Do I need carb? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Bilgewiper · 02-11-2003, 07:30 PM

1971 350 stock Quadrabog. I can move the primary throttle shaft up and down about 1/32 with a resulting rpm change. I can't get motor to idle smoothly. Spraying carb cleaner on secondary pass. side butterfly shaft makes a jump in rpm but that loose primary only makes a small change in rpm. Would buying a Jet performance stage II from Summit make sence? Just want a bolt on. Also another question........if I disable/disconnect the vapor recovery system do I then need to put vented gas caps on? Oh yes, while I am at it........which is the best port on a Quadrabog to have the vac. advance hooked up too. Sorry about all the questions but this is all fresh in my mind considering I was under the hood about 2 minutes ago. Thanks again.

Ethan

bigjimzlll · 02-11-2003, 09:25 PM

fairly stock engine..use the ported vacuum port(the highest one) you cant do much better than those jet carbs...but for a stocker, look at your local parts house for a trade in rebuild

68 Suburban · 02-11-2003, 10:02 PM

What are the differences between the vacum ports?

bigjimzlll · 02-11-2003, 10:04 PM

manifold and timed vacuum...one has vacuum at idle and decreases as the revs come up(manifold) and ported has no vacuum at idle and increases vacuum as the revs come up..

68 Suburban · 02-11-2003, 10:11 PM

Quote:

Originally posted by bigjimzlll
manifold and timed vacuum...one has vacuum at idle and decreases as the revs come up(manifold) and ported has no vacuum at idle and increases vacuum as the revs come up..

Thanks, are they both available on the carb? What would you use the other type of port for?

spinning wheels · 02-11-2003, 10:58 PM

Ethan, instead of ordering a JET carb from Summit. Why don't you call JET directly? They are located in Huntington Beach, Ca. You can find their number in most magazines. They are quite helpful. Good luck.

Bilgewiper · 02-12-2003, 01:36 AM

thanks for the info! I'll check with Jet directly. Any ideas on the vented vs. non vented gas cap when disconecting the vapor recovery system?

02-11-2003, 07:30 PM	#1
Bilgewiper Registered User Join Date: Dec 2002 Location: Citrus Heights Ca. Posts: 186	Do I need carb? 1971 350 stock Quadrabog. I can move the primary throttle shaft up and down about 1/32 with a resulting rpm change. I can't get motor to idle smoothly. Spraying carb cleaner on secondary pass. side butterfly shaft makes a jump in rpm but that loose primary only makes a small change in rpm. Would buying a Jet performance stage II from Summit make sence? Just want a bolt on. Also another question........if I disable/disconnect the vapor recovery system do I then need to put vented gas caps on? Oh yes, while I am at it........which is the best port on a Quadrabog to have the vac. advance hooked up too. Sorry about all the questions but this is all fresh in my mind considering I was under the hood about 2 minutes ago. Thanks again. Ethan __________________ Ethan '71 C-10 LWB Cheyenne 85K miles. "Time spent Boating is NOT deducted from ones lifespan".

02-11-2003, 09:25 PM	#2
bigjimzlll Senior Member Join Date: Dec 2001 Location: Redding,CA...USA Posts: 4,736	fairly stock engine..use the ported vacuum port(the highest one) you cant do much better than those jet carbs...but for a stocker, look at your local parts house for a trade in rebuild __________________ It's called "drag racing" if they called it "tic..tic..WHAM!..BANG! F*&K!!!", they'd have to keep the magazines under the counter with the other men's publications click the clicky to join the site.... http://67-72chevytrucks.com/vboard/payments.php 67 lwb..first hotrod in 25 years..540 best ET is 9.45 @ 141.44 Anderson,CA

02-11-2003, 10:04 PM	#4
bigjimzlll Senior Member Join Date: Dec 2001 Location: Redding,CA...USA Posts: 4,736	manifold and timed vacuum...one has vacuum at idle and decreases as the revs come up(manifold) and ported has no vacuum at idle and increases vacuum as the revs come up.. __________________ It's called "drag racing" if they called it "tic..tic..WHAM!..BANG! F*&K!!!", they'd have to keep the magazines under the counter with the other men's publications click the clicky to join the site.... http://67-72chevytrucks.com/vboard/payments.php 67 lwb..first hotrod in 25 years..540 best ET is 9.45 @ 141.44 Anderson,CA

02-11-2003, 10:58 PM	#6
spinning wheels Registered User Join Date: Sep 2001 Location: Hacienda Heights, California USA Posts: 474	Ethan, instead of ordering a JET carb from Summit. Why don't you call JET directly? They are located in Huntington Beach, Ca. You can find their number in most magazines. They are quite helpful. Good luck. __________________ '72 GMC custom camper 350/350

02-12-2003, 01:36 AM	#7
Bilgewiper Registered User Join Date: Dec 2002 Location: Citrus Heights Ca. Posts: 186	thanks for the info! I'll check with Jet directly. Any ideas on the vented vs. non vented gas cap when disconecting the vapor recovery system? __________________ Ethan '71 C-10 LWB Cheyenne 85K miles. "Time spent Boating is NOT deducted from ones lifespan".

02-11-2003, 10:02 PM	#3
68 Suburban Registered User Join Date: Oct 2000 Location: From Chicago, Live in Phoenix, AZ Posts: 6,802	What are the differences between the vacum ports?



Register or Log In To remove these advertisements.

Register or Log In To remove these advertisements.