Nice one mate ,happy for you , know can you do mine lol
Nice one mate ,happy for you , know can you do mine lol
Been out doing some testing this afternoon, done a few 7k rpm in 4th gear runs at different levels of boost with different jetting to see what it likes best.
So I shimmed the second stage with an extra small curved washer and this seemed to bring the second stage fuel in way to late. The boost gauge would show 7/8psi before the afr's started to richen up, it would be at 15afr until around 5k rpm, wasn't happy with it, I wasn't getting any det but still just seems way to lean.
So I went back to just one washer and went back out, it was still very lean when coming on boost in fourth, again 15 afr. Then at WOT with 15psi the afr's were 12.2 pretty flat.
I was shocked at this given the second stage is 1.4mm .9 A/C so I then remembered I had been fettling around with the A/C pump arm setting so whipped the carb off and re-set it with the 5mm drill bit and dropped the first stage to .9mm from .6mm
This seemed to have the desired affect, from 2krpm foot flat to the floor in 4th gear it initially dropped to 10.9 11.2afr for a brief second then went upto a pretty flat 13.5 until the boost started to come in then it dropped to 11.6 right upto 7k rpm.
So next step was to give it a little more boost, got a little giddy with the bleed valve (it's a new one) only opened it up quarter of a turn and the boost went straight upto 22psi, didn't fancy that for now at least anyway. so dropped it back down to 18psi.
Then it was as above from 2k rpm 10.9 11.2 for a second or so then upto 13.5 then as the boost came on it dropped down to 12.1 afr right upto 7k rpm.
So I have left it at that for now.
My old carb with pretty similar spec (only difference being .9 first stage in this one i'm using) would have been uber rich at 18psi say 11.3 afr it would fuel 11.7 afr at 24psithis carb doesn't seem to be as juicy as my old one
I'm amazed at the difference, the Engine it's self hasn't changed spec wise just a slightly lower comp ratio than before so nothing to do with that.
Ohh almost forgot, last night was the last night it spent in the garage it's now out side open to the elements
Worst thing is the lack of work space nowI have invested in one of those 4 layer storm force covers, should be here on Monday so at least it will have some protection from the elements. Still haven't spoken to my other pal who has some storage space yet so there is still a hope there. after that it will be time to ring the counsel up and see about a garage.
Last edited by GTphil; 09-02-2014 at 17:29.
If you drill the ball out of the end of the 2nd stage enrichment cover you can get to the screw which adjusts the needle.Clockwise gives you the same effect as shimming anti clockwise has the opposite effect.Basically it controls the transition from the 1st stage to the 2nd.
you learn something new every day
best way to fine tune I would imagine. I have a few spare enrichment blocks I could give this a try with.
Really is a black art this carb tuning
you seem to be doing things right
personally I'd set boost to 22/24psi and taper fueling so its 11.5~afr at 8k rpm, then start getting the 1st stage, accel rod and the 1st to 2nd stage change over sorted.
Strange how you have a 1.4mm 2nd and very little afr. Either the engine is setup well and working great or you have a restriction in the carb.
I think it's the carb, my other carb I had (gave it my bro to put on his car to sell) was miles more juicy than this one and the only difference between this engine and that was the last head was 72.8mm and this one is unskimmed 73.5mm.
Out in the cold
I'm sure it won't melt away in the cold and rain
Unless my carb works differently i dont see how you can tune for wot and then start tuning the 1st stage.The 1st stage provides extra fuel and continues to do so at full throttle.Putting a 0.6mm 1st stage in leaned the afrs out at wot on my set up.
This seemed to be the case with mine also, end of the day we are never going to get them perfect as they are carbs, for that it's obvious we need efi.
Trying to get the perfect set up is probably never going to happen.
All we can do is keep trying, I think what he means is get WOT sorted first then play around with the rest afterwards, so if that means that a 1mm first stage is needed for 24psi then that's it, the only other thing we can do is bring the second stage in slightly later. My car did 40000 miles with a 135 main jet and a 1mm a/c and it kept on going no issues at all at 1bar with a T2. Although not ideal to be slightly rich at times it's not the end of the world.
