520 Continental rebuild

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aherr520
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Re: 520 Continental rebuild

Post by aherr520 » Thu Jan 24, 2019 4:26 pm

get a good high torque starter, the factory starter kept breaking on mine because of the compression
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Re: 520 Continental rebuild

Post by flcracker9 » Fri Jan 25, 2019 6:59 am

rowdy1 wrote:Maximum lash is .200, I think the range is .60 - .200 I have two intakes at nearly .250. I live in a world where .035 valve lash is huge, .250 is a quarter inch! I ordered adjustable push rods from Smith Bros this morning. I hope to set them all at .85 - .90 at least they will all be the same.
I hear ya, when I was advised I could go up to .250 I said, are you kidding me, that's a quarter inch!!! like I said in my previous reply, I converted to adjustable pushrods, disassembled my lifters, cleaned and reassembled them, and set the lash at .090. Sounds like you got it licked.
12' Open Palm Beach, IO-0470-L 260hp, 72" NGQ

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Re: 520 Continental rebuild

Post by rowdy1 » Fri Jan 25, 2019 10:40 am

I got a Norman Clays starter/alternator set up delivered Thursday afternoon. I will get on it Saturday morning and hope to have this thing running by Sunday.

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kwanjangnihm
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Re: 520 Continental rebuild

Post by kwanjangnihm » Fri Jan 25, 2019 2:47 pm

how is the battery, cables and grounds? all connections good & clean?
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Re: 520 Continental rebuild

Post by rowdy1 » Fri Jan 25, 2019 3:22 pm

Brand new Optima 1000 cca battery, good cables, clamps and grounds. The aircraft starter doesn't have the nuts to turn it. Hopefully by noon tomorrow the new setup should be ready to spin it.

Gary S
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Re: 520 Continental rebuild

Post by Gary S » Sat Jan 26, 2019 6:57 am

Have you checked the brushes in the starter motor? Its been sitting a while during your rebuild.

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Re: 520 Continental rebuild

Post by John Fenner » Mon Jan 28, 2019 11:52 am

Be sure to put a slug into the bushing for the starter drive in the case or it will dump oil pressure off.
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Re: 520 Continental rebuild

Post by flcracker9 » Mon Jan 28, 2019 1:55 pm

John Fenner wrote:Be sure to put a slug into the bushing for the starter drive in the case or it will dump oil pressure off.
I didn't have access to a lathe when I did mine, so I used a bolt with a shank slightly larger than the hole, cut the threads off, and ground the shank down till it fit into the bushing snug. Then I cut the bolt to length so it just fit under the starter hole cover I made out of aluminum, with the shank seated into the bushing. This way the bolt head will hit the cover before the shank backs out of the hole (if all that makes sense?). Been running like this for 4 years with no issues.
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Re: 520 Continental rebuild

Post by rowdy1 » Mon Jan 28, 2019 3:00 pm

I was going to try to tap the hole and put a set screw in it. You way is probably easier!

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Re: 520 Continental rebuild

Post by Gary S » Mon Feb 04, 2019 7:16 am

Did you get your starter? If so how does it run?

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Re: 520 Continental rebuild

Post by rowdy1 » Mon Feb 04, 2019 2:42 pm

I did get in running. Fired right up, 70 psi oil pressure. I did (2) 15 minute runs. Zero valve train noise! The old motor sounded like there was 5 dollars worth of quarters flailing around in it. However, its running to lean. Spark plugs are still white, like brand new. Manifold vacuum is 15 inches @ 800. I only let it idle long enough to check it. GMAC rebuild the carb about 6 months ago. I need to talk to him about putting more fuel into it. My fuel pump seems a little weak, bounces between 2.5 -4.5 psi. I did check all of the intake hoses and clamps, and used brake clean to check for an intake leak.

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Re: 520 Continental rebuild

Post by John Fenner » Mon Feb 04, 2019 3:30 pm

What carb? Ma6 or 4-5?
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Re: 520 Continental rebuild

Post by rowdy1 » Mon Feb 04, 2019 9:05 pm

MA 4-5, according to GMAC it is one of the best versions you can get. I did try to adjust the carb using a vacuum gauge (like you would adjust a Holley) I couldn't really get the manifold vacuum to change, but I could here the motor tone change. Im hoping someone can tell me how many inches it should pull at idle. The motor seems to have lots of compression!

