B.S. valve guide length/tech


I have been asked several times about how to determine if a valve guide has been cut down. I tell them that it is hard to tell unless there was a measurement and then a tool had to be made. I know Jim Stone has one so today I decided to make one of my own. This is the beginning stages of putting a measurement on the guide to stop those who are tampering with them. Here is my finding: I measured the new JT 141 head that I recently picked up. The guide in it measured 1.070 in length on both the intake and the exhaust. I then began making the tool to a spec of 1.060. This would allow a .010 variance. I then measure the following heads I have here in my shop: hf 02 hf 02 jt 03 jt 03 tg-1 tg-1 tg-1 tg-1 tg-1 tg-1 hf gl05 jt-86 jt-123 jt 109 jt 109 jt 109 jt 74 jt 74 jt 75 jt 75 jt 76 hf 10 hf 29 jt 82 jt 83

Every one of the above heads passed the tooling to where to guide was actually longer than the tool. The longest that I found was .009 longer than the tool with the exception of the JT 141 head that I made the tool from. Not ONE (1) was smaller!!!!
Don, this is one of those items that may not be worth the trouble. We flow tested some heads, then drove the guides halfway back through the head and flowed them again. There was very little gain if any at all on the intake side. We drove them back at least 150 thousandths, so a few thousandths is going to make no difference. Now the exhaust side is different, if you pull air past the valve into the cylinder you will see very little or nothing at all. But if you pull the air from the cylinder out through the port there can be a couple points of gain there. The slight gain on the exhaust side varies greatly depending on the casting. Less desirable castings show a greater gain than the, shall we say good heads. The better castings had very little gain, so unless you have a bad flowing head to start with, you are not going to gain anything. This all assumes that there has been no other port work done.

By the way I measured about 20 valve guides from my parts shelf. One was 1.070 and one was 1.062, the rest all fell between 1.064 and 1.066.
I kinda figured if there was any gain to be had it would be in the exhaust side of the less favorable heads. Thanks for the feed back.
"Devil's Advocate" speaking....Are the Racers asking for 'this'? The thing I 'fear, and see' is that everytime there is new rule (or change) that will have an negitive effect on their pocket book, it drives more racers away than it brings in. It is amost like bringing more 'professionalism' IN and pushing the 'non-pro's' OUT.....(includes racers and builders). What needs too happen is that the Rules and Promotors need too entice those that continually press the limits in the 'Box Stock-Beginner-Rookie-Novice etc etc Class' and 'Force' them too step-up or...get-out!! JMO (u-bet and looking 4company) DO Appreciate ur efforts Don!
the biggest thing that I find when it comes to rules is "who does it benefit"? while we all need rules, even in a rwyb class, the needs of the many outweigh the needs of the few or of the one (thanks star trek!)... I have a situation right now where a small select group want changes to the rules that we've been operating under for the past two years. do I change to make them happy and to keep those few coming to the track, or do I keep what we have that entices others to come? one way outlaws everything but a yellow/red/blue clone and requires certain items that take away from what we have and had in the past.....is this to accommodate them or to exclude those that we'd like to bring in?

I only mention this because of what screamer said..."The thing I 'fear, and see' is that every time there is new rule (or change) that will have an negative effect on their pocket book, it drives more racers away than it brings in."

some don't see the work that goes into making or changing a rule based on what is needed for the sport to grow....but then some don't care as long as the rules are tailored to benefit them or a certain select group.

I appreciate all the efforts that screamnclones, dynodon, youngengines and renegade do to keep all of us honest and also knowledgeable! when questions aren't asked and ideas aren't explored, stagnation happens...when stagnation happens, we all suffer......
If the valve guide is to be unaltered, Don you have or are doing the right thing. Put something concrete in writing, you have stated a specification that is generous and rules in the direction of allowing the benefit of the doubt. It does not affect anybody in the pocket book, it is not a gray area. The only people this affects are the ones who have modified the valve guide which is in contravention of an existing rule. If it costs them a new set of guides so be it. They either meet the rules or not, the ones that are hurting the sport are the ones that don't play by the rules. I guarantee numbers will go up when the playing field is level, as long as the pocket book rules frustration follows. It is not hard to meet the rules as written, it takes more work to gripe and try to bend the rules.
My 'point' is that if this is 'something-else' that I as a motor builder has too look at when building a customer's motor, ie: valve weight and laying out extra bucks for equipment (scales), the 'customer' has too pay for it! That 'indeed' depletes the pocket-book. Pussy-footing around w/people that flagrantly violate the rulebook should be made an example by booting their posteriors Out, or at least....suspending them! JMO
i've always tryed to live by a "code" that if you do things the right way the first time, then you never have to worry....and by the same token, if "they" (the ones that try and bend the rules)....if they would expend half the energy that it takes to violate the rules on making sure that they were legal, they couldn't be beat! they jump through hoops to try and figure out a way to bend the rules...yet if they took that same energy......

the way that i figure it, dynodon....you must have seen or thought that the valve guides were being manipulated outside of stock applications to give an advatage...otherwise, i don't think that you would have looked at them as closely as you have. i'm always in favor of innovations within reason and within a set of guidelines....but sometimes you have to put boots to butts and show that rules will be enforced!!
I don't see any tool needed, I don't see any out lay of cash, hold a flat washer against the bottom of the guide drop the tail of your cheap digital caliper through the valve guide, look at scale determine measurement, a .010 grace has been allowed, if you can't meet it call your customer tell them a $3 valve guide is needed or what ever mark up you are getting away with.
Devil's Advocate definition: "One who argue's against a cause, or position, Not as a committed opponent, but simply for the sake of arguement or, merely too provoke discussion.".....(Job Done!)
If the statement "if it doesn't say you can, then you cant" is true, then its illegal now to shorten them right? If it is truly illegal to shorten them now, why is an additional rule needed? So if there is a AKRA box stock race this weekend and the winner has valve guides that are shorter than 1.060, is he legal? Wouldn't the "compared to stock part" apply now? If the valve travel will allow it, is it legal to simply knock the guides "up" to have less in the port and more in the spring area? They will check "legal" for length that way but still get the benefits of them not being in the way of port flow. Of course the rule doesn't say you can do that either but "mine came from the factory that way".
If yours came from the factory that way, it is not the norm and therefore you should have found another head that had the valve guides in correctly. With the concept of flow your head would be considered altered by all means and could be DQ'd. Not being rude, just making a point!!!
No "rudeness" taken. I think however my "point" has been lost yet again. I don't even have a 196 head. My keyboard does not have a sarcasm button. I apologize. Just trying once again to point out that not all things are as black and white as many want to believe. Sorry for interjecting a "critical" point of view. No award again!
Actually, you gave us valuable information to the topic for discussion and that is always welcome. Now that I read your post again i take the statement that you made " Mine came from the factory that way" as a statement that a racer would use when the guide was found. You are correct about that statement. I have read several of your posts and I like your input.
jmo, but I think some rule changes are made and come to the rule makers attention through their findings in tech of what people are doin in the "grey" areas . for example the dia and bore depth tolerances on back of the carbs, because most of the time hitting the tolerances on parts is most likely where the performance is. I personally feel that these updates/changes also help the diy'er in trying to keep up with the countless hours spent on dynos for a tenth of a hp, which most diy guys/gals don't have ...I may be way off but that's how I feel about it. thanks jack