Smog Equipment Removal?

[ghostflyer]

My truck ia an 86 GMC 1-Ton dually w/454. For the size of the engine, it seems that it should make a lot more power. Gas mileage also sucks!
I would like to remove the smog equipment, but don't know what else might be affected. It has two smog pumps with tubes going to the exhaust manifolds. I've been told that the manifolds are factory stainless (if that matters). There is also a rat's nest of vacuum lines.
Will the distributor need to be recurved? Also will the carburetor (Quadrajet) need to be recalibrated?

Thanks for any help.

PS: No smog inspection required!

[piecesparts]

Pull the smog pumps, put plugs in the exhaust manifolds, remove 80 percent of the vacuum lines and tie them together in a more orderly fashion behnd the engine. Vacuum to the distributor, the solenoid for the tranny shift, if you need it, and set up for your brakes. Install a HEI dizzy from an older engine, get away from the smoggie carb and go with something that only needs the air through it and no electric wires to it.

My 84 has had this done to it and I am running a 383 stroker engine with a 700 R4 tranny and 3.73 gears. I get around 15 MPG on long haul driving and can do a good drive on the street without a lot of pain. Put on an electric fan a remove the parasitic drag off of the engine and that can add as much as 1 MPG change.

[INSIDIOUS '86]

The pumps take power to drive and that kills engine efficiency pull them off and you will feel a diff. If you re curve the distributor and add a little more timing it will make a good difference too. If you add some headers and pull the cat(s) and a good muffler it will run with as good of mileage as you can get and about as much powers as you can get too without adding to the engine. Only other thing you can do is an electric fan
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[406 Q-ship]

When you say the mileage sucks.......a 1 ton 454 truck are never going to be a gas mileage champ. 12 MPG on the highway would be about normal and 9 to 11 in town (with an easy throttle foot).

[ghostflyer]

Originally Posted by piecesparts

Pull the smog pumps, put plugs in the exhaust manifolds, remove 80 percent of the vacuum lines and tie them together in a more orderly fashion behnd the engine. Vacuum to the distributor, the solenoid for the tranny shift, if you need it, and set up for your brakes. Install a HEI dizzy from an older engine, get away from the smoggie carb and go with something that only needs the air through it and no electric wires to it.

Thanks for all the info. Can you be a little more specific about the distributor and carburetor? I have the Hydro-boost brakes, so no vacuum line there. Is the solenoid for the transmission the kick-down? Right now, that doesn't work. Also, no cats on the truck.

Originally Posted by 406 Q-ship

When you say the mileage sucks.......a 1 ton 454 truck are never going to be a gas mileage champ. 12 MPG on the highway would be about normal and 9 to 11 in town (with an easy throttle foot).

I haul camper or tow a 5th wheel, and get about 8 MPG in those situations. Empty, I only get about 10 MPG.

[INSIDIOUS '86]

The wights in the distributor need to be change to medium wight and the quadra of shoul be stomped into a mud hole in my opinion lol. But actually the rods on q jet should be adjusted and for you to understand the rot-Chester you shoul buy a book on them because you have to be a rocket scientist to get them to run right. But once you do you will love it
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[406 Q-ship]

Originally Posted by ghostflyer

Thanks for all the info. Can you be a little more specific about the distributor and carburetor? I have the Hydro-boost brakes, so no vacuum line there. Is the solenoid for the transmission the kick-down? Right now, that doesn't work. Also, no cats on the truck.




I haul camper or tow a 5th wheel, and get about 8 MPG in those situations. Empty, I only get about 10 MPG.

8 MPG is is about right hauling a camper/5th wheel. The empty mileage might be on the low side. Check to see how loose the throttle shaft in the Q-jet is (never get rid of the Q-jet NOTHING will come close to one for MPG) if it is loose then you will need to get the base plate bushed (this will cause a vacuum leak). GM did set the Fuel a bit rich on heavy trucks to keep them from melting pistons when loaded, so changing the main metering rod to a little leaner. Putting a wide band O2 sensor into the exhaust pipe so you can see what the fuel/air is at and to be able to make educated choices on the metering.

