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#1
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Street Demon 625 - tuning results with AFR monitor
Spent the day tuning the Street Demon 625 on my ‘68 Firebird. The engine is 8.9:1 CR with a Pertronix HEI distributor (18 deg. initial + 15 deg. manifold vacuum advance). Here’s what I got today:
> 60/52 METERING RODS > SILVER METERING ROD SPRINGS (8” VAC) > PRIMARY JET: 78 > SECONDARY JET: 80 > IDLE MIXTURE SCREWS 2 ⅛ TURNS OUT > IDLE VACUUM: 16” PARKED, 12.5” DRIVE > IDLE AFR: 13.8 PARKED, 13.5 DRIVE > IDLE RPM: 950 PARKED, 750 DRIVE > 13.6: AFR CRUISE > 13.3: AFR PART THROTTLE > 12.1: AFR HEAVY THROTTLE > 13.0: AFR W.O.T. I have one issue with the gas pedal, - I’m not getting full motion and not getting to WOT as a result. I need to solve that problem before I can focus on the WOT AFR. I’m also thinking about trying the 58/52 metering rods to see how it affects the cruise & part throttle AFR’s.
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Raffi R. 1968 Firebird: 350 .040 over, #11 Heads w/2.05/1.66 valves, Tomahawk TC-03 cam (214/221 flat tappet cam, 112 LSA, .0450/.0465 lift w/ 1.5 rockers), 200-4R w/3.55 gears, Street Demon 625 w/ Edelbrock Performer, H-Pipe dual exhaust w/Delta Flow 50's. |
The Following User Says Thank You to RAFO9A For This Useful Post: | ||
#2
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Are you running a stock air filter assy?
If not then what size air filter are you running, and is it a drop base style? To get more throttle opening sooner with less pedal travel ( which sounds like your issue) you need to lower your cable attachment point closer to the carbs throttle shaft.
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I do stuff for reasons. Last edited by 25stevem; 10-05-2022 at 05:47 AM. |
#3
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The cruise AFR is way too rich. Shoot for at least 15 or 16:1 at part throttle cruise in top gear.
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#4
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He may only be able to get to that ratio in the correct way with a lighter power piston spring seeing as what his close to full throttle ratio is.
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I do stuff for reasons. |
#5
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Quote:
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Raffi R. 1968 Firebird: 350 .040 over, #11 Heads w/2.05/1.66 valves, Tomahawk TC-03 cam (214/221 flat tappet cam, 112 LSA, .0450/.0465 lift w/ 1.5 rockers), 200-4R w/3.55 gears, Street Demon 625 w/ Edelbrock Performer, H-Pipe dual exhaust w/Delta Flow 50's. |
#6
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I currently have #78 primary jets and 60/52 metering rods. The next size leaner would be 62/54 rods. That would lean the cruise & part throttle mixture by about 11%; the heavy throttle mixture would lean by about 8%. Not sure if I want to go there?
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Raffi R. 1968 Firebird: 350 .040 over, #11 Heads w/2.05/1.66 valves, Tomahawk TC-03 cam (214/221 flat tappet cam, 112 LSA, .0450/.0465 lift w/ 1.5 rockers), 200-4R w/3.55 gears, Street Demon 625 w/ Edelbrock Performer, H-Pipe dual exhaust w/Delta Flow 50's. |
#7
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Quote:
I do all the work on it. The pickup came this way. I got the Q-Jet dialed in with Cliffs help. I noticed that it was not getting full throttle. Well, past about 2/3 throttle, the rod end of t h e accelerator arm was touching the underside of the air cleaner base. I ground most of the end of the a rm down, easily leaving enough metal there to support the inner hole(the one you should ONLY be using. No problem after repair.
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1977 Black Trans Am 180 HP Auto, essentially base model T/A. I'm the original owner, purchased May 7, 1977. Shut it off Shut it off Buddy, I just shut your Prius down... |
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