First post! Lets start with carbs lol - The 1947 - Present Chevrolet & GMC Truck Message Board Network

eosrider · 02-14-2010, 11:47 PM

Hi guys! i'm Laurence.

Just made a purchase of a 67 GMC long bed

shes got a 350 with a edel 1405 under the hood.

wanting to start off by making sure my mixture is good as can be for balanced power and fuel econ.

anyone?

1970rs · 02-15-2010, 12:23 AM

First, you need to adjust your idle mixture screws. Make sure the engine is warm and in nuetral. Hook up a vacuum gauge to it. Now adjust each screw an 1/8 turn at a time to obtain the highest vacuum reading. Make sure you keep the screws even.

As for jetting it is best to read your plugs to determine if you need to change the jets or not.

**LEEVON** · 02-15-2010, 09:05 PM

Timing first! Initial and total timing need to be set along with a proper curve if you can. Make sure there are no vacuum leaks by spraying around the carb base with some carb cleaner while it is running.

Then what he said plus you should back off 1/8 turn from the highest vacuum reading. After that you can play with the metering rods and jets but you probably won't need to.

Sinister · 02-15-2010, 09:21 PM

I would add, lightly screw in the mixture screws until they seat. Unscrew them out 1 1/2 turns. Then proceed with setting the exact mixture. You'll probably end up turning the screws in some to get highest vacuum.

**70cst** · 02-16-2010, 01:06 AM

By the way:

and

from Ohio. Glad to have you as part of our internet truck family.

eosrider · 02-16-2010, 05:50 PM

Quote:

Originally Posted by Sinister

I would add, lightly screw in the mixture screws until they seat. Unscrew them out 1 1/2 turns. Then proceed with setting the exact mixture. You'll probably end up turning the screws in some to get highest vacuum.

when you say until they seat. do you meen screw them all the way down then back them out?

Sinister · 02-16-2010, 06:18 PM

Quote:

Originally Posted by eosrider

when you say until they seat. do you meen screw them all the way down then back them out?

Yes, screw them in all the way, but easy does it, lightly seat them. Then back them out 1 1/2 turns. That way you'll know there adjusted the same on each side.

eosrider · 02-16-2010, 07:47 PM

houston we have a problem

my 350 sounds like a diesel engine.

dwell tach says its idling 500-600 rpm

timing light is now broken (just as i need to use it!!! lol )

oil pressure gauge is not working (was yesterday)

oil is at full line.

im sure this is just a coincidence.

Sinister · 02-16-2010, 08:03 PM

Pickup might have fallen off the oil pump. Weird for an oil pressure gauge to quit like that.

eosrider · 02-18-2010, 12:29 AM

Quote:

Originally Posted by Sinister

Pickup might have fallen off the oil pump. Weird for an oil pressure gauge to quit like that.

is there another way besides taking off the pan to find out? im doubting it.

it sounds like my crank and pistons are not knocking but my valves are chattering like a mofo.

Sinister · 02-18-2010, 09:00 AM

You'll have to drop the pan to check. If your valves are making a bunch of noise, it sounds like no oil pressure. I wouldn't run the motor until you figure out what's up with it.

02-14-2010, 11:47 PM	#1
eosrider Registered User Join Date: Feb 2010 Location: Santa Rosa, California Posts: 7	First post! Lets start with carbs lol Hi guys! i'm Laurence. Just made a purchase of a 67 GMC long bed shes got a 350 with a edel 1405 under the hood. wanting to start off by making sure my mixture is good as can be for balanced power and fuel econ. anyone?

02-15-2010, 12:23 AM	#2
1970rs Registered User Join Date: Sep 2009 Location: Glasgow,Ky Posts: 24	Re: First post! Lets start with carbs lol First, you need to adjust your idle mixture screws. Make sure the engine is warm and in nuetral. Hook up a vacuum gauge to it. Now adjust each screw an 1/8 turn at a time to obtain the highest vacuum reading. Make sure you keep the screws even. As for jetting it is best to read your plugs to determine if you need to change the jets or not.

02-15-2010, 09:05 PM	#3
LEEVON Registered User Join Date: Jul 2006 Location: Ozark, MO Posts: 4,887	Re: First post! Lets start with carbs lol Timing first! Initial and total timing need to be set along with a proper curve if you can. Make sure there are no vacuum leaks by spraying around the carb base with some carb cleaner while it is running. Then what he said plus you should back off 1/8 turn from the highest vacuum reading. After that you can play with the metering rods and jets but you probably won't need to. __________________ '20 Silverado Trail Boss ~ '17 Tahoe ~ '79 K15 Sierra Grande ~ '76 Blazer 2wd ~ '71 Cheyenne swb ~ '55 Pontiac Safari ~'50 3100 bagged ~ '80 Wife ~ Late model kids Last edited by LEEVON; 02-15-2010 at 09:05 PM.

02-15-2010, 09:21 PM	#4
Sinister Between Trucks... Join Date: Mar 2002 Location: Los Angeles, CA. Posts: 3,830	Re: First post! Lets start with carbs lol I would add, lightly screw in the mixture screws until they seat. Unscrew them out 1 1/2 turns. Then proceed with setting the exact mixture. You'll probably end up turning the screws in some to get highest vacuum. __________________ Beat it to fit, Paint it to match...

02-16-2010, 01:06 AM	#5
70cst Senior Member Join Date: Feb 2001 Location: New Madison, Ohio Posts: 21,365	Re: First post! Lets start with carbs lol By the way: and from Ohio. Glad to have you as part of our internet truck family. __________________ A husband can be right...or...A husband can be happy. 67-72 Chevy and GMC Trucks...The Classic Truck for the Classic Folk. 1970 CST Two tone green, 402BB, 400 Automatic, Tach, Buckets, AC, AM-FM, Tilt, GM CB, GM 8 Tract, LWB, etc JOHN 17:3...The better side of "LIFE" Remember: Everyday is a good day...Some are just gooder!

02-16-2010, 07:47 PM	#8
eosrider Registered User Join Date: Feb 2010 Location: Santa Rosa, California Posts: 7	Re: First post! Lets start with carbs lol houston we have a problem my 350 sounds like a diesel engine. dwell tach says its idling 500-600 rpm timing light is now broken (just as i need to use it!!! lol ) oil pressure gauge is not working (was yesterday) oil is at full line. im sure this is just a coincidence.

02-16-2010, 08:03 PM	#9
Sinister Between Trucks... Join Date: Mar 2002 Location: Los Angeles, CA. Posts: 3,830	Re: First post! Lets start with carbs lol Pickup might have fallen off the oil pump. Weird for an oil pressure gauge to quit like that. __________________ Beat it to fit, Paint it to match...

02-18-2010, 09:00 AM	#11
Sinister Between Trucks... Join Date: Mar 2002 Location: Los Angeles, CA. Posts: 3,830	Re: First post! Lets start with carbs lol You'll have to drop the pan to check. If your valves are making a bunch of noise, it sounds like no oil pressure. I wouldn't run the motor until you figure out what's up with it. __________________ Beat it to fit, Paint it to match... Last edited by Sinister; 02-18-2010 at 09:01 AM.



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