The "CRUTCH" Blow-thru carburetors *Now with a in-car video*

[Brent Davis]

"THE CRUTCH" system uses a MSD RPM controller to operate a mini air-pump compressor to make the BRPV's open under a desired set RPM that you set via cockpit adjustment.  

Big thanks to blown385 (Dave), Here's a video of a crutch carb system at work.  Notice how well the car is lean while crusing but once he gets into boost, it richens up and stays at a certain AFR of 11.0.  The crutch help keep the main jetting down low so that cruise RPM's can be lean but under boost the secondary enrichement circuit is what supplies the extra fuel via the crutch system opening the dual BRPV's/

http://vimeo.com/moogaloop.swf?clip_id=9771126&server=vimeo.com&show_title=1&show_byline=1&show_portrait=0&color=&fullscreen=1

2 each High flowed PV's                    
4 each BLP .075 jets
2 each .150 downfeed N/S's      
1 each front BRPV spring cup                            
1 each rear BRPV sping cup with fuel extension    
3 each -4 AN straight fitting                              
4 each -4 AN coupler fittings                              
1 each -4 flare union fitting                                
5' of black push-loc hose                                    
1 each -4 90* fitting                                        
1 each MSD Digital RPM switch                            
1 each air pump with plate          
                  
Shipping charges (more for overseas shipments)    

Full modifications to both metering blocks
modifications to the base plate for BRPV signal
Full modifications to the main body
make BRPV spring cup for the front
make BRPV rear extension to keep fuel at the BRPV under hard acceleration
build pump BRPV activation plate
test carb on a test car up to 25 psi of boost for proper AFR

Most carbs that I have built drop main jets down about 6-8 sizes all the way around and get much better low speed drivability but get the much more needed fuel up top via the dual BRPV's feeding the motor thru the PVCR channels under boost and keeping a safe AFR while doing so.

Price is $850 with you supplying me the carburetor and it takes roughly 3-4 weeks to build & test the carburetor.  A deposit of $450 is required or full payment for me to order parts and get started on the build.  Just send me a PM if you may be interested in my mods.

Here's a few random pics of carbs that I have worked with.

[smokin03cobra]

GREAT mod to have done to your carb, i wouldn't have it any other way....and Brent is always a phone call away if any problems!!!! 
thanks Brent

[Brent Davis]

Thanks Carmine.

Guys, Carmine already had one Quick Fuel carb modded by me and sent me the two that you see together in next to the last photo to do, one for another car of his and another for a friend.

A funny story that Carmine told me was that he waxxed a guys ass in a Grand National and the guys friends were saying that Carmine has one of those Brent Davis carburetors on his car, that's why he's running so fast!  LMFAO ......LITERALLY that was some funny chit man to hear.  I mean the carb is a simple mechanical device that I just do my BRPV stuff to and these guys think it is something special going on inside the carb with little elf's or something.

I forgot to add that if you have another way to trigger the pump other than the MSD RPM box, just delete $140 off the $850 total price.

Anyways, back to

[pdqwagon]

I asked about doing demon metering blocks in the other thread before I saw this one, can you do this mod to a Demon carb with similar results? Could it be done for use with E-85 as well with larger jets and PVCRs?

[88MMrocket]

that stuff looks good!!!  I think the pretty polished red one is mine!!! 

[FourEyed]

I'm still new to all of this, but what is the advantage of having your BRPV's open by rpm?

[NITROUSKINGZ]

Thanks Carmine.

Guys, Carmine already had one Quick Fuel carb modded by me and sent me the two that you see together in next to the last photo to do, one for another car of his and another for a friend.

A funny story that Carmine told me was that he waxxed a guys ass in a Grand National and the guys friends were saying that Carmine has one of those Brent Davis carburetors on his car, that's why he's running so fast!  LMFAO ......LITERALLY that was some funny chit man to hear.  I mean the carb is a simple mechanical device that I just do my BRPV stuff to and these guys think it is something special going on inside the carb with little elf's or something.

I forgot to add that if you have another way to trigger the pump other than the MSD RPM box, just delete $140 off the $850 total price.

Anyways, back to

brent  i know that guy with the gn.....he was not happy he lost to a stock bottom end with a carb...lolololololol his buddy got sbc with 2 stages and lost to carmine and another guy with a stock bottom end 302 with a carb.....these guys are just hating what they dont understand!!lolololololol 

[Brent Davis]

I asked about doing demon metering blocks in the other thread before I saw this one, can you do this mod to a Demon carb with similar results? Could it be done for use with E-85 as well with larger jets and PVCRs?

I've never built a Demon carb before but see no reason that it can't be built like a Holley.  I'd have to have it in my hands to see first hand and go from there.  I have modded a set of metering blocks from one though.  Doing the E85 stuff is fine too but you need to have a target HP goal to know if you need the dual needle/seat bowls or not.

that stuff looks good!!!  I think the pretty polished red one is mine!!! 

LOL, yeah I think that one is it.

I'm still new to all of this, but what is the advantage of having your BRPV's open by rpm?

