Technical > Spud Miller's Cave

Spool size on a Crower IR injection.

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dreracecar:
Again, without posting pics its hard to decern issues. the enderle and hilborn cube style BV run the same spool for all types of fuel with the only difference being the idle slot or ramp for fuel at Idle (leak) when you get into the "K" style BV is spool is bigger because the fuel transfer goes to 2 outlet ports.
What flow numbers did you get with the pump?
Are the nozzles crower or hilborn? and do they still have the tiny screens in them? if so could they be plugged with crap?
You also mentioned the spark was good, but what type is it--- magneto or electronic
Trying to figure where you are getting the 4psi number w/ .050 main,  main jet does not come into play until off idle, the secondary Idle (@2#) leans the pump at idle and you fine tune that transision with the link. As soon as the the butterflys open the secondary circut closes off.
when you say the cyls dont run right, is that stationary or does it happen down track and where does it start to go wonkers

Sidewinder:
Ok here are the resault ;)
First we widen the spool slot and rounded off the ramp. This helped some, but we didn't get get the respons we where looking for. So we changed the approtch, focusing on the air, to get more vacume. This unit came from a fuel injection shop in the US, as was resently serviced. But the butterflies was not seated right and a little off the sync, left and right side. After this was fixed, the engine started to work a little better. Still a little too much system pressure, making it very nervous on the leakdown. We consentrated to keep the Leakdown around 26-30%. The vacume was still too veak, but this is due to the extreme cam profile, with over 320 degrees of duration and 112 degrees of lobe seperation.
We desided to plug the air bleed holes in the nozzles, and that was the trick, bang spot on :)
We ended up with this set-up before calling in the day;
Around 28% leakdown
Main bypass was set to open at 4 psi with a #105 pill. (a tad to lean, so we will try a #95 pill next)
Idle bypass (Secondary) set to open at 14 psi with a #140 pil. (We will try to put inn a smaller pill, or shimming it to open a little later as it leans out a little too much goin of the throttle from WOT to off)

All this done stationally, the Altered has not been on the track, so we need to se what the respons is under load.

Hope this made any sence? Bruce ?

Thanks for the input guys :)

denverflatheader:
Kjell - pleased to read you making progress.  Your change to main bypass from .050 to .105 pill makes sense to me.  My 6 cylinder has Hilborn stack injection and the nozzles have air bleed holes, with Hilborn 150A-0 pump on methanol needs 110-115 main pill.  My friend’s Crower 8H has nozzles with the air bleed holes too, he also ran port nozzles off a separate “out” on the BV.  Not sure why plugging the air bleed holes worked; good news to read.  When I read Bruce's responses, I thought he had the solution, either was a "petrol spool" or the nozzle screens were plugged, or both.  That’s big duration number in your camshaft.  Alan

masracingtd1167:
Have you checked all of your throttle plates to see if some are closed all the way . It sure sounds like that is your problem . It takes some time to get them even and it must be done with the manifold on the motor . You need to get them all to close all the way and not bind when you open the throttle . Do one side at a time . I used to take strips of paper and loosen all of the butterfly screws and play around with the plates are nice and even and don't bind . Once you get this done you can set your plates around .003 . If you can borrow or buy a uni sync tool it would be a big help to balance your air flow to the motor . Before you go crazy changing things I think you should start there . You will never get it to idle right if you don't have your butterfly's balanced . I hope this will help with your problem ! Bill

Sidewinder:
Bill, you are right that was one of the problems. We have ajusted the butterflys and opened the up a little.
The challenge is the camshaft, witch does not produce vacume at idle. To compensate for lack of vacume we have to plug the air bleed holes, similar to some blower engine set-ups. As said the engine sound and respond good now :)

Alan
This engine is not mine, I just have helped out some. We are not a big comunity of vintage drag racers, but growing steadily ;) Check out www.svda.se under the menber section.
We usually attend two race's at Kjula Dragway, and this year we might be able to attend at one race at Tierp Arena, check it out, world class track, http://tierparena.com/ :)

/Kjell

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