Is my Carb too big? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

chargedstang89 · 07-01-2003, 05:43 PM

I have a stock crate 350 from GM that I put in my truck. It's an '85 gmc 1/2 ton 4x4. It has 33" tires, a 4" lift, 700R4 Tranny, and 3.08 gears, which were stock. The stock carb on it was trash. I got an Edelbrock model 1904, which is 795cfm. I thought that was way too big, but a couple of peple have told me that it isn't. My truck has little umpfh behind it when I'm driving down the highway or going up hills. I have to keep my foot in the throttle so much that it's ridiculous. Also, towing is horrible, as the truck seems to have no muscle. I know that with tall tires like that and 3.08 gears that I'm really down in the 2.xx range, but could my carb have something to do with that too. How about my horrible gas mileage, like only 100 or 110 miles per tank
(16 gallon) on the highway. Would I be better suited with a 650cfm carb? I also thought about putting a cam in the truck to try and help out, but I don't want to void the 3 year/36,000 mile warranty I have on the crate motor. Any advice? I'm a carb newbie...so, all is welcome.

J

sbc350gearhead · 07-01-2003, 06:02 PM

The only real problem with a big carb is throttle response (and to a lesser extent gas mileage, although not much if it is tuned right). That carb is a little too big for your application. You would be better off with a 600-650 carb.

**swervin ervin** · 07-01-2003, 06:10 PM

I disagree.

The 1904 is designed for 305's through 454's. It's a vacuum operated secondary carb, so your engine only takes what it needs, just like any ole Q-jet always has.

I have a 1904 on my truck and it works great.

Remember, it's a Q-jet. It's the same as any Q-jet ever was. Q-jets came on 4.3 V6's you know?

PHOENIX · 07-01-2003, 06:20 PM

I also have a 1904 qjet on my stock 350 w/ no problems.

Edelbrock does list the 1904 as a direct replacement that meets emissions requirements.

sbc350gearhead · 07-01-2003, 08:30 PM

honestly......I was under the assumption that the 1904 was some type of AFB style carb as most other edelbrocks. Sorry.

Mike76251 · 07-01-2003, 08:37 PM

Get a Holley 650.....this is better suited to a 350 than that "universal" carb you now have.
It will support 6000rpm.

Grim Reaper · 07-02-2003, 11:06 AM

Quote:

Originally posted by chargedstang89
I have a stock crate 350 from GM that I put in my truck. It's an '85 gmc 1/2 ton 4x4. It has 33" tires, a 4" lift, 700R4 Tranny, and 3.08 gears, which were stock. The stock carb on it was trash. I got an Edelbrock model 1904, which is 795cfm. I thought that was way too big, but a couple of peple have told me that it isn't. My truck has little umpfh behind it when I'm driving down the highway or going up hills. I have to keep my foot in the throttle so much that it's ridiculous. Also, towing is horrible, as the truck seems to have no muscle. I know that with tall tires like that and 3.08 gears that I'm really down in the 2.xx range, but could my carb have something to do with that too. How about my horrible gas mileage, like only 100 or 110 miles per tank
(16 gallon) on the highway. Would I be better suited with a 650cfm carb? I also thought about putting a cam in the truck to try and help out, but I don't want to void the 3 year/36,000 mile warranty I have on the crate motor. Any advice? I'm a carb newbie...so, all is welcome.

J

Unless that carb sucked up some crud and has a blocked port the problem is somewhere else.

I bought a stock crate and the harmonic ballanced and timming mark were mismatched. The ballancer needed the timing mark that you veiw between the water pump nad the block and the timing tabe was to the driverside of the water pump. That's about 20 Degrees retarted. It will run like that but like crap.
Mess with your timing and I bet you find the problem.

Your truck may also have ESC spark control and from what I have read the knock sensor for a 305 is different then a 350 so that could cause you problems.

r0lf- · 07-02-2003, 01:16 PM

Before you start messing with your carb. Id get some 3.73's for those tires. They are bottlenecking your power tons.

07-01-2003, 05:43 PM	#1
chargedstang89 Registered User Join Date: Oct 2002 Posts: 90	Is my Carb too big? I have a stock crate 350 from GM that I put in my truck. It's an '85 gmc 1/2 ton 4x4. It has 33" tires, a 4" lift, 700R4 Tranny, and 3.08 gears, which were stock. The stock carb on it was trash. I got an Edelbrock model 1904, which is 795cfm. I thought that was way too big, but a couple of peple have told me that it isn't. My truck has little umpfh behind it when I'm driving down the highway or going up hills. I have to keep my foot in the throttle so much that it's ridiculous. Also, towing is horrible, as the truck seems to have no muscle. I know that with tall tires like that and 3.08 gears that I'm really down in the 2.xx range, but could my carb have something to do with that too. How about my horrible gas mileage, like only 100 or 110 miles per tank (16 gallon) on the highway. Would I be better suited with a 650cfm carb? I also thought about putting a cam in the truck to try and help out, but I don't want to void the 3 year/36,000 mile warranty I have on the crate motor. Any advice? I'm a carb newbie...so, all is welcome. J

07-01-2003, 06:10 PM	#3
swervin ervin You get what you pay for Join Date: Dec 1999 Location: Cherryville, NC Posts: 4,798	I disagree. The 1904 is designed for 305's through 454's. It's a vacuum operated secondary carb, so your engine only takes what it needs, just like any ole Q-jet always has. I have a 1904 on my truck and it works great. Remember, it's a Q-jet. It's the same as any Q-jet ever was. Q-jets came on 4.3 V6's you know? __________________ Mike 1985 Chevy C-10

07-01-2003, 06:20 PM	#4
PHOENIX Registered User Join Date: Oct 2002 Location: Phoenix, Arizona Posts: 4,703	I also have a 1904 qjet on my stock 350 w/ no problems. Edelbrock does list the 1904 as a direct replacement that meets emissions requirements. __________________ * AVOID: LOPER'S PERMORANCE / LOPERSPEED.COM OF PHOENIX, AZ & COTTMAN TRANSMISSION *

07-02-2003, 01:16 PM	#8
r0lf- Hotwheels? Join Date: Dec 2002 Location: Pleasant Hill, CA Posts: 1,145	Before you start messing with your carb. Id get some 3.73's for those tires. They are bottlenecking your power tons. __________________ 1978 Money Pit - CUSTOM DELUXE!!!!

07-01-2003, 06:02 PM	#2
sbc350gearhead Registered User Join Date: Mar 2003 Location: Columbus Ohio Posts: 1,413	The only real problem with a big carb is throttle response (and to a lesser extent gas mileage, although not much if it is tuned right). That carb is a little too big for your application. You would be better off with a 600-650 carb.

07-01-2003, 08:30 PM	#5
sbc350gearhead Registered User Join Date: Mar 2003 Location: Columbus Ohio Posts: 1,413	honestly......I was under the assumption that the 1904 was some type of AFB style carb as most other edelbrocks. Sorry.

07-01-2003, 08:37 PM	#6
Mike76251 Senior Member Join Date: Mar 2003 Posts: 2,499	Get a Holley 650.....this is better suited to a 350 than that "universal" carb you now have. It will support 6000rpm.



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