flak monkey
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| posted on 18/3/10 at 09:02 PM |
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Is there a forum there? If so do you have a direct link as I cant find one. Its getting late and I am in a foul mood!
I should also say I have tried using alpha_n (TPS) based fuelling too breifly just to check and it has the same result. A nice steady 1300rpm
idle....
I also pressurised the bundle of MAP lines with an airline set at around 50psi and couldnt find any hissing joints.
Just to understand what I am trying to find. The engine should flow around 700CFM at 1000rpm idle (assuming 20% VE), to get that up to 1300rpm the air
flow would be in the order of 920CFM, so I am looking for a pretty major leak of 220CFM! And thats assuming the VE is constant of course.
Anyway plan of action for tomorrow:
Replace MAP line from collector to ECU or disconnect and temp plug to see if the leak is at the ECU. Didnt fancy spraying cleaner into the ecu to find
out!
Cover the throttle body inlets with a piece of wood and slowly cover them and see if the idle speed can be reduced that way - if so this points to air
getting past the rollers themselves.
Failing that cover everything with sealant and reassemble. Though I have my doubts....
Sera
http://www.motosera.com
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flak monkey
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| posted on 18/3/10 at 09:04 PM |
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quote:
Originally posted by Dave Ashurst
You tried pouring water over it I guess?
best
D
Hi Dave,
I havent tried that no, although theres a river opposite the house. Would pushing it in there have any effect?
David...
Sera
http://www.motosera.com
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stevebubs
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| posted on 18/3/10 at 09:07 PM |
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http://mailman.se7ens.net/mailman/listinfo/sevens
[Edited on 18/3/10 by stevebubs]
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Dave Ashurst
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| posted on 18/3/10 at 09:08 PM |
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quote:
Originally posted by flak monkey
quote:
Originally posted by Dave Ashurst
You tried pouring water over it I guess?
best
D
Hi Dave,
I havent tried that no, although theres a river opposite the house. Would pushing it in there have any effect?
David...
Yes it often helps.
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Dave Ashurst
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| posted on 18/3/10 at 09:15 PM |
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I poured water over mine and it slowed the fast idle..
Not a permanent solution of course 
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flak monkey
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| posted on 18/3/10 at 09:44 PM |
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High idle appears to be a known issue with roller barrels, so at this point I would like to say I should have fitted conventional throttle bodies at
60% of the price 
Anyone got a set of Jenveys? Seriously!
Sera
http://www.motosera.com
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MkIndy7
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| posted on 18/3/10 at 09:45 PM |
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If the Rollers shut off completely then the engine would stall wouldn't it?
So a small amount of air needs to get past to let it idle.
There isin't some sort of bypass air drillings is there that are a little large for your setup?.
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flak monkey
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| posted on 18/3/10 at 09:49 PM |
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The idle speed doesnt change regardless of where the roller idle stop is set until you get a gap of 6mm or more. Closing them too far results in them
opening up in reverse. Between this point and the point at which speed starts to increase there is no difference in idle speed whatsoever.
Idle bleeds are all completely shut off.
David
Sera
http://www.motosera.com
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MkIndy7
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| posted on 18/3/10 at 10:00 PM |
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Hmm the air is getting in there somehow...
I've heard of checking for leaks on 2 stroke crank cases by smearing them with Grease... maybe not the best thing to be injested into your
engine but something along the same lines could be thought up to check and find exactly where the airs getting in.
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flak monkey
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| posted on 18/3/10 at 10:06 PM |
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My intention is to block off the inlets tomorrow and see what that tells me.
At the moment a set of DTH Jenveys is looking like a possibility
Sera
http://www.motosera.com
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Bigheppy
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| posted on 18/3/10 at 10:14 PM |
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quote:
Originally posted by r1_pete
quote:
Originally posted by Bigheppy
Please humour me for a while, on your last post you said the carb roller/barel was round on the inlet and oval in the outlet of the throttle body. If
the barrel were rotated 180 deg making the oval side the inlet to the throttle body due to the shape of the oval when the throttle was closed a
smaller amount of air could be drawn in so reducing the idle speed. This is how some model aeroplane engines were configured. I appreciate this might
not work in your situation but it might be worth investigating.
That would just mean when the throttle is closed the oval would be opposite where it is now, as the inlet and outlet is symetrial top to bottom it
wouldn't make a difference.
Only on opening the throttle, you'd have an oval against circular and vice versa.
That is assuming the openings are in line not offset
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stevebubs
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| posted on 18/3/10 at 10:15 PM |
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quote:
Originally posted by flak monkey
My intention is to block off the inlets tomorrow and see what that tells me.
That would be my first course of action.
Do you have a synchrometer? When I was fitting my Gixxer bodies, that was a godsend - insert into trumpet and measure the airflow....best £30 I
spent....
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Bigheppy
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| posted on 18/3/10 at 10:19 PM |
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quote:
Originally posted by flak monkey
The idle speed doesnt change regardless of where the roller idle stop is set until you get a gap of 6mm or more. Closing them too far results in them
opening up in reverse. Between this point and the point at which speed starts to increase there is no difference in idle speed whatsoever.
Idle bleeds are all completely shut off.
David
sorry to harp on but isn't this why there is an oval in one side and a circle in the other. On your pevious thread you stated the barrels could
be turned through 360 deg so it might be possible. Please note i'm not critising just trying to offer something you have not tried already, you
stated they were new but not to you is it not possible the previous owner might have messed with them.
