Tips on Installing PMO Carbs

[OZCarrera3]

I'm just starting the installation of my PMO carbs and have a couple of questions for those of you who have fitted them yourself. I promise to do a complete and detailed post when I am complete.

1) The linkage instructions seem pretty straight forward, but are there any 'gotchas' or things to look out for?

2) Balancing the carbs, was this difficult? What is the maximum variation that is acceptable using the STE synchrometer?

3) Did you need to adjust idles, mixtures and airs much? What were the issues?

4) I note (from the picture of ael911's car below - sorry only example I could find quickly) that many of you don't fit the oil breather hoses to the carbs. What is the reason for this?

http://forums.pelicanparts.com/uploads12/DSC02532_21205378953.jpg

5) Is there any other handy tips you have on making the installation go smoothly?

Thanks in advance for your response.

[snbush67]

1) The linkage instructions seem pretty straight forward, but are there any 'gotchas' or things to look out for?

Not really, Perhaps you may have to cut away a bit of material from the engine tin where the accelerator rod passes through.

2) Balancing the carbs, was this difficult? What is the maximum variation that is acceptable using the STE synchrometer?

Real easy, you should not have any varience here, if your engine is idling smoothly at steady rpm's then you should be able to equalize the draw without issue. I think mine pulls about 5.1 at 900 rpms.

3) Did you need to adjust idles, mixtures and airs much? What were the issues?

Make sure you understand the instructions fully. Start with the air screws seated, The mix screws out 2.5 turns (five 1/2 turns) out from lightly seated, and the idles 1/4 turn in after touching the stops.

4) I note (from the picture of ael911's car below - sorry only example I could find quickly) that many of you don't fit the oil breather hoses to the carbs. What is the reason for this?

Cleaner looking set up just to use a catch can, less residual oil and fumes in the engine bay.

5) Is there any other handy tips you have on making the installation go smoothly?

Air synched before mix on a new installation or when starting from scratch;

__1- Initial settings
____a. Air screws seated
____b. Mixture screws 2 ½ turns out (rich setting)
____c. Verify that the butterflies close by turning the idle speed screws all the way and then turn idle screws back in ¼ turn after touching the throttle arm(s).
____d. Measure and adjust injection quantity (small vial .5cc-.6cc)
____e. Check and adjust Wide Open Throttle (WOT) to stop at pedal.
____f. Adjust fuel pressure to 3-4 lbs.
__2- Start and warm engine, adjust idle speed screws to about 1100-1200 RPM’s
__3- With the engine running and warm unhook the short linkage arms
__4- Synchronize the left bank of carburetors (1-2-3)
____a. Check each carburetor of the left bank determine the highest air draw
____b. Adjust each air screw to equal draw with the highest carburetor of that bank
__5- Synchronize the right bank of carburetors (4-5-6)
__6- Synchronize the left and right banks to each other by adjusting the idle speed screw of the bank that has a lower draw to reach the same draw of the higher bank.
__7- Adjust idle speed screws to about 1100-1200 RPM’s
__8- Adjust idle mixture screw in (lean) on one carburetor until idle speed drops slightly, do this in small increments and very slowly listening closely to the sound of the engine. Once it drops, turn it back out 1/8-1/4 turn or until previous idle speed is resumed. Adjust the rest the same way (they should all end up in about the same place, the objective is to get the carburetors as fuel efficient as possible without going lean, but if in doubt richer is better than lean).
__9- Adjust idle speed by adjusting left and right to 950 rpm +/- 50
__10- Check/Adjust left to right bank synchronization to achieve equal draw at 950 rpm +/- 50
__11- Adjust short linkage arms so there is no preload and reattach linkage without changing idle speed.
__12- Check linkage synchronization at 3000 rpm adjust as necessary
__13- Turn off engine, install rain shields
__14- Start engine, test drive
__15- Turn off engine pull the plugs and compare them, make adjustments based upon rich or lean findings

[OZCarrera3]

Thanks for the very detailed response Shane.

I have another question. I've just installed the linkage cross-bar, but it looks a bit odd - its on an angle across the engine (refer pics). Is this right? I think I have followed the instructions correctly (adjustment linkage plate on left side, etc).

[kent olsen]

That angle is normal. Notice the manifold on the right is further to rear than the one on the left.

[dipso]

Yes, that's right. The crossbar mounts at an angle.
Looks a little weird but since the carbs are offset, that is the way it goes.
The PMOs are really easy to get on and running.
Your almost there. Couple more hours.

I didn't put my breather hoses on at first but couldn't handle the smell.
I put them on about 6 months later and like it better that way.

[moneymanager]

Write me if you find the car bogs at low revs in 2nd gear when you floor it. And don't hesitate to write Richard with tuning problems later if you have them; he's very helpful.

[James Brown]

Look at the engine, the left bank of cylinders is farther forward than the right side due to where the connecting rods attach to the crank shaft. Same on every V8 or VW or aircraft engine.

[snbush67]

Update. Make sure you’re getting full throttle.