Maybe you have the cold going around. I've did last week and over the weekend. Perception and Brain function were scrambled.
Maybe you have the cold going around. I've did last week and over the weekend. Perception and Brain function were scrambled.
I couldn't even plumb a FPR the other week. 13 years as a mechanical engineer, educated and reasonably competant, and i couldn't work that out!!!
hmm, this post of mine is a bit immaterial until you get the compression test done, but might help.. what carb is yours?
I've got one of the proper cup carbs with the larger venturi and ALL of the choke flap mech etc removed.. not read the complete thread so apologies if this has been said before but mine on occasions is a real **** to start and hates idling until it is really totally and completely warmed up - pretty much the exact same symptoms as yours. (other than yours doesn't like idling after - which would probably indicate (given a successful compression test) that engine is okay and the carbs either not setup correctly or had it...
(also from past experience tuning na vauxhall lumps on throttle bodies, the more aggressive the cam the harder it is to get a decent smooth low idle - and thats with mappable injection) would assume that it will only get harder with carbs - are you trying to get a smooth idle speed thats too low and not possible with a uprated cam, sure the peeps on here can answer that better than I can - would have thought a smooth idle at 1200 - 1400 rpm on a 285-300 cam would be reasonably acceptable
Is the carb a 'tuner - grp A' carb? or secondhand? only a suggestion, but could it have been fcuk'd at some point and your on the back end of it, have you had the carb working properly before on this engine..?
I've not got much experience with carbs, but if its not run on the engine.. im sure one of the nice peeps on here might lend you a known good, working completely standard carb, then swap it out and see if it eliminates the problem, don't bother setting the jets up for the car or anything as waste of time, if it idles then go down that road...
sounds like duff compression tester if your not getting a reading, even a knackered engine will register something, I would not rush to take head off just yet.
You've either not screwed the tester in far enough/created a good seal on the thread, or the tester itself is fecked...or all 4 plug threads are partially stripped
check you have a good O ring on the connector of the compression tester
Raj, i would at least expect a small deflection on the comp tester needle even if Vvs were removed and you turned the engine over? Test it in your bro's engine like you said before you rip the head off.
Also your engine wouldnt start/run above 2k if it was that bad!
At work with these things i usually find that the best thing in these situations is a fresh pair of eyes (not doubting your abilities bud) to go over the basics from scratch and often they will find somthing silly that has been overlooked
Anyway good luck mate, i would offer to help but your a tad far away from me! Oh and you car looks lovely in the pics you posted, and to cheer you up have a cop at this...
http://uk.youtube.com/watch?v=WaNEDJkALgE
(contains a lot of swearing)
you know that little button on the side that releases the air, make sure that is returning out properly. also, on the tip of the tester itself, where it screws into the hole, there is sometimes a little pin there too, part of the 1 way valve, make sure this is releasing outward also.
even with a foobar engine you'd get some compression, the gauge is telling you fibs mate.
like I said already raj the piston height or compression ratio doesn't play that big a part in your compression test results.
I think your results are fine for an engine that hasn't been run in, but check the valve clearences if like, if they're too tight in places it'll cause a drop in compression as well as a rough running at low rpm's. not as bad rough-running as you're having though, unless they're wildy too tight (in which case the compression results wouldn't not have been as high as they are).
imo, the results are OK.
I think if I were you I'd be doing 2 things:
1/ try yet another known working carb incase you've been incredibly unlucky
2/ do a leak down test on the carb and inlet manifold. this goes something like this:
1) engine off.
2) remove boost hose from the intercooler output.
3) block this pipe off with something, back end of an aerosol, etc, so that the boost pipe is air tight upto the carburettor.
4) with a compressor/air line with gauge fitted (or watching your boost gauge) you want to inject air into one of the carb-top ports to pressurise the carb and manifold upto 20psi or so. You should be able to store pressure in there, it should take a good 10-20sec to leak the pressure away. If there is even the slightest of air leaks you will find it, assuming it isn't via a 1-way valve!
try it, then see if you can work out why it worksOriginally Posted by raj
.how can you get a pressure build up as your always going to have various valves that are fully/partly open
surely you can just use a footpump
i should think that 15 to 20 psi would only only take couple of pumps you should be able to determine how fast ur leaking (if your leaking) id try it before splashing out raj but thats jus me being tightreally? surely it would have been mentioned thoughi just thought that a compressor would get the air in quicker, where as if using a foot pump you wouldnt be able to keep up with the air which actually leaks.?
If its leaking quicker than you can pump then you got big problems mate! Give it ago, its by far the cheapest option!
i should think that 15 to 20 psi would only only take couple of pumps you should be able to determine how fast ur leaking (if your leaking) id try it before splashing out raj but thats jus me being tight
no, you need an air line, it'll leak out faster than you can fill it with a foot pump.
cmon raj tell me it works??????
Why would it leak out so quickly Scoff?
if u have any breath left
I wouldn't like to see you spend money on a compressor just to try something I suggested, it's just the next logical test I'd do if it was me, no guarantee's it'll show anything. it doesn't need to be a big compressor, somone might be able to loan you a portable jobby.
its amazing how non-air tight things like the carb, manifolds, valves, piston rings, etc actually are. like I say, 20psi might last 10-20 sec max in a healthy engine, you won't build 20psi that quickly with a foot pump, there's a lot of volume that needs filling.
Where does it escape too? The breather circuit?
