engine feels weak. - The 1947 - Present Chevrolet & GMC Truck Message Board Network

orange72350 · 11-25-2003, 04:36 AM

put a different engine in my gmc(see sig) and it feels really weak. i didnt expect a rocket, but it should have some more grunt. when i boot on it 2 kick the tranny down, there is a nast backfire outta the carb. its crazy. timing is 8 btdc. the truck seems like it doesnt wanna rev past about 3500 when i shift it manually. if i try to take it further, the backfire is back. i dunoo what 2 do. the carb seems to be tuned right, but im not sure. it revs fine in neutral, but under load it goes funky. thanx in advance
dale

dinnut · 11-25-2003, 04:46 AM

try the mixture screws, the points and playign with the timing.

**'68OrangeSunshine** · 11-25-2003, 06:54 AM

I had a performance gripe on my 350. Usually on a hot day. When I'd step on it to go uphill, or onto the freeway, it would burble, get weaker and then die. Sometimes after waiting 30 to 60 minutes, it would start right up again. I went all thru the HEI system. No effect. I insulated the fuel line to prevent vapor loc, still not it. It was the fuel pump. I got a new one from NAPA and erased the problem.

shuttermutt · 11-25-2003, 08:59 AM

Sounds like you're running lean. My guess is that the carb isn't happy. Could the the accelerator pump or power piston. Regardless, that's where I'd start looking.

orange72350 · 11-25-2003, 01:20 PM

thanx boys. i will start with the carb later today when i get off school, see how happy she really is. or maybe just go get a new edelbrock 600. this poor quadrajet is about finished. well have 2 see what i can do with this thing till then
thanx
dale

tom hand · 11-25-2003, 02:06 PM

If you are still running points, dwell would be my first suspect...and if you run premeium gas you can run more than 8 degrees timing

orange72350 · 11-25-2003, 02:06 PM

what is dwell?

tom hand · 11-25-2003, 02:29 PM

Dwell is the gap setting on the points. You set it thru the little metal window on the distribitor cap with an allen wrench. You need a dwell meter to set it correcty but if turn it clockwise while running till you get a slight miss, then turn it back one half turn it will be close enough

orange72350 · 11-25-2003, 02:30 PM

my bad. ive got hei.

dropped_71chevy · 11-25-2003, 05:43 PM

There's no reason to go buy a new carb, you can get a rebuild kit and a float for under $30. It takes time and patience but you can rebuild your own carb. I rebuilt mine over a year and a half ago and it still works great. I'm a high school student by the way. You don't have to be 30 years old to do it. Just make sure you remember where you get things from and put em back in the right place.

TT

11-25-2003, 04:36 AM	#1
orange72350 Registered User Join Date: Jan 2003 Location: Cold, Snowy High Level, Alberta Canada Eh Posts: 394	engine feels weak. put a different engine in my gmc(see sig) and it feels really weak. i didnt expect a rocket, but it should have some more grunt. when i boot on it 2 kick the tranny down, there is a nast backfire outta the carb. its crazy. timing is 8 btdc. the truck seems like it doesnt wanna rev past about 3500 when i shift it manually. if i try to take it further, the backfire is back. i dunoo what 2 do. the carb seems to be tuned right, but im not sure. it revs fine in neutral, but under load it goes funky. thanx in advance dale __________________ 2003 yamaha raptor. Stock, but it still hauls!!!! 2000 skiddo mxz 700. Camoplast 1.5 inch track, jaws twin pipes, b+b can, custom built and weighted clutch, wiseco piston, high comp heads. its very fast. wow. 72 c-10 longbox. Bright Orange. Brand new 350, rv cam, performer intake, qjet, headers, 2 1/2 inch exhaust into hooker areo chamber mufflers. Body work coming soon. "dont let yer mind wander, its to little to go places by itself." "Forget the herse, cause i'll never die"-ACDC Back In Black "If It's To Loud, Yer Just Too Old" "I Love Anything Fast Enough To Do Something Stupid In" "Instant idiot, just add beer!!""

11-25-2003, 04:46 AM	#2
dinnut Registered User Join Date: Apr 2003 Location: missouri city, tx Posts: 4,486	try the mixture screws, the points and playign with the timing. __________________ 70 longbed 496/th400/Ford 9"

11-25-2003, 08:59 AM	#4
shuttermutt Don't say "Oops!", Doctor Join Date: Nov 2003 Location: Houston, TX Posts: 677	Sounds like you're running lean. My guess is that the carb isn't happy. Could the the accelerator pump or power piston. Regardless, that's where I'd start looking. __________________ 'Mutt 1968 CST LWB: R.I.P. 1967 Chevelle: TPI 454 beast 1967 C10 SWB: Claimed when Bumpster didn't put it on his list

