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Jeep Engine Suggestions |
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dodgerammit
AMC Apprentice Joined: Apr/26/2019 Location: TN Status: Offline Points: 151 |
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I agree to match cam and compression. At 9.0:1 compression with my cam choice (Engle 5052), 21cc dish wiseco forged, zero decking my block, and .040" head gasket thickness (quench) should put me at 7.5:1 DCR which should allow 87 octane usage. That said, the guy at Engle said my cam would be fine at 8.5:1 as well. He specifically said much above 9:1 would not be ideal. If you read SC397's builds, you will see he used a calculator to figure compression ratio. I used that thing extensively, plugging differing values into it to see what changed. Great learning experience seeing what made a big difference and what didn't. Helped me dial in what I needed done to get where I wanted.
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84 Grand Wagoneer Garnet Red (mine)360/727/229 44/20
84 AMC Eagle Wagon (Wife's) Deep blue 258/mushbox/129 30/15 |
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ghcoe
AMC Apprentice Joined: Sep/29/2018 Location: SW Idaho Status: Offline Points: 72 |
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Thanks BassBoat, I probably know enough about engines to be dangerous to myself. I tend to over think things, so I have to turn to people who know more about this than I do before I go crazy... So with that said is there a way to increase compression if I only have the heads rebuilt? I was thinking that valve choice could increase compression without having the heads shaved, which I really don't want to do, plus I have no idea if they were in the first place so there may not be much to play with. I know cam choice does change dynamic compression so that is why I was asking for a good choice. I would at this point assume that I would notice a improvement with the 268H whether with static compression of stock (lowish 8), 9.5 or anything in between, from what people are saying?
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dodgerammit
AMC Apprentice Joined: Apr/26/2019 Location: TN Status: Offline Points: 151 |
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Greyhoundsamx has a cam spreadsheet you can use to plug variables in. It will show DCR. There is a thread on FSJnetwork concerning what a bump in CR does. Basically gives a solid increase in performance across the operating range. Here is another one of my threads with a link to that post: https://www.fsjnetwork.com/forum/viewtopic.php?f=11&t=17097&p=175744&hilit=compression+ratio#p175744 |
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84 Grand Wagoneer Garnet Red (mine)360/727/229 44/20
84 AMC Eagle Wagon (Wife's) Deep blue 258/mushbox/129 30/15 |
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ghcoe
AMC Apprentice Joined: Sep/29/2018 Location: SW Idaho Status: Offline Points: 72 |
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Thanks for the links. Very helpful. George
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SC397
AMC Addicted Joined: Apr/30/2009 Location: Michigan Status: Offline Points: 5476 |
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This was a 8.5:1 360 cheapie re-ring build that we put together with the 268H cam and he seems to really like it. The nice thing about that cam is that you can use your stock length push rods. It is basically the same lift as a stock 401 cam with a little more duration. Stock 401 Cam: 208/210 @ .050" .458" valve lift and 114 LSA
CompCam 268H: 218/218 @ .050" .456" valve lift and 110 LSA Stock 360 Cam: 196/196 @ .050 .426" valve lift and 110.5 LSA Edited by SC397 - Dec/13/2019 at 9:36am |
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ghcoe
AMC Apprentice Joined: Sep/29/2018 Location: SW Idaho Status: Offline Points: 72 |
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Thanks for that!
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Sonic Silver
Supporter of TheAMCForum Joined: Nov/23/2011 Location: East Tennessee Status: Offline Points: 7949 |
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SC397
AMC Addicted Joined: Apr/30/2009 Location: Michigan Status: Offline Points: 5476 |
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My mistake. The 268H is 218/218.
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Sonic Silver
Supporter of TheAMCForum Joined: Nov/23/2011 Location: East Tennessee Status: Offline Points: 7949 |
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Also, not only is there 10 degrees difference in duration at .050 between the 401 and Comp 268, there is a 18 degrees less overlap in the AMC 401, due both to the duration and wider 4 degree lobe centers. Big difference. Edited by Sonic Silver - Dec/07/2019 at 8:02pm |
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Trader
AMC Addicted Joined: May/15/2018 Location: Ontario Status: Offline Points: 6881 |
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As on a 8.5:1 pump gas I have used these for the maximum street, horse trailer/off road crowd, Howards CL312481-11.
Just from experience, Jeeps and cars 360 and 401 seem to like the 111 degree separation angle, and 0.475" is the maximum lift to get the low end torque. The thing to remember on a towing/work vehicle vs a car is you need to have the engine torque come in well before the torque converter specification on the bottom end. Not so critical on a street vehicle, especially if it's lite. If you match RPM's, then the torque converter is putting maximum load to the engine when the engine is just developing it's torque. Under heavy load, in this circumstance, the engine tends to bog down regardless of what accessories you add. I have avoided Comps, but they did replace a couple, that had less then 0.900" lobe widths. They may be better now. If you buy any cam, measure the lobe widths! Return anything with GM lobe widths! Also Howard's lifters are nominally 0.9035" vs Comps 0.0903" which is closer to factory specification. This is a maximum and maybe not what you are looking for. As SC397 has recommended other options I would defer to more experience. Just though I would put out the maximum cam, from my experience, for your application. |
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