GLM pistonees

[ram95]

Has anyone had trouble passing inspection ( ie cc'ing) after installing the GLM pistons in their OMC15 (APBA A motor).

As you may know, the GLM pistons were approved this year at the National meeting.

Your comments please.

Alex
Region 1, SO Commissioner

[Tomtall]

GLM pistons

I highly advise you CC your motor after installing them. If you run a tight motor with the OMC pistons there is a chance you will be under the legal 13.5cc's with the GLM's. Other than that they seem to run fine and we have had no other issues running them. Some people I have talked with say there is no difference to their CC volume and others as we have seen say the CC's are running approx. 1 CC less with the GLM's. I don't feel anything needs to be changed regarding them being an accepted replacment piston you just need to check your CC's after they are installed. Just my 2 cents.

[David_L6]

Some people I have talked with say there is no difference to their CC volume and others as we have seen say the CC's are running approx. 1 CC less with the GLM's.

That's a LOT of difference!

I know that this isn't strictly an "apples to apples" comparison, but I've never been able to tighten up a 4 cylinder Mercury motor a full CC just by swapping (stock/mod legal) pistons. Maybe by switching to Turner alky pistons (illegal), but not with legal pistons. Appears to me that there's a quality control problem with GLM brand pistons if you can switch to them and tighten up a motor anywhere near a full CC.

Does GLM make 44 pistons?

[mike ross]

If you look under the Stock Chairman post here on Hydroracer. 17W posted the testing results of these pistons that where approved. If you look at the chart provided it shows the dome height on the GLM pistons as being higher than the OEM version. Make sure you get your motor checked. If you were close before changing to the GLM version you will probably come in short on cc's and need to search out a head that has not been cut down to get your motor to pass. If you had some room you may have found a advantage by using the GLM version as it gets you close to the cc limit. Lower cc's = more compression. I know of several racers, inspectors that scrambled at the last minute having to find new heads before bringing there motors to the 2009 Stock Nationals in Grass Lake. Mikey

[Tomtall]

More

Appears to me that there's a quality control problem with GLM brand pistons if you can switch to them and tighten up a motor anywhere near a full CC.

I have bought 8 sets of these pistons. All 8 sets were weighed and wrist pin height checked against the OMC slugs. Weight of the GLM's veried +/- .3 grams. Not to shabby. I did notice the wrist pin height veried +/- .0005" between the GLM vs OMC. Another engine builder said he had different measurments on the tops of the piston compared to the OMC pistons which caused him to have to change the cylinder head on his motor to make it legal again. I noticed after break-in and some race time on the engine that was to tight to begin with checked .5 CC more after run in. So like I said in my previous post check it to be safe. Hell I have seen two inspectors get two different CC readings on the same motor before so who's to say the thing was illigal to begin with. We don't need to open up a pandoras box here people. The data was collected and presented to the SORC and they felt these were a viable replacment piston. For what we have to work with for parts for these engines I believe they will work if you take the time to double check your build when it's done.

[ram95]

Pist-on or pist-off...that is the question

I would like to thank all of you who have taken the time to respond to this question about GLM "A" pistons. This is indeed a great website, which unfortunately, not every racer has access to.

I think I'll go out and buy some Sierra pistons and see how they measure up. Maybe I'll present them to the SORC this coming Jan. While I'm at it, maybe I'll buy up some Wiseco slugs as well.

Building an "A OMC" just keeps getting easier and easier.

Keep them koments komink komrades. I can feel the heat already.

[17W]

I would like to thank all of you who have taken the time to respond to this question about GLM "A" pistons. This is indeed a great website, which unfortunately, not every racer has access to.

I think I'll go out and buy some Sierra pistons and see how they measure up. Maybe I'll present them to the SORC this coming Jan. While I'm at it, maybe I'll buy up some Wiseco slugs as well.

Building an "A OMC" just keeps getting easier and easier.

Keep them koments komink komrades. I can feel the heat already.

Alex-

Knock yourself out. Be prepared with similar data which was provided to you & the rest of the SORC last year & you may get some where.

There is always someone who is going to whine & complain.......

Brian Trolian & I were the individuals who lead the charge on getting the GLM piston legalized. Why did we do it? Well there were no longer ANY OEM .030" O/S piston & ring assemblies available. We would not have gone in this direction if Ed Runne, TJ & a few other individuals did not feel it was a suitable fit!

Do any of you guys recall what retail was on the OEM kit when it went away? It was $130.12 each. You can get (2) GLMs .030" O/S Assemblies for just over $100! The finish of the piston is light years better than what OEM was.

