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Discussion Starter · #1 ·
I'm going to 95" with dme 510 cams, stock heads. I'll probably go with the ..030 Cometic head gaskets, because that's what everyone seems to recommed. However, is there any down side to them, or any reason why a thicker gasket would be advised? I'm wondering why if the .030 is the best, anyone even uses any other thickness. Thanks.
 

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The .030 Cometic head gasket helps optimize the quench. The heads overlap the pistons at the combustion chamber. The places where the heads overlap the piston is called the quench area or Squish area. When the piston comes up on the compression stroke and approaches the head, the compressed charge is forced into the combustion chamber. This creates a greater turbulence in the charge and helps promote a quicker and more complete burn of the charge. The distance between the head (squish area) and the piston is less with the .030 head gasket than the thicker gaskets.
 

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The reason that you see the .030 mentioned so often is not necessarily because the .030 is "better" than all the rest, it is simply a good way to increase the compression ratio. That gasket should get you into the 9.8 range with the stock size combustion chamber and a 95" jug. And that compression comes in handy with the DME cam.
 

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Discussion Starter · #4 ·
grock, regarding the dme 510, is it good at around 9.5:1 or so, or does it really need a higher cr? The cam was recommeded to me by a couple of shops, but I really don't know much about it. Thanks.
 

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An Andrews 26 or 37 are both proven winners.

The DME 510 looks similar to the 37 but has a few more *'s of overlap, a little longer duration, and the power-band will theoretically kick-in about 200 rpm's later than the 37 (2500 vs. 2700).

The big andvantage of the Andrews cams is that you can get them in a gear drive version which is mechanically superior in both reliability and efficiency.
 

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Discussion Starter · #6 ·
I note the dme 510 intake close is at 38 and the 37 is at42, so maybe that would equalize the other specs, so as to make the dme come on a little earlier?
 

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you must be looking in a old listing for the 37 it closes at 38
 

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Discussion Starter · #8 ·
You're right; it looks like they did change the specs on the 37. The Andrews site has the specs, and it shows close at 38. I have the 2005 JP catalogue, and the specs are different, as are the specs on the nightrider.com site.
 

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AAL said:
You're right; it looks like they did change the specs on the 37. The Andrews site has the specs, and it shows close at 38. I have the 2005 JP catalogue, and the specs are different, as are the specs on the nightrider.com site.
This was discussed here awhile back. I called Andrews for an answer. They told me that that was to be thier original configuration and that probably less than 100 ever ever went to market before the spec was changed. Chances are that whatever you are reading thay shows the 42 is from the original published specs from several years ago.
At least that's what they told me...
 

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AAL said:
grock, regarding the dme 510, is it good at around 9.5:1 or so, or does it really need a higher cr? The cam was recommeded to me by a couple of shops, but I really don't know much about it. Thanks.
The Mackie 510 and the Andrews 37 are somewhat similar. They both respond a bit better to around 9.8 to 10 compression ratio. Like I said before, with the 95 bore, flat top pistons and the .030 head gaskets, you will be right around 9.8. If you are going to go gear drive, add a +2 cam advance key to make either one bite a little quicker without any worries about detonation or starting. Good luck!

G
 

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springer- said:
The .030 Cometic head gasket helps optimize the quench. The heads overlap the pistons at the combustion chamber. The places where the heads overlap the piston is called the quench area or Squish area. When the piston comes up on the compression stroke and approaches the head, the compressed charge is forced into the combustion chamber. This creates a greater turbulence in the charge and helps promote a quicker and more complete burn of the charge. The distance between the head (squish area) and the piston is less with the .030 head gasket than the thicker gaskets.
I was reading an old artical in American Rider on 95" with Andrews 21g cams and .030 cometic used but the artical also said that SE head gaskets are made by Cometics if true what thickness are they?
Dave
 

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AAL said:
Grock, where do you get the advance keys? And, how exactly would this affect performance - better low end and less high end? Thanks.
You can adjust the cam timing with the metal shim in the gear drive. We make our own here, but Wood sells them for a few dollars. Basically a +2 degree advance moves the entire powerband down the scale around 220 rpm. Not a big deal, but a little quicker hit. It does shorten the HP a tad sometimes, but thats at the top of the scale, where you're not riding. The 37, 26, DM510 590, Wood TW5 and 6H, and even the andrews 67 respond pretty nicely to this mod without causing problems with starting and detonation, especially with the compression you are considering.
 

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No. Both cams with that comp ratio have good manners with or without the cam key. Now stop typing and start building already.

And have a great New Year!

G
 

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GRock said:
The reason that you see the .030 mentioned so often is not necessarily because the .030 is "better" than all the rest, it is simply a good way to increase the compression ratio. That gasket should get you into the 9.8 range with the stock size combustion chamber and a 95" jug. And that compression comes in handy with the DME cam.
GRrock, I thought you needed about 82cc combustion chambers or possibly a little less to get 9.8 CR with flattops and a .030 HG. I must have figgured something wrong. Does it work out to 9.8 with stock chambers?
 

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Deluxe said:
I was reading an old artical in American Rider on 95" with Andrews 21g cams and .030 cometic used but the artical also said that SE head gaskets are made by Cometics if true what thickness are they?
Dave
The Cometic gaskets are made up of layered steel. I believe the .030 Cometic heads gasket has 3 layers. That would indicate .010 thickness for each layer. Cometic also offers a .040 gasket made the same way. While I have never used the .040, I assume it is 4 layers of the same .010 steel material. I have never used the SE head gaskets either but if they are made by Cometic, I assume they would be made of the same thickness per layer .010. The question is how many laters in the SE gasket?

I guess what I am getting at is I don't know how thick they are. :roflback:
 
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