Re: Carb
[Re: Quicktree]
#784856
09/03/10 08:22 AM
09/03/10 08:22 AM
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Joined: Feb 2003
Posts: 12,675 Columbia, CT
moper
I Live Here
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I Live Here
Joined: Feb 2003
Posts: 12,675
Columbia, CT
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I'm not a big time racer but I've never had to use more than a 37 squirtor, and most are fine with 30ccs and 31. It's only supposed to pump during trasition in throttle opening. Not after... After is where the PV and booster come in. If I had to guess, your PCV is fine the way it was. The difference was the lean you had from basically a big vacuum leak. You have an annular booster carb. It's very sensitive to pressure cahnges. I'd go leaner on the shot (like a 28 with the 30cc) and see if that helps. Remember the amount of fuel will never change. It's always going to be 30 or 50ccs. But the time it takes to discharge will. Big squirtors mean a lot of fuel for a shorter time. Smaller shooters mean more time spent enriching the mixture. I think you're way over-rich when the rpms clear 2500 due to the annular boosters and larger pump cam with the larger shooter. It cleans out when the rpms drop with the shift and the acc pump is out of volume.
Well, art is art, isn't it? Still, on the other hand, water is water! And east is east and west is west and if you take cranberries and stew them like applesauce they taste much more like prunes than rhubarb does. Now, uh... Now you tell me what you know.
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Re: Carb
[Re: moper]
#784857
09/03/10 09:50 AM
09/03/10 09:50 AM
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Joined: Jan 2003
Posts: 4,296 Chicago, IL
TonyS451
OP
master
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OP
master
Joined: Jan 2003
Posts: 4,296
Chicago, IL
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thanks for the replys guys. This has been a frustrating situation for sure. Moper - I did try the 30cc, pink cam and 28 squirter and had the same problem. I tried 28 to 47 squirters with the 30cc, and only tried 33's with the 50cc. Whats also very frustrating is that the problem never duplicates itself identically. Some pulls are cleaner than others, with the same hardware.
If the annular carb is more sensitive to pressure, would it help any to route the pcv to a port lower on the intake manifold vs directly to the carb?
2 kids and a dog
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Re: Carb
[Re: TonyS451]
#784858
09/03/10 10:12 AM
09/03/10 10:12 AM
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Joined: Jan 2003
Posts: 32,394
Quicktree
I Win
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I Win
Joined: Jan 2003
Posts: 32,394
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Quote:
thanks for the replys guys. This has been a frustrating situation for sure. Moper - I did try the 30cc, pink cam and 28 squirter and had the same problem. I tried 28 to 47 squirters with the 30cc, and only tried 33's with the 50cc. Whats also very frustrating is that the problem never duplicates itself identically. Some pulls are cleaner than others, with the same hardware.
If the annular carb is more sensitive to pressure, would it help any to route the pcv to a port lower on the intake manifold vs directly to the carb?
why don't you just remove the pcv and add a vented cap? you really don't want to suck that into the mixture
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Re: Carb
[Re: BradH]
#784860
09/03/10 08:51 PM
09/03/10 08:51 PM
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Joined: Jan 2003
Posts: 4,296 Chicago, IL
TonyS451
OP
master
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OP
master
Joined: Jan 2003
Posts: 4,296
Chicago, IL
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not sure about the venturi size. I'll check into it though.
2 kids and a dog
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Re: Carb
[Re: willp]
#784862
09/04/10 08:17 PM
09/04/10 08:17 PM
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Joined: Jan 2003
Posts: 4,296 Chicago, IL
TonyS451
OP
master
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OP
master
Joined: Jan 2003
Posts: 4,296
Chicago, IL
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My engine guy thinks I should try jetting down a few sizes. His theory is that if the engine ran its best with a big vacuum leak, it must have been extremely rich (since normally a big vacuum leak would create a lean condition, especially on hard acceleration). He also thinks my problem is occuring past the point of the pump/squirter consideration. And, he also thinks the pcv is not part of the problem.
Soo, with that I'm going to pull the carb, put the 30cc and pink cam back on, 33 squirters (stock settings), and pull out 3 jet sizes. If that doesnt help any, I'm going to give another carb a try.
Can I route the pcv to a vacuum port on the manifold or is it best to go right to the back of the carb? Or does it not matter either way?
