500ci rebuild steps...

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Miszny

Miszny

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Hi

I just took the heads off of what was supposed to be a good running engine and this is what I found in all the cylinders. It's a 400ci block from 73.

I was given paperwork for this motor and I see that there were Speed-Pro rings the size of 4.375" with .005 oversize (part# R-9799.005). There is nothing about pistons used and I can't find anything based on part # visible on the piston but I'm guessing they are 4.375" given the rings used. I did not measure it yet, I will next time I have a chance to spend time with it.
It was supposed to be heads swap for TrickFlow 240s and where we are...

This motor did not smoke, did not need oil between yearly changes, made power and started right up. All spark plugs look like the one in photo. Oil was clean, just bit dark, filter had no suspicious elements in it. Also cylinder pressure between 130-140psi on all pistons, idled really nice and had really good oil pressure. So yeah, lets upgrade the heads having this nice healthy motor...

So enough bed time story and to the point:
I see that Icon makes forged 4.382" pistons and 4.402" pistons.
My question is what is the biggest acceptable bore for 4.382" piston?
I'm asking because looking at the bores I think there needs to be like .006-.008" taken off to clean them up so this puts me at 4.388-4.390" bore. I would really like not to do .060" over without trying .040" first...

Thanks for your input.

Mopar.jpg


spark.jpg
 
You said the engine runs fine and does not use any oil so I would just run it. When I changed the heads on mine, my cylinders looked pretty much the same as that. The issue seems to be that the pistons in these combos have really short skirts which leads to piston rock (slap) and that's how the bores end up looking. The other question is what heads were on it? Those flat top pistons will result in a pretty high compression ratio with closed chamber heads. Mine are dished and are at about 9.5:1 with Edelbrock heads. (This picture is when it was first put together)

IMG_1062.jpg
 
qkcuda said:
You said the engine runs fine and does not use any oil so I would just run it. When I changed the heads on mine, my cylinders looked pretty much the same as that. The issue seems to be that the pistons in these combos have really short skirts which leads to piston rock (slap) and that's how the bores end up looking. The other question is what heads were on it? Those flat top pistons will result in a pretty high compression ratio with closed chamber heads. Mine are dished and are at about 9.5:1 with Edelbrock heads. (This picture is when it was first put together)

View attachment 1715109166
Click to expand...
Yes compression will be on high side, looks like 11.3... Now this motor has unported 440 source heads and solid flat tapped cam around .570" lift with pretty high duration. I think these source heads are 80cc so not that big of a chamber change.
This motor only runs on 98 and 100 octane gas.

You say run it and you are not the first to say so.

Thanks for your view on this.
How long did you run your motor with bores like this?
 
I'm still running it. The picture was when I originally put it together in 2009. I changed the heads in 2014. Still clicks off mid 11's in street trim with a best of 119.5 MPH.
 
Just to update, I looked at my notes from cylinder pressure measurements and they were all between 145 and 150 psi. I was not sure initially but remember they were good. This is cold cranking dry value.

Did anybody hear about line 2 line coating? I'm thinking to test their solution...
 
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My previous engine builder(he happily retired) has had pistons anodized for .001-.002 coat to account for wear. I've heard good things about L2L coatings, but no personal experience.

Two guys here at the shop said "compression's good, bearing's ok? Wouldn't even pull it down." S/F....Ken M
 
EchoSixMike said:
My previous engine builder(he happily retired) has had pistons anodized for .001-.002 coat to account for wear. I've heard good things about L2L coatings, but no personal experience.

Two guys here at the shop said "compression's good, bearing's ok? Wouldn't even pull it down." S/F....Ken M
Click to expand...

I heard that anodizing is good for ring area of the piston and saw some racing bike pistons anodized for that reason but they also had some sort of coating on skirts.
 
It burnt no oil, compression readings were good. Why fix what isn't broken? Have the bores lightly honed and stick rings in it. Call it good?
 
moper said:
It burnt no oil, compression readings were good. Why fix what isn't broken? Have the bores lightly honed and stick rings in it. Call it good?
Click to expand...
You mean using like hand drill flex brush hone? They don't sell these things here so getting like 120 and 320 grit + shipping from USA + taxes = price of bore and hone job in a machine shop.
If I go with it to machine shop and ask to hone it out they will tell me I'm crazy not boring it before honing for sure and will refuse to do it :)
It's either re doing it right now with custom piston oversize using line 2 line or letting it run until it starts to burn oil and loose compression and then re do... It a 1300$ decision at this point.
 
Save your money and run it the way it is, it will be fine. Once you change the heads you will need the extra money for new tires.
 
Looks like a Wiseco Pro Tru piston part #. I'd call them and ask.
 
I haven't had the chance to use the Line 2 Line coatings myself but a buddy who is a motorcycle road racer swears by it.

BTW, which heads do you have? Seems strange to use that short reach plug in anything but an OE cast iron head.
 
the op said he is using 440 source head, if so, you Sir are using the wrong plug. a champion rc12yc or ngk fr5 is what I use. they are 5/8 hex for a better fit.
 
fishmens67 said:
the op said he is using 440 source head, if so, you Sir are using the wrong plug. a champion rc12yc or ngk fr5 is what I use. they are 5/8 hex for a better fit.
Click to expand...


Yeah...that's what I was asking. I wasn't sure what head he has, what head 440 source sells. Hell...I wasn't even sure I was seeing the picture of the spark plug correctly.

Old sucks. But it's better that daisy farming.
 
And here I thought he was swapping 452 iron heads for 240 Trick Flow heads. It's tough switching back and forth from thread to thread.
 
IQ52 said:
And here I thought he was swapping 452 iron heads for 240 Trick Flow heads. It's tough switching back and forth from thread to thread.
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Different motor. With spark plugs, now worries the one in the photo is actually from mine 452 but I can guarantee it’s identical looking as plugs from this one. Just didn’t have a photo of correct plug.

You guys are good that you see this difference :-D
 
yellow rose said:
I haven't had the chance to use the Line 2 Line coatings myself but a buddy who is a motorcycle road racer swears by it.

BTW, which heads do you have? Seems strange to use that short reach plug in anything but an OE cast iron head.
Click to expand...

You have good eye, for lack of a photo of plugs from this 500ci I used photo of my plug from 452 head that has identical coloration and all... small stretch I guess ;-)
 
fishmens67 said:
the op said he is using 440 source head, if so, you Sir are using the wrong plug. a champion rc12yc or ngk fr5 is what I use. they are 5/8 hex for a better fit.
Click to expand...
NGK BCP6E plugs were used with previous heads. I did not get away with my photo swap...
 
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