My Blazer has just recently started sou8nding really strange when i get above 3000 RPM's It almost sounds liek the valves are floating. It's a 2.8l TBI. '87 4x4 Auto. When ever i get to around 3000 RPMs it sounds like there is another engine revving up right beside mine. It's almost a harmonic pitch. My power and gas mileage have gone way down. It just had a tune up about 20,000 miles ago. I drive it pretty hard so you can take that into consideration. Does anyone know of that particular head has a double valve spring??? It sounds like the one of the two has failed and the other one is only good to 3000. That is saying that I am floating valves. Thanks for you help guys.

Later,
Lars

 

have you checked counts on your knock senser?

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-=ICON MOTORSPORTS=-

 

IIRC they are single springs with damper. However I doubt that's your problem.

If it's a traditional clutch fan, check the clutch. It sounds to me like it's seized, so that the fan is full tilt boogie all the time instead of coming uncoupled when not needed. It will make a loud roaring sound and eat up 10 HP or so which should be good for at least 4 or 5 mpg in that vehicle.

It could also be a clogged catalytic converter.

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"So many Mustangs, so little time..."

[This message has been edited by RB83L69 (edited October 23, 2000).]

 

It has had a little problem of running slightly rich(clogging the cat), and your point about the fan clutch is well taken. I will definately have to check those tonight. Man, I never would have thought of the fan clutch thing. And 5 -10 hp in a truck with 110 is a real noticible difference. THANKS A TON!!!

Later,
Lars