Pro Systems Carburetors

[wanab5150]

I submitted my engine specs to Pro Systems Racing Carburetors. I've heard so much good stuff about them making gains of 50 to 75 HP with their custom built carbs.
I filled out the required form and submitted it with the engine specs on my roush 427/524 HP Engine. I was hoping for a 30-40 HP gain.

My Comment: This is a Roush 427R motor (not SR) 524 HP with a Holly 770 elec. choke, vacuum secondaries. Runs flawless and want it to stay that way. Is there something better and how much performance will I gain? thanks, tom

Response: Hi Tom, If it runs flawless leave it. There's power to be had BUT you will give up your "choke" to get it.

Thanks : ) Patrick James

My Response: I'll give up the choke....what will I get out of it in return? thanks, tom

His Response: Typically 15 h.p. BUT like I said, if it runs perfect, will you notice 15 h.p. as opposed to the loss of a choke?

I was hoping for more, but now I know that some of the claims are inflated from some who have posted here. Also, It seems that Patrick is an honest , no BS man with the knowledge to "leave it alone" when you need to.

I appreciate his honesty which is rare these days, and will absolutely have him build my next carb rather than picking one from the shelf. I'm still considering a 750 double pumper as i just don't feel right about vacuum secondaries with a Tremic 5 speed. Patrick if your watching, I may ignore your comments and have you set up a Double Pumper for me anyway. I could brag about gaining another 15 HP!!!!! I don't need the 524 HP I have now either! tom

[ha_pe_1968]

Hi!

Have heard some very good things about Patrick and his carburators. My respect to his answers ...an other person would do all and would talk about tons of more horsepowers to sell something.

Tom, are you sure that it is a 427R? The 427R is normally around 550HP even with a dualplane intake.

Peter

[289fia_cobra]

just to play devils advocate, but if you have a ROUSH engine, I would believe that they tuned it well with a well matched carb to start with. I think (big guess) that perhaps the gains claimed by Pro-Systems Racing Carburators, is a generalization towards regular crate motors from Ford and GM that may not supply optimum carbs.

The only thing I can think of for a Roush carubrator, is to find out if "blueprinting" the carb will help. We do have an expert carb tuner down here in Burlingame, CA (Ollies Carburator) that may help supply an answer but IMO, if ROUSH specified the carb, then I think Patrick answered you in with an honest answer... that is to say Roush did a good job of putting the correct carb on their motor for it's intended purpose.

One final note: have you played with adding a spacer? Problem is, you'd spend a lot of money on the dyno to prove a 1" spacer added 10hp (or NOT). Just thought I'd throw that in.

[209]

Roush doesn't have all the answers. My install was at 5000 and I'm at sealevel and discrepancies happen. Seems way rich at idle and just above. I'm afraid of anyone touching it till the warranty is over. First rebuild and still using oil. I was advised early to switch to ProSystems for clean running. Now if they could only build an engine............. 209

[Bernica]

WANAB5150:
If it will set your mind at ease, just pick up the phone and call Patrick. He is very easy to talk to and a straight shooter.
Good luck.

[jhv48]

I ordered a new carb from Patrick on Monday of this week. He suggested a 950 cfm 4150 HP with all the bells and whistles I need for sea level driving.

I too have the Roush 427 SRTW and am tired of the lackluster throttle response and poor driveability when cornering and stopping hard from my Street Avenger 770. Has a slight off idle stumble that I never could get rid of. So, wtf, why not go back to a double pumper so that when I open it up, I know the secondaries are in right now.

Should be here next week. Will update after the install.

[Hotfingrs]

I've got 2 carbs from Pro-Systems and love them....The only thing I would suggest is do an A/F check when you get it. Both were a tad rich.

[Jim Vander Wal]

I have a PS 780 double pumper, runs well. Also played with a 940 from Patrick, it was too big. Great after 5,000 and made more power than the 780. The 780 made more power under 5,000 and drove better. With the 780 power is leveling off at about 6,200 and remains pretty flat to 7,000.

Patrick is great to deal with.

I had a Holley 770 Street Avenger that was old but set up well with lots of dyno tuning. It took us a lot of work and time to make more power with the PS 780 but it did and it had better throttle response right away.

But I've seen Roush 427s make more power with the switch to the ProSystems carbs. The tuner has a lot to do with what you'll get from the carb. Nothing against Roush but a good tuner will get more power from their engines some of this may come from a carb change.

Chokes are over rated but they do make the first 3 minutes of operation easier.

