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Decking advantages
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Author:  polara pat [ Fri Aug 10, 2007 7:54 am ]
Post subject:  Decking advantages
I'm building a fairly stock super six with a late model block and was wondering if there are any gains from decking the block and bumping the compression in such a mild motor. It just seems wrong that the pistons sit so low in the cylinders. Will this mod give any performance gains and will running regular still be possible? Sorry if this topic has been asked 100 times already. The motor is for my '64 wagon that we haul lots of heavy food and equipment in if that makes any difference....probably not, I just like giving too much info.
Author:  65deuce [ Fri Aug 10, 2007 8:21 am ]
Post subject: 
Well I would advise that some measuring should be done before hand, chances are you will find the current compression isn't even close to what the engine was originally rated. Milling enough to bring it to "spec" shouldn't create any issuses, but milling it a bit more would likely make an aftermarket cam respond a bit better. Keep it 8.5-9.0 or so and regular should be OK, maybe plus.
Author:  sandy in BC [ Fri Aug 10, 2007 8:54 am ]
Post subject: 
Go ahead and deck it and buy a new cam while its apart.

I run a Comp 264 and 9.25 CR and run on regular fuel.

Decking the block 50 with a stock cam is prolly not a bad idea either (Ive never done it)
Author:  polara pat [ Fri Aug 10, 2007 9:11 am ]
Post subject: 
I've already got everything for the build including a stock cam (thanks Dave) so I probably won't get a new cam. We do have a turbo slant in the works for another car though but that's for another day. While we're on the topic, what's the equation for calculating CR. I assume stock slants come in somewhere around 7 1/2-8.
Author:  slantvaliant [ Fri Aug 10, 2007 9:39 am ]
Post subject: 
Here's a CR Calculator
Author:  Dart270 [ Fri Aug 10, 2007 11:14 am ]
Post subject: 
Yes, a stock 225 Slant comes in around 7.5-8:1. I would go 0.060"-0.080" with a stock cam and you should have no issues.

Lou
Author:  polara pat [ Fri Aug 10, 2007 11:38 am ]
Post subject: 
Quote:
Yes, a stock 225 Slant comes in around 7.5-8:1. I would go 0.060"-0.080" with a stock cam and you should have no issues.

Lou
What kind of performance gains can be expected from this simple task?
Author:  Dart270 [ Fri Aug 10, 2007 1:08 pm ]
Post subject: 
If you have everything working properly, I would expect a bit better mileage, and probably 4-12 HP gain (~5%).

FWIW, degreeing your cam properly and optimizing your ign advance curve will likely net you the same sort of gains, since they (cams/tchains, or adv curves) are often not right.

Lou
Author:  Aggressive Ted [ Sat Aug 11, 2007 10:52 am ]
Post subject: 
I just went through this same process not wanting to be crazy about HP but wanted more torque to pull the 2.76 gears and get good mileage.
Advancing the cam 4 to 6 degrees helps, milling off a .100 helped alot. I have lots more snap with only mild work done on the head.
2.25" exhaust all the way back helped allot too.

Those three things are a must for a hauler like a wagon or a truck.
THere are several other items that can help, like a distributor recurve, carb rebuild, etc. I kept it pretty basic and am very happy with the outcome.
Author:  Dan-o [ Sun Aug 12, 2007 10:28 am ]
Post subject: 
I just had .100 taken off the top of my 62 block, and after asembly, my slugs are still .100 in the hole. To get a CR in the 9.0-9.5 range, I'll have to get head volumed in teh 52-55cc range.
Author:  1969ronnie [ Sun Aug 19, 2007 7:27 pm ]
Post subject: 
hi, i took .060 off a 68 225 and ended up -.115 in the hole. wish i had taken off more. also took .100 off a 69 225 and ended up .070 in the hole. i also found that my new .030 pistons were .025 to .030 shorter than my stock originals from center of piston pin to top of piston. ron
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