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By 58F600 - 3 Months Ago
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Anyone know the mechanical advance vs RPM curve, advance vs Vacuum specs and base and total timing for the factory SuperCharged 312? Getting ready to build a base tune for our 292 Turbo and just need a starting point to work from.
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By 55blacktie - 3 Months Ago
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What heads & cam are you using for the turbo application? Just curious.
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By 58F600 - 3 Months Ago
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Stock 62-64 C1TE
Don't copy us. This is going to see as little boost as possible. It's just for fun. Not trying to go fast. It's a 2bbl, maybe 5psi. 215hp ish
My wife wanted her dump truck to make turbo noises. I'll post pictures in a few days when we get it going
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By 55blacktie - 3 Months Ago
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I thought it was an unusual combination, particularly for an F600, but I've seen stranger builds.
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By MplsMike - 3 Months Ago
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“My wife wanted her dump truck to make turbo noises.”
That may be the only time I ever read a sentence like that!! Awesome!
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By Hoosier Hurricane - 3 Months Ago
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Back to your original post, the following comes from the factory Supercharger Manual. Vacuum advance:
Dist RPM Deg. Inches HG
1000 0 1
1000 0-1 5
1000 1-3 7
1000 9-11 14
1000 9-11 20
Centrifical Advance:
Dist RPM Deg.
300 0-1/2
400 2-3
600 8-9
1500 9 3/4-11
2000 10 3/4-12
Initial timing 3 deg.
John
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By 58F600 - 3 Months Ago
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Thanks John!
Am I reading that correctly, they only ran 15° total advance?
Was there any boost retard solution?
I figured this old 292 would want about 36° total before boost. Pulling 20 degrees for 9psi seems excessive. I was thinking about 4° retard at 5psi(target boost for us)?
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By miker - 3 Months Ago
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I’m not arguing with the F code spec, but this was my experience. 292/312 crank, 320cid. 9:1 true static ratio. 113 Mummert ported iron heads, 270 series cam (20 years ago, spec may have changed). Paxton SN2000, pulleys for 5lbs at 5000 rpm. Premium pump fuel.
I ran 10-12 initial, and 34-36 all in. The vacuum can had probably around 15 or 20 degrees in it. I used an MSD and ran 2* retard at 3 psi (manifold pressure). That came in around 3000 rpm, maybe a little higher. Hot weather, or racing with long WOT periods, I’d need less initial/less centrifugal/ more retard. Didn’t happen enough to do more than set the initial back a bit.
Your results will depend on the engine/cam specs, etc.
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By Hoosier Hurricane - 3 Months Ago
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The specs show 27 degrees total mechanical advance, there would not have been any vacuum at full throttle, probably about 6 pounds pressure. On my car, I'm running SN60 guts in my blower for about 12 pounds boost at 6000 RPM. I used to run 34-36 total advance, lost a lot of head gaskets. I backed down to 30 degrees total, the car ran quicker and head gaskets now live. I get 27 degrees from the specs, 12 distributor degrees times two plus 3 degrees initial.
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By 58F600 - 3 Months Ago
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Hoosier Hurricane (8/18/2024)
The specs show 27 degrees total mechanical advance, there would not have been any vacuum at full throttle, probably about 6 pounds pressure. On my car, I'm running SN60 guts in my blower for about 12 pounds boost at 6000 RPM. I used to run 34-36 total advance, lost a lot of head gaskets. I backed down to 30 degrees total, the car ran quicker and head gaskets now live. I get 27 degrees from the specs, 12 distributor degrees times two plus 3 degrees initial.
"Distributor Degrees"! I missed that, when reading. Thanks for the clarification. 27° sounds more like it!
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By 58F600 - 3 Months Ago
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miker (8/18/2024)
I’m not arguing with the F code spec, but this was my experience. 292/312 crank, 320cid. 9:1 true static ratio. 113 Mummert ported iron heads, 270 series cam (20 years ago, spec may have changed). Paxton SN2000, pulleys for 5lbs at 5000 rpm. Premium pump fuel. I ran 10-12 initial, and 34-36 all in. The vacuum can had probably around 15 or 20 degrees in it. I used an MSD and ran 2* retard at 3 psi (manifold pressure). That came in around 3000 rpm, maybe a little higher. Hot weather, or racing with long WOT periods, I’d need less initial/less centrifugal/ more retard. Didn’t happen enough to do more than set the initial back a bit. Your results will depend on the engine/cam specs, etc.
That's really close to the range I was thinking! I'll probably stay 30° or under on total until we get a feel for things. Long hills in a big truck and I don't want to be swapping head gaskets. We do have a Pyrometer installed as well.
Anyone happen to run a Pyrometer with their set up? I've used a bunch but on diesels. I guess the melting point of aluminum remains the same so we were thinking 1250° was probably the top of the safe zone.
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By miker - 3 Months Ago
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My experience is diesels also, mostly on Cummins, measured right off the exhaust, in front of the turbo. (The Cat’s I was around were after the turbo, much lower). That said, I’d think any long pull over 1000 or so might be too much. Unless the valve cooling was designed for that. I know some guys running factory turbos hard are running up to 1600+, but those engines were designed for pretty high boost to begin with.
As I recall, you’ve got a long drive home. If you’ve got the Rockies, Siskkiyous’s or Sierra’s in the middle, I’d be more worried about the exhaust valves from heat on a hard pull.
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By 58F600 - 3 Months Ago
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1000° continuous sounds reasonable. 1250° for short pulls maybe. The engine is a bit of an unknown, it's very clean in the valley and heads. Looks to have been rebuilt at some point. But probably just a local machine shop ring/bearing/hone job. Certainly nothing hi performance, just stock.
Yes, we are building the truck here in Eastern Oregon at 5k feet, route home is still fluid, but we really want to go through the San Juans in southern Colorado which would put us about 12,500 ft, but very slow 15mph crawl up dirt roads.
Thanks for sharing first hand experience. We really don't want to hurt the old 292.
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By Joe-JDC - 3 Months Ago
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Depending on your static compression ratio, you may not need to pull any timing with less than 5 psi. The crossover point seems to be 9.5:1 compression and over 5 psi boost. We ran 9.0-9.5 with modern heads up to 14psi only pulling out 4* total on SBFs. JMO, but I would not be too concerned with timing with Y block iron heads up to 37* with premium fuel and stock compression. Joe-JDC
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By 58F600 - 3 Months Ago
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Thanks Joe. I'm assuming this engine is a simple stock rebuild 7.5:1,2bbl C1TE heads 160hp 292. It would probably run 5psi on 87 octane lol
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By Deyomatic - 3 Months Ago
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It's apples to oranges but I had a problem with knocking at 10 PSI on a Mitsubishi Eclipse on 91 octane when I lived in AZ. Looks like that had 7.8:1 CR.
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By Joe-JDC - 3 Months Ago
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Big difference between 5 psi and 10 psi when it comes to timing requirements and fuel octane. 5 psi is easy if it doesn't build heat due to restrictions. Joe-JDC
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By 58F600 - 3 Months Ago
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Pictures posted in the street section
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