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Another Turbo Build 67' Dart GT
https://slantsix.org/forum/viewtopic.php?t=58909		 Page 4 of 7
Author:  mopar225 [ Fri Feb 19, 2016 12:42 pm ]
Post subject: 
For idle afr, like you said, i'll just see what it likes.
But good to keep in mind that you guys are running low 12's.
Quote:
if you plan on running more than 8-10 psi i would look into a brpv. the stock setup likes to flutter and not open all the way. you can compensate for that with jets but it will kill any kinda fuel economy. 10 is usually a good safe starting point. if you go the brpv route and open up the power valve channel restrictors accordingly, that can eat a lot of jet so you can go back down. the idea is to use the jets that are going to give you the best driveablity not on boost and use the power valve to give you the extra fuel you will need when on boost. if you do it all with jets it will run horribly rich at partial throttle.
Definitely plan on running over 8psi! And still drive the car as a daily, so fuel mileage does matter haha.

So for BRPV, what kinda the best option?
Flipping the spring on the PV and making a cap to hold it in?
This is an example I found:
Image
Author:  1974duster kev [ Fri Feb 19, 2016 2:37 pm ]
Post subject: 
Basically yes, I think there is a pic of my little arm I made for my BRPV in my build thread.

Kev
Author:  Junior [ Fri Feb 19, 2016 3:09 pm ]
Post subject: 
ive tried quite a few of them. what you have there is the basic brpv. in the ones that i tried that was the base. for low boost it will work fine that way. once you turn it up you'll need something to open it. the boost at the top of the carb is gonna be different from what it sees just under the butterflies where it gets its signal to open. so it will open there's just no telling how much and if it will stay open. i didnt like that. i wound up drilling the main body into the power valve chamber, epoxied a piece of brake line in that hole, blocking off the port on the bottom of the chamber and routing a reference from my exhaust between the head and turbo. the back pressure on the exhaust side is always higher than the boost pressure on the cold side. changing nothing else in my setup besides where the power valve got its signal from netted me like .3-.5 of an afr point. the fluctuation in the afr readings went away under boost and it really made tuning easier. there are other ways to do it that involve hobbs switches (electric switches that use pressure to tip) and air pumps or compressed air. i didnt like that idea either. seemed like there was just more stuff to fail. everyone seems to do their setups a little different. if you are interested i can post some pics of where to drill. might be worth spending some time reading on www.theturboforums.com there are many ways people have done brpvs but only a few work well and reliably.
Author:  1974duster kev [ Fri Feb 19, 2016 7:42 pm ]
Post subject: 
I thought about doing an external line also but I ended up drilling above the curve in the throat of the main body into the PV channel seems to work haven't tried the other way yet though.

Kev
Author:  Junior [ Sat Feb 20, 2016 8:32 am ]
Post subject: 
Quote:
I thought about doing an external line also but I ended up drilling above the curve in the throat of the main body into the PV channel seems to work haven't tried the other way yet though.

Kev
so it gets it signal from the top of the carb? then i would see the same pressure as the bowls. that wouldnt work to well. unless the air flow comes into play and acts like ram air giving it slightly more pressure than the bowls see. i dunno
Author:  mopar225 [ Sat Feb 20, 2016 2:49 pm ]
Post subject: 
Junior.
This this what you did for your BRPV?
but plugged the hole at the bottom where the vac signal is coming in?
Image
Found the image here: http://www.thirdgen.org/forums/carburet ... -your.html

