High-Carb Diet

[Geoff]

Its the bottom part of the header where you can tell if it has the shorter or longer runners. It looks from this picture to be the short runners.


That exhaust would be tuned for high RPM power. So a MSS cam is a good match Is that an MSS header (it would be stamped on the top of the 2-3 flange)?

I'm not sure on the exact size of the pinto valves (I don't have them with me at work nor any of the measurements for the stock valves) but the intake valves are about 2mm larger. Sonett says the stock intake valves are 42mm, so they'd be 44mm. His intake valves are 46mm! The exhaust valves I have are almost 3mm larger than stock (I seem to remember stock being 56mm but I may be way off).

The valve shims are a total pain in the ass to adjust. You measure the clearances, calculate the differences, remove the cam, remove the lifters, replace the shims, replace the lifters, replace the cam, measure again only to find out that for some reason things are still off by a few thousandths. You do this again and again and again and again... With the lash caps that Sonett is using you have to mill down the caps to get the right clearance.

It sounds like you should be able to get some good power from your engine with the bolt on stuff you have. Try running it as is when you get all that stuff on it and tach it up!![/img]

[Jordan]

Yes it is MSS race header. I guess Jack Lawrence no longer lists them in his catalog, but when I talked to him , he will still make them, he just didn't have any left in stock (that he could remember).

Honestly , I just don't want to keep fiddling with the engine once it is together. I'm going to strip the car probably in a few weeks (fall) to do rust repair/repaint, new wiring etc. I don't want to put the CIS back in the car so I'd like to have the carbs be set up so the car will at least be able to run and I can get it to a dyno for tuning (if I can find one).

I was going to build up a head and maybe if everything goes well I will just swap the heads over before the strip down to break in the cam shaft and see how things run. Then, move the head back over to the refinished block which will go in with carbs... I dunno, I'm trying not to make too much work for myself, so I can actually race the car and not spend all my time pulling out every HP i can find. I received all the MSS parts in bulk with a decent discount secondhand, the carbs are second hand, and this is definately a budget racer.
I have a couple of spare heads that besides the cost of new gaskets are fairly painless to swap. But time is money as you know.

Edit: Just as a goal I'd be happy with 150-175hp...

[Jordan]

I split out the other posts to get back into carbs ..

I'm thinking for the initial set up I'm going to start with 36mm chokes and base everything off that. (unless i find a cheap set of 38s).

Doing additional research I found the specs used for a modified 2L pinto engine.

Jetting for modified 2000/2100 Pinto on 45s

38mm chokes
145 main jets
F16 emulsions
180 air correctors
40 pump jets
50f9 idle jets
4.5 aux vents

The book I have has similar set ups as well.

Here is engine specs that Luke found on his carbed set up.

Jets from a 99 rally spec B motor with DCOE 45's, 8500 rpm cam and flat top forged pistons.

- Emulsion tube size: F9
- Venturi size: 38mm
- Main Jet: 155
- Air Corrector Jet: 220
- Idle Jet: 60-F8
- Pump Jet: didnt check yet
- Float needle valve: 225

I'm going to start with a safe running standard and see if I can find a dyno tuner who specializes in weber for the rest of the tuning.

I just hope im not going to be cutting off the airflow with the 36s since the cam doesnt really start making power until 4000rpms ... but I think it will give me a broader torque band. Any thoughts?

[sonett]

Your F9 emulsion tube should be pretty much spot on, the F16 does not really work with the Saab. The rest of the jetting will get you running, but like you have pointed out, you need to get it to someone with rollers and is good with webers.
I'm still not convinced about the choke size, i think it's too big, but this also depends on how well the head will flow. When we set up a standard road car, except for 4-2-1 manifold, the 34 chokes made the car difficult to drive at low RPM, yes this was a road car, but even a rally car can't be at 4500rpm+ all of the time, it's always a compromise with carbs and clockwork ignition, when we dropped to 32mm chokes it made the car so much better to drive, but the peak bhp dropped by around 5bhp.
I wouldn't use the vacuum advance and i would consider altering your total mechanical advance, "Recallibration" of the distributor consisted of bending the lugs which limit the centrifugal advance, thus restricting the total advance. This allows you to set up the initial timing more advanced, so long as you make sure it does not over-advance at full revs. This sounds crude (it certainly is compared to fully mapped ignition) but it works quite well
If your class regs and funds allow, consider using mappable ignition, it can be run from the disi with standard coil, although fitting a hall effect will help, such as pertronix, a TPS is available for the weber carb and then your choice of ECU, megasquirt is more than capable.