Put the finishing touches on this new Drag racing engine today, it is 2380cc, 86 X 94 in a VW mag case, with Compertition Eliminator heads, 12 to 1 compression and 51.5 mm Weber IDA's, the engine was built by Shimmo, heads by Dave Butler, I have just made and fitted all the tinware and "fiddly Bits"
FAHRVERGNUGEN;
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What car in the back ground? there's no car in the back ground!
The "weight" on the end of the crank is a Dave Stoker made equalizer pulley, It will be sent away to have a belt groove machined in it, as soon as I work out the alignment.
Not sure if we will have time to run it before Warwick, still have a lot to do.
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Very,very sweet Dave,Fabio, Tells us little more about combo guys!!!!! What carb jets combo ,to start with (190 square) Is that a 4Quart sump !what oil level will you run.!(Rods ,just on oil stick ).Great to see another dragcar on the scene. Has Fabio got any old Pics when he got the beast.(show us)
Ran it on the Dyno yesterday, carbs are all over the place, too rich down low and good up top, will be running it again next saturday with some venturi changes.
Motor runs strong and makes all the right noises from 5 - 8000 rpm, just got to make it better down low.
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Rules of thumb are venturi 2mm smaller than valve = 46 absolute max.
And 4 x venturi on mains...again I would use a max of 195 to start.
This will be rich down low (with same size "air") I would guess(its a guess..you must dyno with A/F meter)
In this case I would dyno till you get the main correct up to 5-6000 rpm,
and then use smaller airs to correct when the engine gets lean up high(F7s?)
Most engines I know with IDAs seem to drive nice with smaller mains and airs,
than what our American friends seem to use and recommend.
Hope this info is of some assistence.
Smaller venturies than 44 will be better but restrict those heads.
Dave (Dangerous Dave),
It has 46mm vents now, I think we will try some 44's, the air fuel is good at 5000 rpm and up, with a 155 main but way rich down low, almost undrivable. it has F7's and idles are 55's
Try again on saturday.
FAHRVERGNUGEN;
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Menangler wrote:Dave (Dangerous Dave),
It has 46mm vents now, I think we will try some 44's, the air fuel is good at 5000 rpm and up, with a 155 main but way rich down low, almost undrivable. it has F7's and idles are 55's
Try again on saturday.
Man that is unusual for such a small main.
Must have a very small air jet, or a float level that is too high.
Pete and rod run about 180 and 180 in their main and airs, with 44 vents.
My pref is to run slightly smaller mains than that, but a smaller air will then be needed.
Have a talk to Henry.
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Things are looking good guys.I hope I can help,dave. What fuel was being used ,Was motor in car or out , fuel pump and presure. The big venturi helps at top-end ,so I would start with 42 or44 to get going for 1/8th mile racing.Those heads and 51carbs will flow lots in rev range latter on. The yanks like to start with 3full steps apart when it come mains, airs.(1) AIR jet- effects higher rpm , 0.15 increase in AIR jet =0.05 reduction in main fuel jets.(2) 1mm increase in Venturi dia ,you can expect to move your main jet size up by 0.05 (3)Main jet effects full rpm range - any change made to the main jets ,has 3 times the effect as similar change in the AIR corrector jets. The yanks like to start with 200airs becouse it's nice round figger Then 3full steps smaller in main jets =170mains .Dean Lowry starts with square tune up on LARGE VENTURIS in dia's.(46mm).THEN tune air jets because its a safer way .MY motor 2332 -14plus fuel ( 11to 14 in compression ) 170mains ,195airs ,65idle, 44vents .Anything below 3000 rpm LOOK at float level,main jets to small (look at plug colour) ,check pump jets are clear,idles not dripping ,timing on motor ?????? Hope we can help !
Thanks Pete,
I have asked the jetting question on the cal-look forum, just to get a ball park idea, the more info I get the better at this stage, we then can then try a few combo's on the dyno and see what works best.
Can't wait for Warwick. it will be a great weekend.
FAHRVERGNUGEN;
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What is your jetting and venturi plan Dave ?
Oh, those valves are 48mm.
With those heads and that cam, it will most likely come on at about 5000 anyhow.
