurements it would have been sorted.
Anyway Ill call in tomorrow and ask the guy.
The figures arent actually represented as a ratio.
1500rpm 15.7
2000rpm 20.0
2500rpm 18.5
3000rpm 18.3
3500rpm 18.2
4000rpm 20.0
4500rpm 18.3
5000rpm 20.0
5500rpm 20.0
6000rpm 19.3
Their machine didnt measure any higher than 20. it doesnt specify anywhere that these figures are " to 1 " as a ratio I just assumed that this was so?
I have limited experience, so do these numbers look odd.
Mark
Just curious, but were you monitoring fuel pressure while all this was going on? There may be a fuel supply problem which is causing the weak mix under load. You might have great fuel pressure at low rpm but at high load can the system actually keep the carb full enough?
I'm pretty sure my stock Rover (with Weber 500) suffers this, but I've not yet bothered to investigate and rarely give it a hard full throttle blast for many seconds. I have the second smallest Facet pump available, which is probably not really man enough for the job since I ditched the 38dgas and fitted the Weber 500.
Very good point.
No fuel pressure was not monitored.
Although the regulator is set to 5psi and Im using a brand new Facet red top pump. Fuel tank is also brand new.
I have a blanking plug on the regulator so will get a guage and see whats hapening when on the rolling road.
katanaman Posted: Sun May 20, 2007 6:57 pm Post subject:
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Are you tuned better with the 500 or the 600?
Well its hard to say both stups drive very well but there is a difference.
I really need to do a track day to find out what its like when driven flat out.
Although the 600 carb will flow more air at the end of the day its down to wether my heads can keep up.
Mark
No fuel pressure was not monitored.
Although the regulator is set to 5psi and Im using a brand new Facet red top pump. Fuel tank is also brand new.
I have a blanking plug on the regulator so will get a guage and see whats hapening when on the rolling road.
katanaman Posted: Sun May 20, 2007 6:57 pm Post subject:
--------------------------------------------------------------------------------
Are you tuned better with the 500 or the 600?
Well its hard to say both stups drive very well but there is a difference.
I really need to do a track day to find out what its like when driven flat out.
Although the 600 carb will flow more air at the end of the day its down to wether my heads can keep up.
Mark
I have about the same spec engine and 500 Edelbrock carb. The torque / hp figures are also a close match. Your max torque rpm may be a touch low but max hp rpm sounds about right. However, I doubt very much that you could have been that lean and get figures like that. Besides, getting down to 20:1 would mean a lot of pinking, very much audible.
I fitted a 1 inch thick spacer underneath the carb and fitted a 92 secondary jets due to full throttle ratio of 10,5:1. I found out that around 3000 rpm there is a momentary leanout to about 16:1. It is very much audible ! I have a wideband lambda fitted but it only confirms what the ear tells me.
As for 500 vs. 600, the carbs are just about the same apart from the auxiliary venturies, 500 have a very much smaller orifice in the middle whereas 600 has a larger one. Throttle plates and venturies of 500 and 600 are the same.
I fitted a 1 inch thick spacer underneath the carb and fitted a 92 secondary jets due to full throttle ratio of 10,5:1. I found out that around 3000 rpm there is a momentary leanout to about 16:1. It is very much audible ! I have a wideband lambda fitted but it only confirms what the ear tells me.
As for 500 vs. 600, the carbs are just about the same apart from the auxiliary venturies, 500 have a very much smaller orifice in the middle whereas 600 has a larger one. Throttle plates and venturies of 500 and 600 are the same.
