What type elusion tubes for 2 litre pinto twin 45dcoe and 38mm chokes cheers mario.
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What type elusion tubes for 2 litre pinto twin 45dcoe and 38mm chokes cheers mario.
Sorry I dont know what size, but I assume you mean Emulsion tubes rather elusion tubes.
Yes emulsion tube tryed a f16 very rich in low rpm tryed a f2 low down all ok but midrange is still to rich what tube can i try next cheers Mario.
F16 and f11 seem most commonly suggestedQuote:Originally Posted by mariors2000
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What cam are you using? Rich between 2000 and 4000 is usual because of faster cam and spitting back fuel in the carb (double enrichment). Very difficult to get rid of. Right cam is for this reason very important.
Hi onyd will raising the compression from 10:5:1to 12:1 fix the problem or do i have to use a softer cam cheers mario.
raising the compression isnt going to fix a mixture problem!
I have know idea about this but as a suggestion when using the F2 tube could you not come down a bit on the main jet size to weaken it off a bit?Quote:Originally Posted by mariors2000
F11 is best.
My 2 ltr pinto has got f11 tubes on twin 40 score and a Newman’s 276 deg cam
Please let me know the camshaft you are using, this will say a lot more about can we fix the problem and how to fix it. If the rich mix and low torque at this place is a problem because of a (to) fast cam, no you can't fix the mix problem but yes, you can probably minimise the downsize by using the correct CR. A good Pinto cam is most of the time happy with 11/1. With Bansai cams you may be better of with 12/1 but I would suggest to fit an other cam and fix both problems.
Double enrichment because of excessive valve overlap is very difficult to cure and usual out of the woking era of emulsion tubes. There are other ways to come around but most are not predictable. Let say, full race engine always ask for individual solutions and is the reason why they are so difficult (and expensive). If you are happy with just one step less, live is a lot easier. Cams like RL31, Piper 300, Newman ph 4,75 are just at the edge of this problem, just about the point the negative side is less than the advances. Hope I'm clear here. And the less duration, the less problems, if you are happy with even less, live start to be more and more easy.
hi onyd,
camshaht is 312 duration 250 @ .50 .500 inch lift at valves 100 degures overlap inlet and exhaust same lobes the same
lift at tdc is 4.4 mm compresion is at 11.1 now but i have an other head that will give me 12;1 compresion cheers mario,
OK, problem solved or at least we know where the problem is coming from. 4,4 mm lift at TDC will give a lot of double enrichment in lower RPM, easy up to 4000 RPM. You may drill and solder as many emulsion tubes as you can find, none will cure the problem. I've got a small rule (but it is not based on any kind of calculations and also does not take into account how good the head is working etc..) but my rule is, 2mm and engine will start making power round 2000 RPM, 3mm is 3000 RPM, 4mm is 4000 RPM, 5mm.......
You will have to think again and check what you got. Is your cylinder head really so good it can run very high RPM's and still make good cylinder filling (and Power). Or do you need to step back a few cams so you got the right one for your head (and max RPM / Power) so the double enrichment will decrease and make the head / cam work where it is build for (or as good at it could be build).
Believe me you need a damn good f*cking head to make this cam work. Fit an RL31, Piper 300, Newman ph 4,75 and your carb tuning problem is solved.
If your intention is road use also, the cam is far to fast.
hi onyd engine is making 175 flywheel hp with 11.1 compresion now i want to raise it to 12.5.1 what do you think, its got
145 rear wheel hp. car run a 14 .8, 1/4 mile time at 90 miles an hour , car weighs 1000 kgs i like to keep this cam and try other head i got. I put flow figures up of head to get your feedback thank you for your help i want to make about 190-195 hp pinto. cheers mario.
hi all head flow are @ 28
.050 35
.100 70
.150 104
.200 139
.250 152
.300 165
.350 170
.400 176
.450 183
.500 189
.550 192
cam lift is .500 lift.
what hp should i see with this head cheers mario.
its not quite as simple as head flows "y" so you will get "x" power but you have enough airflow for 200bhp
hi graham
how do you read hp figures from flow figures at what point of lift to work out hp figures cheers mario.
If figures are correct, it's indeed possible this head can make 200 Bhp. About the cam, if the power band is not wide enough, read it as you can't keep the engine on cam between the gears and the driving situations, your cam is almost for sure "faster" than needed. For any engine there is a camshaft that will do the job over a wide enough RPM line.
As long as you are "on cam" the mixture can be dialed in more or less correct (using main jets, air jets and emulsion tubes). The RPM range where you have problems (usual to rich at lower RPM's) should be out of the working area for your engine. And than you got the right cam.
The good thing with fuel injection is, even where the engine is "of cam" you can still have the mixture right. Make the car drive better if you ever change wrong gear or come into and unexpected low RPM. The worse the cam (to fast) the bigger the difference between fuel injected cars and carbs.
There are people who feel they can make more power with a faster cam and fuel injection because of this better way of tuning. Until date, I did not found any engine making more power with faster cam and fuel injection as the same engine with the "right cam" on carbs. Again, there are advances but the most important thing is, get the cam right. The right cam is more than often a lot softer as what most are willing to believe. 90% of race engines use a cam faster as what is needed with only negative effects. Making it perform better on fuel injection.
thanks graham and oynd i will put new head on and see how it goes thanks again i keep you informed cheers mario.
very roughly speaking @28 inch pressure on a 4 cylinder engine around 500cc per cylinder you will get 1bhp per cfm. but that makes a lot of assumptions!!!!!Quote:Originally Posted by mariors2000
Hi graham and onyd what camshaft would you recommend with my flow figures and 12:1 compresion cheers mario.
Will try to replay and explain when I got little more time but if you want the best cam for a race engine, start looking for a very large budget, the rest is trial and error.
