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matty 401
AMC Addicted Joined: Jul/06/2007 Location: Iowa Status: Offline Points: 1728 |
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want to sell the 391's ? used eldo head gaskets harland sharp rockers S4003 and eldo push rods according to the web site is saying bumps the compression to 9.5 they have a smaller chamber inbetween the 291c's and the later heads
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72 matador 401 the beast
79 concord 2 door 72 matador 304 grasshopper 68 Rogue 406 93 Cherokee 4.0 5 speed |
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jpnjim
AMC Addicted Joined: Nov/25/2007 Location: New England Status: Offline Points: 2752 |
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I'm keeping the 3.91 rear since it's original to the car (I swapped in a whole 3.15 rear in), Dennis addressed the 9.5:1 cr thing at one point, the answer didn't entirely make sense but he wasn't the ad exec that came up with it, so I don't blame him at all. I also appreciate him tracking down the answer (I'll try to find the post). The answer went something like: stock 401 will have 9.5:1 compression with Eddy 54cc heads, but not with the stock pistons. I believe he gave the piston dish volume needed, and it wasn't any stock piston I had heard of. Someone did the formula (might even have been the same thread) and I believe it was in the upper 8's, like 8.8 or 8.9 or so. I'm using Crane Gold Rockers I got here from jtsllc1, and I just made an adjustable pushrod last night to try to figure what length I need with them. I'm kicking myself for not being able to find any used head gaskets here just to check for pushrod lenght and valve clearance (don't want to torque down and then remove a new gasket to check piston to valve clearance) |
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71 P-code 4spd Javelin/AMX
some Jeeps and some Fords |
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jpnjim
AMC Addicted Joined: Nov/25/2007 Location: New England Status: Offline Points: 2752 |
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This isn't the thread I was looking for,
but "RB401" calculated compression with stock low compression pistons to about 8.8:1 here |
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71 P-code 4spd Javelin/AMX
some Jeeps and some Fords |
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matty 401
AMC Addicted Joined: Jul/06/2007 Location: Iowa Status: Offline Points: 1728 |
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edelbrock claims the changed the design of the chamber not sure if it is true or not that is where they come up with the 9.5 with the stock piston
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72 matador 401 the beast
79 concord 2 door 72 matador 304 grasshopper 68 Rogue 406 93 Cherokee 4.0 5 speed |
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matty 401
AMC Addicted Joined: Jul/06/2007 Location: Iowa Status: Offline Points: 1728 |
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the rockers you have are they for 3/8 or 7/16 stud
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72 matador 401 the beast
79 concord 2 door 72 matador 304 grasshopper 68 Rogue 406 93 Cherokee 4.0 5 speed |
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Sonic Silver
Supporter of TheAMCForum Joined: Nov/23/2011 Location: East Tennessee Status: Offline Points: 7882 |
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jpnjim
AMC Addicted Joined: Nov/25/2007 Location: New England Status: Offline Points: 2752 |
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The chambers do look different/more modern/better to me, but if they're 54 cc's they'd still drop compression ratio compared to the 51's. I think I might scrape 9:1 with the thin stamped gaskets, or if I spent the money for thin Copper Gaskets, but with the Low CR stock pistons and Eddy gaskets I'm *thinking* it's in the 8.7-8.8 ballpark. I looked for the post where I remember Dennis clarifying which pistons were used for 9.5:1 but I got sidetracked before I could find it. Maybe it was on the other board(?)
They're 7/16", Jim was nice enough to include the 7/16" studs. If I was going to keep the 3/8" studs I was thinking about just running stock rockers (assuming they'd work), but it worked out with the 7/16" Cranes, so far anyway
That's pretty much what I'm hoping for, I still have the stock rod bolts so I don't want to risk spinning it too high. Self imposed 5800 RPM should be perfect for me. & I'd be thrilled with 13" of vacuum, I put manual brakes in the car a long time ago anticipating a stupid big cam that I never ended up with. If the vacuum is there I'll put the power booster back on. I'm hoping this combo will have a nice fat torque curve right in the middle, to pull the gears no problem, but hopefully it won't challenge the low-ish torque rating of the 2.64 T-10. I'll just have to play nice with 1st and 2nd gears I think.
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71 P-code 4spd Javelin/AMX
some Jeeps and some Fords |
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jpnjim
AMC Addicted Joined: Nov/25/2007 Location: New England Status: Offline Points: 2752 |
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Well, I checked the piston to valve clearance with a little hobby clay, without any gasket (since I didn't have a used one here), I was worried with the close lobe seperation and .564" lift the intake might get close to the piston yeah, it doesn't. Those stock cereal bowl pistons sure give you lots of valve clearance valves don't get within a mile of them with this cam Just thought I'd follow up on it here since I mentioned it earlier in this thread.
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71 P-code 4spd Javelin/AMX
some Jeeps and some Fords |
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matty 401
AMC Addicted Joined: Jul/06/2007 Location: Iowa Status: Offline Points: 1728 |
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IT IS ALIVE !!!!!!!!!!!!!!!!!!!!!!!!!!!! runs really good turns 5000 in a heart beat now i need a rev limiter hahahahahahahahahaha
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72 matador 401 the beast
79 concord 2 door 72 matador 304 grasshopper 68 Rogue 406 93 Cherokee 4.0 5 speed |
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jpnjim
AMC Addicted Joined: Nov/25/2007 Location: New England Status: Offline Points: 2752 |
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YOU are the rev limiter Are you running the stock rod bolts like I am Matty? I'm going to try to keep my RPM's under 5500 just because it would be a shame to put a window in a 401 block my old 360 never complained about 6000-6500 with the stock bottom end but you can find 360's stacked like cord-wood for pennies a pound Glad to hear it's moving around under it's own power, I bet if you set the idle real low the cam will lope like you want
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71 P-code 4spd Javelin/AMX
some Jeeps and some Fords |
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