dm440c
Feature Winner
derby drivers against drama- there's no crying in demo derby!
Posts: 2,824
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Post by dm440c on Jan 27, 2017 9:12:31 GMT -5
You're a wise man, I wouldn't go messing with new cams unless the existing one had excessive wear. There is no valve setting, Mopars have hydraulic lifters and shaft mounted rockers so you just torque down the shafts and move on. While you have the heads off I would suggest having the valve seats cleaned up but keep the old guides even if the machine shop tells you they are worn.
Compression ratio- some books claim 10:1 in 1966 but from my measurements of the piston depth and head cc of the 516 castings assembled with an .019" steel shim head gasket I would put it closer to 9.5:1, and if you use the .040" composite gaskets it will be closer to 9:1. The engine is rated at 350 hp and even though that is optimistic it will make stupid power for a derby car without the fussyness of built small block, however, the biggest obstacle you must overcome is the motor mounts. Stock is a joke, forget it. Some guys solve the problem with a spider web of chains but that has never been a good solution for me. I don't know of anyone still making cradles for these but I would take the money you didn't spend on engine parts and invest in building your own cradle for it. The "ears" on the sides of the big blocks break off extremely easy so build some kind of lower cradle that uses these plus some other mounting point on the block to spread out the forces that would otherwise break the ears.
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Post by seventyonehemicuda on Jun 25, 2017 13:20:20 GMT -5
400 been sitting for 9 months, wished i would have checked oil last year. Head Gasket or cracked head? what's more common for late 70's big blocks? could this just be moisture built up over the winter/spring? If Im doing head gaskets i will be putting in MP steel shim gaskets, should I be getting the heads planed before putting in these thinner gaskets?
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Post by cowdoc on Jun 25, 2017 23:28:30 GMT -5
400 been sitting for 9 months, wished i would have checked oil last year. Head Gasket or cracked head? what's more common for late 70's big blocks? could this just be moisture built up over the winter/spring? If Im doing head gaskets i will be putting in MP steel shim gaskets, should I be getting the heads planed before putting in these thinner gaskets? ugly, might be from rain in carb or headers but I'm betting the intake gasket has rusted out and moisture is running down the valley. I've had lots of big blocks sitting outside with carb and headers really covered well that I thought were safe get water in from the air gap
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Post by seventyonehemicuda on Jun 26, 2017 17:54:54 GMT -5
Not the valley pan I put a new one in last spring.
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dm440c
Feature Winner
derby drivers against drama- there's no crying in demo derby!
Posts: 2,824
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Post by dm440c on Jul 4, 2017 7:37:33 GMT -5
don't panic yet... clean it all out and put in fresh oil & water so you can run it around the yard then check if it is still mixing before you tear anything down. I had a lot of instances like that where water gets in somehow over the winter. Anymore I cover my engines with at least 3 layers of protection. I see guys who just throw caps on the stacks and leave it out all year, for the life of me I don't know how they get away with that because I sure can't. The only way I've ever permanently damaged a Mopar engine is to have rain get inside it and rust it up.
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Post by demodeputy28 on Jul 5, 2017 8:44:02 GMT -5
Readi barrel or aluminum radiator???
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Post by seventyonehemicuda on Jul 5, 2017 20:18:14 GMT -5
don't panic yet... clean it all out and put in fresh oil & water so you can run it around the yard then check if it is still mixing before you tear anything down. I had a lot of instances like that where water gets in somehow over the winter. Anymore I cover my engines with at least 3 layers of protection. I see guys who just throw caps on the stacks and leave it out all year, for the life of me I don't know how they get away with that because I sure can't. The only way I've ever permanently damaged a Mopar engine is to have rain get inside it and rust it up. I've drained and changed the oil twice now, oil looks much better. this was the first time ive experienced this issue. thanks!
