Emissions Controls on a 76 305 - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Kenneth · 09-17-2003, 12:16 PM

So I'm slowly taking apart my 1976 Chevy 305 (my first time, so I'm trying to understand everything, and my shop manuals are very helpful). I'm basically about to pull out the engine, but I was getting curious about all the emission controls. Do I need to reinstall them? The PCV seems pretty straight forward, but the EGR has got a whole slew of hoses and I'm not sure what it does or how well it works. I'm not too impressed with this year of car but I thought I'd play around with it.
any other emission controls worth removing?

79BIG10 · 09-17-2003, 01:25 PM

Here in Texas anything over 25 years old is exempt from emissions testing. I'm free now (since it was built in 78) and have all my emissons off. If you want to keep stuff on there you can but not necessary for your truck.

Kenneth · 09-17-2003, 04:05 PM

So I guess that's my point. If you want to remove the emissions stuff is it as easy as removing hoses and just plugging holes?
My service manual and the 1976 supplement don't really cover the what if's very well (as in what if you remove the EGR stuff, etc.).
thanks for the help.

79BIG10 · 09-17-2003, 06:30 PM

Sorry I missed that

Yes that's pretty much all you have to do. I have only 5 vacuum lines on my truck now. One to PCV from carb, from carb to HEI advance, to brake booster from behind carb, and last two off a T behind the carb going to the heater controls and to the tranny. All the others have been removed and plugged off. On a qudrajet you will have alot of ports plugged off. On the EGR and hot air return (?) ports on the intake you can get some block off plates for them. They came with my engine when I bought it. Some guys may need that stuff on the board so once you have them off post on the parts board.

*mike reeh* · 09-17-2003, 09:11 PM

i thought 77 was the first year for the 305?

mike

Kenneth · 09-17-2003, 09:44 PM

hhmm, that's an interesting point. I bought the car used and just took the guy's word for it. I never verified that it was indeed a 76. Although, I'll confess it's an el camino, which might make a difference. ??? I'll have to look into the VIN number stuff and see if it is 76.
But the 76 supplement service manual I have does talk about 305 V8 models.

Kenneth · 09-17-2003, 09:55 PM

Okay, I'll have to look under the hood and compare the hoses you mentioned. I do remember the carb to PCV, carb to brake booster, and the T on the back of the carb, which incidentally one of the lines on the T was blocked with a bolt. I'm not sure about the carb to HEI advance, that's over my head.

thanks again.

**swervin ervin** · 09-17-2003, 10:13 PM

76 was the first year for the 305, at least in our trucks. I have no idea is this is the first year for the 305 in any vehicle. I'm thinking it was. A El Camino should be the same as our trucks.

Oh, on a 76 pickup, the VIN for a 305 2 barrel was Q.

79BIG10 · 09-17-2003, 11:12 PM

Quote:

Originally posted by Kenneth
I'm not sure about the carb to HEI advance, that's over my head.
thanks again.

This is the hose that runs back to the HEI model distributor itself that connects to the circular round connection on the passenger side of the distributor. This tells the distributor to retard or advance your firing to the engine.

jimfulco · 09-18-2003, 12:18 AM

You will need to recalibrate your carburetor if you remove the EGR. Removal without recalibration will cause pinging (detonation) under part-throttle acceleration. When you remove the exhaust gas from the intake charge, its volume is replaced by air, resulting in a lean mixture which will detonate. The EGR is not active at full throttle, so it shouldn't make a difference in power.

Kenneth · 09-18-2003, 01:01 PM

okay, my VIN number starts 1D80Q6R... etc. so yes there is a Q in it, but I'm not sure if it's what you're refering to. Did you mean the first letter?

Great, I understand the HEI vacuum line. Okay, all that makes sense. I'll just have to find the stuff to block off the vacuum lines. Of course, I'm not doing any welding so I'll trust I can still do it.

Since I'm in the process of rebuilding the carb. It will of course be recalibrated.

Thanks for all the help!!! You guys are awesome!

