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| How much should i mill the head? https://www.slantsix.org/forum/viewtopic.php?t=38789 |
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| Author: | 65cuda [ Wed Jan 27, 2010 2:46 pm ] |
| Post subject: | How much should i mill the head? |
I have a 65 and a 71 apart in the garage floor. my plan is to put the crank from the 71 in the 65 block. do a hone and file to fit rings in the 65 block. new bearings on the rods and mains. now the question the pistons are 160 down in the hole. the steel shim was about .023 the felpro is about .055 so i am losing about .030 just on the new head gasket. the FSM says it was 8.4 CR so when i take to the shop to get a valve job and maybe some hardened seats how much should i have it milled to get it up to the best CR for Reg. gas and best MPG. i also need a new cam and lifters. whats the best cam for this combo. |
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| Author: | plymouth6 [ Wed Jan 27, 2010 3:36 pm ] |
| Post subject: | |
As far as how much to mill the head you should never mill the head more than a few thousands unless you cc the chambers so you know what you have. I have a head that I milled 90 thousands to get my compression where I wanted it. Your machine shop will do this for you for a fee but is well worth it. The last thing you want to do is mill off 100 and find out you have to much compression for your build. I am sure a few more people will post as well but wile you wait you should use the search function and search engine builds to get some ideas. Have fun with your build |
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| Author: | Charrlie_S [ Wed Jan 27, 2010 3:48 pm ] |
| Post subject: | Re: How much should i mill the head? |
Quote: I have a 65 and a 71 apart in the garage floor. my plan is to put the crank from the 71 in the 65 block..
You are aware that the 65 and 71 crankshafts, have a different size converter/flywheel/flexplate register, right?
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| Author: | 65cuda [ Wed Jan 27, 2010 4:00 pm ] |
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yes i know that the crank registers are different. but i didn't when i bought the 65. i thought i had a drop in. thats why i am changing the crank. the 65 is a better cleaner block than my 71 that came out. it's going in a 71 dart with a 904. Thanks for letting me know. well i guess i will have to CC the head. i was hoping that 71 heads were all close in size and work from the average. |
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| Author: | Aggressive Ted [ Wed Jan 27, 2010 4:01 pm ] |
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The SL6 is pretty forgiving on compression. Mine is at 9.5 to 1 and I wish I went to 10 to 1 for a little more torque. As mentioned, cc your head to find out where your at first...... |
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| Author: | 65cuda [ Wed Jan 27, 2010 4:05 pm ] |
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does the same formula work for the slant as the other mopars .060 off is 1 point |
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| Author: | 66aCUDA [ Wed Jan 27, 2010 6:24 pm ] |
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Thats .006 NOT .060 about equals 1 CC. Frank |
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| Author: | 65cuda [ Wed Jan 27, 2010 6:49 pm ] |
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Thanks Frank i will need that one too. after i cc the head i will have to work backwards to see how many CCs the chamber needs to be. but i was asking about rasing the CR one point. in SBs we say the 60 thousands off the head will rase you 1 point or 8.4 to 9.4. Does that work for the slant too. |
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| Author: | 65cuda [ Thu Jan 28, 2010 2:15 pm ] |
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Ok i broke out the CC stuff today and my head works out to be 64cc. now i put that in the calc. at the KB site and it says i am at 7.8 So i play with the CCs till i find that 20 less cc gives me 9.0 to 1. But using the math Frank put up looks like i would need to shave off .120 . 1 am i doing this math right thats sounds like a lot. 2 is it possable to take that much off if i did would i need shorter pushrods? |
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| Author: | Aggressive Ted [ Thu Jan 28, 2010 5:43 pm ] |
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To offset what your milling off the head, just send your cam in and have it ground to a taller profile by the same amount and that will equal out the need for new push rods. I went 9.5 to 1 on my engine and had the cam ground for a Erson 254 profile (.435 lift) and that worked out fine. The cost for the regrind was only $35. 
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| Author: | 66aCUDA [ Thu Jan 28, 2010 7:16 pm ] |
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Quote: Ok i broke out the CC stuff today and my head works out to be 64cc. now i put that in the calc. at the KB site and it says i am at 7.8 So i play with the CCs till i find that 20 less cc gives me 9.0 to 1. But using the math Frank put up looks like i would need to shave off .120 .
Your math is correct. I have found the make or break point for "new" push rods to be right around .140+/-.1 am i doing this math right thats sounds like a lot. 2 is it possable to take that much off if i did would i need shorter pushrods? Your .120 should be ok. This is a common amount to take off the slant. There is a lot of meat there unlike a sb. Frank |
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| Author: | 65cuda [ Thu Jan 28, 2010 8:45 pm ] |
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Thanks Frank . off to the mach. shop it goes tomorrow. i will ask for a .120 shave. Ted you said you had 9.5 and wish you had more. are u running reg. or prem. is it cheaper to send them a cam and have it reground. i have a couple laying around here? Thanks you guys for the help i am new to slants. i always liked them but just never built one. i drive a wore out 72 everyday. i don't know if it almost has 200k or 300k. Gary |
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| Author: | Aggressive Ted [ Thu Jan 28, 2010 10:09 pm ] |
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Gary, I have it tuned (distributor recurved) for regular but do get a little better mileage with mid grade on long trips. I used a local cam grinder Delta Cams in Tacoma, WA. They charged $35 to regrind my cam which is very reasonable. Then you know you have a good cam especially if it came out of your engine......if you have other known good cams, why not? If your after torque be sure and advance it a few degrees. It does help! |
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| Author: | 65cuda [ Fri Jan 29, 2010 6:44 am ] |
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Thanks Ted. i don't know of any cam grinders local but i will ask around. i have a 2 bbl on my 72 it seems to get real good MPGs. did you try one. i also have a 1 bbl setup too. not sure which one i will put on when i put this motor back in. love the looks of your car. makes me want to get a nice valve cover too. my other motors are dressed. i take them to car shows in the summer. no shows for now it's 5 degrees this morn. Gary |
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| Author: | Aggressive Ted [ Fri Jan 29, 2010 9:13 am ] |
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Gary, Yes, I have a complete two barrel set up with a untouched stock BBD but have not tried it on this car. Still running a 1920 Economaster. I keep trying and adding new things to see how much mileage I can get out of it. For a daily driver it is very economical and spunky. I had the Super Six on my 77 Volare. It's best was 28 mpg. |
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