11-25-2003, 01:20 PM	#5
orange72350 Registered User Join Date: Jan 2003 Location: Cold, Snowy High Level, Alberta Canada Eh Posts: 394	thanx boys. i will start with the carb later today when i get off school, see how happy she really is. or maybe just go get a new edelbrock 600. this poor quadrajet is about finished. well have 2 see what i can do with this thing till then thanx dale __________________ 2003 yamaha raptor. Stock, but it still hauls!!!! 2000 skiddo mxz 700. Camoplast 1.5 inch track, jaws twin pipes, b+b can, custom built and weighted clutch, wiseco piston, high comp heads. its very fast. wow. 72 c-10 longbox. Bright Orange. Brand new 350, rv cam, performer intake, qjet, headers, 2 1/2 inch exhaust into hooker areo chamber mufflers. Body work coming soon. "dont let yer mind wander, its to little to go places by itself." "Forget the herse, cause i'll never die"-ACDC Back In Black "If It's To Loud, Yer Just Too Old" "I Love Anything Fast Enough To Do Something Stupid In" "Instant idiot, just add beer!!""

11-25-2003, 02:06 PM	#6
tom hand CCRider Join Date: Feb 2000 Location: Olive Branch,MS,USA Posts: 2,232	If you are still running points, dwell would be my first suspect...and if you run premeium gas you can run more than 8 degrees timing __________________ 72 GMC Sierra SWB almost finished---- 84 Softail Olive Branch MS

11-25-2003, 06:54 AM	#3
'68OrangeSunshine Senior Member Join Date: Feb 2002 Location: Tucson, AZ USA Posts: 7,504	I had a performance gripe on my 350. Usually on a hot day. When I'd step on it to go uphill, or onto the freeway, it would burble, get weaker and then die. Sometimes after waiting 30 to 60 minutes, it would start right up again. I went all thru the HEI system. No effect. I insulated the fuel line to prevent vapor loc, still not it. It was the fuel pump. I got a new one from NAPA and erased the problem.

11-25-2003, 02:06 PM	#7
orange72350 Registered User Join Date: Jan 2003 Location: Cold, Snowy High Level, Alberta Canada Eh Posts: 394	what is dwell? __________________ 2003 yamaha raptor. Stock, but it still hauls!!!! 2000 skiddo mxz 700. Camoplast 1.5 inch track, jaws twin pipes, b+b can, custom built and weighted clutch, wiseco piston, high comp heads. its very fast. wow. 72 c-10 longbox. Bright Orange. Brand new 350, rv cam, performer intake, qjet, headers, 2 1/2 inch exhaust into hooker areo chamber mufflers. Body work coming soon. "dont let yer mind wander, its to little to go places by itself." "Forget the herse, cause i'll never die"-ACDC Back In Black "If It's To Loud, Yer Just Too Old" "I Love Anything Fast Enough To Do Something Stupid In" "Instant idiot, just add beer!!""

11-25-2003, 02:29 PM	#8
tom hand CCRider Join Date: Feb 2000 Location: Olive Branch,MS,USA Posts: 2,232	Dwell is the gap setting on the points. You set it thru the little metal window on the distribitor cap with an allen wrench. You need a dwell meter to set it correcty but if turn it clockwise while running till you get a slight miss, then turn it back one half turn it will be close enough __________________ 72 GMC Sierra SWB almost finished---- 84 Softail Olive Branch MS

11-25-2003, 02:30 PM	#9
orange72350 Registered User Join Date: Jan 2003 Location: Cold, Snowy High Level, Alberta Canada Eh Posts: 394	my bad. ive got hei. __________________ 2003 yamaha raptor. Stock, but it still hauls!!!! 2000 skiddo mxz 700. Camoplast 1.5 inch track, jaws twin pipes, b+b can, custom built and weighted clutch, wiseco piston, high comp heads. its very fast. wow. 72 c-10 longbox. Bright Orange. Brand new 350, rv cam, performer intake, qjet, headers, 2 1/2 inch exhaust into hooker areo chamber mufflers. Body work coming soon. "dont let yer mind wander, its to little to go places by itself." "Forget the herse, cause i'll never die"-ACDC Back In Black "If It's To Loud, Yer Just Too Old" "I Love Anything Fast Enough To Do Something Stupid In" "Instant idiot, just add beer!!""

11-25-2003, 05:43 PM	#10
dropped_71chevy Registered User Join Date: Sep 2002 Location: Northern Colorado Posts: 198	There's no reason to go buy a new carb, you can get a rebuild kit and a float for under $30. It takes time and patience but you can rebuild your own carb. I rebuilt mine over a year and a half ago and it still works great. I'm a high school student by the way. You don't have to be 30 years old to do it. Just make sure you remember where you get things from and put em back in the right place. TT



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