Then you still did the cap and reversed the spring on the PV?
Feel free to pic some pics if you have!
Author:  Junior [ Sat Feb 20, 2016 4:31 pm ]
Post subject: 
yup thats it. im running a 2.5 power valve spring in this setup.
<img src="http://i125.photobucket.com/albums/p79/weesers1/Mobile%20Uploads/20141130_155126_zpsz4tfm3iz.jpg" border="0" alt=" photo 20141130_155126_zpsz4tfm3iz.jpg"/>
<img src="http://i125.photobucket.com/albums/p79/weesers1/Mobile%20Uploads/20141130_160244_zpslwbqsep7.jpg" border="0" alt=" photo 20141130_160244_zpslwbqsep7.jpg"/>
<img src="http://i125.photobucket.com/albums/p79/weesers1/Mobile%20Uploads/20141130_160645_zpsqjcan5ko.jpg" border="0" alt=" photo 20141130_160645_zpsqjcan5ko.jpg"/>
here you can see the coiled line coming up from before the turbo. there is no flow so heat shouldnt be a factor but just for the sake of being cautious i put the coils in there to dissipate any heat if it did manage to make it up there. welded a nut into the exhaust and used a compression fitting to attach the line.
<img src="http://i125.photobucket.com/albums/p79/weesers1/Mobile%20Uploads/20141221_113646_zpsnkx1uhqu.jpg" border="0" alt=" photo 20141221_113646_zpsnkx1uhqu.jpg"/>
Author:  Junior [ Sun Feb 21, 2016 1:33 pm ]
Post subject: 
have you done anything with the timing?
Author:  mopar225 [ Mon Feb 22, 2016 5:04 pm ]
Post subject: 
Thanks for those pics!
If I have a IC, would the boost signal from turbo not be higher than what the carb see's? With the pressure drop?
Quote:
have you done anything with the timing?
No I have not.
Limit it to 18* correct?
Author:  Junior [ Mon Feb 22, 2016 8:54 pm ]
Post subject: 
it should be. not sure how big the difference would be and if it would be enough to open the pv. worth a shot though.

timing is tricky. the 18* comes from the guys running lots of boost. at lower levels i dont think you need that little amount of timing. my first run out at 5psi i hadnt done anything to the distributor yet and i didnt hurt anything. im not really sure where its necessary to start pulling timing. 18* is safe though. keep your vacuum advance hooked up so you get a little more when you are cruising off boost.
Author:  mopar225 [ Thu Feb 25, 2016 6:17 pm ]
Post subject: 
Ok, well I'll do that BRPV mod, run it from the turbo, and leave my timing as is to start off with.
Jet up 10 sizes before I hook up all the turbo press side.

Thanks for the help Junior.

I'll post some updates when I get back home and get at it again.
Author:  Junior [ Thu Feb 25, 2016 9:43 pm ]
Post subject: 
while you have time off, look into vent tube extensions. might be able to run them instead of jetting up. i dont remember how much they gave me but it was a lot. i only run one on my secondaries. a lot of people run them on both and they do work.
Author:  mopar225 [ Fri Feb 26, 2016 5:56 pm ]
Post subject: 
Quote:
while you have time off, look into vent tube extensions. might be able to run them instead of jetting up. i dont remember how much they gave me but it was a lot. i only run one on my secondaries. a lot of people run them on both and they do work.
I'll check into that for sure!!
Should I also be thinking about removing the choke horn as well?
Author:  Junior [ Fri Feb 26, 2016 8:28 pm ]
Post subject: 
everyone ive seen with a blow through does remove the choke horn. i did. not sure how much of a difference it really makes. i guess it would depend on where the inlet on your carb hat is. if its straight on i dont think it would be an issue. of its on any kind of angle i could see how that might affect the flow. the professional blow through carbs are the hp series that didnt come with one. i honestly dont know. you could try it with it intact and see how it responds. a lot of people just cut them off and leave the outline. i like to grind that down as well. i wanna make it as easy as possible for the air to find its way into the venturis. thats just me though. sorry i cant give you a definitive yes or no.
Author:  Junior [ Fri Feb 26, 2016 8:31 pm ]
Post subject: 
<img src="http://i125.photobucket.com/albums/p79/weesers1/Mobile%20Uploads/20150310_195248_zps9ztevgrc.jpg" border="0" alt=" photo 20150310_195248_zps9ztevgrc.jpg"/>
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