As for cyl heads hitting.....sucks that guys went crazy w/the fly-cutter & cut the back of the block to the negative(-) side of the spec.

But I too could get OEM pistons to hit the head, if I was not paying attention when assembling a P/H.

[mike ross]

Brent & Brian, you two did a fantastic job in presenting the info on all the possible replacement piston options. When ever you approve a after market replacement item such as a piston. You stand a very good chance of having it not mach up perfectly against what you replaced it with. The cc issue seems like it should have come up when the testing was being done. When it did finally get noticed that there was a potential problem. I feel it might have been in the best interest of the membership to maybe post something like we have done here. The top guns new and kind of kept it hush hush. The good thing I see is that some racers got improved performance for a cheaper price as Brent pointed out. This whole deal is what the SORC has worried about when trying to keep old motors in the mix. Unfortunately this is what we have and until we have a abundance of new replacement motors for racers to purchase this will be a hurdle we have to tackle. The A sidewinder is in a perfect position to capitalize on this. Hopefully they will have about 50 of these motors available for immediate delivery so they can hit the ground running for 2010. Mikey

[thepiranhabros]

Alex-

Knock yourself out. Be prepared with similar data which was provided to you & the rest of the SORC last year & you may get some where.

There is always someone who is going to whine & complain.......

Brian Trolian & I were the individuals who lead the charge on getting the GLM piston legalized. Why did we do it? Well there were no longer ANY OEM .030" O/S piston & ring assemblies available. We would not have gone in this direction if Ed Runne, TJ & a few other individuals did not feel it was a suitable fit!

Do any of you guys recall what retail was on the OEM kit when it went away? It was $130.12 each. You can get (2) GLMs .030" O/S Assemblies for just over $100! The finish of the piston is light years better than what OEM was.

As for cyl heads hitting.....sucks that guys went crazy w/the fly-cutter & cut the back of the block to the negative(-) side of the spec.

But I too could get OEM pistons to hit the head, if I was not paying attention when assembling a P/H.

Forgive my ignorance in asking a question that probably has an obvious answer (if I looked hard enough for it), but where would one procure a set of these piston assemblies?

In other words, I want some; where do I send a check?

(Also, I assume these assembly sets include rings and wrist pins, yes?)

Michael Mackey
21-V

[26V]

It looks like Dicks marine and tri-state marine are glm dist in your area.
anyway a web search for glm pistons will get you the info you need.

[17W]

Forgive my ignorance in asking a question that probably has an obvious answer (if I looked hard enough for it), but where would one procure a set of these piston assemblies?

In other words, I want some; where do I send a check?

(Also, I assume these assembly sets include rings and wrist pins, yes?)

Michael Mackey
21-V

Dick's Marine
Fox Lake, Il

He probably has them on the shelf.

[thepiranhabros]

Thanks

Dick's Marine
Fox Lake, Il

He probably has them on the shelf.

Thanks, Brent. You too, Gene.

Michael

[Graham]

cc's

I thought it was "not legal" in the "stock" classes to mill the head or block to get at the min cc requirement. Is that summation correct according to current rules/specs. I.e. no machining of parts, etc.. According to this thread I take it as if folks do this all the time. As we know, a "stock" engine in most cases does not come close to the min cc #'s. That would make any motor who is at the min cc illegal. Right.

[ram95]

[QUOTE=17W;142481]Alex-

Knock yourself out. Be prepared with similar data which was provided to you & the rest of the SORC last year & you may get some where.

Gentlemen,
The presentation at the SORC was excellent. I posted my comments as an effort to get people talking and comparing notes, so that the FACTs might surface. And, this is exactly what seems to be happening. And, I did this because I sensed the scenarios being offered were leading to the wrong conclusions, ie the pistons were to blame when in fact other parts had been machined to a zero tolerance causing a cumulative out of limits in the cc department.

Certainly the stock OMC pistons are sickeningly over-priced and hard to get. I can sell you a GLM piston, std or .030 for $48 including wristpin and circlip.

Again, thanks to Hydroracer for providing a medium for this discussion.

Alex

[David_L6]

I thought it was "not legal" in the "stock" classes to mill the head or block to get at the min cc requirement. Is that summation correct according to current rules/specs. I.e. no machining of parts, etc.. According to this thread I take it as if folks do this all the time. As we know, a "stock" engine in most cases does not come close to the min cc #'s. That would make any motor who is at the min cc illegal. Right.

Appears to me that no one races a stock motor - they are all modified in some manner.