Engine: RDI aluminum Windsor 427, 34 degrees advanced, 230-240 degrees at .050, .610" lift I&E. Vic Jr, AFR 225s, 1/78" custom headers & sidepipes from Firefly Performance. 450hp/425tqe at the wheels on a Mustang dyno.

Jim

[wanab5150]

Jim, you sound like you're on the ball ...I concur with your statements.

209.....check your jets and accelerator squirter size. As you read on maybe some of it will make sense. If you have a 2 inch exhaust, the potential for horsepower is already gone.

I spent a week jetting the carb....good thing I'm retired. I raced bikes for 30+ years and jetting is jetting. If you know what to feel for, a Holly is a very easy carb to dial in.

The Avenger came on the Roush with 70 pri. and 73 sec. jets, and this was the carb on the engine from Roush. What Roush internet ads don't make clear is that they CAN have 550 HP if you opt for the single plane manifold and 750 Double Pumper. Torque and HP starts at like around 3500 rpm rather than down lower with the dual plane and Holly Avenger 770 or Double Pumper. I think the avenger is what they come with now instead of the earlier Double Pumpers. Not positive on that…

Before I go further, I have to say that a Roush engine has only one part made by Roush that I can find....the spark plug wires! The block and lower end is all "Dart", heads are "AFR", manifold is "Edelbrock, carb "Holly" Ignition "MSD” etc. Smedding builds the exact same motor with the addition of a Quick fuel carb and advertizes 560 HP for $2500 less. It says Smedding on the valve covers. I didn’t do enough research when I bought the Roush or I might have gone with the Smedding.

I've seen numerous 427R motors and they have all been between 520 and 535 HP with the Avenger. I've seen 565 out of one Roush with a single plane and a Double Pumper. I should note I used to go up to the installers shop a lot, and he had these motors all over the place waiting for installation. SR motors with the the Avenger are advertized at 525HP but realistically put out around 510 or 515 HP.

I didn't do any jetting until I replaced the mufflers with 3 inch up from the factory Superformance 2 inch. Crap...my Harley has 2 inch pipes and that's just for 1 cyl. I did a whole other thread on pipes and the whole jetting thing. Lots of good comments and arguments. Go to the search box and type in "Superformance Exhaust"...it's about 10 down from the top.

Anywho...I don't know who got hold of my Avenger (Roush or the installer) and dropped the jets from stock (72-75) to (70-73). It ran very well but had a slight stumble right off idle. It was nothing to write home about, but irritating none the less. It pisses me off that someone messed with the stock jetting because it wound up being the best combination!

After a week of jetting up to very fat then down until I started getting a lean pop, I ended up with the stock jetting (72-75) up from two sizes on the pri. and sec. from what it was. I've been to Tahoe climbing to 7000 feet, to the Calif. coast and it runs perfect up to about 3000 ft. and then gets fatter as you climb higher. But, we just did the Snakes to the Lake for three days in Tahoe and it performed perfectly fine with a little HP loss which is to be expected.

One addl. change I did make was a switch to a 40 accelerator pump squirter from a smaller 37. I will say that when I say it runs perfect It really does not have a sputter, pop, off idle acceleration ....nada!

Oh, I forgot to mention that part of the HP gain with a 750 Double Pumper is the lack of a choke horn that’s a little restrictive on the top of the carb.

[Bernica]

FWIW, Here is how my 4150 DP with mech secondaries and no choke came from Patrick after filling out his spec sheet and talking to him. My motor is a 482 Shelby FE with around 11:1 comp, Stage II Shelby heads and a .572" cam with 236 dur and 108 LSA.

In no way am I suggesting that you jump to a build like this. It's just an example of what Patrick came up with for my motor. As we all know, every motor is different. But if anyone can do it, it's Patrick.

JETS
Primaries: 80
Secondaries: 88

PUMPS
Primary: 50cc
Secondary: 30cc

SQURTERS
Primary: 42
Secondary: 42

POWER VALVE
Primary: 6.5
Secondary: Plugged

AIR BLEEDS
Hi Air: 36
Idle Air: 76

[ekrupa2]

Hi Tom - was in you shoes last winter with my 402SR. I decided to replace my 770 Street Avenger when I had to pull my intake to replace the gaskets. The 770 was a good carb (after Roush rebuilt it when I experienced a severe stumble right after install). Patrick built the following: 4150 950 HP. Flowed at 830. I was prepped by some of my pals I would regret no choke. I do not as the car starts great. Takes 3 minutes or so where you can let off the gas.

The Good - when the secondaries kick in and at higher RPMs, the car now screams....almost scary. I definitely noticed a power difference (and I am sure failing intake gaskets didnt help any either).

