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#141
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I don't remember my initial but my total is 36-38 per my dial back light. Yes, I'm using vacuum advance, connected to ported vacuum on carb. I did confirm TDC was correct last time the engine was out, 10 years ago. |
#142
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Also when running a Quadrajet be aware that the secondary throttle plates sometimes hit the opening of the plenum so make sure you don’t need to add some clearance before installing the intake.
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1964 Tempest Coupe LS3/4L70E/3.42 1964 Le Mans Convertible 421 HO/TH350/2.56 2002 WS6 Convertible LS1/4L60E/3.23 |
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#143
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#144
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Z, if your current setup is still in the car then just loosely ball up a piece of aluminum foil and set it on top of your air cleaner and close the hood. Open it back up and measure the thickness of the foil. That will tell you how much clearance you have. If you are not already using one, a drop base air cleaner will allow you a little more clearance.
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#145
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#146
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Update:
I measured and the bottom of the carb with the Performer as it sits now, will be almost EXACTLY the same height as it will be on the RPM. So that's a relief. I also blew compressed air past the venturi for the vacuum secondaries and they didn't budge. I'm thinking maybe they have never worked, or years ago when I was dinking around with springs, I messed something up. The spring quick change adapter hasn't arrive yet. That will have a new diaphragm and cork gasket. I'm starting to think, maybe with functioning secondaries and the RPM, I might be plenty happy with the car. I also need to keep in mind that this is a family, street cruising convertible, where street manners are of the utmost importance. Seat of the pants feel when mashing the pedal is the bonus. |
#147
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Did you have a spacer on the performer?
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466 Mike Voycey shortblock, 310cfm SD KRE heads, SD "OF 2.0 cam", torker 2 373 gears 3200 Continental Convertor best et 10.679/127.5/1.533 60ft 308 gears best et 10.76/125.64/1.5471 |
#148
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Yes, the Edelbrock Spreadbore to Squarebore, 2696, which is .850" thick.
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#149
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General Z – With your current 0.85” tall adapter plus the 3/8”+ clearance, so 0.85” + 0.40” = 1.25” total, that is the same height difference as the stock RPM intake. Certainly that is too close for comfort. If your secondaries weren’t functioning properly, you’ll have 100 hp instantly when they do open, so maybe you won’t need that new RPM after all. I would still check everything else that was mentioned by all the others just to be sure.
Dennis |
The Following User Says Thank You to SD455DJ For This Useful Post: | ||
#150
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I hope you're right about the power. I won't be using a spacer with the RPM. It appears that the thermostat height is the same on both intakes. I used a level from the base of the carb on the current setup and measured vertically from the thermostat flat to the bottom of the level. Then, I measured on the RPM in the same manner. The measurements are nearly identical, so I'm optimistic. |
#151
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Well, I may have exaggerated a bit, but it'll feel like it when all 4 bbls open when they're supposed to. Here is an actual dyno comparison of a 2-bbl (2GC) and 4-bbl (Q-jet), both on stock cast iron factory intake manifolds on the same 455 on the same day. This 455 has the 2802 cam and 9.94 static compression with small valve #15 heads.
You can see that the average torque and hp through the pulls (3000 to 5000 rpm) are way in the favor the Q-jet (412 lbft/309 hp vs. 478 lbft/360 hp) Dennis Last edited by SD455DJ; 01-28-2024 at 02:38 PM. |
#152
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#153
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Keep in mind that the primary side of a Q-Jet is substantially smaller than any of the 2GCs, particularly the larger ones that would have been installed on a 400+ CID engine.
The difference between a Q-Jet without, and with the secondaries functioning would be even more dramatic. |
#154
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Stan
__________________
Stan Weiss/World Wide Enterprises Offering Performance Software Since 1987 http://www.magneticlynx.com/carfor/carfor.htm David Vizard & Stan Weiss' IOP / Flow / Induction Optimization - Cam Selection Software http://www.magneticlynx.com/DV Download FREE 14 Trial IOP / Flow Software http://www.magneticlynx.com/DV/Flow_..._Day_Trial.php Pontiac Pump Gas List http://www.magneticlynx.com/carfor/pont_gas.htm Using PMD Block and Heads List http://www.magneticlynx.com/carfor/pont_pmd.htm |
The Following User Says Thank You to Stan Weiss For This Useful Post: | ||
#155
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Which would be half the cfm at 375 (assuming square bore), similar to the Rochester 2GC (from a '71 455 - which this one was for the dyno test).
Dennis |
The Following User Says Thank You to SD455DJ For This Useful Post: | ||
#156
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__________________
72 Luxury Lemans nicely optioned |
#157
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Did you lower your shift points with your governor? |
#158
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yes,made a big difference. th-400 though.
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72 Luxury Lemans nicely optioned |
#159
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the drag strip is a good place to test is what I meant.
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72 Luxury Lemans nicely optioned |
#160
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Update: I changed to the Performer RPM intake. I replaced the diaphragm, cork gasket and went to the next to lightest spring on the vacuum secondary. I finally took it for a ride, and there's a noticeable difference. The guys that said the intake was choking it seem to be right. I didn't end up doing step by step testing, just did it all at once. I haven't driven it yet with the G-tech meter set up to see any quarter mile improvement. The difference is big enough that I'm doubting I'll change cams when I pull the engine to do the rear main seal. This 2802 is broken in and doing fine.
I'll still probably lower my shift point from 5000, per the suggestions above and try that. Thanks everyone for all the support and suggestions. |
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