[steve25]

Since he’s running a performer now I have to assume he’s also running a Q-jet.
If that’s the case then and to save on cost I would stick with the performer, but add a 1/2” spreads bore spacer / insulator under the carb.

In a A body you should have the room for the spacer.
With stock 6X heads and 428 cid this should provide him with peak hp at 5000 rpm if his cam has around 228 intake duration at .050”

[steve25]

I take issue with the notion that a Perfromer will no do well atop anything bigger then a 350.

Here's the results of dyno test from McCarthy in a old issue of HPP mag.
The 455 with stock heads and a Q-jet made 394 hp , so what's bad about that?

[Half-Inch Stud]

Yea, P4B definitely had abour 3 straightbore versions, and then the sweet Spreadbore version. I remeber epoxy-filling the dam across the front, and grinding the Secondaries open to support a Q-JET. Also have seen the Spreadbore, and may have owned a Spreadbore P4B ( but the ident was ground off by a prior !! ).

Long ago in the 80s i ran into the Throttle Cable bracket mount being too far forward. Seemed difficult then to bend-fit.

Also sure the Torker I has two versions: bigger runners. Some Torker-Is had soft port-able aluminum and others has hard un-portable ceramic-like aluminum.

PMD iron is darn good with the water log cut off, in favor of aluminum log.

[72projectbird]

Had a P4B with an old Holley 750 mechanical secondary setup on a healthy 455. It worked quite well.

[Cliff R]

Below is a pic of the P4B-QJ version beside a stock intake. It does not clear an HEI without modification and the carb doesn't sit in in the same place as a factory intake. From what I can remember the carb sits back further and down in the back some. I could still use the Shaker with it but the fit wasn't that great. Due to the negatives involved I decided not to use it.


Even with the poor fit I did some testing with it and the RPM a while back. Neither one would outrun the "modified" stock intake at the track so I ditched both of them in favor of something with a perfect fit with the Shaker parts vs requiring some "cobbling" to use them.

I had a "standard" P4B here for years and it did not have enough material to bolt a Q-jet to it without an adapter so I never tried to use it........

[David Jones]

I've run a P4B-QJ on engines now for over 10 years. I suspect it's at least as good as the factory cast iron intake and somewhat lighter.
The other P4B? Dunno.

[Cliff R]

I've lost count of how many times I took a pile of intakes to the track to test them. I figured out very quickly that with most of them we aren't really chasing a lot of ET or MPH.

With perfect traction and having my car (sometimes we took a couple of well set-up cars to get more testing done) set up to be DEADLY consistent run to run I'd make a couple of passes to get a "baseline" on the first intake, then quickly swap on another one and make a pass with it. Time permitting I'd make at least one more.

To make this possible I had removed the water crossover from all of them and put car paste wax on the intake gasket sealing surface. I could iiterally swap one out in a couple of minutes since Pontiac was gracious enough to have the distributor going directly into the block and not thru the intake.

Prior to track testing I had already tested every intake involved in the track testing on the street. Street testing simply involved doing some "normal" driving, heavy part throttle or spirited driving without the secondaries, and some full throttle blasts. On the street there is almost never perfect traction so the testing is almost 100 percent "seat of the pants".

I very quickly found that street testing is highly flawed and that your "butt meter" will lie to you every single time. Installing a single plane intake, for example shifts power to a higher RPM range. When you go to full throttle on the street the tires spin and the engine very quickly revs right into the ideal power range for the intake. With the tires spinning and tach heading quickly for the shift point your butt-meter evaluates this as making a LOT more power and the vehicle faster in terms of ET. What we "feel" is the transition from not making a lot of power to going right into the good power of that intake, or it's "sweet spot". The "rush" of power and noticable transition fools us into thinking that we are not only making more power but the car will be faster in a drag race as well.

Carry that intake to the track, hook solid and the car doesn't leave as hard or roll out as quick, then when the engine revs into the upper mid-range and top end where that intake shines you get a nice blast of power much like a small shot of nitrous. You get up the return road, pick up your ticket and your heart sinks. In every single instance I've done that sort of test the intake I thought was going to win was no faster if as fast as the one replaced. The time slip simply showed a shift in power by giving up ET on the launch/short times and charging harder on top end. Overall ET usually suffered some simply because a "soft" launch means we really have to run harder on top end to make up for it.

Testing dual plane intakes on the street the will ALWAYS loose in every catagory if you use your butt-meter to evaluate testing. They produce a smooth/flat/broad power curve which has little if any transition at all. The "locomotive" power curve is evaluated as boring and without any big "rush" of power anyplace, or noticable transition, or strong upper mid-range and top end charge we are fooled into thinking it will be slower at the track than a single plane intake.

I've been going thru all that drama since clear back in High School when I swapped intakes nearly every single week on my 440 powered Roadrunner engine. The stock intake and a 440 Performer ran about the same and every single Torker or Taranantula I put one won in every single catagory when butt-meter tested but the car slowed WAY down at the track with them. Those intakes KILLED my 60' times (didn't have much converter in it back then) and never even came close to making up all the lost ground on the upper part of the track. However on the street once again with tries spinning and engine heading instantly for the red line they felt so strong I'd have bet a whole months pay check they'd be faster at the track.....NEVER happened.

So with all the testing and knowledge I've accumulated with direct testing I have absolutely ZERO faith in any sort of "seat of the pants" evaluations of any of these parts. The only way one is going to know if they work or not is to get your car dialed in so it's deadly consistent and head to the track with a trunk full of intakes, or carbs, or spacers, or anything else you can quickly swap out run to run and find out if they help or not? You are also going to have to hit a "test and tune" session with poor attendence or a private track rental so you can get in enough runs close enough together to take out other variables in the testing like weather, wind, temperature, track conditions, etc, etc..........FWIW.......

[steve25]

I have seen the power loss of a single plane intake help out a racer at the strip on what was basically a hopped up street car.
It detuned its low speed level of torque which helped make the car leave more consistent, which some folks seem to forget is the key to bracket racing.

Yup, the car was much more fun to drive around town with the iron intake, no question about it.

[Half-Inch Stud]

@CLIFF, agreed. I too eval'd intakes, but found the carb to be the most diff, regardless of manifold; the 1050 beat the Q-JET. Took me awhile to make & Tune the Q-JET to be same ET, but MPH usually was a touch less.

My 2 best manifolds were a spreadbore aluminum (prob a P4B) and a hogged-out Torker I.
No 1/4 mile diff but 1-2" improved idle vac with the Dual-Plane, when over-cammed. Mix balance always excellent.

Also, noticed that assuming the 60-foots were same ( by data-factoring against the best 60-foot) the most MPH, & best ET was made during 3rd gear performance. Yet the Q-JET needed differing Sec Rods in the hotter afternoon to stay on the optimal bubble.

Whereas for me, the best 60-foot seemed to favor the Q-JET (ease of attaining) no bog, and no need to tune across the day. My 1050 caused a bog with slicks. I figured too much fuel dump. Spotts said he found a problem with my 1050 (vent-spill needed the rubber hose bridge) but overheat fuel-boil also caused a bog on a 98* late day, while awaiting Staging.