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Posted: Wed Jun 26, 2013 8:12 pm
by sidecar
Here's another....
86 68-52 rod.....12.5% leaner on cruise, 0% leaner on acceleration
Posted: Wed Jun 26, 2013 8:51 pm
by Raffa
sidecar wrote:Here's another....
86 68-52 rod.....12.5% leaner on cruise, 0% leaner on acceleration
Hi Sidecar
Your a legend mate and i cant thank you enough, rods have been ordered and this old man has finally got his head around this issue, but between me and the misses, for the life of us, we could not work out how you get the % using your maths, still hopefully this will stop the hunting and i can get it to a garage for them to tune.
Kind Regards
Ralph
Posted: Wed Jun 26, 2013 9:20 pm
by sidecar
Raffa wrote:sidecar wrote:Here's another....
86 68-52 rod.....12.5% leaner on cruise, 0% leaner on acceleration
Hi Sidecar
Your a legend mate and i cant thank you enough, rods have been ordered and this old man has finally got his head around this issue, but between me and the misses, for the life of us, we could not work out how you get the % using your maths, still hopefully this will stop the hunting and i can get it to a garage for them to tune.
Kind Regards
Ralph
Hi Ralph, The percentages are all percentages leaner or richer than what I call the base setup. The base setup is basically the jet and rod combo that is fitted as standard to the carb. (86, 65-52)
In order to work out every jet and rod combo 'by hand' and then to compare it to the base setup would drive anyone mad which is why I use and excel spreadsheet. I just bung in the jet and rod combo and it compares it to the base setup.
Working out the cruise setting is really the only setting you can do just by driving the car without monitoring the exhaust gases. This is because you can start at the base setting then just keep leaning the mixture off until the engine starts to hunt and won't respond well to the throttle when the throttle is in the cruise position and the car is running at a constant speed. You would then just go one stage richer on cruise and that would be the cruise setting sorted out. In my experience the AFR of this setting tends to be 14.5-15:1. With EFI you could go leaner but not with the Eddy carb.
Unfortunately the other settings such as when accelerating or running at WOT require some method of monitoring either the BHP being produced or the exhaust gas.
Posted: Wed Jun 26, 2013 9:43 pm
by sidecar
Check this out, you bung in your current setup then state whether you want to go richer or leaner on the cruise and power step then it will give you all the jet and rod combinations that you could use. I guess when it states for example 104% it means 4% richer.
http://www.302w.com/Edelbrock-Carbureto ... lator.aspx
Posted: Thu Jun 27, 2013 7:52 pm
by Raffa
sidecar wrote:Check this out, you bung in your current setup then state whether you want to go richer or leaner on the cruise and power step then it will give you all the jet and rod combinations that you could use. I guess when it states for example 104% it means 4% richer.
http://www.302w.com/Edelbrock-Carbureto ... lator.aspx
Hi Sidecar
Thank very much that's very useful, I will post my findings after tomorrow as the rods should be with me and hopefully will be a little nearer after 2 years completing the car
All the best
Ralph
Posted: Sat Jun 29, 2013 6:05 pm
by Raffa
Hi Sidecar
Mate i cant thank you enough, your a bloody legend, cars running sweet and you've made an old man very happy.
All the best
Ralph
Posted: Sat Jun 29, 2013 9:22 pm
by sidecar
Raffa wrote:Hi Sidecar
Mate i cant thank you enough, your a bloody legend, cars running sweet and you've made an old man very happy.
All the best
Ralph
No problem Ralph, just for my records what spec is your engine, i.e. capacity and what inlet manifold are you using? (I don't know anything about TVR engines!)
What jet and rod did you end up using?
Cheers,
Pete
Posted: Sun Jun 30, 2013 4:12 pm
by Raffa
sidecar wrote:Raffa wrote:Hi Sidecar
Mate i cant thank you enough, your a bloody legend, cars running sweet and you've made an old man very happy.
All the best
Ralph
No problem Ralph, just for my records what spec is your engine, i.e. capacity and what inlet manifold are you using? (I don't know anything about TVR engines!)
What jet and rod did you end up using?
Hi Pete
Its a Rv8 vitesse 3.5 engine, with an Eldebrock performer manifold and carb with a hurricane cam fitted and the set up is
83 prim/ 62-52 rods/80 sec's
Its not perfect, but believe me mate, its a hole lot better than it was, am going to book it in this week to have it RR tuned and will let you now how I get on Pete
All the best
Ralph
Cheers,
Pete
Posted: Sun Jun 30, 2013 7:49 pm
by sidecar
I did not know it was a 3.5! I've worked on a couple and I could not get them to run leaner than about 8% from the base setup on cruise.
86 67-55 rod is what the setting that they ended up with.
Posted: Sun Jun 30, 2013 8:12 pm
by Raffa
sidecar wrote:I did not know it was a 3.5! I've worked on a couple and I could not get them to run leaner than about 8% from the base setup on cruise.
86 67-55 rod is what the setting that they ended up with.
Hi pete
As I said its not perfect mate, I did try the 7.9% leaner rods, but it was still hunting and once I swapped over to the 3.9% leaner rods it pretty much stopped, however the engine feels a little on the tight side on upper revs 4K, but it has been rebuilt, so maybe needs a little more running in and for £6 am happy to buy some more, I already have the 86 prims and assume the 80 sec's are fine, so I,ll pick some up and take them with me to the RR.
All the best
Ralph