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which carb do I want for an O-320-E2A

IowaRV9Dreamer

Well Known Member
The Lycoming Parts Catalog lists four different carb part numbers for my O-320-E2A. They are all MA-4SPA, but have the following numbers:
10-3678-32
10-4910
10-5009
10-5135 - UPDATE - I found a previous post that recommended this one as the "richest" of the bunch, which will help for both 160HP and for Vans higher airflows.... so I guess I'm all set. Sorry I couldn't find the way to delete a post.

Does this mean any will work and be legal for a certified engine?

Also, if I convert to 160HP pistons will that influence my choice?

Thanks for any info,
 
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My O-320 D model uses the 10-5135 carb

Dave,

My O-320 160 hp D3G model uses the 10-5135 one according to the parts list I have. If you can find the parts list for your engine it should say. The parts list I have is for B and D models. I asked for a link for the parts list on this forum and someone replied back with the site I downloaded for my Lycoming model.
 
The certified part numbers are not always helpful because - as has been said before - the Van's airbox flows more air than any certified airbox, so the carb tends to run leaner. That's often why the 5135 is recommended. My experience on converting to 160hp was that I needed all the fuel I could get!

Pete
 
My O-320 160 hp D3G model uses the 10-5135 one according to the parts list I have. If you can find the parts list for your engine it should say. The parts list I have is for B and D models
My parts list is for -A and -E models, and it lists all 4 part numbers as applicable to my -E2A. That's why I'm confused. Seems funny that I can use one of 4 carbs and still be a certified engine... but maybe it's because the same engine was used by different airframes? I wonder what the difference is? I'm going to email Tempest and find out.
 
TCDS has carb number/model?

Would the Type Cert Data Sheet have the carb number for a given engine? And do you really need a rejetted carb on a RV? Mine works fine as is.

Also, Lycoming says it's a no-no to simply go with high compression pistons to raise a 150hp engine to 160hp, boost comp to 8.5:1....If that's what we're talking about here.

Lyc even points out that simply hanging fuel injection on a carb'ed engine is a no-no.

Do people do this stuff all the time? Perhaps. The Lycoming Flyer gets into a lengthy discussion on these topics, the whys and the why nots.
 
Would the Type Cert Data Sheet have the carb number for a given engine?
Nope - it seems to just call out the model number, not the part number.
Also, Lycoming says it's a no-no to simply go with high compression pistons to raise a 150hp engine to 160hp, boost comp to 8.5:1....If that's what we're talking about here.
Hmm... I'm not sure what you are referring to? How does Lycoming "say" not to change pistons to increase HP?

I'm planning on converting my -E2A from 150HP to 160HP by changing pistons (and wrist pins and cylinders), and I believe I will have a legal, certified engine when I'm done. That is because I plan to implement this STC, which I think is actually this STC. I believe it essentially converts an E2A to a D2A. Note that the STC applicability list only includes a couple of O-320-Exx engines. Note also that the STC apparently changes the carb, which was the original question.
Do people do this stuff all the time? Perhaps. The Lycoming Flyer gets into a lengthy discussion on these topics, the whys and the why nots.
I found the following in the Flyer Key Reprints:
Lycoming builds O-320 engines that produce 150 HP or 160 HP. The 150 HP O-320-E series engines operate at a compression ratio of 7.0:1. The O-320-D series has high-compression pistons which raise the compression ratio to 8.5:1, and increase rated output to 160 HP. Those who believe that the pistons are the only difference in these engines will be disappointed if they plan to upgrade their O-320-E to the higher horsepower by simply changing pistons. Many models in the O-320-E series were designed for economy. Thousands of these low-compression engines were built with plain steel cylinder barrels instead of the nitrided barrels used in the O-320-D series engines. They also had two narrow bearings instead of one long front main bearing. The engines were certified at 150 HP and were not intended to withstand the additional stress of higher horsepower.

The way I read it is that some E series engines can be converted, and some cannot. Looks like Lycoming wants to you have the large main front bearing, and nitrided cylinders. I think I'll be good to go on both counts.
 
(Slightly OT) While all that has been quoted has been stated by Lycoming it is not necessarily borne out by experience. Lycoming is not in the business of helping builders to modify their engines away from TC standard. Years of field experience has shown that, for the number of hours that the average homebuilt flies, modifying and E series O-320 to 160hp by fitting high compression pistons works just fine. A better solution is to fit 160hp cylinder assemblies. Most people leave the front bearing the same and don't have any problems. The same applies for fitting Fuel Injection. Its not cheap but perfectly possible, Airflow Performance have kits to use the primer port if your cylinders don't have injection ports drilled. All these changes are a well trodden path.

Pete
 
Do you have the longer forward main bearing?

Dave,

Do you know if you have the longer forward main bearing on your engine? I see where you posted you thought you were good to go but just wanted to reinforce that would be preferred for the higher horsepower.

While rebuilding my engine I had to change cases and the two rear bearings were different even though I was using the same series of cases. I didn't discover this until I split the cases apart ready to get the crank in. I had ordered the bearings based on the previous cases after miking the crank. It took about four phone calls between myself, the parts supplier and serviced case supplier until I got the correct ones for my serviced replacement cases.
 
here we go

Some may not be aware of the Lycoming Flyer, what's in it. My point was if you have the 160hp Lyc, it does not simply have higher compression producing pistons, and/or the IO vs O model did not simply have FI replace the carb.

