Need some 101 Weber help

[RoninLB]

Originally posted by Va914
Interesting about the coil.?

ditto


Does anyone know if I have ballast resistor? [/QUOTE]
afaik.. about the oldies it should depend on your stock ignition system? And more fun is that there are 2 ways to resist. Either as an external unit or as part of the coil.


And it's usually easy for me to figure whether fuel or ignition w/ carbs. I'll wack the throttle a few times till it starts to detonate. Then play with the edge of high detonation while watching in the venturis. It gets easy to figure after doing a few.

If you have to fake fixing the detonating engines it's probably safest to just remove the spark plug if it's a single cylinder or at least drive it with as little torque as possible imo.

If you have a single idle jet fully clog the combustion crashes, ie no ignition and no EGT.. and the CHT drops 10-30deg depending on conditions on the street. If it's partially clogged that means that there is ignition of a lean miss. Under load EGT will climb well over 1500degF. Lean miss CHT may not climb noticably when measuring w/plug gasket probe. You can also fake a wide open float by keeping it above 3.5k.

it's a carb eat mfi world.

[}{arlequin]

don't mean to hijack, and if it's too far off let me know, but I think this should belong in a thread about carbs.

I'm looking to get into this type of setup (recirculating w/ cis pump etc.) and I'd like to learn something from you guys. I know absolutely nothing about fuel pressure regulators. When I do a search, 30 pop up. How do you know what's a "good one" and what's not? Are there any established companies? (Mallory, Holley.... any others?)

What to look for when getting a FPR? Ability to rebuild is great, but what else? 2 port vs. 4 port? What's that mean- just how many attachments/hoses it will accomodate?

As for the fuel filters, I see many using the inline filters, which are nice. What's the micron rating that's recommended for this? What's overkill, but nice to have? Two inline filters of different sizes? Are both placed *before* the fuel reaches the FPR?

As for the fuel pressure gauge, many are mounted on the FPR itself, but I've seen some on a recirculating systems that are on the fuel line connecting boths sides carbs. Is that significant? Is the reading more accurate?

sorry for the barrage of questions, I've searched all over for some of these topics and figured that maybe I can gather them all in one place. If this is too much and requires its own thread, let me know (or cut-'n-paste and start another one.)

thanks.

[RoninLB]

Originally posted by }{arlequin
sorry for the barrage of questions

Questions are easy. It gets tricker when you don't know what question to ask.

I picked up a comment about de-psi carbs w/using a dead head regulator. I'm currently looking into using a NOS jet out of Summit and plumb fuel from the carb psi side into the return line.

[911pcars]

"...I was looking at the cranecam website and noticed this:

XR3000 only. If a miss occurs
at high RPM, make sure any
ballast resistance has been
bypassed.

Does anyone know if I have ballast resistor?"

Connect a voltmeter to the source voltage wire. If it reads about 9 volts (instead of 12V), you have a ballest resistor (or equivalent). The ignition box needs 12.

"Does anyone know if I can swap out the PS-91 with an OEM type coil, just to test the possibility of the above problem?....."

VA914,
I'm using the factory coil with my Hi6-S Crane box. Works fine. Coil is from my original 911T (same as 914-6) engine.

BTW, if after having checked all that was suggested, have you checked the fuel pump output? Fuel pump requirements under load are different than at no-load.

Sherwood

[randywebb]

PMO makes a good fuel pressure regulator. only about $40 so no reason to look further...

[Va914]

Thanks guys.. I spent the few hours after work and recleaned the Main jets, installed the 30mm Vent's, adjusted the timing, lowered the fuel pressure (it was at 5.75psi), and plugged the missing vent lock bolt

Left the rain shields off and took her for a spin :

She runs very nice and the carbs sound so so so much better without the rain shields.

Thanks to all I am back on the road after just about a year of wrenching and paying :

[rrichar]

Grady,

Are you saying that all 3 auxiliary venturis will NOT point in the same direction? Just asking for clarification.

[Grady Clay]

Yes, they point in different directions.

I put a red line in the direction of the vent.
The retaining spring is on the opposite side.
IMAGE: WeberAuxVenturi03.jpg


Best,
Grady

[rrichar]

thanks, I will have to check mine. I believe all mine point in the same direction.

I remember in some previous posts you had some nice things to say about Hal Shaw. Someday we should talk about Hal. I used to help him out in the Trans Am and Endurance races in the mid 70's.

[RoninLB]

Originally posted by }{arlequin


I'm looking to get into this type of setup (recirculating w/ cis pump etc.) and I'd like to learn something from you guys. I know absolutely nothing about fuel pressure regulators.

I should have started with installing a fuel line and gauge between the engine comp fuel pump feed line and the return line. My stock return line currently has a back pressure of 6-7psi.

Either I had to install a new larger return line or design a system around that 6-7psi to get carb psi down to 3.5.

The other option was a 914-6 fuel pump which has a low psi discharge and is designed for carbs.

[Va914]

Interesting issue has come up. Last night I drove the car and it ran fine. I pulled it in the garage and called it a night. I got home tonight to take her out for a spirited run and Blah.............CRAP

It turns out the dam water shields are causing the problems. I pulled over into a parking lot and removed the OEM water shields for the drive home. It ran great WTF

[Va914]

PROBLEM

What are these small filters used for?