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540 rods in 470 continental

G

gat2013

Active member
Has anybody had the chance to run the 540 rods in a 520 or 470 and if so can you tell a diff. just looking for any info on the subject thanks..
 
I asked a bit back if there was any type of chart to compare ac engine stuff like the rod stroke, piston Dia , cyl bores , Hp ect the only one I was told of was the Hp vs weight chart . if you want that I get the link for you later today and post it
 
The Lycoming rod is about .125 longer. There are two journal diameters there is a small journal and a large journal Lycoming. The Contenetal and Lycoming Large journals are the same diameter so you can just swap rod's. However most people put the small journal rod on a Contenetal crank when they do this they offset grind the crank to the small journal size this can add up to .100 more stroke if you use a standard crank. I have done this but the two rod's have a different width at the big end. So there is a large gap between the rods on the crank journal when you run Lycoming rods on a Contenetal however since these motors only turn 3,500 and don't need much oil pressure to live, it works. If you look in my gallery there is a picture of a Green GPU470 with Lycoming small journal rod's with a .100 stroked crank from offset grinding!
 
Jim,

it sounds like gat2013 was asking if anyone has tried a stroker ac engine if I understood his post right but those charts should give him some good Reference material , I would like to hear those results also :?:

As for me........... my comment is "You the man! :D :D " that is just the charts I have been trying to get a hold of :D :D I will have to see if I can get some 0-1430 rods tomorrow when I am out putting up my case for that 550 build :shock:
 
Actually, I think the extra length on the Lyc rods just puts the piston up more in the bore at TDC, so it would have a smaller combustion space and therefore a higher compression ratio.

But as Thunder pointed out, using the small journal rods allows for offset grinding of the crank throws. That moves them out away from the centerline of the main journals, and therefore increases the stroke. This will ALSO increase the compression ratio in 2 ways; for one, it increases the displacement which increases the compression if the chamber size stays the same, but it also raises the piston even more at TDC, which is decreasing the size of the combustion area.

It amazes me how much extra space is built into the combustion chambers on these engines. Try that with an auto engine and you will have a lot of piston sticking through the bottom of the cylinder heads!!!
 
When I stroked my 470 and installed the 1/8'' longer rods I also had custom dome pistons made so I could cut the chamber and build my own quench pad in the head and piston! Like you do with the 440 Mopar or 340 Mopar. Most jug's will need to be either bored or have the lip removed at the very top of the bore. My pistons actually hit the heads but I did this on purpose so I could cut a new chamber in the head and have some quench!
 
can you tell a diff. in the rod change i mean i realize its not like NOS but i would assume it has to make a noticeable diff. in performance.
 
Out of the 20 or so things I did to a 220GPU the largest improvement’s I found was in ring seal. I used Iron rings with the second ring being gappless, this made a bigger difference then stroking it, a longer rod, a dome pistons or a cam even a 2 barrel Holley. I built a few 220GPU’s with the small dome piston with gapless rings with a good 5 angle valve job. A stock 220GPU doesn’t use valve seals. I learned the hard way when I improved the ring seal so much the motors were sucking a ton of oil past the guides and I had to start using valve seals. Ring seal in a automotive or aircraft engine is one of the biggest factors for throttle response and low end torque! A motor with poor leak down will not make any good bottom end power. The accepted leak down numbers are for engines operating at higher RPM’s. I try to keep all the car motors below 5 %.
 
thunder,
where those 220's with stock jugs or 520,540, or 550 jugs any other recommendations for those 220?? 550jugs, cam 4 barrel Holley carb???
 
The 520 and 550 jug's have the same bore 5.250 the difference is the stroke of the crank! However putting 520 jug's on a GPU will increase the cubic inches it will actually make it a 520! The 470 and 520 have the same 4.00 stroke the bore is what's different! The 2 barrel Holley 500cfm is the best way to go. I tested at least 4 at least intakes and 5 or so carb's and the 2 barrel with the carb on top the intake worked the best!
 
ok is the two barrel Holley just better compared to the other two barrels or would a four barrel add more power?or is the reason to stay with two barrel simple fuel economy? here is the reason I ask I just started building a 220 case with 550 jugs and figure I will have to fabricate a intake that comes to the front of the engine and I have a 4 barrel Carter (old model with is now Holly) laying around extra and i was thinking of use that but if the two barrel is that much better I will start looking for one
 
Gold, The predator carb works very well on the gpu/520 conversion. JC Stanley builds an intake for the gpu conversion to adapt a holley or predator. Skeeter has run both carbs and likes the predator best.
 
I can build a aluminum intake adapter just have to decide if I want the carb in front of the engine or on top and what carb to use . I was leaning towards the four barrel just because I had one and would not have to buy a new one but it sounds like I should just buy one of the two barrels
 
The Predator works the best but the other four barrels don't run any better then a 500CFM 2 barrel. I ran a 390 CFM , 450 CFM, 500CFM, 600CFM and 650CFM four barrel and the 500CFM two barrel out performed all of them
 
77 jets, 10.5 power valve. on the 500 2bbl holly.
also the rise (from top of the flat part of the intake to the bottom of the carb flange should be 3.25 to 3.75 inches, not just flat on top.

Also a problem I had on my GPU was I had to put a piece of sheet metal on the back of the filter element (toward prop) to keep the prop from sucking air/fuel out the top of the carb. When the filter would turn around, the motor would run crappy.

Bob
 
Swampjet,
the plate if I understand correctly is mounted behind your carb witch is on top of your engine like a standard GPU (right?) would I have the same problem if I mounted in front of the engine like this picture? picture is one O found on airboat trader but is how I was thinking to build my intake would I still need the plate or would that be far enough forward to not bother it?

Robert

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