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Author Topic:   Boosting Compression
ryan
Member
posted August 19, 2001 11:17 AM
What is the best way to raise my compression to 11 to 1. No domed pistons, Bowtie's are the only preformance head allowed besides stock. Right now I have flat top pistons My heads are: 1.94 1.5 76cc. This is my first year in Street Stock and I could use all the help I can get. Also what kind of oil do you think is best to run that I can buy at my local parts store? Thanks


CUSTOMPERFORMANCE
Member
posted August 19, 2001 01:23 PM
use 2 valve relief flattop pistons, have the block decked to zero deck, which puts the piston right at the top of the bore. use the minimum thickness headgasket , make sure you have plenty of valve clearence. this will get you close, if it isnt you can have the heads angle milled also.


sdhnc29
Member
posted August 19, 2001 11:41 PM

Why are you using 76cc heads ??

As Custom said :"use 2 valve relief flattop pistons, have the block decked to zero deck, which puts the piston right at the top of the bore. use the minimum thickness head gasket ". Also , get your self some 64cc heads !! Even if you do all of this , you will still have to get the heads milled if they are on a 350 . I'd shoot for around 12:1 - 12.5:1 if it's in your budget !! Of course this will involve angle milling , valve relief notching , and correcting your intake face of your heads . How many $$ do you want to spend ?? It directly relates to how fast you want to go !

As for oil , we normally recommend Mobil 1 15w-50 synthetic .

ryan
Member
posted August 20, 2001 02:00 PM
I am running those heads this year because it was what I had and after building the car I wasn't in my budget last year. The most we can run is 11:1 Max compression its in the rules. I would like to get right at 11 to 1.


RangeRover
Member
posted August 21, 2001 06:20 PM
This may not be a very popular comment but I am the cheapest racer I know. Decking the block and 64cc heads cost money (you would not believe how much in Canada) What I've done the last few years is run 305 4 bbl heads. O.K. I know that the intake valves are smaller (1.85 vs 1.94) but unless your twisting thay motor past 5500 rpm the smaller vavle won't hurt too much. I get these heads at the local pic a part. have them checked for cracks, treat them to a good vavle job and go. These heads have as small as 58cc chambers and with steel shim head gaskets your compression should be 10.7 give or take a .1 Just a suggestion!


Good Luck!!


ryan
Member
posted August 30, 2001 12:33 AM
Would using a longer rod work instead of decking the block. What are the pros and cons of using a 6.0 rod?


RangeRover
Member
posted August 30, 2001 12:42 PM
Apples and oranges, dude. The 350 rods are 5.700" long- that's .300" shorter than the 6 inchers. You can imagine the pistons popping way out of the deck by only swapping rods. To use the 6" rods you need to get pistons that make up the distance difference by locating the wrist pin higher up in the piston. This will put the piston to deck clearance back where you started with the only difference being having longer rods. There are some advantages to running longer rods like: reduced side loading on the cylinder walls and more cylinder pressure by leaving the piston at TDC longer. Generally though, the longer rods tend to move the engine's power higher on the rpm range. Some experts simplify the decision by using 5.7 rods on short tracks and 6.0 rods on longer speedways. You should be fine with 5.7 rods for most applications, however.


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