Baffle Mod - Page 2

Arizona RV7A · #11 01-06-2009, 04:32 PM

My 7A has a AFP FI Superior O-360, with a James cowl and plenum. #3 cylinder always ran about 20 degrees hotter than #4. This was not typically a problem until climbing out of Phoenix in the summer, when #3 would get up to 420F or so (per the ACS-2002 readout). I saw Chris' post back in August 2007 and thought it was impossible until I tried it today -- a standard washer really does drop the temperature by over 20F! Seeing is believing! Thanks!

David-aviator · #12 01-07-2009, 12:01 PM

I was looking at my engine today and thought I'd check the clearance between baffles and fin area. Heck, I can see day light all the way down to the bottom baffles on the front and aft sides of the cylinders. There seems to be exposed fin area all the way through except maybe between 2 fins. I even poked a thin rod down to confirm it.

Could it be what your images show closed fin area of the angle valve cylinders? It does not seem to be the case with parallel valve engines.

Could also be I am missing something here....

DanH · #13 01-07-2009, 03:47 PM

David, mine is an angle valve. I don't remember what a parallel valve looks like on the intake side. It has been ages since I've seen one naked, and well, I'm 53 <g>

Anybody have a close-up picture?

revenson · #14 01-08-2009, 07:33 AM

Quote:

Originally Posted by Tom Martin

Another method, that I have used many times, is to rivet a piece of 1/8" flat bar to the outside of the area that Dan is modifying. The flat bar goes in the location where the mounting hole to the cylinder is. It is about a couple of inches long. This is a simple modification, solves the cooling problem, and strengthens the baffle at the attach point.

Tom, I can't visualize your method. Any pictures?
Roger Evenson, 7A finishing

DanH · #15 06-10-2009, 10:47 AM

Bumping an old thread.

Doug posted two photos of a new ECI engine on the front page today, and I noticed something interesting about the ECI cylinder head.

Looks like ECI tried to address the "no fin depth" problem on the intake side of the head. Three fin gaps are still fully blocked, but the majority seem to have depth enough for some flow to the lower fin set.

dealfair · #16 06-13-2012, 03:04 PM

Hi Gents,

I'm experiencing high cht's on climbout on my James cowled -4. I remember seeing this thread and resolved to look it up and make some changes. I see Doug is down on donations so I just made one today. This forum has helped me out so many times ... I really appreciate everyone's input.

Thanks to all for sharing your info and Doug for keeping this resource alive.

Cheers,

N8RV · #17 06-13-2012, 03:21 PM

Just out of curiosity, Dan, couldn't the same effect be obtained by using a couple of spacers as others have done but seal the unwanted space with a bead of high-temp RTV?

(I never knew that this was an issue, and since all of my CHTs are good and within about 10-15 degrees of each other, I don't think I'll mess with it.)

[EDIT: I didn't read the whole thread. I have ECI cylinders. Maybe that's why it hasn't been an issue for me. Duh.]

Captain_John · #18 10-21-2012, 08:23 AM

Dan and All,

I am mocking up my baffles now. I have hammer formed a duct that is probably about 3/32" deep behind the aforementioned area.

It really isn't too visible in this pic because the bend in the baffle somewhat obscures it. Nevertheless... I am wondering if I should be concerned with the gap I have parallel with the cylinder extending outboard or if I should simply install shims and call it done.

Would that also aid in cooling this problematic area???

I welcome opinions!

CJ

DanH · #19 10-26-2012, 04:43 PM

Quote:

Originally Posted by Captain_John

.. I am wondering if I should be concerned with the gap I have parallel with the cylinder extending outboard or if I should simply install shims and call it done.

Sorry for the delay John...missed your post.

In general I'd say promote flow where there are fins present, and minimize gaps that have no fins.

The finless area on the intake side of the cylinder head starts just inboard of the injector and extends outboard to the valve cover. Mine has a bead of black high-temp RTV there, but a small gap (1/16") can't hurt and may even be beneficial.

Captain_John · #20 10-26-2012, 10:04 PM

Thanks for the reply Dan.

I am leaving it like it is then.

Will let you know how it runs!

. CJ