SC12 on a 22r

[Earlyrolla]

This would most likely explain the extreme heat of the boosted air going to my engine, because the chargers breathers are blocked the heat is being kept in and overheating the hole setup.

Um, I think you may have misunderstood the purpose of those 'breather tubes'... They are to equalise the pressure either side of the supercharger bearings so that there is no pressure differential across the bearings. A pressure differential obviously results in air movement from the high pressure region to the low pressure region, this in turn can cause the lubricant in the bearings to get blown out. Bearings without lubricant dont generally last long!

The SC14 is definitely not one of the most efficient superchargers, well it is more one of the least efficient roots superchargers. Compressing air means the air gets hot. Doing it with less efficiency means the air will get hotter again! Depending on the overdrive, manifold temperatures up to and exceeding 100degC are possible on average day

From what I have read so far I am guessing this is a draw through application in which case it is not possible (safe) to intercool.

[charged22r]

i am running a blow through 32/36 webber carby with plenty of pressure from the electronic fuel pump and malpassi regulator to equal out the boose pressure in the carby.

Earlyrolla what am i supposed to do with these 3 hose connections to set them up right because at the moment the back one is plugged off and the front ones have a tube running from one to the other. This can't be the correct way to set these up please help

[Earlyrolla]

Just like other people have said, plumb them into your manifold.

Plumbing them into the boost gauge line for the time being would be fine. Try to plumb it in as close to the the manifold as possible to minimise the depressions caused in the line from attaching the breathers.

Has the power valve circuit in the carby been modified for blow through?

Like Jon asked, do you have the carby enclosed in a box? Another problem with blow through is leaking of the fuel/air mix around the throttle shafts, which can lead to a disaster should it ignite. It is possible to have better seals fitted to the throttle shafts to prevent this, or the alternative is to enclose the whole carby in a sealed box.

As long as fuel pressure is referenced to manifold pressure then there should always be the correct differential pressure in the carby for the float and needle valve to work properly.

[charged22r]

great i have a day off on tuesday will hook them up then.

this may sound dumb but WTF is a power valve circuit?????

no the carby isn't in a sealed box so when i take it in to a carby specialist next week i will be getting him to completly set it up properly for boost

And yes the rising rate regulator is hooked up to the intake after the charger so the pressure of the fuel is referenced to the amount of boost

[Earlyrolla]

Most carburettors like the weber down draught have three main fuel circuits. An idle circuit, a power circuit and a main circuit, as well as the fuel pump plunger/diaphragm.

The power circuit supplies fuel in reference to engine load by sensing the vacuum just after the throttle blade. In some installations it is necessary to modify this reference so that the power circuit receives the correct signal (and hence supplies the correct fuelling) based on engine conditions.

Have a read of 'Turbochargers by Hugh MacInnes'. Although your engine is not turbocharged it has some useful information regarding blow through carbs.

If your taking your car to a specialist to get tuned then it probably doesnt matter too much as they will sort it out

[jonra23]

There is a fair bit of work in getting blow through Carby settup working properly.
One of the main issues is maintaining a constant fuel pressure differnce across the needle and seat, with the rising and falling of the boost pressure in the manifold needing to matched with fuel pressure constantly to maintain a constant fuel level in float chamber, especialy with Webers being that they are fairly touchy with fuel pressure anyway.

Unless you are realy attached to the Webers EFI will be easier to deal with in and give better results in the long run.

regards
jon

[Screamn_Sleeka]

i am running a blow through 32/36 webber carby with plenty of pressure from the electronic fuel pump and malpassi regulator to equal out the boose pressure in the carby.

Carbies dont work well with high psi fuel pumps, the pressure effectively pushes the float back down. So i hope thats not a EFI pump you are using.

[thechuckster]

the RR Malpassi should get you around issues of the float being pushed open.

[jonra23]

the RR Malpassi should get you around issues of the float being pushed open.

If the Malprassi RR set up have a increase in fuel pressure greater than the increase in sensed line pressure then the needle and seet will have trouble trying to maintain a constant fuel level. (I have never used a rising rate fuel pressure regulator as I recon that they are masking some other problem so am not familiar with their operation)

Even if it a parralel rate on fuel pressure it will only work if the vents to the carby float bowls are plumbed into the same pressure signal as the fuel pressure regulator and the hose between the the regulator and the needle and seat is pretty short.

regards
jon

[charged22r]

well hopefull all will be fixed and set up correctly once i get it back from the carby guy.

Next question is where is a cheap place to order some 2.25 inch 90 and 45 degree silicone hoses so i can plumb up my intercooler????

[charged22r]

ok silicon pipes are ordered

now i am wondering if it is possible to buy a ready made pressure top for a weber 32/36 carby so i can conect up the intake piping any info would be good. I have tried on the net but maybe i am just not looking in the right places.....

[Screamn_Sleeka]

ive u ever put this thing on a dyno when its done, id be very interested in how it goes, and im sure a lot of other ppl would be too.

[charged22r]

when the carby is done on thursday and i get the cooler connected up it will be going on a dyno to be tuned and tested. don't worry i will prowdly put my stats on here when its done