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Post by bluredvision on Aug 16, 2017 21:05:46 GMT -5
Maybe Ive just had a run of bad luck, but i keep burning up mini starters on big block motors. its as if they melt down when cranking a hot motor. I've burned up 2 in the last month one was from a wrecker, the last one was brand spanking new. is there a certain brand that works better than others? are genuine chrysler starters better? is anyone else having the same problem? Im really lost here because i love the high speed cranking with the mini, but hate the thermal melt down when they get hot. is this just my bad luck?
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Post by 4sasquach on Aug 18, 2017 7:46:00 GMT -5
^^ well they are mini starters.. Lol.. the windings are different than stockers.. most stock starters regardless of make take quite a bit of abuse.. the small motors on the mini's just cant take repeated long cranking.. find someone to go through a good stock unit and rewind it for some more speed..?
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Post by cclark009 on Nov 11, 2017 14:56:41 GMT -5
Does anyone have pictures of the engine mounts after they break on a 400, I am going to be designing a lower cradle of some sort and would like to see what I'm up against.
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Post by seventyonehemicuda on Nov 12, 2017 22:30:34 GMT -5
Does anyone have pictures of the engine mounts after they break on a 400, I am going to be designing a lower cradle of some sort and would like to see what I'm up against. Not much to see in a pic, just imagine the mount ears being gone, what would they look like if you hit one with a hamme? Would look the same. They usually shear off flush with block or crack and break out the bolt holes, usually left hand side goes first. I spent about 20 hours trying to design a lower cradle for a bbm before tossing my mess into the scrap bin. Welding warps things quickly, parts need to be bolted to the block to ensure they dont move while welding. Unfortunately you cant do this on a bbm. If i were to try it again, id have a machine shop cut a set of mounts from solid stock on a mill, and build my cradle outward from there.
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Post by cowdoc on Nov 12, 2017 23:03:23 GMT -5
Does anyone have pictures of the engine mounts after they break on a 400, I am going to be designing a lower cradle of some sort and would like to see what I'm up against. Not much to see in a pic, just imagine the mount ears being gone, what would they look like if you hit one with a hamme? Would look the same. They usually shear off flush with block or crack and break out the bolt holes, usually left hand side goes first. I spent about 20 hours trying to design a lower cradle for a bbm before tossing my mess into the scrap bin. Welding warps things quickly, parts need to be bolted to the block to ensure they dont move while welding. Unfortunately you cant do this on a bbm. If i were to try it again, id have a machine shop cut a set of mounts from solid stock on a mill, and build my cradle outward from there. I like to run the outlaw flanges on my headers and weld/reinforce the mounts to them.-I think theyre 3/8", cant remember but it works decent
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Post by seventyonehemicuda on Nov 15, 2017 23:09:10 GMT -5
Cowdoc, Are you talking about welding the stock mounts to the header flanges? do you have any pics you could share?
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dm440c
Feature Winner
derby drivers against drama- there's no crying in demo derby!
Posts: 2,824
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Post by dm440c on Nov 16, 2017 19:42:55 GMT -5
I've got a nice supply of great running engines with broken mount tabs... I have all these ideas about how to build a cradle for one but never quite get to it. If you come up with something good and post pics I'd sure appreciate it, maybe it would inspire me.
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dm440c
Feature Winner
derby drivers against drama- there's no crying in demo derby!
Posts: 2,824
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Post by dm440c on Nov 16, 2017 19:44:56 GMT -5
Maybe Ive just had a run of bad luck, but i keep burning up mini starters on big block motors. its as if they melt down when cranking a hot motor. I've burned up 2 in the last month one was from a wrecker, the last one was brand spanking new. is there a certain brand that works better than others? are genuine chrysler starters better? is anyone else having the same problem? Im really lost here because i love the high speed cranking with the mini, but hate the thermal melt down when they get hot. is this just my bad luck? I only run the ones I get from junkyards off the 90's trucks. Now, the funny thing is for me they seem to die in storage, not in the middle of being used. Don't know what the story is there.
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