The Bad (and it's not so bad) - did take some initial set up changes (floats, idle mixtures, and idle)...a wideband A/F computer really helps verify when on target. Luckily had one loaned to me. All A/F ratios were dead nuts on out of the box. Idle is a little rougher than I remember...but again this is more of a racing carb. Also, I have a slight bog (actually goes rich..to around 10) when entering a slow right turn (barely noticable on a left turn) from a stop 0or extremely slow speed. A slight touch of the accelerator removes this bog. Not sure if the jet extensions are the cause but so far this has not bothered me. The float adjustment was key in minimizing this versus balancing a stumble upon acceleration (which I do not have).

The Ugly - nothing to report here.

Summary - glad I made the change, good customer service. Would reccommend Pro-Systems with no hesitation. - Eric

[WardL]

I bought my 427 SRTW used and the previous owner said the Roush supplied carb was "junk" and he bought a Bigs Stage 5 750 Holly w/o a choke. So I have never seen the original carb performance. I wish I had a choke as 427 CI can barely move a 2,500# car when it is cold without a choke! I have to sit on the driveway for at least 5 minutes before heading out. Once it warms up it is perfect: starts in one quick crank, never heard a backfire, pop, studder, nada. OK, in one situation I was on a hairpin curve and I lost power. I'm assuming that was a carb issue. The other point I'll make is my mpg averages about 14 on the highway and 11 around town.

[289fia_cobra]

ok, so I stand corrected: Roush just assembles engines but it appears doesn't really "tune" carbs well. That's what I'm getting from this thread.

[Got the Bug]

Originally Posted by 289fia_cobra

ok, so I stand corrected: Roush just assembles engines but it appears doesn't really "tune" carbs well. That's what I'm getting from this thread.

There was a know issue with the Holley Carbs for a period of time a couple of years ago. I had the same hesitation issue that Eric had, but it was completely resolved by Roush and the dealer and the car runs great.

I'm not 100% sure, but I think Roush was taking the Avenger carb and doing some mods to them. Holley made some tweak in the design that screwed Roush up. I haven't heard this issue crop up recently.

[WardL]

I don't mean at all to trash Roush. I wasn't there when previous owner swapped out carbs. The problems would have been in 2007. I find it hard to believe one of the more high end engine builder would supply a poor carb setup. Just to say anything can happen and it is always good to ask questions.

[PANAVIA]

The Roush Carburetors that we have seen have been fine for street use, (mostly Holley Avengers ) --by no means state of the art,-

I am sure there are many things that can be done , the removal of the choke air horn and the milling and smoothing off of many small components are , and can lead to horsepower increases. this is the thing ;

100ths add up to make tenths, ,tenths add up to full seconds , - full seconds make your day.

now -- carburetors and their castings are much like cylinder heads, porting and polishing can lead you to the power at the top of the envelope.

However, do remember that increases in overall peak flow can hurt you 'down below in the lower rev ranges. The ranges of revs that are usually used to get the car stuck in traffic, used for waiting in line at IN-N-OUT or something similar.

Decide what you want to use the car for, and tune to that spec.

Steve

[Bernica]

PANAVIA (Steve) is on the spot.
It's pretty easy to put the wrong carb on and end up having to "flush the toilet" just to keep it running in traffic or cruising....

[wanab5150]

It's funny that you guys would say that some of the carbs on Roush motors were screwed up. It late 2006 and early 2007, the guy that did my install said he sent a bunch of carbs back to Roush because they were so screwed up.

When I did a test drive in a Superformance in '06 the Roush 402 had a horrible stumble. I remember him telling me that the carbs that were comming on Roush engines were totally screwed up.

Like I say....Mine runs perfect and it would take a huge amount of HP gain to make me switch.... really.

I could use a little less torque as it's still sideways through 2nd and part of third under 3500 RPM. A bigger carb than a 750 WILL produce more HP at the expense of torque. In the world of racing I would definetly go the bigger carb route. For the street, I'll probably stick with the Avenger unless I get bored and just need to throw some money at it.

[Sledge]

I had a street avenger, which was okay. Not a very exotic engine build. I put in one of Pat's 4150 DP's tuned for my engine specs and am very happy with the results. A big plus is that Pat is always available to answer questions. I had to set the floats, adjust the idle speed front and back, and idle mixture all 4 corners. I got a much nicer engine in terms of driveability and power. I didn't measure the power increase but I am able to burn more rubber easier and for longer distances than before.

Absolutely no regrets.

Cheers