In other threads, the RVAtor has lots of pertinent information that goes to the subjects of those threads as well.

If you're already familiar with these pubs, then fine and dandy. Carry on at a high rate of speed as a friend of mine is prone to say.
 
Lycoming

If you search the lycoming yahoo forum you will find much info on all these subjects. Many posts by Mahlon Russell from Mattituck on all these issues. Basically he says it is ok to convert 150 hp to 160 hp with the four bearing setup and plain steel cylinders. The cylinders are mostly a wear issue. Over 160 hp I personally would want the D style front main bearing. On the carb, at some point the main nozzle was changed to a more efficient design, and this would be the most desirable carb. At least some carbs can be upgraded to equivalent of latest design for homebuilts.
 
Some may not be aware of the Lycoming Flyer, what's in it. My point was if you have the 160hp Lyc, it does not simply have higher compression producing pistons, and/or the IO vs O model did not simply have FI replace the carb.

Link,

I am certainly aware of what is in Lycoming Flyer. However, I think you need to bear in mind Lycoming's desire to sell spare parts, protect the company from any kind of litigation and uphold their reputation. They are not about to tell you that its OK to modify their products. Field experience says the modifications we are talking about are satisfactory and do not lead the engine to self destruct in 100 hours. Will it self destruct in 1000 hours? Who knows? With most people only flying 50 to 100 hours a year there is really no way of knowing what caused an engine to start making metal 1000 hours and 10+ years after higher compression pistons were installed.

As for the changes between an O and an IO not being just the FI parts being bolted on, well that statement is not borne out by the parts catalogue.

Pete
 
The Lycoming Parts Catalog lists four different carb part numbers for my O-320-E2A. They are all MA-4SPA, but have the following numbers:
10-3678-32
10-4910
10-5009
10-5135 - UPDATE - I found a previous post that recommended this one as the "richest" of the bunch, which will help for both 160HP and for Vans higher airflows.... so I guess I'm all set. Sorry I couldn't find the way to delete a post.

Does this mean any will work and be legal for a certified engine?

Also, if I convert to 160HP pistons will that influence my choice?

Thanks for any info,

10 years late but might be worth passing this on.

We received different advice from MS regarding which Carby is richer/leaner at WOT.

(Specifically for an O-320, 150HP E2G converted to 160HP D2A, MA4-SPA 10-5135)

"The 47-828 nozzle used in the 10-5135/5217 carburetors has a main jet size of nominally .093 of an inch."

"The 47-773 nozzle used in the 10-3678-32 carburetors has a main jet size of nominally .1065 of an inch."


Hope this helps someone.

Pat.
 
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And just to follow this up, our newly fitted 3678-32 now produces around 10-13 LPH more fuel flow during the takeoff run than our original 5135.

Gone from an unreliable reading of 45 to rock solid 57 LPH thanks to the new carby and repositioning our RedCube.

We now also get better climb performance and more importantly much, much cooler CHTs for the entire climb regime.
 
Which carb?

I've got the 5217 carb in my o320-D1A (160hp) and I'm having issues with CHT temps. I've had the AVSTAR (Marvel Schebler competitor) folks enlarge the main jet and it has helped, but I'll still see 420 degrees on climbout on my #3 Cylinder (it would exceed 435 if I didn't intervene before the enrichment). AVSTAR is saying the 3678-32 carb will give me at least another 1 GPH. Any other folks have experience with the 3278 carb on a 160hp 0320?
 
I have The 3678-32 on.my 150hp. Huge improvement over the 5009. The 5009 stumbled.during engine break in. Sometimes I lean on takeoff . Happy with this carb and learned from.others on this forum. Rather run to rich than lean
 
I have The 3678-32 on.my 150hp. Huge improvement over the 5009. The 5009 stumbled.during engine break in. Sometimes I lean on takeoff . Happy with this carb and learned from.others on this forum. Rather run to rich than lean

Were you able to get core credit for the 5009? I'm thinking I may need to dump my 5009 and go with the 3678-32. I've got the 150 HP E2G engine.
 
High CHTs fixed!!

I wanted to add this to the conversation.. Just got the new carb on, did one quick test flight, I gotta say, so far I’m impressed. On a -9a with a O-320 160 HP and a 5217 carb, we would get a max of 11.9GPH on takeoff from KVGT (2200 feet MSL) we would have to lower the nose and climb at 120 to 130 indicated to keep the CHTs under 420-430. The engine baffles are tight, all leaks have been sealed up, upper cowling ramps in place.
Now with the new carb (10-3678-32) I am seeing 14.1GPH on takeoff, and I can climb all the way up to altitude (8500 on this quick test flight) at 95 knots and the CHTs never got above 390! And that’s in Las Vegas heat! I’d call that a great success so far.. more data to collect. But I think this solved the high temps we were having. Really wished the original builder started with this 3678 carb from day one!!

Sent from my iPhone
 
My Results With 3678-32 Conversion

When I built my RV6A I obtained an O-320 E2D (150 HP) and the accompanying carb, a 5062N. I had ongoing overheating CHT issues especially on hot days with a heavy load. It was manageable, and for several years I would power back as necessary but sometimes to the point that the climb rate was lackluster. Recently after reading this thread and speaking with Mark at Tempest, I bought and installed a 3678-32. The results have been most favorable. I can now climb out on hot days at full power. Also, the CHT and EGT temperature spreads are lessened making me think that there is less mixture maldistribution. Thanks guys for taking the effort to post.
 
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