tuning for performance

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Mar 3, 2005 | 11:10 PM

AK429

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Joined: Apr 2004

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tuning for performance

I am just trying to get the ultimate power out of my carbureted 460. I really need a boost in power right now, and am wondering what I can fine tune to make it faster.It came with a full MSD ignition with box and distributor. I also have a performer intake and performer cam in it. I just got my headers installed, and I don't think I am seeing the gains I should be. Can i tweak the timing, A/F, or anything else....

Mar 4, 2005 | 12:43 AM

Bear 45/70

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Joined: Mar 2004

Posts: 6,056

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From: Union, Washington

First off need to know what the max mechanical advance of the timing is set at now and the intitial timing also. Is the carb stock, rejetted or replaced or what if anything? What color are your plug electrodes? Transmission, rear gear ratio, tire size and how big are your exhaust pipes?

Mar 4, 2005 | 10:09 PM

The "Mad Porter"

Mountain Pass

Joined: Aug 2004

Posts: 143

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From: Tacoma, WA.

As a general rule...

Most stock headed BBFs do not respond to performance upgrades as well as other engine makes with better exhaust ports. The problem is one of extreme exhaust port turbulence and lack of flow capability as cast. Until the crappy exhaust port is addressed you will always be some 30 to 50 HP down vs. a combo with good heads be they ported iron or aftermarket aluminum. What you have done is increase intake side efficiency with out addressing exhaust efficiency. The headers are nice but with stock heads the exhaust port passage itself is the restriction.

I have seen dyno tests that show 25 to 30 additional RWHP in a stock to mild application by just addressing the exhaust ports.

One area you might explore is the distributor and its advance curve. I like to see about 14 degrees initial timing in your application and another 26 degrees centrifugal for a total of 38 to 40 degrees not including part throttle vacuum advance.

http://www.reincarnation-automotive.com/Duraspark_distributor_recurve_instructions_index.h tml

Another issue will be the stock holley carb if you are using it. It is only 580 CFM but more inportantly it is quite lean for emissions reasons.

This is a pic of an RHP exhaust port that functions very well...

http://www.reincarnation-automotive.com/ExhaustExitViewD3220.jpg

This is a stock port...

http://www.reincarnation-automotive.com/port-exit-tboss-bump-labled.jpg

Scott J. / RHP
Http://reincarntion-automotive.com
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Mar 5, 2005 | 06:54 PM

AK429

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Joined: Apr 2004

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I am using a edelbrock 600 carburetor right now. I haven't checked my plugs yet. I am pretty sure my timing is set @ TDC right now. C6 tranny with 3.5 open rear end, and 295/50/25's. I have short header sthrough dual 2.5 mufflers

Mar 6, 2005 | 01:15 AM

Bear 45/70

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Joined: Mar 2004

Posts: 6,056

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From: Union, Washington

TDC is way retarded, should be at a minimum 6 to 10 degrees with a total mechnical of 30 to 34 degrees (vacuum hose disconnected and plugged). I have 10 and 30 degrees marked on my damper and run 16 initial but I recurved my dist and with a stock dist use 6 to 10. To check the total hook up the timng light and set initial, then rev the engine with the light still on and watch the advance roll in. By about 3500 to 4000 you should see total, the mark will stop advancing.