Dynoed my L48
Race Director
Joined: Oct 2000
Posts: 15,055
Likes: 79
From: central FL, near the beach.
Nice numbers Toddalin especially for factory heads. Your Torque curve just seems to maintain itself much longer than mine does. The only thing that I see that I may be able to transfer over to my set up from yours is the RPM intake and maybe the roller tip rockers. Maybe I could go with the 1.6 ratios on the intake like Matt said. No one seems to have mentioned the stock intake being a possible restriction, which would be my first guess as the primary bottleneck.
Matt do you have a part number for the jet plate that I would need, sorry im not to familiar with these carbs, i've built engines before but im new to this whole tuning for power thing. Also do you mean using something like a timing light and looking for missing pulses to detect the misfire?
Matt do you have a part number for the jet plate that I would need, sorry im not to familiar with these carbs, i've built engines before but im new to this whole tuning for power thing. Also do you mean using something like a timing light and looking for missing pulses to detect the misfire?
1. dyno
2. drags
3. stopwatch
4. G-tech etc
that L-82 intake might be very good IIRC
use search or call holley for jet plate info.
I like the cam, but it may be very sensitive to back pressure! uncorked could show big gain on dyno, and increase hearing aid sales
low back pressure a must!When u forced the carb open, it still had that spike?
.060 plug gap, if missing, renders entire dyno test just practice.(like drag racing w/1 plug wire off)
Last edited by Matt Gruber; Sep 21, 2009 at 06:36 AM.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
Just for additional info: The plug gap used must be appropriate for the type of ignition system and plugs selected. Essentially, your coil [and voltage to the coil] define how much spark voltage your system is capable of producing. As the spark gap increases, it takes higher voltage to be able to jump that gap. So, your spark gap needs to be appropriate for the voltage capability of your system. A stock 'points' system/coil will generate less than 20,000 volts; and 20K volts is not enough to reliably jump that large of a gap. Set plug gap to .035"...or change the ignition system to a HEI or electronic unit with a higher voltage coil. Then set the gap per the instructions on the new ignition system.
Burning Brakes
Joined: May 2008
Posts: 860
Likes: 0
From: Stratford Ontario
I would try a bigger carb,and intake change.If you can find someone with a used carb you could at least do tests? With those heads and cam your motor should not start to fall off that soon in power.Im sure if you got at least a bigger carb you would feel the power at about 60MPH and over.Just a thought.
Race Director
Joined: Jan 2003
Posts: 15,176
Likes: 88
From: State of Confusion
for what it's worth, I had my L83 less-CFI on Tracy Lewis' DynoJet at RevXtreme last week, just to see what it made:
stock 28,000 long-block with a 650 double-pump Holley, older Street Dominator intake (#300-48?), non-computerized HEI, 1.6:1 roller-tip rockers..... rest of drivetrain is stock manifolds, 2-1-2 exhaust with an empty catalytic converter & OEM mufflers, a looser TQ converter in-front of built 700-R4, & 3.73 gears.
car has run a best of13.93 @ 99+ MPH at the drag-strip deep-staged in cool weather, with 1.99 short-times and 9.00 in the 1/8-mile (then ran 14.06 @ 95+ in stiffling 95*f temps yesterday):
results were 232 HP @ approx 4900 RPM, and 291 TQ @ approx 3400 RPM, while the screen also showed 97*f & 38% humidity in the shop
sorry, didn't get a print-out sheet, we were only looking for proper A/F ratios, and 'just-curious' to see what the actual numbers really were.
stock 28,000 long-block with a 650 double-pump Holley, older Street Dominator intake (#300-48?), non-computerized HEI, 1.6:1 roller-tip rockers..... rest of drivetrain is stock manifolds, 2-1-2 exhaust with an empty catalytic converter & OEM mufflers, a looser TQ converter in-front of built 700-R4, & 3.73 gears.
car has run a best of13.93 @ 99+ MPH at the drag-strip deep-staged in cool weather, with 1.99 short-times and 9.00 in the 1/8-mile (then ran 14.06 @ 95+ in stiffling 95*f temps yesterday):
results were 232 HP @ approx 4900 RPM, and 291 TQ @ approx 3400 RPM, while the screen also showed 97*f & 38% humidity in the shop
sorry, didn't get a print-out sheet, we were only looking for proper A/F ratios, and 'just-curious' to see what the actual numbers really were.
