ANY LUCK WITH EITHER OF THESE ? I SEARCHED THE ARCHIVES AND DIDNT FIND ANYTHING... I FOUND ARTICLES ON ANOTHER SITE BUT I WANT MORE INPUT. I REALLY APPRECIATE ANY IDEAS,TIPS, OR INFO ON THESE TOPICS.I WANT TO MAKE AN ADJUSTIBLE UNIT FROM THE STOCK ONE

I've done it to my OEM and a few others:

AFPR Coversion.pdf

If you decide to do this, forget using the ball (since no one can seem to find the right sized ones) and use the steel disc. The article explains it.


I've also relocated the MAT to the intake air duct:

MAT Relocation.pdf

Moving the MAT/IAT on a MAF car does little good, if any. It may help some on a speed/density car, however.

THANKS FOR THE RESPONSE VADER. CAN THIS AFPR BE ADRESSED TO THE TPI 383? AND IS IT WORTH THE TROUBLE SINCE ID LIKE TO REPLACE THE DIAPHRAM AND IT COSTS 40 BUCKS.

If you are going to replace the diaphragm, it may be easier to purchase an AFPR kit. Many of them include a diaphragm, screws and will save you the steps of altering the stock spring can. Rumor is that the Holley AFPR is better quality than the Accel, but I cannot verify that.

I SAW A THREAD FROM A WHILE BACK WHERE THE GUY USED A T NUT AND JB WELD. WAS THAT STEEL JB WELD OR EPOXY OR BOTH. THIS INFO WOULD BE VERY USEFUL IN MY PROJECT.

a guy told me you can just stock a quarter in the fpr and raise the pressure a good 5psi

MAYBE IT IS TRUE BUT I WANT TO BE ABLE TO FINE TUNE MY RIDE. DID YOU TRY THE QUARTER TRICK ? WELL ANYHOW , I WANT TO HEAR FROM PEOPLE WHO HAVE TRIED THIS AND I WANT TO HEAR SUCCESS AND FAILURES. OR IS IT JUST FOOL PROOF? THE MAT SENSOR OR HOMR MADE AFPR.

Nothing is "fool-proof" since no matter how easy something can be made, they'll always be able to find a bigger fool.

The MAT relocation is about as straightforward as can be for anyone who has any business modifying an engine control system. It doesn't change much at all on a MAF system, however, since the MAT isn't used for much of anything in the fuel trim.

The AFPR conversion is relatively easy with the proper tools and equipment. My method requires either brazing, silver soldering, or TIG welding. JB-Weld and other kinds of epoxy aren't going to cut it. The metal disc I recommend is basically just like the "stick-a-quarter-in-it" method, but allows adjustment from stock pressure to peak pump pressure. The "quarter" method only raises pressure above stock, which may or may not be a good thing, and allows no fine tuning.

More isn't always better. If you want evidence, read this thread:
https://www.thirdgen.org/forums/tpi/...ning-rich.html

THANK YOU SIR .THAT WAS INFORMATIVE. NOW WHAT IM TRYING TO ACHIEVE IS MORE POWER FROM MY 383 NOT SO MUCH AS GETTING RID OF THAT RATTLE WHEN I NAIL THE GAS. FROM EXPERIENCE ITS DETONATION BUT ONLY AT WOT. SO I FIGURED IT WAS TIME TO DO THIS SINCE PREV. OWNER DID NOT WORK OUT DETAILS THATS HOW I GOT THE CAR SO CHEAP. GOT EXAUST, HEADERS,CUSTOM PROGRAM,K AND N . ALL ELSE IS STOCK. I REALLY APPRECIATE YOUR AND ANYONES VALUABLE TIME.

You may need to increase fuel pressure with your existign injectors, and if you do you'll probably also have to reprogram. You may also be able to solve the problem entirely with reprogramming. You would really need to look at AFR during a run and see if it is definitely going rich or lean, and then adjust accoringly.