How long does it take to pump a bike tyre up? and they don't hold much pressure... You won't get anywhere with a foot pump.
it escapes in all directions, out of gasket joints, past carb-top o-rings, past throttle seals, past valves that arn't sealing that well, past piston rings into the crank case and finally out the breather
LOL not very long mate! I pumped my spare tyre from flat to 2bar in a matter of minutes! I was f***ed afterwards mind!
With all this in mind then, is there not an easier way of pressure testing the important bits i.e. the carb and manifold by taking it to an engineering shop? Just a thought dont know if its possible?it escapes in all directions, out of gasket joints, past carb-top o-rings, past throttle seals, past valves that arn't sealing that well, past piston rings into the crank case and finally out the breather
whats easier than sticking an air line on the carb top ?!?!?!
if there was an easier or better way I would have told him that instead
Exactly the point... If you've got air leaking out within a matter of seconds and your ''uprated'' twin piston foot pump takes you a couple of minutes to get your tyre to 29psi, you don't stand a chance of getting a reading from an engine...
when i did a leak down test with tommyb we used alot of psi cant remember the figure we used det phones and could hear the compression escaping out the carb top. turned out the gudgeon pin has scored the liner but is a better way to diagnose doing a leak down over the compression tester. JUST MAKE SURE your at tdc or the car will try to move.
LOL fair comment!
Alot if you havent got onewhats easier than sticking an air line on the carb top ?!?!?!
any old bit of hose, I used to use a dust blower attachment with a bit of old silicon pipe pushed on the end
That first link looks like the bollywood version of thriller!!!!ok will will check on the things you mentioned scoff.
in the meantime.. alistair,that link is sh1t
the dubbing done by this guy "buffalax" cracks me up no endhe redubs everything into what it sounds like in english
http://uk.youtube.com/watch?v=ZA1NoOOoaNw
http://uk.youtube.com/watch?v=MSsXlR...e=channel_page
now they cheere me up
Raj please dont shoot me if i have missed this but
have you removed the breather hose with the restrictor in it from round the back of the carb?
Only saying as i once removed mine and i gave scoff a headache trying to find the problem of a sh*t idle.
Ah i am getting too see how this all goes together now!!
i think thats the one.
and while im thinking about it
take the carb top off and see if the long brass needle is leaking.
https://www.rtoc.org/boards/showthread.php?t=460 - third photo down
photo of it there.
not sure if that would effect the idle, but if its leaking surely it will be over fueling.
i put an oe breather pipe back on and swapped that brass needle and everything run fine in the end.
hummm
i cant remember if we removed mine in the end or not.
Last i remember is we had to pu the OE pipe on to get it to idle.
But my car is garaged miles away currently so i cant just stick my head under the bonnet and double check.
But it wouldnt be the first time someones had idle issues and rtoc pointed out the breather pipe with the restrictor in it as the cause.
good air tools and compressors cost good money. If you need them buy good, otherwise don't bother, noisy underpowered tools will just piss you off.
That size compressor is fine for blowing up your tyres and doing a leakdown test.
Where compressors are concerned you want as high cfm as you can afford. its not all about the size of the pressure vessel.
a come on raj you will get there mate.
my 1st ever 5 drove me 2 frustration but after after havin loads of things wrong with it
and fixing them and them braking again i got rid of it despite me having another 15 after the 1st 1 i wish i had kept the 1st 1.
i always found with 5s persistance is the key so do a bit go in then come out again the 5 will not win you will in the end just think how happy ull be when u get it right.
so just keep at it ull get there
OE worked wonders. Thats all i can say fella.
Why not try reverting back though? at least that is one less thing to suspect being the cause.
Because it won't make a difference.
Providing the breather port on the inlet manifold is blocked off (which you would do anyway if running the Cup type breather setup), then nothing else on the breather circuit, or what's left of it, is going to affect the idle.
hhmm well it appears someone else doesn't share the same opinion.
The cup mod breather system doesn't affect the idle, no point in going back to o.e. Imo this has got to be carb related or air leak.
Then they're wrong
lol fair enough at least I know now.
Pass. If it was an immobiliser though, the engine wouldn't be firing up full stop.
Unless it's intermittent & precise in where it fails (which I v much doubt) then you're barking up the wrong tree with this one mate...
could be an old immobiliser that was disconnected when the toad alarm was fitted and left in place rather than leaving the hole. most just tap into ignition ciruit but doubt this would cause your problem as it wouldn't run at all
how did you block off the one way valve you removed? may be the bolt is loose sucking air there, hense unable to see any change when adjusting carb as the leak is below
Lost track a bit so dont hurt me, but have you checked the carb body doesnt have a hole in it?
only reason i say that is i used to have a real horsesh*t carb body which we replaced.
ive had more bad idling issues than i can remember.
anyone with more knowledge than a mear ant on here know, if the brass needle at the carb top was leaking fuel would this affect his idling?
i had an issue with mine and swapped it. Also i remember aaeron had a problem with the idle on his gtt clio and we slapped the brass needle about a bit in his as well, that seemed to do the trick. might of been a couple of flucks
Back-firing through the carb top usually means either the ht leads are wrong, the carb is seriously over-fuelling, the cam timing/dizzy gear is wrong, or a valve(s) isn't opening, which could be a bent pushrod, or the valve itself is bent & stuck in the head.
I think you'd know if the latter was the case, as the engine would be sounding rough (as in running on 2 or 3 cylinders), and assuming you've got the ht leads the right way round, and the fact you've swapped out the carb a couple of times, that leaves one thing...which has what's been mentioned to death throughout this thread...
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