Inlet manifold bonanza...

[1990Z71Swede]

Someone says the air cleaner spacer ring is restrictive? It's larger than the TBI bores so I don't see how.

Richard

I think the issue is how it shrouds the bores in the TBI. There is an article about the "sallad bowl" mod somewhere on the interwebs. I was going to solve that with just a standard air cleaner base without spacer. But you need to get the Throttle body spaced up for the base to clear the EGR solenoid and some other doohickeys mounted on the passenger side of the manifold.

 

[someotherguy]

I think the issue is how it shrouds the bores in the TBI. There is an article about the "sallad bowl" mod somewhere on the interwebs. I was going to solve that with just a standard air cleaner base without spacer. But you need to get the Throttle body spaced up for the base to clear the EGR solenoid and some other doohickeys mounted on the passenger side of the manifold.

I feel like most of the TBI mods are tilting at windmills, but not having a dyno and unlimited spare time to play with and debunk all the myths, I'll just shrug. About the only one that makes any real sense to me is pulling the ductwork out of the inside of the fender on the early trucks as it does indeed appear to be very restrictive at the front opening.

Oh, and I'm a big fan of ditching the heat riser flap just because by this age most of them have failed wax pellet actuators and they tend to stick closed.

Richard

 

[1990Z71Swede]

I feel like most of the TBI mods are tilting at windmills, but not having a dyno and unlimited spare time to play with and debunk all the myths, I'll just shrug. About the only one that makes any real sense to me is pulling the ductwork out of the inside of the fender on the early trucks as it does indeed appear to be very restrictive at the front opening.

Oh, and I'm a big fan of ditching the heat riser flap just because by this age most of them have failed wax pellet actuators and they tend to stick closed.

Richard

Yeah had to replace the Air cleaner base. Cant remember if the flap on the better one was gone or just working correctly, heat riser duct is long gone though.

And yes that ducting on the passenger side is tiny, in fact when I first saw it, it never crossed my mind that it was the engine breathing trough that tiny thing.

Sometimes it is done like that I think to dewater the air, but I have not seen the rest of that ducting so I don´t know if that is the case here. The way it is supposed to work me thinks is that the small opening is meant to speed the air up and then there is usually some kind of sharpish flow direction change that the water can´t follow, instead it falls out of suspension and trickles down into some kind of drain, letting the water out.

 

[someotherguy]

Yeah had to replace the Air cleaner base. Cant remember if the flap on the better one was gone or just working correctly, heat riser duct is long gone though.

And yes that ducting on the passenger side is tiny, in fact when I first saw it, it never crossed my mind that it was the engine breathing trough that tiny thing.

Sometimes it is done like that I think to dewater the air, but I have not seen the rest of that ducting so I don´t know if that is the case here. The way it is supposed to work me thinks is that the small opening is meant to speed the air up and then there is usually some kind of sharpish flow direction change that the water can´t follow, instead it falls out of suspension and trickles down into some kind of drain, letting the water out.

From all evidence I've seen, GM omitted that inside-the-fender piece after 1993. The initial ductwork remains from the core support up to the fender, then nothing inside the fender, until the adapter piece where the resonator box hooks up.

Richard

 

[Schurkey]

PS: @Schurkey Do you still have that offy crossram? My Camaro "needs" one and I´m pretty sure I can fix those hogged out bolt holes.

I do. I don't think that the manifold needs any "repair" to fit a standard, old-style 6-bolt-per-side cylinder head...just a bigass washer to cover the hogged-out bolt holes.

If you're serious, I'll start thinking about how much I want to keep it. I've had it for years and haven't done anything with it...yet.

 

[L31MaxExpress]

Someone says the air cleaner spacer ring is restrictive? It's larger than the TBI bores so I don't see how.

Richard

The spacer is restrictive, powerbowl or flat base air cleaner has repeatedly gained 6-10 hp.