Which MSD rev limit chip to use? - Team Camaro Tech
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post #1 of 15 (permalink) Old Jan 28th, 10, 12:51 PM Thread Starter
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Which MSD rev limit chip to use?

I have installed my MSD6AL ignition box and have an assortment of rev limit chips, My question is which one best fits my build? I have a Howards cam #120031 with .505 / .525 lift and 290 / 300 duration the duration at 0.050 is 215/ 225 with LSA of 112 .The springs have a seat load of 112# and open load of 309#. The operating range of the cam is 1600-5200 rpm. I drive mostly on the street but I can not rule out a little fun now and again.

1969 SS 454ci TKO 600
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post #2 of 15 (permalink) Old Jan 28th, 10, 02:32 PM
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Thumbs up Re: Which MSD rev limit chip to use?

I would say you are safe to @5.5K (5,500rpm) if the bottom end is also capable.
You can probably get away with a higher chip, but why ... the cam is beyond it's design area and depending on your build the engine is probably way beyond it's torque curve so you're not gaining much if anything after that. Mainly a few MPH in an overall drag run if you have very steep gears

The springs are in the lower-mid range for use with a high performance flat tappet cam, so depending on the number and duration of the 'little fun' runs you take they should not be a problem and last well.

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Last edited by Vintage 68; Jan 28th, 10 at 03:46 PM. Reason: I type faster than I can spellin'
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post #3 of 15 (permalink) Old Jan 28th, 10, 03:04 PM
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Re: Which MSD rev limit chip to use?

What size engine. I'm assuming from the cam specs it's a SBC. Probably a healthy 350, 383, or a 406. In any case the 6k chip that cam with the box would be a good place to start, as any of these combo's even in stock form can handle spinning up to 6k from time to time without issues. Without knowing more about the motor, and only going with those cam specs I would say your max shift point would be 5600-5800. So the 6k still gives you a little room for a miss-shift.


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post #4 of 15 (permalink) Old Jan 28th, 10, 03:11 PM Thread Starter
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Re: Which MSD rev limit chip to use?

Quote:
Originally Posted by HarleyD67 View Post
What size engine. I'm assuming from the cam specs it's a SBC. Probably a healthy 350, 383, or a 406. In any case the 6k chip that cam with the box would be a good place to start, as any of these combo's even in stock form can handle spinning up to 6k from time to time without issues. Without knowing more about the motor, and only going with those cam specs I would say your max shift point would be 5600-5800. So the 6k still gives you a little room for a miss-shift.
Its a 454 with RE-BUILT iron heads, the bottom end is all new and balanced.

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post #5 of 15 (permalink) Old Jan 28th, 10, 03:18 PM
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Re: Which MSD rev limit chip to use?

5,500
That cam is done before 6,000rpm

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post #6 of 15 (permalink) Old Jan 28th, 10, 03:18 PM
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Re: Which MSD rev limit chip to use?

Sorry I miss read your cam specs. I thought it was 1600-5800. That's a pretty mild cam for a 454. With a BBC you could still use the 6k chip, but your shift point will be much lower. Again without knowing all the details I am guessing 5000-5200. As mentioned you peak torque is probably going to happen at 4700-4900. Again this is only an educated guess without the rest of the engine specs.


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post #7 of 15 (permalink) Old Jan 28th, 10, 03:57 PM
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Red face Re: Which MSD rev limit chip to use?

I only assumed (bad on my part) BB as the Howard's part number started with '12' (big block) vs. 11 (small block)

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post #8 of 15 (permalink) Old Jan 28th, 10, 06:03 PM
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Re: Which MSD rev limit chip to use?

5500.....
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post #9 of 15 (permalink) Old Jan 28th, 10, 06:25 PM
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Re: Which MSD rev limit chip to use?

Quote:
Originally Posted by Vintage 68 View Post
I only assumed (bad on my part) BB as the Howard's part number started with '12' (big block) vs. 11 (small block)
I think you were right when you said big block.

Trevor - we are talking about a 454 BBC - correct?

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post #10 of 15 (permalink) Old Jan 28th, 10, 06:38 PM
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Re: Which MSD rev limit chip to use?

Those springs are kinda soft.I would put a 5500 chip in it.That cam is mild.
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post #11 of 15 (permalink) Old Jan 28th, 10, 06:54 PM
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Re: Which MSD rev limit chip to use?

I use the 6k chip on my stroked small block but I agree with the majority here, go with the 5500 for that motor.

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post #12 of 15 (permalink) Old Jan 28th, 10, 06:59 PM
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Re: Which MSD rev limit chip to use?

It's a bbc cam in my catalogue. Says great low and midrange, heavy veh ok.

I personally adj valves at 1/2 turn preload, take them out and see where they fall on their face (or go flat) then re-adj valves at 1/4 and go out again. Usually gain a couple hundred rpm and get there quicker. Right in between those 2 spots is where you need to have shifted by. And leave the preload at 1/4. For where you would want your chip, you haven't said if you had cast stuff or forged. If it's forged you don't need no stinking chip; I got a nickel says that cam with .505 lift on a 454 is done way before forged stuff will get hurt. All you need to do is shift accurately.

Chips just piss ya off anyway.

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post #13 of 15 (permalink) Old Jan 28th, 10, 10:15 PM
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Re: Which MSD rev limit chip to use?

I agree, just valve float it until it bumps a piston.
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post #14 of 15 (permalink) Old Jan 28th, 10, 11:20 PM
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Re: Which MSD rev limit chip to use?

Now that I think of it, the motor is probably done AT OR NEAR 5,500, but if it has some to go, and your really pushing it, just for fun or if it decides to make power at 5,500, the 6k shouldn't hurt anything.
go with the 5,500 or 6k, always good to have a little more rpm past the power band if you want/need it.
Say my motor made power at 6,500, i'd install a 7k chip.
what ever you decide to go with, it's much better if your not paying attention or miss a shift and the motor spikes to dangerous rpms (it happens fast)

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post #15 of 15 (permalink) Old Jan 29th, 10, 04:23 PM Thread Starter
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Re: Which MSD rev limit chip to use?

Quote:
Originally Posted by bcm66 View Post
I think you were right when you said big block.

Trevor - we are talking about a 454 BBC - correct?

Yea, Its a BBC, This cam is a large step up from the one we pulled out. And all the internals are cast not forged. Looks like a 5500 chip is going in. Thanks for the help.

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