Raffle 262 builds

[CJ Brown]

It's kinda funny that @PA Dan and I were talking a few days ago about recording all the port timing numbers in various 262XP cylinders, then running them all back to back to see what numbers worked the best. And here you are doing something along the same lines. Good stuff!

 

[RI Chevy]

LOL. Just funnin ya Dan.
Keep up the good work. I am enjoying your thread. Living vicariously through you, as I do not have the expertise to do what you guys do. [emoji106]

 

[p61 western]

When I get some more time to go over this I'm going to. Thanks for sharing this method of measuring.

 

[paragonbuilder]

It's kinda funny that @PA Dan and I were talking a few days ago about recording all the port timing numbers in various 262XP cylinders, then running them all back to back to see what numbers worked the best. And here you are doing something along the same lines. Good stuff!

Well if we think about that we know the KS cylinders are hot rods out of the box, and look at those numbers, we can learn something I think.


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[CJ Brown]

Dan, can you tell us what method you are using to calculate timing in degrees from the position of the piston in the cylinder? Do you use a formula, or is it a program you have?

 

[paragonbuilder]

I use this program to save on more math...
http://torqsoft.net/piston-position.html

There are a few things that need to be considered when using it.

It calculates from distance from top of piston at TDC, to port opening.

So squish measurement is involved, as well as piston height for the intake.
Also I measure from the base down to the ports and need to convert to piston down.
I do this because I can get a more accurate measurement this way.


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[CJ Brown]

I use this program to save on more math...
http://torqsoft.net/piston-position.html

There are a few things that need to be considered when using it.

It calculates from distance from top of piston at TDC, to port opening.

So squish measurement is involved, as well as piston height for the intake.
Also I measure from the base down to the ports and need to convert to piston down.
I do this because I can get a more accurate measurement this way.


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That's great - thank you Dan!

 

[paragonbuilder]

Honestly it’s probably quicker to put a wheel on, but somehow all the numbers help me see what’s going on.



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[RI Chevy]

Have you ever cross checked the mathematical compilation with the degree wheel for accuracy?
Sort of double checking your measurements.

 

[paragonbuilder]

Have you ever cross checked the mathematical compilation with the degree wheel for accuracy?
Sort of double checking your measurements.

If I measure and do the math right, it’s more accurate than a wheel. It’s really not hard, just got tedious today with all the cylinders.
I haven’t used a wheel to check yet, but I know Doc has.
Also more room for error with the wheel, so which one would I trust if they were different?
The numbers I came up with today are all within what I would expect, except the low blowdown on cyl #4, so I double checked it.
It’s just a oddball I guess


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[RI Chevy]

OK. Cool. Just asking. I was good in math in college. Just a way to check yourself and your answers.

 

[drf256]

Try a 106.5 Ex and a 78 intake Dan. The intake already has more area stock than the intake tract, so just lower the floor and round the corners into the factory vertical sides. You’ll be a happy man.

Thanks for taking the time to do this.

Do you find the KS to have bigger transfer tunnels than the Mahle? That’s what people claim. I can’t tell if it’s an illusion or not.

 

[CJ Brown]

Mahle transfer tunnel:


KS transfer tunnel:

 

[RI Chevy]

Wow. From my screen looks like KS jug has bigger tunnels and bigger ports.

 

[Sleeper]

Wow. From my screen looks like KS jug has bigger tunnels and bigger ports.

Yes... and it definitely shows when you run each cylinder stock... but it should not be hard to make the Mahle cylinders look real similar and perform just as well. Maybe not as well as a "unicorn" KS, but as well as an average KS that was lightly and properly worked over.

I have yet to run a 262, but I like my stock 372 XT, I know I'll like the ported 262.

Which reminds me, I will be picking up a bar for it tomorrow. Yes, a 20" as hearing 24" is pushing it and especially 28" are beyond the capacity of the oil pump.

Like the idea that it will be using the same chains as my 372... 72 DL 3/8" .058" Just simplifies things.

 

[PA Dan]

Love this thread! Anyone know the number for the thinnest base gasket for the 262? I think I heard it was for a 254 or something? @Tor do you know?

 

[CJ Brown]

Love this thread! Anyone know the number for the thinnest base gasket for the 262? I think I heard it was for a 254 or something? @Tor do you know?

Base gaskets:

503 70 48 01 = thin gasket

503 70 48 02 = thick gasket

 

[PA Dan]

Base gaskets:

503 48 70 01 = thin gasket

503 48 70 02 = thick gasket

Thanks Chris!

 

[CJ Brown]

No problem Dan. I hope I didn't mess that up but I'm pretty sure that's right. I am sure @Tor R or @Spike60 could verify those numbers, or supply the correct ones.

 

[paragonbuilder]

Try a 106.5 Ex and a 78 intake Dan. The intake already has more area stock than the intake tract, so just lower the floor and round the corners into the factory vertical sides. You’ll be a happy man.

Thanks for taking the time to do this.

Do you find the KS to have bigger transfer tunnels than the Mahle? That’s what people claim. I can’t tell if it’s an illusion or not.

Thanks Doc,
If I go that low with the intake, do I need to decrease my blowdown?

Looking at these tunnels in these jugs, the pto side looks very close. The flywheel side on the KS jug looks much bigger!
Also the uppers in the KS jugs aren’t as wide as the Mahle


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