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Jenvey Throttle Body Balance


jonjh1964

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I'm trying to balance the Throttle Bodies on a 2.0L Zetec with an OMEX 600 ECU. At idle the bay-pass screws don't seem to make any difference - should the grub screw thats just in-board and at 90 degrees to the by-pass screw be fitted?

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You don't say what Jenveys you have. Also knowing what you mean by the grub screw at 90 degrees would help (you don't mean the full throttle stop screw do you). Pic please.

The balancing at this point has nothing to do with the ECU as the balancing is totally mechanical on Jenveys. That said if you map is way off then a stable tick over might be out of you grasp but for now lets say it's OK.

Start by following the set up instructions that Jenvey provide.

General Instructions - Balancing throttle bodies

Idle bleed screws (if fitted) should be closed at the start of this operation.

Before starting the engine adjust throttle balance by setting the single idle adjuster screw so that the nearest butterfly is just visibly open, then adjust the cross-link screws so that the remaining butterflies are at a similar angle. Start the engine and use a flow meter (SYNC10) to check airflow through each throttle body bore, adjusting as necessary. It may be necessary to re-adjust the idle during this process. Always re-check the balance on all bores after each adjustment and with the cross-link adjuster locking nuts tightened. Idle bleed screws (if fitted) may now be used to balance ports on twin bodies.

Initial set-up can be done with a feeler gauge matching the gap under the butterflies. If a flow meter is not available reasonable results can be achieved by using a length of small bore tube to listen to the flow through each bore.

Watch this if it helps.

More stuff here if you get bored with the one above http://www.youtube.com/user/terryathome?feature=watch

Terry

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Terry,

I've watched your video (very helpful like all of them) but at an idle of ~1000 rpm mine were sucking 12 kgs/hr and play with the adjusters didn't make any difference only the idle setting. I've posted a picture ( a 1st for me!) and the grub screw I mentioned can be seen just above the adjusters.

th_0309b049.jpg?t=1345907991

Jon

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Sorry, makes me feel old, but that pictures to small for my eyes!

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the adjusters are the grub screws with the lock nuts round them near the manifold mounting flange end in this picture.

clicky

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Sorry, don't know Zetec's that well, but 12 kg/hr sounds an awful lot for 1000 rpm? FWIW my XE probably pulls around 6.5 kg/hr at 1100 rpm. And even the monster tuned 290 ish BHP XE's don't really pull any more than that.

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Sorry about the midget photograph - I did say it was my first attempt! Could be that my brand new synchrometer is out of calibration - it's the same as Terry's.

I'm okay with which are the adjusters but I'm trying to understand how they work. I originally thought they were a by-pass to allow more air into the TB beyond the butterfly. Mine have a smooth taper at the end which I assumed was the way they let in more air but where does the air come from, hence the question about the grub screw. Looking at Terry's video his seem to be much further open than mine perhaps I need to open them up much further to get the taper to start to function?

Posted photo of TBs and a short video of the engine running on my blog http://2js-westfield-build.blogspot.co.uk/ if it helps.

Jon H

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From you video i would suggest that a bit of mapping of the ECU is requied as mine popped a bit before being dynoed. The Map that i used was to get the engine running for 1 get the engine running. 2 running in the cams and 3 check for any oil/water leaks all done before the Dyno session. The comments was that the map was way off but it didn't pop after that.

If you say you can't lower the tick over, which you should be able to do i would go down a check route.

1. Do the items in the general setup instructions as posted. to the letter.

Close the 4 number air adjusters on each body (screw in clockwise, you must do this)

Set the left 2 bodies butterfly open by adjusting the tick over adjusting screw then balance the 2 left bodies to the right 2 bodies by using feeler gauges between the butterfly and the inside wall of the body. Adjusment is made where the throttle cable is terminated. This needs to be done so you get them somewhere near for starting the engine.

Start your engine and using the Snyc adjust between the 2 sets of bodies using the single adjuster (as in my video) You may have to adjust the tick over if the revs get to high. If you can't do this check that there is enough slack on you accelerator cable (about 2 or 3 mm will be OK at this point) this maybe keeping your tick over high. You may also want to check for any air leaks (it's a vacumm so hard to spot but some soapy water may help you) Lastly check that the linkage has enough springs to return it to the fully closed position aginst the tick over stop screw.

When you have done the above you can fine adjust on the air bleed screws.

Think i have got everything from memory but read the instructions just in case i've missed something.

On another note is the TPS giving out the correct voltage before starting the engine?

Looking through you web site i notice the routing of your front brake lines, mine are installed with a pigs tail in. Is your to the manual? they look a bit tight to me, whats it like when you put full lock on?

Terry

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Terry,

Thanks for this, I will address as I continue through next week. OMEX have stated that the map is good for road use and have confirmed I have the correct one. I'd planned to get the engine run in before going to visit Troy at NMS for a mapping - hopefully when the Saints have a home game as I don't get to the Gardens much since moving to the SW. TPS - I had some concerns and both OMEX and WF have seen a previous DATA3000 run and were happy to continue to balancing the TBs

wrt the brake lines, are you talking rigid or flexible? - Rigid I think I followed the manual plus various blogs - flexible I followed Rhett's blog and he got the thumbs up at the IVA - positive comments compared with factory built cars. Have you got any photos of yours to help?

Jon H

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And where do you think your going at this time, letting the dog out in the garden. And why have you got the garage keys Errrrrrrrrrr Errrrrrrrr take pics for a fellow WSCC menmber. Scorne/eye roll/walks away!!!!!

Flexible and now ridged

https://picasaweb.google.com/113992112805904719213/25082012?authkey=Gv1sRgCJ_uy-qyhZ64zwE#

Terry

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Terry,

At least you were let back in the house!

Followed the link and got lost in google picasaweb and couldn't find the pictures.

Jon

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The link takes you to your own, (if you have one) Picassa home page. (if you aren't on Picassa, it takes you to a sign up page), Terry needs to link to an actual album or pic, not just the "my photos" page. :p:d

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Terry,

I've just looked through the latest manual and there are no instructions on the fitting of the front brake calipers and flexi hoses. However, the latest chassis has a bracket to mount the in-board end of the flexi hose and then the rigid brake line mounts to it, I've checked photos I took at the factory and mine is as per the current factory output and, just to be really sad, I've watched the brake chapter of the Mark Evans "A Racing Car is Born" DVD and his chassis has the same bracket. I've also looked at circa 2000 manual for a 1800 Sport Injection and it matches they way yours is built, so it looks like they're both correct just for slightly different chassis build standards.

FWIW I think it should be easier to ensure the IVA requirement that there's no contact with the bodywork for all front wheel radius of operation with your configuration but the latest format allows the rolling chassis to be completed before the bodywork is fitted.

Jon

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