88-93 chevy truck owners

[rjrhoades]

Originally Posted by J-Ri

Oh, and I forgot... the trucks that have the heat riser go back well before 88, I know 86's have it, and I think it goes back to the earliest models.

Yes, it goes back into the 70's (god, am I that old?) at least. These also complement the work of the heat riser valve in the exhaust manifold (I think that is what it is called) that helps to divert warm exhaust air through passages in the block to aid in a quicker warm-up. The heat riser valves are spring loaded. The springs operate with exhaust tube temperature and open as the exhaust pipe warms. As the metal ages, they can "stick" with age and the bolts that hold the manifold to the exhaust tend to loosen, especially on replacement exhaust systems. I always had to periodically retighten these bolts when I started hearing an exhaust leak (which can sound like its coming from the exhaust header at the block).

[roadrunner_70]

The ones used back in the late 80's and early 90's, and possibly even now are a "wax pellet" type. No vacuum hoses like the older versions of the eighties. As the wax in the small cylinder heats up, it expands, and moves the lever forward, closing off the heated air from the stovepipe, and allowing the cooler air from the fenderwell. I checked mine out the other day and found that it worked fine, except the valve had jammed so it was stuck on hot air intake. Most of the time, it's the sensor that karks it, and won't move no matter what the temperature.

[Xrrider280]

what would happen if I were to take this stovepipe off? would it hurt my engine or just take longer to warm up?

[rjrhoades]

Originally Posted by Xrrider280

what would happen if I were to take this stovepipe off? would it hurt my engine or just take longer to warm up?

When it is not functioning (whether from mechanical malfunction or removal) it can be difficult to keep the motor running at a cold start before warming up (pumping the accelerator syndrom). So while it probably won't directly cause mechanical destruction, it can cause mental destruction and early engine wear from unburned fuel/possible engine backfire from misfiring.

[roadrunner_70]

Remember the old days? You used to have to wait five minutes or more for your truck to warm up? It would run rough if you attempted to just start it up and drive away. The technology then didn't allow for immediate driveability. Sure, they had stovepipes since the sixties, and heat riser valves, but carburetors used anything from manual chokes to crude bimetal springs that slowly moved them off. Modern fuel injection systems are much better at metering fuel, especially when coupled with sensors that give feedback. Defeat any one of those and the others suffer. Think about it, if you take away the warm air during warm up, the fuel takes longer to vaporize, therefore you'll need more fuel to reach the right ratio. This richer mixture may not completely burn, and passes those HC down the line to your oxygen sensor, and your catalytic convertor. Neither one of them are receptive to excess amounts of anything. Since your oxygen sensor doesn't even come into play until around 600 degrees, when it starts to register Oxygen in the exhaust, doesn't it make sense to make the conditions as close to ideal as possible until the system goes into closed loop?

[rjrhoades]

Well Said!!!

[TOMMCCONATHY]

The Guys In The Cold Climates Are Right. It Is Best To Fix The Valve Rathar Than To Block It Open. You Might Not Care About The High Emmisions During Warm-up, But On The Other Hand, It Came From The Factory Running Good With That Valve Working. As Vehicles Get Older We Kind Of Expect Them To Not Work As Well As They Did. Keeping All Of The Mechanical Parts Functional Will Help Your Vehicle Running The Best Possible. Sure Advances Have Been Made, After Market Parts Are Available, So Take Advantage Of Any New Info You Can. Just Make Sure If You Up-grade A System, That All Of The Original Functions Are Present In The Upgrade [unless The Original Functions Have Been Prooved To Be Wrong].

[tacoma200]

Originally Posted by big_blue_chevy2006

i dont have a stock air intake nemore but i did notice that i have a k&n air intake assembly. well about that adding 25 horses i REALLY HIGHLY doubt that, my k&n air intake dont even add that, when air intakes say they add up to 15 horses or so that normally means with very big mods otherwise it might add like 3 or 4 horses.

Just wondering about the sound of the K&N or Airaid intakes. I have heard that it adds a great sound to the motor. Is it kind of like the sound of the old 4 barrels when they kicked in? Any input welcome.

[Xrrider280]

Do most aftermarket air systems have a valve for the stovepipe. I was thinking about getting a cold air intake for the summer and was wondering if it would be best to switch back to stock for the winter. I live in the Upper Penninsula of Michigan where it is pretty cold in the winter