**swervin ervin** · 09-18-2003, 03:35 PM

I don't know off hand the VIN order on El Camino's. I'm saying on a 73-80 truck the third letter would Q for a 305 2 barrel.

KIILew · 09-18-2003, 09:38 PM

Kenneth:

Your VIN should break down as follows...

Interpreting your VIN characters from left to right yield the following:

1=Chevrolet Division
D=El Camino Classic (as opposed to the base El Camino designation of "C")
80=designation for the El Camino pickup body style
Q=305 engine, as mentioned by Mike
6=1976 model year
R=manufactured at the Arlington Texas assembly plant

Incidentally, the 305 2bbl V8 was introduced for the '76 model year, but only in the Nova, Camaro, and Chevelle (Malibu and El Camino) lines.

The 1976 305 was originally scheduled to replace the LF5 350 2bbl engine option heretofore offered in the C10/C1500 pickup and G10/1500 van/Sportvan truck lines, too. That fact is even mentioned in the '76 New Product Information guide published by Chevrolet's Product Assurance Department. However, various administrative issues and certifications delayed the 305's introduction into the C and G series, so the 350 2bbl was granted one more year of survival until the start of the '77 model year. At that point, the 305 joined the C/K and G light truck line "for real". Accordingly, the C/K pickup dealer brochure introduced the "LG9" 305 2bbl as "new for 1977".

Just more trivia...

Ken Lewis

09-17-2003, 12:16 PM	#1
Kenneth Registered User Join Date: Jul 2003 Location: Austin, Texas Posts: 53	Emissions Controls on a 76 305 So I'm slowly taking apart my 1976 Chevy 305 (my first time, so I'm trying to understand everything, and my shop manuals are very helpful). I'm basically about to pull out the engine, but I was getting curious about all the emission controls. Do I need to reinstall them? The PCV seems pretty straight forward, but the EGR has got a whole slew of hoses and I'm not sure what it does or how well it works. I'm not too impressed with this year of car but I thought I'd play around with it. any other emission controls worth removing?

09-17-2003, 01:25 PM	#2
79BIG10 I'm back with 2nd truck! Join Date: Feb 2002 Location: Texas Posts: 3,775	Here in Texas anything over 25 years old is exempt from emissions testing. I'm free now (since it was built in 78) and have all my emissons off. If you want to keep stuff on there you can but not necessary for your truck. __________________ 1979 Chevrolet Bonanza Big10 "Tootsie Roll" 1985 Chevrolet Silverado (wife's) Member of the Southern Bowties Club "Don't underestimate how sexy a fat man who drinks to excess can be." Homer Simpson

09-17-2003, 06:30 PM	#4
79BIG10 I'm back with 2nd truck! Join Date: Feb 2002 Location: Texas Posts: 3,775	Sorry I missed that Yes that's pretty much all you have to do. I have only 5 vacuum lines on my truck now. One to PCV from carb, from carb to HEI advance, to brake booster from behind carb, and last two off a T behind the carb going to the heater controls and to the tranny. All the others have been removed and plugged off. On a qudrajet you will have alot of ports plugged off. On the EGR and hot air return (?) ports on the intake you can get some block off plates for them. They came with my engine when I bought it. Some guys may need that stuff on the board so once you have them off post on the parts board. __________________ 1979 Chevrolet Bonanza Big10 "Tootsie Roll" 1985 Chevrolet Silverado (wife's) Member of the Southern Bowties Club "Don't underestimate how sexy a fat man who drinks to excess can be." Homer Simpson

09-17-2003, 10:13 PM	#8
swervin ervin You get what you pay for Join Date: Dec 1999 Location: Cherryville, NC Posts: 4,798	76 was the first year for the 305, at least in our trucks. I have no idea is this is the first year for the 305 in any vehicle. I'm thinking it was. A El Camino should be the same as our trucks. Oh, on a 76 pickup, the VIN for a 305 2 barrel was Q. __________________ Mike 1985 Chevy C-10 Last edited by swervin ervin; 09-17-2003 at 10:15 PM.

