Increasing compression with an Andrews 37
HDF Community Team
Joined: Jun 2006
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From: san antonio
You still have to decide what to do with the heads; compression releases would be a good idea. Please don't put a set of 40K miles heads back on that fresh top end. There's the entrance to the rabbit hole.
Last edited by djl; Mar 17, 2016 at 03:57 PM.
Seasoned HDF Member
Joined: Mar 2010
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From: Poolville
OK, I am with you now. However, I would use a .030" head gasket and install the 4* advance sprocket and shoot for 9.86 static, 9.28 corrected and 192CCP at sea level; may need to correct. That puts you in the neighborhood of snappy, happy 95" engines. You still have to decide what to do with the heads; compression releases would be a good idea. Please don't put a set of 40K miles heads back on that fresh top end. There's the entrance to the rabbit hole.
You still have to decide what to do with the heads; compression releases would be a good idea. Please don't put a set of 40K miles heads back on that fresh top end. There's the entrance to the rabbit hole.
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Grand HDF Member
Joined: Jun 2013
Posts: 4,998
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From: Iowa
OK, I am with you now. However, I would use a .030" head gasket and install the 4* advance sprocket and shoot for 9.86 static, 9.28 corrected and 192CCP at sea level; may need to correct. That puts you in the neighborhood of snappy, happy 95" engines. You still have to decide what to do with the heads; compression releases would be a good idea. Please don't put a set of 40K miles heads back on that fresh top end. There's the entrance to the rabbit hole.
You still have to decide what to do with the heads; compression releases would be a good idea. Please don't put a set of 40K miles heads back on that fresh top end. There's the entrance to the rabbit hole.
HDF Community Team
Joined: Jun 2006
Posts: 12,774
Likes: 2,606
From: san antonio
I'm with you on what you are saying and in the end you are saying put off doing anything until it can all be done at once, meanwhile ride with 8.09 compression on an Andrews 37? Really it just seems like I should have waited to put the cam in until I could do the heads, cylinders, and pistons at the same time.
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Grand HDF Member
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From: Iowa
Sort of saying that but nothing wrong with the configuration I outlined in my last post but, at a minimum, you should have the heads cleaned up, valve job and new guide seals and delay porting for another day. It just depends on what you want to do. How bad do you want more power and how much you want to spend; it's all up to you. We all make decisions based on our own wants and needs based on what we have to work with. Doesn't matter what might be logical or what others think; we all need to get where we want to be.
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Joined: Mar 2012
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From: Centennial, CO
I'll enter my experience. I ran the 37s in a stock 88" and like you, I liked the bump in power but it did come on late. Enter a 98" kit from Hillside with the compression bump and the cams came on earlier which was great. I have just installed a set of '07 heads that were cleaned up, shaved .010, valve job and seals. Dyno to come soon, but so far my butt dyno seems to feel the cams are coming on right where Andrews advertises them to. I really like what I've done so far. But I am no genius when it comes to this stuff. DJL 98 and Scott at Hillside are the guys to listen to.
HDF Community Team
Joined: Jun 2006
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From: san antonio
Thanks for clearing that up, dj. I had wondered what I should do to get the heads cleaned up after taking them off. I can do a valve job and get the tool to seat new valve guide seals. I'm going with the 95" cylinders, the 4.6CC domed pistons, the .040 gasket, and taking off the cam offset to get 9.66 static and 8.96 corrected. See how that goes and if I feel the itch to do more I'll get the porting, the chamber cced to 84 and the .030 gaskets for 9.96 static and 9.23 corrected. That way I have a lower compression until I can get the releases installed. I'll post up results after I get it dynoed.
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Grand HDF Member
Joined: Jun 2013
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Likes: 870
From: Iowa
I'll enter my experience. I ran the 37s in a stock 88" and like you, I liked the bump in power but it did come on late. Enter a 98" kit from Hillside with the compression bump and the cams came on earlier which was great. I have just installed a set of '07 heads that were cleaned up, shaved .010, valve job and seals. Dyno to come soon, but so far my butt dyno seems to feel the cams are coming on right where Andrews advertises them to. I really like what I've done so far. But I am no genius when it comes to this stuff. DJL 98 and Scott at Hillside are the guys to listen to.
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Grand HDF Member
Joined: Jun 2013
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From: Iowa
Did you ever get it dynoed? I am on the path to get a 98" and headwork done. Hope to dyno tune in the spring or summer.