There's no more significant advantage having the PV's open under a RPM set versus using a boost activated MAP sensor of some sort.  I have guys all the time that want the carb mods but have their own ways of activating the PV's via MAP sensor for boost or whatever the case.  I am able to use my LM-1 to tell me how much boost at a desired RPM range and that is how I know what RPM to activate the PV's, therefore I do it by RPM.  Even the guys that I have built carbs for and use the RPM box don't have issues using the RPM way.

brent  i know that guy with the gn.....he was not happy he lost to a stock bottom end with a carb...lolololololol his buddy got sbc with 2 stages and lost to carmine and another guy with a stock bottom end 302 with a carb.....these guys are just hating what they dont understand!!lolololololol 

LMAO, that was funny when Carmine told me about the "Brent Davis" carb is the reason he is so fast.  That had me rolling man as I know that there's nothing special at all to the carb.  Heck look at his stock motor, 15+ year old heads, E-303 cam and waisting these guys like he is and his AFR's are STILL 10.0's .  Being that carmine has a stock block and the car is as quick as it is in the 1/4, it is a good idea to keep the fuel there like it is to save the block as best as possible.  If he leaned that thing out to mid 11's, it probably would hurt him on the street because he'd pick up about a 60-100 HP range

[88MMrocket]

got my carb yesterday slapped it on and it cranked on the first try and idles/sounds better than ever  

thanks Brent!  I will take it out today to put some miles on it, then off to the track tomorrow!!!

BTW, this carb is the polished Quick Fuel with red billet blocks in the pics.  It was built originally for another member (Carm) who sold it to me.  Brent was kind enough to go back through it for us and put his stamp of approval on it.  Also, Brent is giving me HIS service plan with it!!!!! and I didn't even buy it from him!!!

That's some service "rite thur"

Ken

[Mikey B]

Hey Brent , Do we also get to knock off for the Msd window switch if we already have one.   I also need to call you to see if i need the  "Crutch" . Oh yeah my buddy Rick Furr from Jackson ,Ms said thanks for the carb he sent you.  He bugged me for about a week on the blow thru carbs so i sent him your way.

[blown385]

I forgot to add that if you have another way to trigger the pump other than the MSD RPM box, just delete $140 off the $850 total price.

 

[Mikey B]

Thanks Blown385 

[Brent Davis]

Hey Brent , Do we also get to knock off for the Msd window switch if we already have one.   I also need to call you to see if i need the  "Crutch" . Oh yeah my buddy Rick Furr from Jackson ,Ms said thanks for the carb he sent you.  He bugged me for about a week on the blow thru carbs so i sent him your way.

Yeah man ole Rick got a brand new built carb for his ride.  He had a camshaft issue and had to get that fixed up but it runs great now he said.  You talk to him lately?  I lost his phone #.

Thanks big money Dave for posting my quote on that MSD box.  Mikey, just take off the $140 and we go from there.  This is strictly a limited time since darn near all the parts like PV's, jets, needle/seats and the RPM box went up in price.  That dang box used to be $109 from Jegs or Summit but is now $139   Mikey, just let me know man and we can get it done.

[Mikey B]

Yeah  he got it running and traded it for to rollers. He said it worked great.

[Brent Davis]

Yeah  he got it running and traded it for to rollers. He said it worked great.

he traded the car for two rollers?  What did he get?  He never really ran it then did he?

[Mikey B]

He traded it for a 95  mustang, 92 coupe.  I was told both of the cars looked nice.  He runs a speed shop  here in town ,  he got rid of it before he even took it to the track i think.   Hey i sent you my combo , let me know what i need Mr. Brent

[Brent Davis]

All, this is an older log from one of my "CRUTCH" carbs with 32 psi of boost.  I had 70/70 squared jetting in the carburetor and .080" PVCR's.  I did change the PVCR's out to .060" and the AFR's leaned out to 11.5 with the same boost level.

[cold69bird]

Brent, how much do you charge for just modding the metering blocks. I already have the carb setup to turn the pv's on with c02 so i wouldnt need any of that stuff, i can do it with rpm or boost as i have it setup right now.

[smokin03cobra]

i beleive he has another thread just for blocks take a look around

EDIT...http://www.theturboforums.com/smf/index.php?topic=132935.0

[countryboyspeedncustom]

Brent,
My name is Charlie and I have stumbled into a 950 Proform carb and was wondering how we get the ball rolling on the mods...plus if you are able/or willing to help me out, I want the carb Anodized Black, not really crazy about the purple!. Do you know anyone, should this be done before you get it or after, are you able to have it done when you take it apart so all the right parts get the right stuff?
Thanks for your time and I look forward to hearing from you.
Charlie

[domn8rx]

The last carb you'll ever need...unless you sell the car  

john

What, you have too much time one your hands?? Good luck with the sale.

[Sponge]

Sorry but english is not my monther language... For that price, does it include the carb or only the mods?

Thanks

[Brent Davis]

Sorry but english is not my monther language... For that price, does it include the carb or only the mods?

Thanks

Only the mods, parts, labor & shipping .

[Brent Davis]

Thanks to blown385 (Dave), he did a video of his truck driving around while taping the gauge panel that RI85GT (John) built and it has an LED of a crutch to show when the pump is activated to open the dual BRPV's.  This video shows basically how well a tuned carburetor can drive around AND supply all the fuel needed when under full boost and actually stay down.

Thanks again Dave.  

[HP]

Pretty incredible I must admit!