Le Mans Master
Joined: May 2006
Posts: 9,993
Likes: 1,136
From: League City Tx
for what it's worth, I had my L83 less-CFI on Tracy Lewis' DynoJet at RevXtreme last week, just to see what it made:
stock 28,000 long-block with a 650 double-pump Holley, older Street Dominator intake (#300-48?), non-computerized HEI, 1.6:1 roller-tip rockers..... rest of drivetrain is stock manifolds, 2-1-2 exhaust with an empty catalytic converter & OEM mufflers, a looser TQ converter in-front of built 700-R4, & 3.73 gears.
car has run a best of13.93 @ 99+ MPH at the drag-strip deep-staged in cool weather, with 1.99 short-times and 9.00 in the 1/8-mile (then ran 14.06 @ 95+ in stiffling 95*f temps yesterday):
results were 232 HP @ approx 4900 RPM, and 291 TQ @ approx 3400 RPM, while the screen also showed 97*f & 38% humidity in the shop
sorry, didn't get a print-out sheet, we were only looking for proper A/F ratios, and 'just-curious' to see what the actual numbers really were.
stock 28,000 long-block with a 650 double-pump Holley, older Street Dominator intake (#300-48?), non-computerized HEI, 1.6:1 roller-tip rockers..... rest of drivetrain is stock manifolds, 2-1-2 exhaust with an empty catalytic converter & OEM mufflers, a looser TQ converter in-front of built 700-R4, & 3.73 gears.
car has run a best of13.93 @ 99+ MPH at the drag-strip deep-staged in cool weather, with 1.99 short-times and 9.00 in the 1/8-mile (then ran 14.06 @ 95+ in stiffling 95*f temps yesterday):
results were 232 HP @ approx 4900 RPM, and 291 TQ @ approx 3400 RPM, while the screen also showed 97*f & 38% humidity in the shop
sorry, didn't get a print-out sheet, we were only looking for proper A/F ratios, and 'just-curious' to see what the actual numbers really were.
Race Director
Joined: Jan 2003
Posts: 15,176
Likes: 88
From: State of Confusion
with no squeeze, camshaft, induction or exhaust, the car has no-business breaking into the 13s, but it has by a few hundredths
Safety Car
Joined: Aug 2001
Posts: 3,685
Likes: 202
From: Waterford Mi
I run the same Holley. Out of the box it ran real rich. I had to downsize the discharge nozzles from the 40's that it came with to a size 21. I put it on a dyno a while back it it showed that the secondaries once opened dropped the afr from 14's down to 10.3. The carb has a metering block for the secondaries so I changed it from a 54 to a 49. I have yet to put it back on the dyno but I do know that I am not cleaning the black soot off the exhaust any more and my mpg increased.
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Thread Starter
Intermediate
Joined: Dec 2005
Posts: 32
Likes: 1
From: Lunenburg MA
Just for additional info: The plug gap used must be appropriate for the type of ignition system and plugs selected. Essentially, your coil [and voltage to the coil] define how much spark voltage your system is capable of producing. As the spark gap increases, it takes higher voltage to be able to jump that gap. So, your spark gap needs to be appropriate for the voltage capability of your system. A stock 'points' system/coil will generate less than 20,000 volts; and 20K volts is not enough to reliably jump that large of a gap. Set plug gap to .035"...or change the ignition system to a HEI or electronic unit with a higher voltage coil. Then set the gap per the instructions on the new ignition system.
Nice runs GlensGages. My goal was to make it a car that could run into the 13's at the 1/4 mile and still be a nice car to drive around town. Comparitively it looks like I may be close. The last time I was at the drags with a relatively stock motor I was running in the 15's at 91 mph.
Thanks for the info redwingvette. The thing that I noticed with this carb is that when I was running the stock heads, it ran way richer, my plugs were always covered in really thick carbon build up. Now with the brodix heads it runs much cleaner, plugs looked almost close to perfect when I puled them, maybe a little rich.
I know turttle vette, its probably not an L48 anymore, what do you guys think, would it be too rice to call it an L48 stage 3+ ? The heads were actually $1000, not bad for what you get. heres the summit link: http://www.summitracing.com/parts/BRO-1021004/
Last edited by J.Aro75Vette; Sep 21, 2009 at 10:12 PM.
Thread Starter
Intermediate
Joined: Dec 2005
Posts: 32
Likes: 1
From: Lunenburg MA
Timers:
1. dyno
2. drags
3. stopwatch
4. G-tech etc
that L-82 intake might be very good IIRC
use search or call holley for jet plate info.
I like the cam, but it may be very sensitive to back pressure! uncorked could show big gain on dyno, and increase hearing aid sales low back pressure a must!
When u forced the carb open, it still had that spike?
.060 plug gap, if missing, renders entire dyno test just practice.(like drag racing w/1 plug wire off)
1. dyno
2. drags
3. stopwatch
4. G-tech etc
that L-82 intake might be very good IIRC
use search or call holley for jet plate info.
I like the cam, but it may be very sensitive to back pressure! uncorked could show big gain on dyno, and increase hearing aid sales
low back pressure a must!When u forced the carb open, it still had that spike?
.060 plug gap, if missing, renders entire dyno test just practice.(like drag racing w/1 plug wire off)