09-17-2003, 04:05 PM	#3
Kenneth Registered User Join Date: Jul 2003 Location: Austin, Texas Posts: 53	So I guess that's my point. If you want to remove the emissions stuff is it as easy as removing hoses and just plugging holes? My service manual and the 1976 supplement don't really cover the what if's very well (as in what if you remove the EGR stuff, etc.). thanks for the help.

09-17-2003, 09:11 PM	#5
mike reeh 5 day ban, learn to behave. Join Date: Nov 2002 Location: san diego, ca Posts: 684	i thought 77 was the first year for the 305? mike

09-17-2003, 09:44 PM	#6
Kenneth Registered User Join Date: Jul 2003 Location: Austin, Texas Posts: 53	hhmm, that's an interesting point. I bought the car used and just took the guy's word for it. I never verified that it was indeed a 76. Although, I'll confess it's an el camino, which might make a difference. ??? I'll have to look into the VIN number stuff and see if it is 76. But the 76 supplement service manual I have does talk about 305 V8 models.

09-17-2003, 09:55 PM	#7
Kenneth Registered User Join Date: Jul 2003 Location: Austin, Texas Posts: 53	Okay, I'll have to look under the hood and compare the hoses you mentioned. I do remember the carb to PCV, carb to brake booster, and the T on the back of the carb, which incidentally one of the lines on the T was blocked with a bolt. I'm not sure about the carb to HEI advance, that's over my head. thanks again.

09-18-2003, 12:18 AM	#10
jimfulco Registered User Join Date: May 2003 Location: Shreveport LA Posts: 3,170	You will need to recalibrate your carburetor if you remove the EGR. Removal without recalibration will cause pinging (detonation) under part-throttle acceleration. When you remove the exhaust gas from the intake charge, its volume is replaced by air, resulting in a lean mixture which will detonate. The EGR is not active at full throttle, so it shouldn't make a difference in power.

09-18-2003, 01:01 PM	#11
Kenneth Registered User Join Date: Jul 2003 Location: Austin, Texas Posts: 53	okay, my VIN number starts 1D80Q6R... etc. so yes there is a Q in it, but I'm not sure if it's what you're refering to. Did you mean the first letter? Great, I understand the HEI vacuum line. Okay, all that makes sense. I'll just have to find the stuff to block off the vacuum lines. Of course, I'm not doing any welding so I'll trust I can still do it. Since I'm in the process of rebuilding the carb. It will of course be recalibrated. Thanks for all the help!!! You guys are awesome!

09-18-2003, 03:35 PM	#12
swervin ervin You get what you pay for Join Date: Dec 1999 Location: Cherryville, NC Posts: 4,798	I don't know off hand the VIN order on El Camino's. I'm saying on a 73-80 truck the third letter would Q for a 305 2 barrel.

09-18-2003, 09:38 PM	#13
KIILew Active Member Join Date: Mar 2002 Location: Prosser, WA 99350 Posts: 147	Kenneth: Your VIN should break down as follows... Interpreting your VIN characters from left to right yield the following: 1=Chevrolet Division D=El Camino Classic (as opposed to the base El Camino designation of "C") 80=designation for the El Camino pickup body style Q=305 engine, as mentioned by Mike 6=1976 model year R=manufactured at the Arlington Texas assembly plant Incidentally, the 305 2bbl V8 was introduced for the '76 model year, but only in the Nova, Camaro, and Chevelle (Malibu and El Camino) lines. The 1976 305 was originally scheduled to replace the LF5 350 2bbl engine option heretofore offered in the C10/C1500 pickup and G10/1500 van/Sportvan truck lines, too. That fact is even mentioned in the '76 New Product Information guide published by Chevrolet's Product Assurance Department. However, various administrative issues and certifications delayed the 305's introduction into the C and G series, so the 350 2bbl was granted one more year of survival until the start of the '77 model year. At that point, the 305 joined the C/K and G light truck line "for real". Accordingly, the C/K pickup dealer brochure introduced the "LG9" 305 2bbl as "new for 1977". Just more trivia... Ken Lewis



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