Power piston height 8213 carb

[chvlle67]

Hi folks, first post here actually any forum. I’m inquiring into where to set the power piston height on this baseplate apt Carb 17058213 modify for use on a mild 454- found the apt set at .060”.  The new rods from Cliff are .010 shorter in length from the rod step to hanger tip than the oem rods. This will set the rod step .010 higher/richer than the oem rods. So I’m thinking about setting the the new Cliff adjustable apt screw setting to .050”. Is my thinking correct here? There is very little info on setting these- much more on the main body carbs.
   Lars G has a procedure to set the main body type apt screw - and I’ve used it before,however, when i try to apply it to this carb i end up with the apt all the way down and the rod step .020’ higher than the minimum recommended. Does this procedure not apply to baseplate carbs? If i follow Lars “ballpark” recommendation then I end up with the apt set at about .040–top of brass on pp set .030 higher than plaster retainer. What am I missing here?

[chvlle67]

Hello again, I’ve got 5 of these baseplate apt carbs. The apt tang on each has different height ranging from .060” to .100”. The rod step to hanger tip varies as much as.020”. The factory has had to have a procedure  to set this height either for application or component variation. What are your thoughts

[Cliff Ruggles]

I set them to where the thickness of the adjustment "wire" bottom edge is flush with the gasket surface or top of the baseplate.  That will get you on and running, then fine tune if as needed once the vehicle is placed in service.

You can also do a "tip-in" test with the engine set to apprx 2000-2200rpm's, but all final testing should be done by driving the vehicle to achieve the best transition, smoothness, power, throttle response and fuel economy. 

You are adjusting the part of the carb where you spend most of the time (light engine load) so it may take several tanks of fuel to nail down the best settings........

[chvlle67]

     Thanks Cliff for that info. That’s about .045 as I measure it. Also corresponds to Lars .020 over PP retainer info. Due to differences in the various components I would also like to know where the rod step should be in relation to the top edge of the jet. At your recommended apt/pp height they are hanging with the step edge .020  above the jet edge- with the oem rods they would be even with the jet edge-your rods are .020 shorter step to tip than the oem rods
      On another note my first comments were based on fake info. Lars says that earlier paper is fake. His latest paper doesn’t mention where the step resides only that it rides higher in the 2nd gen 4mv carbs than the first gen carbs. Go figure fake news!

[Cliff Ruggles]

I don't really worry about any of that. 

What I do make sure of is that the power piston hanger arms are level and EXACTLY even.  99 out of 100 times if someone was in that carburetor before you one or both sides will be bent up or down and the rods not even in the jets.

I really don't care where they end up at after assembly.  I simply make sure that my external APT screw has FULL control from rich to lean being able to drop them deep in the jets, then be able to lift them well out of the jets at the highest position.

I set them in the middle of their travel, verify that the piston has full range of motion without sticking or binding up, install the carb on the engine, then fine tune if/as needed.  You can use my "tip-in" procedure to get close, then drive the vehicle and dial it in from there.  It may take several tanks of fuel to nail down the best setting.  I also like to vary vacuum advance timing in conjunction with APT tuning to come up with the best possible results.......Cliff