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Re: 520 Continental rebuild

Post by GMAC 76 » Mon Feb 04, 2019 9:35 pm

The carb was an MA-4-5.......10-4404....OEM 0-540 260HP engine....there is no bigger stock jet than the 47-779 that is in that carburetor that I am aware of.....it is essential that the l/r lever be in the full rich position at all times...and an adjustment of the economizer may help...I seem to have heard of this problem before on the carb converted 520 with the log intake and it had something to do with the size of the crossover pipe or a leak in the crossover pipe on the intake system...... also the 6AA helicopter carb for the 540 works well on this conversion

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Re: 520 Continental rebuild

Post by John Fenner » Tue Feb 05, 2019 8:54 am

I would suggest an MA 6, use the aneroid to adjust fuel mixture by backing it out a 1/4 turn till plugs tan up. Or have a manifold built to hold a Holley 500 with #78 jets.
Also, main jet in the 4404 can be drilled out, it just takes many R&R of the bowl to get it fatter, I would ream the pilot jet a wee bit as well.
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Re: 520 Continental rebuild

Post by GMAC 76 » Tue Feb 05, 2019 9:23 am

John Fenner wrote:I would suggest an MA 6, use the aneroid to adjust fuel mixture by backing it out a 1/4 turn till plugs tan up. Or have a manifold built to hold a Holley 500 with #78 jets.
Also, main jet in the 4404 can be drilled out, it just takes many R&R of the bowl to get it fatter, I would ream the pilot jet a wee bit as well.
I agree John that is some good info.....but I always wonder why the main jet on a carb designed for 540ci engine has to be drilled out or on the 6AA reset to work on a 520ci engine.....seems like it should provide enough fuel as it is......I have done the adjustment on the 6AA carb AMC unit as you suggested and it works well but is a very patience testing procedure...LOL

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Re: 520 Continental rebuild

Post by John Fenner » Tue Feb 05, 2019 10:32 am

Feeding the lower velocity of the intake system, 540 has single plenum going to 2" tubes, 520 has 2-1/4" logs.
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Re: 520 Continental rebuild

Post by rowdy1 » Tue Feb 05, 2019 5:49 pm

Greg, do you have a 6AA carb I could try? You know, I have a sweet MA 4-5 we could trade if it works. I have a brand new Holley 500 from another project I can try next if the 6AA doesnt work.

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Re: 520 Continental rebuild

Post by GMAC 76 » Wed Feb 06, 2019 9:04 am

I do not have one at this moment but I have several carb cores coming from Airzona and I believe there is a 6AA in that bunch maybe 2....

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Re: 520 Continental rebuild

Post by rowdy1 » Wed Feb 06, 2019 9:36 am

Is there any logic in drilling out the jet on the carb I have now, or am I wasting time and money?

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Re: 520 Continental rebuild

Post by John Fenner » Wed Feb 06, 2019 9:49 am

Yes, I have drilled the jets to tune engines many times, like I said above, it is repetitive to pull the bowl to sneak the size to where it is tanning the insulators, I would suggest number drills of good quality, spin nozzle in drill and hand feed bit through jet, the jet does come out of the nozzle FWIW I have made new jets, and put Holley jets into them as well also built nozzles, too, never have had to touch the economizer seat adjustments, treated the carbs as they never had it, as they are glorified tractor "model A" carbs.
As I stated above take the pilot jet out to the next little red pubic hair reaming it to a tiny bit bigger.

P.S: the Holley will respond better and burn a lot less fuel!!
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Re: 520 Continental rebuild

Post by rowdy1 » Wed Feb 06, 2019 9:58 am

I am exploring the Holley option as well, I just happen to have a fresh rebuild w/ a 50cc accelerator pump.

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Re: 520 Continental rebuild

Post by GMAC 76 » Wed Feb 06, 2019 10:05 am

if in fact your are 100% sure the engine is running too lean and needs more fuel then the only way to provide more fuel on the 4-5 carb would be to enlarge the main nozzle/jet....but like John said it is a time consuming job till ya get the results ya want cause ya need to drill in such small increments and then test it on the engine ......but it can be done....but be very careful....you could easily ruin a $175 nozzle/jet

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Re: 520 Continental rebuild

Post by John Fenner » Wed Feb 06, 2019 10:14 am

Can solder jet and redrill smaller if gone too far, but yes, baby steps when sizing up.
Holley 500 comes with 50cc accelerator pump, put a power valve plug in it and #78 jets with a #31 squirter nozzle, try both and do fuel consumption trials :toothy7:
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Re: 520 Continental rebuild

Post by GMAC 76 » Wed Feb 06, 2019 10:49 am

my neighbor here at the fish camp has a 520 gpu conversion with the holley setup and it is really sweet......fuel consumption is real good and acceleration is terrific...actually seems like a better application for the log intake system to me

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