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Old 07-09-2013, 07:11 PM
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Dirt Track Chevy 350 tuning

Alright guys, I'm looking for any and all advice on this one.

I run a local dirt track racing circuit, and I built a new motor (1978 Chevy 350) for this year. Some specs are as follows:

-Bored .030 over (technically making it a 355)
-Line bored / crank ground
-New bearings / seals / etc
-Stock .030 pistons (generic. Nothing too special)
-New valves / valve seals
-New lifters
-RV cam with .420 / .433 lift and 278/288 duration
-Stock GM aluminum intake manifold
-Stock HEI ignition
-Edelbrock Performer 1406 carb (650 cfm, I believe)

With this cam selection, I've been reading online about how I will need to change out my vacuum advance canister on my dist. / mess with timing / etc etc.

What do you all recommend to get the most power out of the motor with the parts I have? I compete in a limited class, so I can't run fancy MSD ignition and aftermarket heads / intake. I'm "limited", so to speak, on aftermarket parts.

Thanks for any help in advance!

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Old 07-09-2013, 07:51 PM
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set your total timing to w/e the engine can tolerate with w/e fuel you are allowed to use. Vacuum advance is more for mileage and off throttle response,all that doesnt matter for you.
If those are the parts that you can use(nothing better?) then all other power will have to come from blue printing
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Old 07-09-2013, 08:48 PM
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Why is it that none of you guys give us the camshaft part number so that we can look it up easily and try to help you?
I spend the majority of my time just looking up part numbers and specs on stuff. It's very frustrating.
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Old 07-10-2013, 10:27 AM
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The camshaft is way too small for racing with that motor.
There are many many good cams for this .
I'd change the cam. spark timing 34-36deg BTDC when using 92 octane gas.
vacuum advance won't matter, Your racing not cruising.
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Old 07-10-2013, 02:16 PM
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Dakotah, are the replacement pistons flat tops or dished (which is what your stock pistons should have been)? Are they the full 1.56" compression height pistons or are they shorter "rebuilder" pistons. It will make a difference on your compression ratio.

As far as ignition timing, for an oval track I never even hooked up the vacuum advance, the only time your engine will have any meaningful vacuum is when you let off for the corners, when you don't need power. As soon as you stomp the long pedal on the right side your vacuum drops, so no help there. The mechanical advance on any advance curve will be all in by 3000-3500 rpm, so the advance should be all in before you're at racing RPM, so it doesn't really matter either. If your rpm are dropping enough in the corners that your advance curve comes into play at all you need to be revving that 350 higher! Set your ignition timing for total advance (you'll have to have the engine revved enough that it doesn't advance anymore). When I ran dampers that weren't marked far enough for total advance I would use a small triangular file to put another mark on the damper for 36* advanced. Then you just set the 36* mark on the damper to the "0" mark on the timing tab to set your timing for 36*. If I remember right on a 6 3/4" damper 36* is just a few thousandths under 2.125". If you need a few degrees more or less the tab will have enough marks to let you put it where you want it. To do this just measure the outside circumference of the damper and divide by 10 (36* is one tenth of 360*).

What are your cam rules? The cam lift you've listed sounds like the "generic" grind for RV/torque cams with 204*/214* durations on the intake/exhaust. As F-bird'88 pointed out, that is a very small cam for dirt tracking, unless that is what your rules restrict you to. Even with "stock lift", duration, or vacuum rules that is a small cam, even with your limited compression ratio and stock heads. I would recommend a bigger cam. Even the GMPP #24502476 cam from the 350 HO or the "602" street stock crate engines (or the equivalent "copy" cams like the Summit K1103 or SpeedPro CS-1013R)would be a big step ahead from what you've got now, and wouldn't cost any more than you had to pay for the RV cam.

Check out my website at:
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Old 07-10-2013, 03:15 PM
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Quote:
Originally Posted by DakotahRusley67 View Post
Alright guys, I'm looking for any and all advice on this one.