2 kids and a dog
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Re: Carb
[Re: willp]
#784864
09/05/10 02:59 AM
09/05/10 02:59 AM
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Joined: Feb 2005
Posts: 5,221 Branson, Mo.
joedust451
super gas
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super gas
Joined: Feb 2005
Posts: 5,221
Branson, Mo.
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Quote:
I still believe the metering calibration is off on that carb.
I agree.
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Re: Carb
[Re: 540DUSTER]
#784867
09/05/10 01:33 PM
09/05/10 01:33 PM
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Joined: Jan 2003
Posts: 32,394
Quicktree
I Win
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I Win
Joined: Jan 2003
Posts: 32,394
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Quote:
Did he add the fuel pressure before or after the regulator?
have to guess it was after
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Re: Carb
[Re: 540DUSTER]
#784869
09/05/10 07:48 PM
09/05/10 07:48 PM
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Joined: Jan 2003
Posts: 4,296 Chicago, IL
TonyS451
OP
master
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OP
master
Joined: Jan 2003
Posts: 4,296
Chicago, IL
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I am running a clay smith mechanical pump and I really doubt the pump is going away. Cant say with 100% certainty especially since I still havn't figured this out yet, but the pressure is always rock steady wherever I lock it in at. I'm going to try jetting down first and see if there is any change. I will try different pressure settings too if need be. I will say this though, at my last test session when it ran its hardest with the pcv detached, I had the pressure up at 8.5. I kept the same pressure with the follow up pass (with the pcv attached) and it returned to the same breaking up symptoms.
Thats why I dont think its the pump or regulator...but im definitely not ruling it out entirely.
So tonight my test run will keep the 50cc pump, 33 squirter, jetting 3-4sizes down (forget what jets are in there now..I think 79 and 87). Going to keep the pressure at 8.5, and run the pcv hose to a port behind the intake.
If it shows signs of improvement or cleans it up all together, I may try going back to the 30cc and pink cam and also try dropping the fuel pressure to a more street friendly rate - 7-7.5.
Thanks everyone for your input. Its been very helpful.
2 kids and a dog
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Re: Carb
[Re: TonyS451]
#784872
09/06/10 12:26 AM
09/06/10 12:26 AM
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Joined: Sep 2008
Posts: 2,840 Flint, Michigan
B1Fish540
master
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master
Joined: Sep 2008
Posts: 2,840
Flint, Michigan
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Quote:
I will say this though, at my last test session when it ran its hardest with the pcv detached, I had the pressure up at 8.5. I kept the same pressure with the follow up pass (with the pcv attached) and it returned to the same breaking up symptoms.
This is the part i dont get, Tony. If i understand it, it runs perfectly w/out the PCV hooked up? Plug that port and see how it runs, that will eliminate a bad PCV valve as the culprit. right? Or confirm it.
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Re: Carb
[Re: TonyS451]
#784873
09/06/10 12:38 AM
09/06/10 12:38 AM
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Joined: Jan 2003
Posts: 4,296 Chicago, IL
TonyS451
OP
master
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OP
master
Joined: Jan 2003
Posts: 4,296
Chicago, IL
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I made a few "runs" around the 'hood tonight. First I tried jetting down 4 sizes front and back with fuel pressure at 8.5, and sputtered like heck. Came back jetted back to 79 and 87 bumped the pressure up to 9 and ran much better, but still with some sputtering. When I set the pressure above 8.5 it appears to be too much for the regulator cause the needle starts bouncing. As soon as I back it off to 8.5 or below it stays steady.
I even popped the pcv hose off just to see if I could duplicate my awesome pull from the other night, but no such luck this time. I must have just been lucky last time.
I'm going to pick up a fuel pressure gauge that I can see from inside the car and really see whats happening. At this point, I think thats the only way to really narrow down the problem.
BTW, The car still idles like a champ and street cruising is nice and crisp, so for now I see no reason to put the 30cc pump and pink cam back in. I'll let you know what happens after I verify the fuel pressure on a "pull".
2 kids and a dog
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Re: Carb
[Re: willp]
#784875
09/10/10 06:11 PM
09/10/10 06:11 PM
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Joined: Jan 2003
Posts: 4,296 Chicago, IL
TonyS451
OP
master
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OP
master
Joined: Jan 2003
Posts: 4,296
Chicago, IL
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I just plumbed a fuel pressure gauge in the other night (one that I can see while Im driving). Got too late to take it out for a "run" and havnt had a chance since. Gonna take it for a spin tomorrow...will let you know what i find. Thanks!
2 kids and a dog
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