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tul214
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| posted on 18/3/10 at 10:22 PM |
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Have you spoken to Minster?
Minster Power
1.6 Raw Super6 sold
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stevebubs
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| posted on 18/3/10 at 10:23 PM |
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Have you tried leaning out the mixture?
[Edited on 18/3/10 by stevebubs]
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flak monkey
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| posted on 18/3/10 at 10:32 PM |
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I have leaned the mixture out as far as 14.7:1 as best I can. Runs really rough and at around 1400-1500rpm.
The throttle bodies were brand new essentially and untampered.
It is not possible to turn the barrels through 180deg and run the engine, for a start its not going to tell me anything, I know that with minimal
opening on the outside there is no opening on the inside (infact anything under 4mm opening on the outside leads to no opening inside) so they are as
closed as they can be at this point.
I do have a syncro, but having no trumpets fitted makes using it impossible as the port in the throttle body is too big in diameter to get a seal.
And yes I have seen the Minister datasheet, the same principles apply and I have applied them where appropriate
David
Sera
http://www.motosera.com
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beaver34
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| posted on 18/3/10 at 10:41 PM |
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have you not just though that is how they will be? as you said they are know to have a high idle but there are allways compromisers for advantages
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flak monkey
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| posted on 18/3/10 at 10:50 PM |
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Speaking to Titan they tell me to expect a higher than normal idle, but that my expectation of getting an idle of around 1000-1100rpm wasnt
unreasonable.
I have mailed them again tonight with the findings and will see what they say tomorrow.
I will also be on the phone to Raceline in the morning enquiring after a set of DTH Jenveys.
Dave Walker at Emerald has had similar problems to what I am experiencing with roller throttles and the way it was solved was to change to
conventional Jenvey throttle bodies.
This is annoying though in 2 respects:
1 - there is now an awful lot of work to do to convert all the back plates I had laser cut and machined to fit the plenum to the roller barrels to fit
a set of jenvey throttle bodies instead. Sure I can find a way, but its going to be another day lost. It also means that the plenum is going to have
to make a guest appearance outside of the bonnet of the car, another thing I wanted to avoid purely for aesthetic reasons!
2 - the cost. A set of jenvery replacements is going to run me around £675 by the time I have sorted a throttle linkage and TPS.
I really could do without the hassle, but there is no way I am going to put up with a 1300rpm idle thats rich and crap just to be say I am running
roller throttles!
Sera
http://www.motosera.com
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dlatch
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| posted on 18/3/10 at 10:53 PM |
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After the lengths you have gone to try and find the cause of the problem i am still convinced the issue is the amount of air that leaks past the
roller barrels and the only way to fix is new barrels maybe? or completley new Throttle bodies.
either way i feel for you david poo situation to be in but please don't lose heart it will be worth it in the end
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MikeR
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| posted on 18/3/10 at 11:00 PM |
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i'd like to hear the results of the tests i suggested that you're going to do next .........
one thing springs to mind though - are you sure the rollers you've got aren't knackered? Is there anyway to test?
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jollygreengiant
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| posted on 18/3/10 at 11:10 PM |
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Just a thought mate, but are you getting cross air bleeing through the 4 map air sensors that you have fitted. Have you tried fitting one way air
valves for the time being (yes I know that you would need to get rid of these once you have the supercrarger fitted)??????
Beware of the Goldfish in the tulip mines. The ONLY defence against them is smoking peanut butter sandwiches.
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stevebubs
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| posted on 18/3/10 at 11:31 PM |
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Is there not room to mount the injectors below the throttle bodies if you go Jenvey route? would this then bring down the height of the plenum?
Depends on the design of the plenum of course (thinking about it makes it less likely to work)
[Edited on 18/3/10 by stevebubs]
[Edited on 18/3/10 by stevebubs]
[Edited on 18/3/10 by stevebubs]
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stevebubs
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| posted on 19/3/10 at 12:28 AM |
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Just read your other threads.
If the roller clearances in the barrel are too large, could grease around the barrels help reduce the flow?
(Mechanical numpty on some of this stuff so please shoot me down in flames)
What does your synchrometer show as the airflow when pushed into the trumpet?
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flak monkey
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| posted on 19/3/10 at 07:04 AM |
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If i did go down the jenvey route I would leave the injectors in the head anyway and blank the ports in the throttle bodies and use them for MAP take
off.
I dont really want to smear loads of grease around the rollers, they are meant to be run as they are (I have a copy of the Cosworth Duratec engine
build manual and have followed it to the letter). All that would tell me is if there is air leaking past the barrels.
I did get some rough readings with the synchro when I first fired it up, and th readings were around 6-7 on the scale, which is high for idle, this is
also without a proper seal on the synchro. The pinto would normally have idled showing 3.5-4 on the scale, so there seems to be more air being pulled
in.
Sera
http://www.motosera.com
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flak monkey
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| posted on 19/3/10 at 07:05 AM |
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quote:
Originally posted by MikeR
i'd like to hear the results of the tests i suggested that you're going to do next .........
one thing springs to mind though - are you sure the rollers you've got aren't knackered? Is there anyway to test?
The rollers are new. When I got them they had never been fitted to an engine.
I'll do the test this afternoon.
Sera
http://www.motosera.com
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