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10sec.et
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Joined: 29 Mar 2006
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Location: Houston,Texas
346658.74 points


1969 Oldsmobile Cutlass

PostPosted: Thu Aug 04, 2016 11:48 pm    Post subject: Reply with quote

you say plugs look "good". where is the timing mark on the plug? should be right in the bend.
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af2 wrote:
It seems we can look at our magical Balls and come up with a fix?

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robins44
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PostPosted: Sat Aug 06, 2016 4:21 pm    Post subject: Reply with quote

I guess i should have said no signs of detonation that i could see
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10sec.et
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Joined: 29 Mar 2006
Posts: 3473
Location: Houston,Texas
346658.74 points


1969 Oldsmobile Cutlass

PostPosted: Sun Aug 07, 2016 10:55 am    Post subject: Reply with quote

when you read the plugs, it needs to be a new plug (as in never ran). tow to the staging lanes and tow back. otherwise your idle circuit will mess up the read.
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af2 wrote:
It seems we can look at our magical Balls and come up with a fix?

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robins44
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PostPosted: Wed Aug 10, 2016 7:53 pm    Post subject: Reply with quote

Ya im familar with plug chops and reading them, havnt done one on this motor yet.
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Big Dave
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PostPosted: Thu Aug 11, 2016 9:14 pm    Post subject: Reply with quote

Pushing octane to a minimum and ignition lead to a maximum might get you down the strip today; but tuning for the strip on a street driven car is an invitation to detonation.
Weather changes every day (ambient temp and humidity are deciding factors on how far you can tune for the strip which is why the pro's have portable weather stations in their semi trailers).

If you tune it to the max today and the temp climbs or humidity falls (something that hardly ever happens in Florida with us being surrounded by water) next day while cruising down the road you may well hear a death rattle as your pistons are hammered with preignition.

I thought I read this was a street strip car. Better to leave a few ponies back in the coral than loose them all on the street to an over ambitious tune.

Big Dave
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10sec.et
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Joined: 29 Mar 2006
Posts: 3473
Location: Houston,Texas
346658.74 points


1969 Oldsmobile Cutlass

PostPosted: Thu Aug 11, 2016 10:57 pm    Post subject: Reply with quote

are you running a retard box when you spray it? thats a lot of timing if you dont. i agree with Dave. dont tune on the ragged edge. not that you would but its easy to be there before you know it.
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robins44
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PostPosted: Fri Aug 12, 2016 2:11 pm    Post subject: Reply with quote

Yes sir. Havnt sprayed this one yet. Wired it up per your diagram back in 06 or 07 i think. This motors always been ran with 36 in it according to my freind i bought it from. Seems to run mint even with old gas in it. But i am thinking about turning it back to 32 or 34 after talking with you guys.

If i did dynamic compression calculator correct its 9.5 to 1 or so with that cam.
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Paul P
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Location: Townsend, Mass.
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1971 Chevrolet Chevelle

PostPosted: Sun Aug 14, 2016 5:37 pm    Post subject: Reply with quote

With that DCR you are pretty safe. Premium pump gas should be fine under normal conditions. Spraying it might be best to have some higher octane in the tank at least a mix or some race gas additive like that orange and white can that Summit sells. Have a friend that uses it for road racing and he loves it.
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2001 Focus 2.0 Zetec
stock cams, bolt-ons and tune
15.63@87 MPH 1/4mi

1971 - Chevelle 408 SBC N/A
6.86@102.5 MPH 1/8mi
10.78@122 MPH 1/4mi
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robins44
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PostPosted: Sun Aug 14, 2016 9:41 pm    Post subject: Reply with quote

Went and got 5 gallons of 110 and dumped in to be safe. For as much as it gets drivin, ill just do that. Plus it smells nice

Thanks guys!!!
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Big Dave
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PostPosted: Wed Aug 17, 2016 1:42 pm    Post subject: Reply with quote

That nice smell is what is wrong with building a high compression engine today. That smell is the light aromatics, ketones, and esters that are mixed into the base gas to raise the octane. They evaporate (aka boil) at 78 degrees and above. Most are evaporated by 96 degrees. So by the end of the week that 110 tests closer to 94.

I used to buy race gas in 55 drums and transfer that into a large collection of plastic 5 imperial gallon gas cans (6.2 gallons US) to prevent it from evaporating. If the gas can is full, or nearly so the vapor pressure in the can is high enough to raise the boiling point (works like a radiator cap raising the boiling point of your car's coolant). You have to open and pour race gas in at the track to maximize it's usefulness.

Big Dave
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