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Thread: 50 Pacer engine baffles

  1. #1

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    Default 50 Pacer engine baffles

    I am looking for pictures for the installation of the RH fwd engine baffle on a 1950 pacer with 290D. I have seen how the baffle attaches on the SWPC drawings but would like to see a 3D view. I have fabricated the part from the old baffle dimensions, but never saw it installed. Does anyone have a good picture or can take one?

    Thanks,
    Todd
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  2. #2

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    Default Re: 50 Pacer engine baffles

    Here are a few photos I took with my cell phone last night. Maybe these will help until someone can post some better pictures with the cowling off.
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    Default Re: 50 Pacer engine baffles

    Frogdad,

    Great pictures, thanks. Next time you have the cowling off I would love to see how the baffles attaches between the cylinders. It appears to me that the baffle is straight back with no cut outs for the cylinder fins.

    Todd

  4. #4
    Administrator Steve Pierce's Avatar
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    Default Re: 50 Pacer engine baffles

    Quote Originally Posted by 61Chuck View Post
    It appears to me that the baffle is straight back with no cut outs for the cylinder fins.

    Todd
    That is how the Clippers were as well.

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    Default Re: 50 Pacer engine baffles

    Steve,

    I saw the print for the baffle on the clipper, which is almost identical to the pacer. Does that baffle attach at the rear to the inter-cylinder baffle with the same rod and tubing or does it have its own rod and tube ?

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    Administrator Steve Pierce's Avatar
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    Default Re: 50 Pacer engine baffles

    I don't remember an inner cylinder baffle.

  7. #7
    PeterL's Avatar
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    Default Re: 50 Pacer engine baffles

    Interesting subject, my Pacer with 290D2, has the baffling that is open at the bottom of the cyl. in the front. Most engines have the bottom blocked which would force the air up and over the cyls for the greatest cooling. My baffles look fairly new which makes me wonder if they are correct or not. Have to check the CD.

    Question, has anyone installed a baffle just inside the front that covers around the propshaft to help reduce drag.

    Peter.

  8. #8
    Zac Weidner's Avatar
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    Default Re: 50 Pacer engine baffles

    Our 160hp PA-22 has a long rod between the front and rear baffles, each baffle wrapping part way around the fins, with a nut on each end of the rod. The inter-cylinder baffles are independent and have their own rod with an 'S' hook on each end and a rectangular plate on the top that 'hangs' the baffle and keeps it firmly in place. I can try to find some pictures when I get home tonight.
    The inter-cylinder baffles are Lycoming parts, so they will be in the engine parts illustration.
    I remember having some trouble figuring all the baffling out as well, because our baffles were all thrown in a box and I had to put together the puzzle, much like the rest of the airplane. We also had extra baffling from some other airplane.

  9. #9

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    Default Re: 50 Pacer engine baffles

    Oh, yes... The inner cylinder baffles came from Lycoming already installed on the shipped engine. The rest of the baffles were "airframe parts". These intercylinder baffles are absolutely required to force the cooling airflow to flow THROUGH THE CYLINDER FINS, as with the "open hole" between the cylinders, the air flow would follow on of the basic laws of fluid dynamics, and flow through the "path of least resistance", robbing the cylinder fins from their intended airflow. On the right side, the front section "bottom" airframe baffle is longer than the left side and uses a second vertical rod (or, a spring on certain installations) through a tube with flattened ends (similar to, but MUCH shorter than the tube that goes between the "jug" part of the cylinders which has a wider gap). Right and left hand side inner-cylinder baffles were the same Lycoming part number (on a given model engine) and both sides used the longer tube "strut" to lock the baffle in place. Anyway...the right side lower has a shorter "strut" between the heads and serves to keep the longer back end from slapping the cylinder (and gettin "grooves" worn into it in not too very many number of hours). Then, the lower edge of the REAR lower bafflle is held to the front lower baffle by a threaded rod to keep the rear baffle tight to the cylinder fins.

    The left side is similar, but the front and rear LOWER baffles are more nearly the same length, and the bottom edge of the aft baffle is attached to the rear (bottom) edge of the inter cylinder baffle with it's own "threaded rod". Then, the front bottom edge is tied BACK to the front edge of the inter cylinder baffle with another rod.

    If that's too confusing, lemme try it THIS WAY... the right lower baffle never locks into the inner cylinder baffle on that side in the front, nor to the aft baffle, at all. Put another way, it's two PIECES locked together, and a tube supports the inter cylinder baffle in place without it being attached to anything in it's lower front. The right front [bottom] is a third piece that attached separately, and was held up by another separate vertical "hanger" off a "tube" between the cylinder HEADS, and extends under and PAST the inter cylinder baffle (even tho' the inter cylinder baffles are the same p/n on both sides, the one on the right only used the AFT hole to attach to the rearmost baffle with a rod. The LEFT loer side installation is three baffles "bolted together in a line" and forms "one solid unit". Only the inter cylinder baffle is "suspended" from a rod on the left side. I have NO IDEA why Piper did it this way rather than doing the same thing on the right side as they did on the left. But this is something you can only "know" by having directly dealt with these baffles before somebody Butchied it up and did it their own [wrong] way. More inter-cylinder baffles are found months or years later in a cardboard box as "leftover parts" after an amateur "restores" an airplane. You can't "read this stuff ion a book", and I have to admit it isn't "all that clear" from the Drawings...but if you had seen and worked on "unwrenched" units that came from the Factory, THEN sat down with the Drawings, you can "see it" immediately. Counting on "how something was when you took it apart" is always a TRAP, because more times than not...the "Last Guy" didn't know how it was done, either! Later "more modern airplanes and engines" did stuff differently sometimes.

    edit; Zac's Post, being "sent" just before mine, speaks to the LAST SENTENCE in mine. This may VERY WELL be exactly correct FOR ZAC's ENGINE. But the -235 and -290 engines used on ON THE 1950 PA-20 Pacer where baffled the way I have detailed. Did Piper do it "right or wrong" or "better one way than the other"? I do not know. You'd hafta ask Piper. They did it "right, for the way that they did it", of THAT I am sure.
    Last edited by JohnW; 02-03-2012 at 08:59 AM. Reason: speaking to Zac's Post

  10. #10

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    Default Re: 50 Pacer engine baffles

    PeterL; you're baffling is incorrect, as far as having no "bottom baffle at the front". NO Piper shortwing had such an arrangement with a Lycoming engine. The inleted air through the nose cowl was "forced" to travel OVER the cylinders on both sides, then dammed at the top and forced to flow DOWN, IN BETWEEN the cylinders. They ALL (including the O-145-B2 in the -15, which had a "closed box" built around the heads) had baffles mounted between the cylinder "jugs" to force as much air to travel DOWN between the cylinder fins themselves as was available. NO Lycoming powered shortwing had the airflow allowed to "bypass" the designated flow path. You must run high temps all year! You need to correct that.

    Furthermore, NO Piper shortwing had to have "mini-baffles" installed alongside the opening, near the cases. Believe me when I say that when you install proper original baffles, there will be NO SUCH necessity as that. Yes, I am fully aware of Maule 5s and 6s that have the baffling that you ask about. They must need them...they are woooly monsters, and if nothing else they probably go SO FAST through the air that baffles like "Our Old Girls" have may have flapped in the breeze and dumped cooling air everywhere EXCEPT across the fins.

    You have perfectly "proved" my "Last Guy" comment (thx).
    Last edited by JohnW; 02-03-2012 at 09:17 AM.

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