HI my first post , i have a 66 impala 350 sbc twin to4e csu carb A1000 pump 132-02 reg. The carb is second hand it started leaking out of the vacuum advance port . Under someone else's advice they told me to just block the vacuum circuts seeing as im not using them. I think i have the actual problem fixed now an old seal between the brpv and the metering block. My question is will having blocked the vacuum circut have a bad effect on my carb and how? if i have miised anything out sorry in advance. Thanks heaps any help-advice would be appreciated. I tried to link a pic but the file was to big i need help here to . Cars and computers they both hate me.

 

when you say blocked, do you mean with a rubber cap, or pull the fitting and seal it-if not in use, the vac ports need to be blocked anyway
some guys do pull the fittings and seal them-anyway, if not in use, need to be capped, blocked, etc

 

When ibought the carb, both metering blocks had the fitting already removed . my carb dude tapped and blocked the circut just before it exits the blodk with some little blanks and punched some brass blugs where the fittings use to go . I dont understand if they were never blocked b4 and the carb worked very good except a rich idle 12-1. cruize was 13-1 and wide open throttle 12-1 again in top gear. I figure now the rich idle was from the leaking pv seal and it was also hard to start if left sit for about 30 mins. When i put it back together with new seals in pv and vacuum circut blocked car idled mint 13.5 no hesatation on free rev, ileft the driveway light accelaretion pig rich 8.8 afr's ,so i blocked rear brpv completely by totatly winding it in and wound front one in all the way in and then back out 2.5 turns . Car idles ,cruizes ,okay still needs a bit of playing with but on the highway afr's drop down to 10-1 for no reason, my fuel pressure is not rising when it drops,,. i have the gauge in the car so it makes me think its not brpv's opening . The only other thing different is blocking the vacuum circut, can this cause some kind of pressure problem or non venting issue? And if it was never blocked b4 and worked good why didi block it I could drill it back out but dont want to if it suppose to be there But why wouldnt csu of blocked it had to be done , assuming it is a genuine csu carby. Thanks for the help .

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So does everyone onthis forum have there vacuum circut blocked?

 

I blocked mine with plastic caps just beacuse I didnt need to use them anymore. I dont think it would hurt anything,

 

What did he block on the metering blocks ? Are you talking about #22 or #12 on pic below ?

If it goes fat for no reason at cruise , I would have to think its a leaking PV .

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Thanks 4 the reply blown385 ive read alot of your posts i feel privileged, the top of #2 circut has been taped and blocked with a brass screw and #12 has a brass dowl smashed into it.
would a leaking pv cause fuel to push up thru the #12 hole?. I dont know if i have fixed the problem of Why the fuel was leaking out of the #12 hole because it is blocked, but i put new seals in where brpv"s screw in.
The other thing its doing differnt now is i could stall it befor make boost leave the line like an animal and spin the wheels into top gear and keep em spining till i got scared,but now as soon as i stall it up it just falls over,i take my foot off the brake and it clears its throat staight up to full boost and wheel spin. I dont know where the extra fuel is comming from at stall?
ohyeah i luv your vids you gotta teach me how to post video's.

 

Thanks . The video isnt hard .

That circuit could have been modified for an outside air source to control the PVs . Yes if the PV gasket was leaking into the PV cavity AND that circuit was used for the BRPVs then you would see fuel from there .

A leaking PV gasket would not cause a rich condition at cruise , but a PV that is not staying seated will . How old is the carb ?


Anyone else know CSU carbs , that have seen this used for PVs or extra fuel ???

 

I bought the carb about ayear ago from a guy on ebay america who said it came off a rx7 but shanged to injection it had a fuel log built on the side as well when i got it. How long he had i dont know i wanted a new one but kevin never responded to any of my emails ON the highway it fluctuates from 13-1 down to 10-1 when iback off the accelarator it comes back up real slow. I wound the pv in a couple of turns incase it had hat pressurebut the fuel pressure gauge wasnt rising above 6lbs so i didnt think it would have enuf pressure to open the pv?

 

you could plug the PVs just to see if its a PV issue . Obviously no boost .

 

I'm not a carb or turbo expert, but some of this doesn't sound right to me.
How are you "putting new seals in the power valve"?
Blocking the power valves by "winding it in & the front back out 2.5 turns"? Are you adjusting the idle mixture screws?
The part about the fuel pressure...explain this in some more detail if you would, I'm not following what you are getting at. Lorne

 

Hes talking about the PV gasket

the BRPVs are adjustable . Turning them in means it will take more pressure to open them . He is cranking them down so there is no chance they are opening . ( blocking the power valves )

He is saying that he knows there is no pressure on the PVs because there isnt any pressure in the hat . Because if there was , he would have seen higher fuel pressure .




At least thats what I got .

I think I would start by making sure the PVs are working correctly .

What is the jetting ?

 

Thanks blown385 you hit the nail on the head onall 3 points. I will do what you suggested with the pv's this weekend and do some sudate driving.

What is the jetting ?
Ihad 70's up front and 72's in the rear but i changed to 70's allround when i wound the rear pv closed. I also have a trunk mount water/meth kit that comes on at 8lbs manifold pressure, but that should have nothing to do with my issue on cruize .Once again thanks for the help even if its moral support cause i sure as hell dont get it off my misses.