One more ? (well...maybe more)

gman415

Dragway Regular
May 19, 2009
883
0
0
Chattanooga
My regulator has a vacuum ref port, My intake and carb do not, Is it worth it to drill a port in my intake?
It also has a "Idle Bleed For Vapor Lock Prevention" I don't this will be a problem only running 1/8mi, Your thoughts?
I know it's been said a 7-10* change in the 1/4 is good,What would be a good temp rise in the 1/8mi?
 

bbc-olds

Frequent Racer
Jun 7, 2008
542
2
18
Malin OR
Drilling into the intake will not work. As the top end of the track the vacumm will increase as the load on the engine decreases and will cause an unsafe drop in fuel pressure.
 

gman415

Dragway Regular
Thread starter
May 19, 2009
883
0
0
Chattanooga
Still trying to get this straight. Where would you get vacuum for a regulator then?
 

gman415

Dragway Regular
Thread starter
May 19, 2009
883
0
0
Chattanooga
"Plumbing the 1/8” barbed fitting to a vacuum port below the carburetor base plate will reduce fuel pressure at high RPM off throttle conditions (corner entry). This will make the engine “cleaner” when you pick up the throttle on corner exit. Idle pressure will also be reduced."

Found this off the "racepump"web site.
I think I'll just leave it unpluged.
 

bbc-olds

Frequent Racer
Jun 7, 2008
542
2
18
Malin OR
Your talking circle jerking as apposed to drag racing. Different applications. They may want it to go lean going into the corners and be that way until picking up the throttle coming out. Going lean on a strip will cause problems. If you are running alcohol fuel it is a good idea to use a vacuum referenced regulator. Best explanation I have seen is on the pro systems website. http://www.prosystemsracing.com/frienddom.html If on gas just set it to what ever psi you run and go for it. They use a specially drilled port in the carb to keep vacuum low as long as you are on the throttle .
 

Night Stalker

Dragway Regular
Nov 3, 2009
1,125
0
0
Genoa,Oh
But that only holds true to Pro systems and how they meter the fuel in they're blocks and carb...Not all carb builders use this method.. Not saying Pro systems is bad, butthis set-up is not needed to run alcohol.. ;)
 

Hitman

Dragway Regular
Oct 15, 2004
1,321
0
0
OKC
I've never seen a successful alcohol racer using a regulator with any sort of vacuum reference.

I think the best alcohol fuel system is a belt drive pump and either a diaphragm or poppet style return regulator. I use a diaphragm BG.

People also have success with the big electric pumps and deadhead regulators. I just like the ease, reliability, and decreased electrical draw that belt pumps offer.
 

Malibu355

Pro Stocker
Feb 21, 2009
1,803
0
0
La Marque, Texas
bbc-olds said:
Your talking circle jerking as apposed to drag racing. Different applications. They may want it to go lean going into the corners and be that way until picking up the throttle coming out. Going lean on a strip will cause problems. If you are running alcohol fuel it is a good idea to use a vacuum referenced regulator. Best explanation I have seen is on the pro systems website. http://www.prosystemsracing.com/frienddom.html If on gas just set it to what ever psi you run and go for it. They use a specially drilled port in the carb to keep vacuum low as long as you are on the throttle .


Thats odd. I bought my carb from Patrick in February and even asked him about a recomendation on a regulator and he didnt mention this at all to me. Oh well I am doing fine with what I have...
 

gman415

Dragway Regular
Thread starter
May 19, 2009
883
0
0
Chattanooga
We made it to the track!!!
It rained every test session since we got the car running, So all we had was one hour of open time trials and then two qualifying rounds before eliminations. We left the car set up the same as before to get a comparison as close as we could get it. So the shift was only at 5200 and four threads showing on the bolt under the throttle. (to run the 7.00 index)
We staged the car at 160* and 6.80 seconds later it was still at 160* even back to the pits. I was expecting to make a jet change but my son (the driver) said he left the fan on. After talking to some guys that run close to the same setup as ours, we left it alone as this is how they did it.
So that's a two tenths gain not counting the air temp was 20* warmer.
 

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