Lets face it doing what I'm doing it probably isn't going to be that long before it all comes apart anyway
Also when you read the carb article Scoff mentions he uses a .6 first stage jet, but he also used a large main jet. So the .6 may have been good for that set up. As I have a larger second stage the .6 may not be as good, making things to lean.
Perhaps the only option with a larger second stage is to control when it comes in and that's your lot, unless you start upping the main.
Get the boost turned upYou should have raised the comp up to standard instead of dropping it more lad!
Smaller 1st stage made no difference to wot on my setup. All it done was stopped the black smoke on spool up.
I will do once this carb decides to fuel properly
just shows how different each lump/carb is, although mine was always rich when coming on boost it never used to stutter or kick out black smoke, if it wasn't for the afr meter I wouldn't have even known.
The comp wasn't raised this time round because of budget mainly but I'm still confident it will make the power I'm after with a bit of ignition timing.
Scoff did say to me once that high comp and retarded ignition is generally better than low comp with advance ignition. Plus MS motorsport used to do well with high comp motors.
yes these are quite low cr, which is why i'm not too fussed about skimming heads
I'd think a 8.5.1 ratio + mappable timing will give a nice engine that's responsive to drive and get good power without having to arse about mapping it too much.
Been out in the five doing some more testing tonight.
Turns out the Air Corrector jet I thought was .9mm was actually 1mmEither way I have chucked a .9 in now and it's added enough fuel for some more boost
It's upto 21psi now, done a fair few 4th gear pulls from 3k upto 7k fuels ok. The afr's still seem to be a little lean on spool up/low boost the at WOT the afr's don't drop into the 12's until 4/5psi, then they hit 12 flat at 7psi.
Then they slowly drop to 11.8 once up at 7k rpm.
Seems a little lean still on spool up with the .9 first stage jet.
No adverse symptoms that I can hear with the steth or see on any of the temp/oil pressure readings.
When going from 2k rpm in second right upto 5k in fifth flat shifting all the way I don't seem to get any lean spots that show on the aem apart from the small part on spool up.
So I decided to up the boost some more to 24psi, however I started to hear the tell tail pings of knock an the afr was 12.6 so not to good so backed it off did plenty of fouth gear pulls again at 21psi and it was fine.
Think I need to up the first stage back to 1mm to try to richen it up at 24psi.
Either way nothing broke so that's a bonus (jinksed myself now
Felt I would say 185/190 hp Think the lower compression is the cause for the slightly low figures, this engine since being built has always been just short of other higher comp c1j's by 9/10hp. It's now the lowest compression it's ever been. Need to get it upto 24psi 11.6 arf how it was before then swap the timing leads round for some advance. Will wait for the rollers before I do this as The knock detection is much much better than a pony £12 mechanics steth
I couldn't resist posting this one. The Lotus is my mates recent purchase
Took advantage of the few hours of dry weather we had this morning up north, went out doing some more testing.
Boost is now upto 24psi manifold I would like the afr's a touch richer they are a pretty flat 12.4 upto just under 7k when they creep upto 12.6
I think if I put the first stage back to standard it should give me just that little bit extra that I need up at the top of fourth. it's currently .9 going to change it to 1mm.
Feels nice and powerful, second gear is an absolute comedy gear now that's for sure it's not even to cleaver in third when it comes on boost
Well done mate she sounds like a real beast
What sort of power do you think it might have at that boost level?Originally Posted by GTphil
Took advantage of the few hours of dry weather we had this morning up north, went out doing some more testing.
Boost is now upto 24psi manifold I would like the afr's a touch richer they are a pretty flat 12.4 upto just under 7k when they creep upto 12.6
I think if I put the first stage back to standard it should give me just that little bit extra that I need up at the top of fourth. it's currently .9 going to change it to 1mm.