[86454k30]

I have an 86 K30 with the original 454, it had dual smog pumps from the factory. Here is what I know:

Tubular manifolds are stainless steel, the oil fill plugs on NP208 transfer cases fit the smog tube holes in the manifolds.

Remove both smog pumps and remove/cap vacuum lines

The 86 trucks had problems passing emissions that is why they had dual smog pumps and ALL stainless exhaust, they ran way lean.

The timing chain on the 86 454's are also retarded. Put a new double row chain and set it to 0.

The distributor and carb are fine as these trucks DO NOT have computer controlled carbs or distributors since they were 8600GVW.

My 86 has had all this stuff done to it and it runs REALLY good.

Don't expect better than 10mpg TOPS out of these BB trucks.

[86454k30]

Oh...if you decide to put headers on your truck, put me first in line I will buy those factory exhaust manifolds.

[donut]

Clean up the vacuum hoses, most of mine were rotted off. Smog pumps don't make that much of a difference, but it sure does make it easier working on the engine.
When you remove the "spider" from the exhaust, be careful. Mine all galled so the threads were shot. Got headers now as the cheap headers were almost cheaper than 1 replacement manifold. (manifold was 95.00, headers 135.00 iirc)
Check your ignition timing, it can make a big difference. I'm currently @16btdc. When I'm back on the road, I'll look at the curve as per the ignition sticky in the engine section of the forum.

Transmission- You've got a vacuum modulator that controls shifts. More than likely you have a tbh400 trans. Kickdown is electric, 1 wire to the trans. Switch should be down by the accelerator pedal in the cab.

Mine hasn't been on the road long enough to track mileage.

[ghostflyer]

Thanks for all the replies, guys. Now I have my work cut out for myself.

Originally Posted by 86454k30

The timing chain on the 86 454's are also retarded. Put a new double row chain and set it to 0.

I don't understand the retarded timing chain. I've always just lined up the marks, per the manual. Is this engine different to make less pollution?

Originally Posted by donut

Clean up the vacuum hoses, most of mine were rotted off. Smog pumps don't make that much of a difference, but it sure does make it easier working on the engine.
When you remove the "spider" from the exhaust, be careful. Mine all galled so the threads were shot.

Transmission- You've got a vacuum modulator that controls shifts. More than likely you have a tbh400 trans. Kickdown is electric, 1 wire to the trans. Switch should be down by the accelerator pedal in the cab.

I guess the first thing to do is soak the manifold threads with Kroil, then go from there.

The transmission is a TH400. The kick-down has not worked for some time. I've just gotten in the habit of pulling into second gear with the shift lever.

[86454k30]

The factory retarded the timing on the 454's in 86. If you were to install a new timing chain you would be correct in lining the dots that would put the timing at 0. That would help out some power and give you piece of mind if it has never been done. 454's are no clearance motors....if the timing chain breaks, valves touch pistons.

[donut]

86454k30- thanks for that bit of info, I knew about GM doing that, but didn't remember when.

AFAIK, it was an emissions thing. My '86 is not "unleaded only". No cats, larger gas fill nozzle...

ghostflyer-good luck on the Kroil. In my experience, galled is galled. That's why even if I look at stainless, it gets slapped with never-seize.
the 400 has 1 wire down to the case. electric "pass through" the case, and a solenoid inside. It should be visible and accessible when you drop the pan to change the fluid.

[ghostflyer]

I have the air pumps and all related vacuum lines, hoses and valves removed. I was not able to remove the air tube fittings from the manifolds. I have the holes plugged right above the check valves for now.
I had to get a shorter belt to run the alternator, since it also went around one of the air pumps. The other pump did not share it's belt.

I still have a few things that I am not sure about. They are the deceleration valve, the EGR valve, the control module, and the control relay. I don't know if they will have to stay or not.

Thanks for all the replies. You guys have been a big help.

[Cue-Ball]

Originally Posted by ghostflyer

I haul camper or tow a 5th wheel, and get about 8 MPG in those situations. Empty, I only get about 10 MPG.

That's about what I get with my 305! Quit yer complaining!