OK, WITH YOUR ARTICLE AS A GUIDE I MADE THR AFPR. WORKED OUT FINE. NOW AT IDLE I CAN REV UP FASTER AND NO RATTLE. UNDER LOAD ITS ALMOST GONE ONLY RATTLES WHEN I REALLY LEAN ON IT, FEELS FASTER TOO. IM GONNA GET A PRESSURE GUAGE SOON. DONT HAVE THE CASH FOR DYNO TUNING YET(4 MONTH OLD AND 3 YEAR OLD). BUT IS THE VOLT METER SPLICED INTO THE O2 SENSOR A GOOD METHOD? DO YOU KNOW ANYONE IN L.A. WHO CAN DO MY ROC RIGHT?THE P.O. SAID HE HAD A CUSTOM PROGRAM DONE FOR THE CAR.I ALSO NEED EXACT SPECS ON THE PROGRAM AND MOTOR BUT THE P.O. ONLY KNEW HOW TO THROW MONEY AT THINGS BUT WAS NOT TECHNICAL AT ALL.

JB weld can work, you’re just not creative enough…

Here, this is what I ended up with:


I just took a T-nut that I had a matching bolt for, broke the teeth off of it with a pair of pliers, drilled a hole in the top of the cap, flattened and even bowed the cap outwards a little with a ball pein hammer on a block of wood (something with some give, gently shaping it so it looks like it was supposed to be that way)to make room to put something inside the top of the cap to push against and glued it in with JB weld.


Finally, all the pieces from the top, you can also see where I chucked up the bolt in the drill press (using it kind of like a lathe) and cut a nipple down in the middle of it to center a washer that was put in the extra space in the top of the cap to push against the spring assembly:


Even if I didn’t have the hardware sitting around it would have cost less then the $.99 can of cheap flat black spray paint that my **** retentive *** used to make it look pretty. Make sure that you measure everything as you’re doing it to leave room between it and the bottom of the plenum. I actually left mine a little longer then it had to be and ground a rounded reliefe in the bottom of the plenum for it and between that extra height and the lubrication the non hardening sealant that I used on the threads gave I can work it with my fingers. If you’re worried about it moving (mine never did) you can put a jamb nut on it…

The "T" nut is a good idea. Thin enough, strong enough, and the only concern would be getting it sealed to hold vacuum. The epoxy should solve that. as long as you form enough relief in the spring can so that pressure can be adjusted all the way down to the stock setting, it should work fine. Nicely done.

SO BOUGHT A GUAGE ON SUNDAY AND MY READING OFF THE BAT WAS 20LBS.!
I ADJUSTED IT AND THE GUAGE DANCED ONCE I HIT 27 LBS UNHOOKED AND PLUGGED . FLUCTUATED ABOUT 5-6 LBS. THE MAX WAS ABOUT 36-37 LBS. THE CAR RAN REALLY GOOD BUT GOES LEAN AT WOT. FINE OTHERWISE. SO I PUT IT BACK TO ABOUT 30 LBS WHERE IT RUNS REALLY GOOD. AND AT 36 LBS IT IS HARD TO START IF I DONT GET IT ON THE FIRST TRY WHEN WARM. I'VE ONLY WORKED ON CARBS ALL MY LIFE AND THIS IS MY 1ST TPI. SOMETIMES I I MISS MY 67 SS/RS!!!!!! THANX GUYS IM STILL LEARNING.

I pounded out that whole dip/coutour that the stock one had, if I remember right that gave me a usable adjustment range from around 33-85psi...

I don't know what I did wrong, but I left out the ball and like 83cta I used JB weld on the nut and ground a small point on the bolt- but if I raise the pressure above stock at all it fluctuates like mad, and I'm afraid it will rupture the diaphragm or something.

Did you give it something to push against?

The reason that I ground the end of my bolt was to keep it centered in that washer. If you push against the pin in the center of the spring retainer it won’t work right, that pin has to stay free of the retainer plate on the back of the spring.

Yeah, I gotta take the plenum back off and see what I did wrong one of these days!