Feels nice and powerful, second gear is an absolute comedy gear now that's for sure it's not even to cleaver in third when it comes on boost
Not sure exactly but the last time it was on the rr at 24lb and the addition of a BMS downpipe it was 215hp. 210fr/lbs
:edit: I would put it about that power as it is.
The low compression definitely caps the numbers slightly.
With less boost and more ignition advance it did 220 @22lb.
I need to get a few hours in on the rollers and then sort out a trip to pod.
Last edited by GTphil; 23-02-2014 at 17:57.
Love this car
The level could be low in the bowl too. Level plays a big part in how the emulsion tube works. Its a long time ago now but I think I remember playing with different height copper washers behind the needle jet. I don't remember what height I settled on sorry Phil!you seem to be doing things right
personally I'd set boost to 22/24psi and taper fueling so its 11.5~afr at 8k rpm, then start getting the 1st stage, accel rod and the 1st to 2nd stage change over sorted.
Strange how you have a 1.4mm 2nd and very little afr. Either the engine is setup well and working great or you have a restriction in the carb.
fantastic progress thread and some really valuable trail and error posts here, defo something that im taking on board as im going to be fettling my carb soon
I remember Rob (backyard) mentioning this to me something I will try and see how it gets on.
Cheers Andy, just seems to be taking an age for everything to come together so I can get upto pod and get what I'm after.
When I started this project my Mrs was only a few months pregnant (with twins)
I had no idea how life changing this was going to be and how little time I would have for myself or indeed the fact I would have to start working part time.
I was also diagnosed with Crohn's Disease 2 years ago and this has also held me back a little.
Now my twins are nearly three, the Crohn's seems to be under control (for now at least) I'm starting to get a little more time to work on the car and also have the energy and enthusiasm back for it.
Fingers crossed I can squeeze enough power out of it and keep it in one piece and finally manage what I have been after for so long.
Now you can all get your violins out for me
Good on ya Phil. My 5 is my escape from all the stress that builds up at work, even though it sometimes lays dormant at times while I try to find the time to fix/mod/replace stuff. My missus hates it, but understands that it keeps me happy.
Have to admit that I've never quite mastered the Solex 32 DIS and there's an itch that stops me going full EFI until it gets scratched! That's why I posted up the Gp.A Venturi Kit.
Keep up with the good mate, it's all worth it.
Woz
Coming along nicely mate
I am just wondering though, why not make the tdc completley adjustable so you could fine tune the advance a bit better instead of a flat 4deg?
I have given this a try with a bran new timing sensor and it mullered it! I put the bolts in so the holes didn't go oval gave it a few taps and the plastic sensor just came off.
Is there some different types of sensor or was i just a little to heavy handed?
Ah I see, would be annoying to bust another
To be fair I think you were just unfortunate, its easily damaged.
I did mine in situ, removed the cover and tightened back up, then used a blowtorch to roast the bracket, a few taps with a hammer and it was free
May have an old one in the garage (somewhere) if its any use to you, but has been chopped and joined due to some damage - Reckon its still useable though
You defo need to heat them up a little Phil.
I just held the sensor in the vice, gave the metal bracket a few taps and bam sorted..
I may have a gt tuning adjustable one in the spares box, remind me after 8 tonight and I'll check.
GT tuning......not sure i could afford that
Cheers pal, let us know
Does anybody know what sort of compression readings i should be getting with a compression test with a retarded 285 cam and low comp dished pistons and a head that's only had 4 thousandths taken off it.
I did a test the other day and got
125 120 125 120
in psi
from the flywheel end with the throttle fully open and all the other plugs out on a cold engine.
I know that the low comp and the retarded cam timing do cause low cranking compression but is it normal for it to be this low, most gtt's are 140/150 psi
No idea mate ive just realised ive been driving my car half throttle all year...
Haz installed a new throttle cable and laughed the throttle body was only opening half at full foot down....but wow its like driving a totally different car. Lol
Ha, that is quite funnyNo idea mate ive just realised ive been driving my car half throttle all year...
