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#21
12-01-2023, 08:51 AM
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1978 Trans Am Pump Gas 461 Stroker |
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#22
12-01-2023, 05:18 PM
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Just wanted to add here, that I found my receipt from where I purchased the carb, and it has the Jet Size, Primary Rod, and Seconadry Rod on the receipt. I am still awaiting the rest of the Specs from Sean Murphy, if he will get back to me.
Q-Jet #17084231 (S.M.I. #36002 800cfm) Main Jet- "74" Primary Rod- "52M" Secondary Rod- "DA"
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1978 Trans Am Pump Gas 461 Stroker |
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#23
12-01-2023, 05:27 PM
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....and the picture attachment below is what got me to really thinking about the spacer adapter that we are using to adapt the Spreadbore Q-Jet to the Squarebore Performer RPM Intake..... you don't notice much of a problem installing it, until you take a look at it from the bottom side of the carb, looks very restrictive to me .... we will be switching to the Spreadbore Performer RPM intake when we receive it for sure!
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1978 Trans Am Pump Gas 461 Stroker |
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#24
12-02-2023, 07:26 AM
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No big secret here but I am NOT a fan of adapters. Most spacers are a complete waste of time/funds unless you have the hood clearance to keep from having to "cobble" everything up to get the install done and can keep the air cleaner lid at least 3" away from the top of the carb. Folks going to "high rise" intakes and adding spacers have no idea how much power and vehicle performance they are loosing with some of these "upgrades".
Keep in mind that I dyno tested my iron intake against the RPM (port matched) and 455HO (re-pop) intakes on the 428 engine mentioned earlier in this thread. The iron intake made 497hp, RPM 491hp, HO 487hp. There were NO OTHER CHANGES done for those dyno pulls. Even though we LOST power putting the bigger/taller RPM on an 440cid engine with KRE heads (260cfm), 10.6 to 1 compression and 236/242 @ .050" custom ground HR cam with nearly .600" lift I see folks ditching factory intakes for the RPM on engines making a LOT less power. Not to mention having to "cobble" up the intstall 9 times out of 10 to get it under the hood, especially with factory Ram Air and Shaker cars.....FWIW. Below is a pic showing how much "miss-match" there is putting a square flange spacer on a spread bore intake. I'll also add here that a spread bore intake offers a power advantage over a square flange intake with a spread bore carburetor on it as the plenum areas are wider AND the spread bore carburetor lines right up in the middle of them.......
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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 4 Users Say Thank You to Cliff R For This Useful Post: | ||
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#25
12-02-2023, 08:23 AM
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I fully agree Cliff.
So many times when I see the corner bottom of enthused post that list there upgrades / parts to there build, and the performance results there getting from those I end up saying to myself that …. Well you had a good start but in the end all you have done is mis-spent funds in exchange for less performance and eye candy.
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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: | ||
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#26
12-02-2023, 09:21 AM
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Agreed. After a LONG career and extensive "learning curve" with all this "high performance" stuff I need to write a book about it, however it would be WAY to lmuch "against the grain" and I'm good enough at making enemies with the little involvement I do have these days so I'll just continue to enjoy my little parts business, being retired, and throwing lots of sticks for my dogs!........
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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: | ||
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#27
12-02-2023, 10:26 AM
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I have read from rocky rotela's testing that the SR replacement HO intakes made after the original production HO intakes had a shorter plenum floor that can affect power some... do you know if the HO you tested was a SR or original production? I ran a 1969 iron intake ported by SD on my E-head OF cam 467 that did low 11's, then switched to a SD ported production HO I found for the weight savings & nicer looking, didnt notice any loss at the track or street but also no gains, runs pretty much the same. I realize 10hp probably wont show up at the track due to other variances from different days, just curious what your thoughts are on the 10hp loss for what should be identical intakes. |
| The Following User Says Thank You to 78w72 For This Useful Post: | ||
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#28
12-02-2023, 11:23 AM
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Maybe something a little informal. Like "Quads. According to Cliff" Excerps from here and other forums that pertain to the real world experiences and knowledge only gained from 'been there done that'. Would make a good Bourbon book I would buy. |
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#29
12-02-2023, 01:22 PM
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"Good info cliff, can you comment on why the HO intake was down 10hp from the iron? I thought they were basically the same intake just the HO is made from aluminum?"
It's just not a very good part from a how it was cast perspective. Instead of sending the Chinese something they "cleaned up" and spent some time with, it appears they sent them a completely stock intake. The originals had pretty poor port alignment, and the re-pop was HORRIBLE. I spent some time tring to straighten it up some, but it just wasn't made very well. I did open it up under the carb to look exactly like my "modified" iron intake and the RPM. Since I "modified" the intake some folks cried "foul" with the testing, oh well. At least I didn't TIG them up and make the runners bigger, and raise the flange over an inch. Aside from opening them up under the carb and a port match to the intake gasket the runners were pretty much as-cast.......FWIW....
