The triple webers on my 6 have trouble staying in tune. At certain rpm's I get minor backfiring through the carbs.

At 48 years old the carb bodies are probably worn and need extensive rebuilding.

At Okteenefest Bob Saville was telling me I should check out PMO carbs. Although expensive, the testimonials certainly sound good.

Anyone have experience with PMO carbs? The engine is so strong I want to get everything I can out of it.

Try calling Eurometrix about rebuilding what you have, it may be a good way to gauge the price.

Eurometrix full rebuild is $2340.

New PMO carbs (only) are $3400.

Your throttle shaft bushings are worn and/or your manifolds are warped.

PMO's are good, but it's 6 of one, or half a dozen of the other.
You can buy PMO's and flog your old Webers on the bird board or you can get your Webers rebuilt by Performance Oriented or Eurometrix. In the end each route will cost about the same.

One caveat is new carbs won't help a tired engine.

There are still a lot of purists who will pay a pretty penny for original Webers, even in poor condition. You could make some money towards a new set of PMOs that you wouldn't (hopefully) have to mess with.

PMOs are nothing short of beautiful. As much as I like rebuilding carbs, I really enjoy seeing really well executed designs. As hard as it is to improve on the original Weber design, the PMOs are a step up.

I love my PMOs

Click to view attachment

Click to view attachment

Click to view attachment

Check out http://www.performanceoriented.com/ as well for Weber remanufacture/rebuild. I used him for a minor fix and he's a great guy to deal with - I strongly recommend him.

Engine is A1 as verified by a couple long time Porsche factory mechanics. The carbs are original to the engine...(a '65 2.0 bumped to 2.2) so I'm 99% sure the carbs are the issue.

I'll keep the carbs to go with the engine. I've already been offered more for the engine than I paid for the car so as early cars keep going up in price the early engines follow.

So, the question is to gamble that the carbs can be rebuilt properly or make the leap to PMO's.

Carbs can be Re-Built properly, but you are still dealing with a 40 year old Part.

When ordering PMOs, Richard Jets them to your Engine's specs, so they are basically Plug n Play

Since it's an early engine personally I'd go with the full meal deal rebuild of the Webers from Performance Oriented.

Looks like I have some thinking to do!

Thanks everyone for your replies.

Paul at Performance Oriented is a Meistro.

Not sure how someone can tell your bushings are worn (Mark) without looking at them

What your describing are running issues that might be cause by shaft bushings but I'd make sure the items on performanceoriented.com are followed for tuning. It starts with a valve job. Then follow his lean best method to tune.

They probably need to be rebuilt. You can clean and get new gaskets in them yourself. If there are worn shaft issues you can see them as carbon traces on the butterflies when you turn them upside down. If you check out Paul's site you can see the amazing work he does. I spent a couple months with mine. Here's some recommendations:

1. Valve job
2. Get the proper syncrometer.
3. Rebuild the carbs
4. Find out everything you can about your jets and emulsion tubes.
5. Have the peak rpm of your cam on hand
6. Make sure you have the proper jets.
7. Make sure the emulsion tubes match the cams.
8. Make sure you have 3.5lbs of fuel pressure at the carbs.
9. Follow all Paul's tuning guidelines, especially the linkage adjustment procedure.

Even if the shafts are worn, that should get you running 100% better.

If he posts a pic of the throttle plates I most likely could and checking the thrust wear can be done in the car. Worn shafts is common issue in webers (and stock TB's and VW carbs and IDF webers and etc....), I've re-bushed more than a few sets over the years.

Slight hijack - Mark, I've always been curious, how are the bores bushed? I have a pair of Webers that have been and it looks like a total PITA, particularly on the inner bores.

Also, the IDFs never had bushings from the factory, correct? The body of the carb itself was drilled to close enough tolerances that they deemed bushings unnecessary. So any carbs with brass bushings have had the bores drilled out, the plugs inserted (somehow) and then redrilled?

You can sell your Webers as-is for about $1400, so if you factor that in plus the Re-Build cost and you will spend less for the PMOs

The throttle shaft? I've always made custom bushings with about a .0005 press fit, install and ream to size. Some have bearings, the thrust wears out on them from incorrect linkage geometry. Real PITA job because every thing is so tiny and the housings don't take much to crack.

[quote name='carr914' date='Oct 13 2013, 07:28 PM' post='1940128']
Carbs can be Re-Built properly, but you are still dealing with a 40 year old Part.

[/quote]


[quote name='Mark Henry' date='Oct 14 2013, 08:58 AM' post='1940340']
[quote name='ThePaintedMan' post='1940310' date='Oct 14 2013, 08:05 AM']
the housings don't take much to crack.
[/quote]

Exactly!