Haz installed a new throttle cable and laughed the throttle body was only opening half at full foot down....
Lol tell me about it how stupid do i feel. I though it was because i had 16s on that was why i wasnt getting torque steer at all..lmao now i feel scared putting my foot down
Right team,
I think I have broke something
What has happened to people who's head has lifted under boost?
I did the head bolts upto 70nm warmed it up let cool over night then re tourqed them to 85nm.
I have fresh oil from the headgasket seal on the flywheel side of the engine, pretty sure it's not coming upwards and after a few pulls this afternoon at 24psi it looked like a fair amount of oil had come from said area.
the gasket appears to have also ever so slightly mushroomed out at this point also, pretty sure it was perfectly even when it went on.
Done a comp test as above
125 120 125 120
from the flywheel end, low comp and retarded cam.
Plan of action is to check the headbolts first of all then if they are ok should I suspect the gasket?
If the gasket has mushroomed out (pushed out of shape) i would suspect its been detting
Hmmm, I have heard a few tell tail pings durin setting up, plus I'm at 12.4afr at the very top of fourth. Nothing for more than a nano second tho
it's only mushroomed out very slightly by 1mm at the most. But the rest of the gasket is flush.
might be head off time again
You can still be within the limits of the fueling but still have the engine det alotHmmm, I have heard a few tell tail pings durin setting up, plus I'm at 12.4afr at the very top of fourth. Nothing for more than a nano second tho
it's only mushroomed out very slightly by 1mm at the most. But the rest of the gasket is flush.
might be head off time again
Doesn't take long for it to cause havoc once it happens
Never had one spit oil out tho, seemed a lot over the front of the block and down the top seam of the hesdgasket. Unless it is coming upwards.
Also the comp readings are even over each cylinder if a little low
For the gasket to push out like that its the one of the main reasons i can think of, not many things cause the gasket to push out
Could be wrong but to be honest in this case i think the head will have to come off to be sure what it is and replace the miss-shaped gasket
only other cause to det I can think of would be liner heights wrong?
This is the oil
This is how much the gasket appears to have mushroomed out, the rest of the gasket is flush with the head
Seems more like a gasket fault to me tbh!
I must add this is a standard headgasket
My collection of old gaskets and headbolts is becoming impressive
standard
a least fit blue millers 1.9mm or a steel gasket but then if the steel gasket does not give way liners will start cracking.
are you running super unleaded and some fuel additive octane
Use millers cvl turbo and always super unleaded.standard
a least fit blue millers 1.9mm or a steel gasket but then if the steel gasket does not give way liners will start cracking.
are you running super unleaded and some fuel additive octane
Standard one was to try and raise the c/r a little. Suppose I was asking for trouble really
I think the gasket pokes out alittle further that side, looks normal to me not miss-shaped at all
As its leaking from there the gasket has deffinately failed or some reason, i have used the red seal gaskets before for high boost ok but tended to use the blue seal
For me instead of torquein to 70nm then 85nm at a later date i use torque then to 75nm, run it then check they were still torque later. Never had issue.
I have checked the pictures from when the head first went on and it does look pretty much the same.
I need to rule out the headbolts first of all I think, my first thought was if it's coming from the head gasket then how has the seal round a cam follower been damaged.
Hence why I thought it may be lifting under boost.
I don't lose any coolant it doesn't over heat and there are no mixing of oil/water at all, it actually runs quite well. I do get a slight random bogging down on idle when it's warm every now and then.
I'm sure that it I haven't heard det through the steth, done a fair few pulls listening for it.
I need to double double check for no leaks from anywhere else that travel upwards, even so, yesterday it was all over the front of the block and on the top part of the headgasket and head after only 5 mins of driving. I have had a good look round whilst it's idling and can't spot any leaks, only seems to appear after a long pull in either third or fourth.
Posting Permissions
Reply With Quote
