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#1
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73-74 Iron Intake vs. 68-72
I've decided to use an iron intake on my 400 build over a Performer. I have a spare casting no. 495106 intake to use. It is the style with the EGR bulges on the bottom. I won't connect EGR. Is there really any difference in performance between these and the earlier 68-72 intakes? I think HPP did an article on this years ago, but I wanted to see if any of you had any firsthand experience or insight. The build will be fairly mild. 400 .030" over, XE262, 8.5-8.6 CR, mildly ported 6X-4s. The main reason I want to use the stock intake is for the "sleeper" look. Or is the Performer a better choice than the 495106?
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73 Formula. 9.1:1 400 .030" over, TRW forged pistons, hand ported 6X-4s milled to 85cc, Ferrea 2.11/1.77, Crower 68404 springs, 276°/284° 228°/236° @.050 .474"/.474" 112 LSA, Performer RPM, Shaker Tuned Qjet, Hooker 1.75" headers. TH400, Hughes GM25 converter. 4.10 gear for now. 1st Drive: 12/30/16. *SOLD* 74 Trans Am 455 AT Buccaneer Red |
#2
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No flow difference, but the '73-74 is definitely heavier. And it requires a deep-center valley pan.
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#3
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About 200 pounds heavier!
Seriously, they flow just fine as Rocky mentioned, but really ugly with all that gear hanging under them and EGR on the side.....Cliff
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If you can read this, thank a teacher. If you can read this in English, thank a Veteran! https://cliffshighperformance.com/ 73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile), |
The Following User Says Thank You to Cliff R For This Useful Post: | ||
#4
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And the added bottom mass of the manifold even with the deeper valley pan does not pass thru as much air as the non EGR set up. as a result the manifold does run hotter and with todays alky spiked fuel can make for tuning / running problems at times , not to mention the slight power reduction from the added heat.
I would plan on blocking the exh crossover and swapping over to a electric choke if need be. If your hood scoops are not open already, I would plan on doing that and ruuning the air cleaner set up to have them feed the carb.
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Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! |
The Following User Says Thank You to steve25 For This Useful Post: | ||
#5
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Quote:
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73 Formula. 9.1:1 400 .030" over, TRW forged pistons, hand ported 6X-4s milled to 85cc, Ferrea 2.11/1.77, Crower 68404 springs, 276°/284° 228°/236° @.050 .474"/.474" 112 LSA, Performer RPM, Shaker Tuned Qjet, Hooker 1.75" headers. TH400, Hughes GM25 converter. 4.10 gear for now. 1st Drive: 12/30/16. *SOLD* 74 Trans Am 455 AT Buccaneer Red |
#6
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Yes. IMO
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Bull Nose Formula-461, 6x-4, Q-jet, HEI, TH400, 8.5 3.08, superslowjunk |
The Following User Says Thank You to Blued and Painted For This Useful Post: | ||
#7
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Is there a specific way to block off the EGR? Or should I just put it on the side of the intake and just not connect it to vacuum?
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73 Formula. 9.1:1 400 .030" over, TRW forged pistons, hand ported 6X-4s milled to 85cc, Ferrea 2.11/1.77, Crower 68404 springs, 276°/284° 228°/236° @.050 .474"/.474" 112 LSA, Performer RPM, Shaker Tuned Qjet, Hooker 1.75" headers. TH400, Hughes GM25 converter. 4.10 gear for now. 1st Drive: 12/30/16. *SOLD* 74 Trans Am 455 AT Buccaneer Red |
#8
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HPP dynoed a late EGR intake with the D shape secondary holes and found no difference between it and the earlier intakes. The D shape reduced reversion into the carburator. The 73-74 intake should make the same power as earlier intakes. I have a car with a electric choke on the Rochester. It starts the car cold fine but if you drive it down the street only a short distance then turn it off getting it started again can be difficult. I prefer the choke on '67-72 cars.
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The Following User Says Thank You to android 211 For This Useful Post: | ||
#9
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You can make a plate to block it off, but I just connect the valve up and disconnect the vacuum line.
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#10
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i have a q-jet with an elec choke added & have some of the same problems you mention on restarts. it starts great in the cold (< 45*) but the restarts are kind of touchy. mine is a fresh rebuild from cliff on a fresh engine so im still working out some bugs on the choke setting & idle tuning etc. i have a 78 t/a with the same q-jet but original hot air choke & it starts & restarts great in cold or hot weather.
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#11
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I have a performer RPM intake & use a 79 301 Q-jet that I've went through & played with similar to some of the mods like cliff does & I have an electric choke on it. I like the elec. choke as once I got it adjusted correctly it works great & the car starts cold or hot better then it ever did, except when it was brand new in 73-74.
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#12
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you can also use a 72 intake that doesnt use an EGR but heat crossover is the same.
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#13
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Thanks for all the help! I started sandblasting the 495106 yesterday. I'll just stick with the heat choke for simplicity's sake now and see how I like it as for the EGR, I'll connect the valve and leave it unhooked. Thanks again
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73 Formula. 9.1:1 400 .030" over, TRW forged pistons, hand ported 6X-4s milled to 85cc, Ferrea 2.11/1.77, Crower 68404 springs, 276°/284° 228°/236° @.050 .474"/.474" 112 LSA, Performer RPM, Shaker Tuned Qjet, Hooker 1.75" headers. TH400, Hughes GM25 converter. 4.10 gear for now. 1st Drive: 12/30/16. *SOLD* 74 Trans Am 455 AT Buccaneer Red |
#14
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What should I do about the EGR ports in the plenum floor? Should I try to fill or plug them? Or does it not make a difference?
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73 Formula. 9.1:1 400 .030" over, TRW forged pistons, hand ported 6X-4s milled to 85cc, Ferrea 2.11/1.77, Crower 68404 springs, 276°/284° 228°/236° @.050 .474"/.474" 112 LSA, Performer RPM, Shaker Tuned Qjet, Hooker 1.75" headers. TH400, Hughes GM25 converter. 4.10 gear for now. 1st Drive: 12/30/16. *SOLD* 74 Trans Am 455 AT Buccaneer Red |
#15
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I would drill and tap them for a allen set type pipe plug.
and during the tapping process leave enough uncut threads to really lock the plug into, and some red Loctite would not hurt eitheir!
__________________
Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! |
The Following User Says Thank You to steve25 For This Useful Post: | ||
#16
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id like to see if one could modify a 1972 iron intake for the hot air style choke like the 73-74 intakes..that way you get no egr, and the tailoring of the choke much better than the divorced choke style..anyone ever modify one for this???
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#17
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As long as you have the '72 choke on the crossover passage you can use an older Rochester. I think the rod is even the same. For some reason they rotated the little coil device 90 degrees. Used a '72 intake with a '71 Rochester on a 400 with 6X4 heads; car still runs great almost 10 years later.
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