Compression Release
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Novice
Joined: Oct 2009
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Compression Release
Can i run 10-1 compression with out releases on a 2004 efi im doing a 95in cams and heads but i don't have compression release in the heads. with out them will i have any starting problems
Seasoned HDF Member
Joined: Mar 2008
Posts: 9,384
Likes: 1,776
From: Central Texas
I am running 10.5:1 with no releases, however I have the
high preformance 1.4 kw starter. My stock starter did ok,
but every now an then I would have to mash the starter switch
twice if the bike was hot
high preformance 1.4 kw starter. My stock starter did ok,
but every now an then I would have to mash the starter switch
twice if the bike was hot
HDF Community Team
Joined: Jun 2006
Posts: 12,779
Likes: 2,609
From: san antonio
Compression releases are a good idea if you cranking compression starts to approach 190psi. They will extend battery and starter life but if you don't need them, you don't need them.
HDF Community Team
Joined: Jun 2006
Posts: 12,779
Likes: 2,609
From: san antonio
Forget about compression; you have it bass akwards; select the cam first and build around the cam. Cam selection will depend on where you want the power, i.e., how you ride the bike. That's the first step. The Andrews 37 is a good cam, very predictatble results and will not require compression releases. Have heads setup at 82cc chamber volume, use .030" head gasket for good results, your static compression will be 9.6-9.7 and cranking compression willl be mid 180s; no realeases required. High flow A/C, exhaust and good tune and you are looking at 100+TQ/90+HP with a very broad torque curve.
Thread Starter
|
Novice
Joined: Oct 2009
Posts: 24
Likes: 0
Forget about compression; you have it bass akwards; select the cam first and build around the cam. Cam selection will depend on where you want the power, i.e., how you ride the bike. That's the first step. The Andrews 37 is a good cam, very predictatble results and will not require compression releases. Have heads setup at 82cc chamber volume, use .030" head gasket for good results, your static compression will be 9.6-9.7 and cranking compression willl be mid 180s; no realeases required. High flow A/C, exhaust and good tune and you are looking at 100+TQ/90+HP with a very broad torque curve.
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Elite HDF Member
Joined: Mar 2006
Posts: 4,722
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From: Biddeford, Maine
My last build was at 9.6:1 and I wish I would have had the releases then.
Now I'm at 10:1 with compression releases installed, and I use them all the time.
If the heads are off, do the releases.............you'll regret it later if you don't do it now.
Steve
Now I'm at 10:1 with compression releases installed, and I use them all the time.
If the heads are off, do the releases.............you'll regret it later if you don't do it now.
Steve
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HDF Community Team
Joined: Jun 2006
Posts: 12,779
Likes: 2,609
From: san antonio
Ok heres where i'm at 2004 flhti with 26000 mile,on the bike already i have A/N Big sucker,V&H true duals with oval slipons,&PC3 USB tuner. When i stop riding long enough to do a the upgrade i already have parts to put on the bike, cly-bored 95" wiseco forged pistons, s&s crankcase breather, black ops lifters, Andrews adjustable pushrods,and SCREAMIN EAGLE MCR heads That are not drilled for compression releases new in the box because they were dirt cheap. I havn't got a cam yet because i want too check my crank runout and use grear drive cams if i can. Doing the work my self and hopefully on a weekend.
The SE MCR heads (PN 16952-08/16953-08 are drilled for compression releases NIB; are you sure those are the heads you have? Addtionally, the chamber volume of those heads is speced at 76cc which changes the whole picture. The SE203 and 204 are out of the question with those heads and any of the other cams that you are likely to select will generate cranking compression above 190psi; so now you "need" compression releases.
The MCR heads ahve the 06up symetrical intake flange pattern, so you will need '06 up intake flanges. The retainers are very close to the rocker boxes and it is best to grind them. Suggest you change valve springs as the SE springs are a little too stout IMO for most performance applications. The valve stem is 5/16" and there are beehive valve springs available that make clearancing the rocker boxes easier, less material to remove; they may fit without any clearancing.
I assume the Wiseco pistons are flat tops? If they are not, you have more compression problems to deal with.
I would still recommend that you pass on gear drives and consider the late hydro tensioner/roller chain setup. It is very quiet, very depandable and much easier to work with but that's JMHO.
You really need to select a cam and get the head details sorted out before you start or your weekend plan will go up in smoke.
