Balancing and "blueprinting"

[JimLill]

I have it just the way it reads in 2006 ITCS page 5.

But, how much can you do. Can you machine anything that remains in factory spec? Correct cam profiles, etc?

[tom_sprecher]

The object is to get rid of any "+ or -" tolerance between parts (pistons, rods, bearing clearances, hell everything for that matter), and minimize and maximize tolerances where doing so would be advantageous. As long as you remain within the factory specification dimensionally I can't see where you would be violating any rule.

I am sure someone (Rules and Regs frequent flyers) will point out the fallacy of my opinion if one exists.

[lateapex911]

The classic "balance" showroom stock/It build starts off buying lots of parts. Kim Baker (SS Corvette engine builder in the 80s) had a deal with Chevy. They sent him boxes of parts, and his lackey weighed each one. Hundreds of parts...and the light ones were saved, the rest were either ground and balanced to match, or sent back. Evidently the tolerances can yeild a real light one. Perfectly legal.

Then there is machining. Loose is faster. Compression and all specs are built to the limits.

There are tricks that are very dubious like slotting holes slightly to gain cam timing and such.

gear sets get polished just so for the least friction, but more to shed lubricants.

And on it goes.

But to answer your question, build to the factory limits, and match to the lightest part you can find stock.

[Renaultfool]

When balancing one part, the lightest one, of a multiple part assembly will remain untouched to be legal. If all are touched then it is lightening (illegal) not balancing (legal). When matching ports, one port, the larger one, or part of each side of the mating ports in the case they are offset, will be untouched. If both ports are ground out all the way around you are enlargeing the ports (illegal) instead of matching (legal). Diameters may be machined to the advantageous side of the factory specs (legal) but not opened up beyond the factory tolerances (illegal). Grinding on cams is always a questionable thing. You have to be careful about valve jobs as they should match what is instructed in your shop manual. No seven angle valve jobs etc. unless called for in the shop manual.
And more of that kind of stuff.
Carl

[Geo]

When matching ports, one port, the larger one, or part of each side of the mating ports in the case they are offset, will be untouched. If both ports are ground out all the way around you are enlargeing the ports (illegal) instead of matching (legal).
[/b]

I don't read it that way.

[zracre]

it depends on what you are matching your ports to...a larger opening header? legal...i guess the intake would be questionable though...

[joeg]

The gasket

[zracre]

a larger opening header has as large a gasket hole as you want...

[lateapex911]

The gasket
[/b]

Well, gaskets are free.

So that means I can cut whatever gasket I want and port to that?

(Of course the 1"limitation really limits tha amount of fun you can have, but I question the gasket as the defning issue)

[Geo]

Well, gaskets are free.

So that means I can cut whatever gasket I want and port to that?

(Of course the 1"limitation really limits tha amount of fun you can have, but I question the gasket as the defning issue)
[/b]

The way I read it, you can match the ports. No further limitation. If someone wants to hog out ports up to 1" deep on both sides, they can knock themselves out as long as the ports do match on both sides.

If you can find any limitation to the rule in the ITCS I'll be happy to know.

[Bill Miller]

When matching ports, one port, the larger one, or part of each side of the mating ports in the case they are offset, will be untouched. If both ports are ground out all the way around you are enlargeing the ports (illegal) instead of matching (legal).[/b]

I agree w/ George on this one. As long as you don&#39;t touch material further than 1" in from the mating surface, you can do whatever you want. If you want to make it look like this =<>=, knock yourself out. Most likely, that will make less power, but have at it.

[Renaultfool]

I have always found it interesting how we can read things so differently. In my mind the word "match" is the limiting word here. It clearly defines how far you are allowed to go.
I think we would all agree that there is a definable difference between the word "match", the word used in this rule, and the word "enlarge", the word that could have been used if that was the intent.
Nowhere in the rule does it mention the word "gasket" at all. Maybe that is because gaskets are free so they really don&#39;t effect the interpretation of this rule.

Then just to be onery for the fun of it, the rule says that you can "match" to the "manifold". All cars come with an intake "manifold" and an exhaust "manifold". That is the exact wording used in my factory parts book to define the stock parts. We can clearly "match" to them.
Now, another rule allows us to use any any exhaust "header". The matching rule does not say we can match to the "header", just the "manifold".
It has long (even back with the rule was written) been a common defination when talking about car parts to refer to the stock exhaust cast part as an "exhaust manifold" and the aftermarket thin steel tubing exhaust part as a "header". Thinking of these common definitions, what does the rule, as written, actually allow?

I find it amusing how the IIDSYCYC applies sometimes in folks minds, and not at other times, depending on what they want to do, or have already done.
Carl

[lateapex911]

Carl, that sounds reasonable, except..........

Except that I don&#39;t see the part of the rule that states that you must "match TO the manifold".

It states:
"Manifold and cylinderhead port matching is permitted. No material may be removed further than one (1) inch from the manifold to cylinder head mounting face(s)."

To my eye, it seems the neither has been called out for matching TO.....so I would think that it is a case of a little of each, but not both in any one area.

And i don&#39;t see the gasket being a limiter in any way.

[ddewhurst]

***I find it amusing how the IIDSYCYC applies sometimes in folks minds, and not at other times, depending on what they want to do, or have already done.***

Great call Carl.


ps: When the sleding gets tough some people back out of a rule conversation.

[Knestis]

Hell, yeah.

K

[Geo]

ps: When the sleding gets tough some people back out of a rule conversation.
[/b]

I don&#39;t know if you&#39;re referring to me David, but I have full confidence in my interpretation. The rule says you can port match. The only limit placed upon it is the 1" rule. If anybody wishes to interpret is more strictly, knock yourself out - especially if you&#39;re in my class.

If it says you can, you bloody well can.

[tom_sprecher]

Yeah, I dunno, but w/o a spec gasket to reference, or stating that one side is to be matched to the other, it states you can match them, whatever dimensions you what to go with, even if it will hurt performance. The only limitation I see is the 1" rule. I think most people realize with that limitation all you will want to do is pick a gasket and do a gasket and port match. Unless you know something about laminar flow and air velocity that no one else does.

[Chris Wire]

I think Geo has this one nailed as it is written.

The only limiting factor is the depth to which you can port. That factor alone will keep all the other factors in line relative to actual performance gains. I suppose the rules writers could have added a lot more superfluous language but, in this instance, I think the rule says enough as written.

IISYCTYBWC! The "Geo Rule".

[Knestis]

IISYCTYBWC

That acronym is pronounced "Icy City Bewitch," by the way. That&#39;s Geo&#39;s favorite brand of Novosibirsk vodka.

K

[Geo]

IISYCTYBWC

That acronym is pronounced "Icy City Bewitch," by the way. That&#39;s Geo&#39;s favorite brand of Novosibirsk vodka.

K
[/b]

Kirk, you crack me up.