I run a local dirt track racing circuit, and I built a new motor (1978 Chevy 350) for this year. Some specs are as follows:

-Bored .030 over (technically making it a 355)
-Line bored / crank ground
-New bearings / seals / etc
-Stock .030 pistons (generic. Nothing too special)
-New valves / valve seals
-New lifters
-RV cam with .420 / .433 lift and 278/288 duration
-Stock GM aluminum intake manifold
-Stock HEI ignition
-Edelbrock Performer 1406 carb (650 cfm, I believe)

With this cam selection, I've been reading online about how I will need to change out my vacuum advance canister on my dist. / mess with timing / etc etc.

What do you all recommend to get the most power out of the motor with the parts I have? I compete in a limited class, so I can't run fancy MSD ignition and aftermarket heads / intake. I'm "limited", so to speak, on aftermarket parts.

Thanks for any help in advance!
First of all does the track you run have a( Caimer rule ) how much is the claim are you limited on valve lift and duration and carb butterfly size can you angle cut the heads to raise compression and keep the flat top pistons,

I guess before I get to far ahead The claimer rule would change things.
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Old 07-11-2013, 02:01 PM
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A good start is too list your engine rules. EVERY decision you make will depend on those.
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Old 07-11-2013, 02:24 PM
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Quote:
Originally Posted by BigEd36 View Post
Dakotah, are the replacement pistons flat tops or dished (which is what your stock pistons should have been)? Are they the full 1.56" compression height pistons or are they shorter "rebuilder" pistons. It will make a difference on your compression ratio.

As far as ignition timing, for an oval track I never even hooked up the vacuum advance, the only time your engine will have any meaningful vacuum is when you let off for the corners, when you don't need power. As soon as you stomp the long pedal on the right side your vacuum drops, so no help there. The mechanical advance on any advance curve will be all in by 3000-3500 rpm, so the advance should be all in before you're at racing RPM, so it doesn't really matter either. If your rpm are dropping enough in the corners that your advance curve comes into play at all you need to be revving that 350 higher! Set your ignition timing for total advance (you'll have to have the engine revved enough that it doesn't advance anymore). When I ran dampers that weren't marked far enough for total advance I would use a small triangular file to put another mark on the damper for 36* advanced. Then you just set the 36* mark on the damper to the "0" mark on the timing tab to set your timing for 36*. If I remember right on a 6 3/4" damper 36* is just a few thousandths under 2.125". If you need a few degrees more or less the tab will have enough marks to let you put it where you want it. To do this just measure the outside circumference of the damper and divide by 10 (36* is one tenth of 360*).

What are your cam rules? The cam lift you've listed sounds like the "generic" grind for RV/torque cams with 204*/214* durations on the intake/exhaust. As F-bird'88 pointed out, that is a very small cam for dirt tracking, unless that is what your rules restrict you to. Even with "stock lift", duration, or vacuum rules that is a small cam, even with your limited compression ratio and stock heads. I would recommend a bigger cam. Even the GMPP #24502476 cam from the 350 HO or the "602" street stock crate engines (or the equivalent "copy" cams like the Summit K1103 or SpeedPro CS-1013R)would be a big step ahead from what you've got now, and wouldn't cost any more than you had to pay for the RV cam.

Check out my website at:

I just set this pic as a background on my computer for a while!!

Hope you don't mind...love it!!



Duke
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Old 07-11-2013, 02:26 PM
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Also what size track are you running a 1/8 will be set u p much different than a 1/2 mile
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Old 07-11-2013, 07:10 PM
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Quote:
Originally Posted by thinwhiteduke View Post
I just set this pic as a background on my computer for a while!!

Hope you don't mind...love it!!



Duke
Glad you like it, Duke! That's my all time favorite! Just wish it was in color.
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Old 07-19-2013, 03:18 PM
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I wonder what happened to DakotahRusley67............He hasn't logged onto the forum since he made his initial post!
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Old 07-19-2013, 03:31 PM
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Must not be what he wanted to hear.
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Old 07-20-2013, 10:33 PM
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Quote:
Originally Posted by 496CHEVY3100 View Post
Must not be what he wanted to hear.
What do you all recommend to get the most power out of the motor with the parts I have? I compete in a limited class, so I can't run fancy MSD ignition and aftermarket heads / intake. I'm "limited", so to speak, on aftermarket parts.

If you're not going to change anything....then

Maybe a lot of magic fairy dust will help....
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