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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: | ||
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#30
12-02-2023, 01:42 PM
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Sorry my mistake, I overlooked the part that said the HO was a repop intake... Ive heard and seen pics of the repops that were pretty bad, plus from my understanding they used a SR intake with the shallow plenum floor for the repops vs original production HO intakes. Pretty sure the original production HO intakes were the same castings as the iron and when either is ported by SD they are great intakes that can support up to 600hp according to SD. |
| The Following 2 Users Say Thank You to 78w72 For This Useful Post: | ||
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#31
12-02-2023, 05:42 PM
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"Sorry my mistake, I overlooked the part that said the HO was a repop intake... Ive heard and seen pics of the repops that were pretty bad, plus from my understanding they used a SR intake with the shallow plenum floor for the repops vs original production HO intakes."
Whatever they did to it cost 10hp on a 500hp engine. I seem to remember measuring the depth of the plenum floor and it wasn't quite as deep as my iron intake. At the 500hp mark the RPM brought nothing to the table and cost a little power. This tells us that bigger runners aren't worth more power if what we already have is big enough. With all that in mind one has to wonder how many other aftermarket "high performance" parts marketed as bolt-on power adders actually cost us some power? From what I know about these things the abolute WORST place to spend more for power improvements are "bug-zapping" ignition systems. The BEST place to spend money for improved power and vehicle performance........cylinder heads and torque converters.......IMHO......
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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 2 Users Say Thank You to Cliff R For This Useful Post: | ||
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#32
12-03-2023, 01:37 AM
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#33
12-03-2023, 02:01 AM
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Heaps of cars with idle misfire due to excessive overlap/reversion/lean idle air/fuel mix get magically "fixed" with a spark-box. But they wouldn't need the spark box if the cylinders had a proper air-fuel ratio to begin with. I also believed that the spark-boxes made a worthwhile improvement in extreme cold weather. Again, with a properly-functioning choke and some OEM-level intake manifold heat combined with OEM air inlet heating, the in-cylinder air-fuel ratio is more correct, and largely removes the spark-box advantage. But most of these cars aren't driven in extreme cold any more, and for those that do...automatic chokes WHEN ADJUSTED PROPERLY along with an exhaust crossover under the intake manifold and a heat-stove on the exhaust to warm the incoming air stream makes a world of difference. Note that the air/fuel ratio at the carb is not the same as the air/burnable fuel ratio in the cylinder, particularly when the engine is cold/cool. The choke provides a supremely-rich "mixture", but only a fraction of the fuel vaporizes, and gets burned in the cylinder. This is one of several reasons bore-wear tends to be worse with carb'd engines compared to port-injected engines--excess gasoline washing the oil off of the upper cylinder. Last edited by Schurkey; 12-03-2023 at 02:13 AM. |
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#34
12-03-2023, 08:02 AM
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Correct. When I tested MSD distributor with the 6AL box there was a really nice improvement in how quickly the engine started in very cold weather and I actually saw a tiny bit more vacuum at idle and could move the idle mixture screws in about 1/8th of a turn.
Otherwise no improvment whatsoever in power improvement on the dyno or at the track.....NOTHING. Matter of fact when we replaced the completely stock points distributor in my good friends 406 SBC full race engine with an MSD billet distributor the car slowed down at the track. Not very much but like most youngsters who finally save up enough to buy these well advertised "high performance" parts we were fully expecting a nice improvement as MSD advertises. Anyhow we lost about .02-.03 seconds and some MPH as well. This happened many years ago before I understood these things like I do now. How could our race car SLOW DOWN adding a very expensive billet distributor vs a plain old $5 junkyard variety points unit. All I did to the points unit was to brase down the center plate and "lock-out" the advance. The MSD was also locked-out, and with both distributors we set the timing at idle speed at 36 degrees exactly. Hum? Well it turns out the day we tested the new MSD at the track on "old timer" was pitted next to us. He watched us youngsters frantically trying to find why the car was running slower. Eventually he wondered over and started talking to us. We told him what we'd done and now running slower. He just smiled and told us that you lost your natural timing retard at high RPM's when the dwell falls off slightly. Me and my good friend Mike looked at each other with a "duh" expression on our faces!.......
__________________
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: | ||
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#35
12-03-2023, 09:58 AM
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The factory did the same with the Ho Intakes like what they intensional did in the 72 Ho heads exh ports to kill off some high lift flow and pick up low lift flow to give the motor better every day low speed drivability .
They new that the 5200 red line on the tack would rarely be leaned on.
__________________
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: | ||
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#36
12-03-2023, 10:27 AM
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Heres the article from HPP magazine if anyone wants to read it that hasnt seen it before. https://www.motortrend.com/how-to/hp...ld-comparison/ |
| The Following 3 Users Say Thank You to 78w72 For This Useful Post: | ||
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#37
12-03-2023, 11:08 AM
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Any updates? 
__________________
Carburetor building & modification services Servicing the Pontiac community over 25 years |
| The Following User Says Thank You to shaker455 For This Useful Post: | ||
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#38
12-03-2023, 12:00 PM
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Quote:
__________________
1978 Trans Am Pump Gas 461 Stroker |
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#39
12-03-2023, 12:23 PM
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While we wait ... , here are a few pictures of the 383 on the stand before it was installed....
__________________
1978 Trans Am Pump Gas 461 Stroker |
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#40
12-03-2023, 02:00 PM
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I did a 383 awhile back, strong runner!
__________________
Carburetor building & modification services Servicing the Pontiac community over 25 years |
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