O-320 Cylinder Head Temps

Will Bentley · #1 10-25-2008, 03:50 PM

I have an RV6-A with an O-320 D2J and fixed pitch prop. On climb out my number 3 cyl will go to around 430 degs until I reduce climb. Once cruising it stays in the neighborhood of 340 to 360 degs F along with the other 3 cyls.

I was recently told by a friend that the GAMI guys say the temps should NEVER get above 400 degs unless I'm looking to buy a new jug soon.

Your input on this would be more than appreciated. Do I need to start working on the engine baffles??

Thanks,

Bill

vic syracuse · #2 10-25-2008, 04:38 PM

Bill, how much time is on the engine? If it's new, then that's not out of line. After break in, then you should be able to see less than 400 on an O-320 on climb out.
If it's not new, then make certain you have the carb jetted properly. Plenty of information on that if you search the forums.
What climb speeds are you using? REducing power with a fixed pitch prop takes away some of the cooling effect of the enrichment valve in the carb at full power. Try lowering the nose and let the speed build up.

Vic

Will Bentley · #3 10-25-2008, 05:09 PM

Vic,

Thanks. The engine has 400 SMOH. Great point about keeping the throttle advanced and speed up on climb out. I'll increase my forward speed and see if that doesn't cool that cylinder some. I'll search the forums on properly jetting the carb. I will generally climb out around 110k.
Is there any chance I have done damage by allowing that cylinder to go into the 400 deg F range? My oil samples always come back looking good and my compressions are good.

Do most of the RVs out there stay below 400 on climb out? Should I be concerned? I try to do everything by the book and this one has me concerned. Why is it we treat our RV's better than our kids???

Bill

Radomir · #4 10-25-2008, 05:25 PM

No prob there.. I believe some of the info got distorted by the time it got to you.. Keep in mnd that the red line is 500 deg.. I'm not a proponent of high CHTs, but to suggest that the moment you hit 400 that jug is trashed is absolutely ridiculous ...

rv6rick · #5 10-25-2008, 05:52 PM

Sure....I know what you're talking about but I've been around a while

. I'm also sure that the poster that asked the question won't have a clue as to WHAT you're talking about and WHY he should add the washer

.

If you have time you might volunteer some additional info and elaborate on your (worthwhile) suggestion. This way the poster can get an education and be on the road to solving his issue.

I'd add to it myself but I wouldn't want to steal your thunder

.

Quote:

Originally Posted by LifeofReiley

Try adding one washer to the back side of the #3 baffle... should solve your issue.

-d-

Will Bentley · #6 10-25-2008, 06:07 PM

That's a hoot! Sure nuff...I didn't know why I was going to add a washer to the backside of my nr3 baffle...but I was definitely going to do it. Thanks to the both of you for the suggestion...I'm gonna wait and find out where this washer goes, exactly...and why.

I think I really enjoy troubleshooting this way!

Bill

Will Bentley · #7 10-25-2008, 06:40 PM

I'm heading to the airport now to try this. I'm not precisely sure what to look for, but from your description I'll bet it will be easy. Thanks a lot...think I'll go do some night flying and see what the temps are "down" to...

Thanks again...
Bill

Kyle Boatright · #8 10-26-2008, 09:34 AM

Quote:

Originally Posted by Will Bentley

I'm heading to the airport now to try this. I'm not precisely sure what to look for, but from your description I'll bet it will be easy. Thanks a lot...think I'll go do some night flying and see what the temps are "down" to...

Thanks again...
Bill

On my 0-320 D2J I saw the exact same issue. I added the washer as discussed in this thread and also installed a small cylinder blocker in front of the #1 cylinder. Measured from the inlet ramp, I think it covers an additional 1 or 1.5" of the cylinder head height.

Works like a charm.

Will Bentley · #9 10-26-2008, 04:52 PM

Vic, Rick & Kyle

I've been out changing the oil/filter on my 6A. I placed a washer behind each location where the baffle attaches to the cyl. I flew it and found
all to be the same. I also climbed out at around 120 kts & full throttle but it still went to around 410F..the other 3 cyls were in the mid to high 300s.

Kyle, can you amplifly a bit on the fix you were talking about regarding
the nr1 cyl blocker. And anyone else wanting to input...I'd be very receptive.

Bill

vlittle · #10 10-26-2008, 06:10 PM

Quote:

Originally Posted by Will Bentley

Vic, Rick & Kyle

I've been out changing the oil/filter on my 6A. I placed a washer behind each location where the baffle attaches to the cyl. I flew it and found
all to be the same. I also climbed out at around 120 kts & full throttle but it still went to around 410F..the other 3 cyls were in the mid to high 300s.

Kyle, can you amplifly a bit on the fix you were talking about regarding
the nr1 cyl blocker. And anyone else wanting to input...I'd be very receptive.

Bill

Your symptoms may be explained by a couple of things that are easy to check:
1) Induction leak on cylinder 3 causing it to run lean. Check Intake runner for leaks.
2) Cylinder casting flashing on the cylinder fins between the spark plugs. Look down between the plugs and see if the airflow is being blocked in this area. Compare it to your other cylinders. I cleaned out these flashings and saw a 30-40F reduction in measured cylinder temps.

Vern