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#11 | |
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Location: Bartlett, IL
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1990 Corvette ZR-1 #1051 Watson Headers (2" Primary) - Borla Catback Late Model IH - Plenum Coilovers - 4.10s Custom Interior NCM Lifetime Member #978 |
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#12 |
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Location: Crystal Lake, IL
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Jeff, oddly enough on my 90 I did not put the baffle plugs in and it was smoking a lot....was not doing that prior to the change...although my compression readings were low.
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LGAFF 90 #966-150K miles-sold 92 #234-sold 1987 Callaway TT #17 1991 ZR-1 #1359 |
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#13 | |
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if it is an issues I need to get the older IH back on it
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1990 Corvette ZR-1 #1051 Watson Headers (2" Primary) - Borla Catback Late Model IH - Plenum Coilovers - 4.10s Custom Interior NCM Lifetime Member #978 |
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#14 |
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What if you stuffed the Oil vapor galleys with Brillo pads(copper) would that reduce the flow enough...older European cars had that in their breathers...Jerry?
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LGAFF 90 #966-150K miles-sold 92 #234-sold 1987 Callaway TT #17 1991 ZR-1 #1359 |
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#15 | |||||
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I'm sure it wasn't theoretical. There were significant problems with crancase pressure in the LT5 during development. As such, you see some unusual crankcase ventilation parts on the LT5, compared to a typical engine. The big holes in the 90MY heads were enough to precipitate a design change to install restrictor baffles (washers in the 90 model injector housings. Nothing theoretical about it, just too much oil in the intake via the PCV system. Quote:
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2. Originally (for 1990 MY), the heads were machined out to 3/4". 3. Testing resulted in too much oil in the PCV system,so restrictor/baffles were added to the 90MY injector housings as a fix. 4. Greg VanDeventer said " hey, why are we opening up a big hole in the cyl head and then making a small hole restrictor/baffle to install in the injector housing? Why not save a few unnecessary steps and some bucks by just opening the heads up with a small hole for ventilation & leave the injector housings alone, with no baffle? So, for 1991 & later, heads have small hole & it was not necessary to make & install baffle washers in the injector housings. Quote:
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Jerry Downey JERRYS LT5 GASKETS & PARTS http://www.jerrysgaskets.com 1994 ZR-1, Black/Black, Lingenfelter Aerobody, 416cu in, 3.91 gears, coil-over susp, Brembo brakes, etc. 2016 Black-Red, 3LT-Z51 Auto 8-speed. |
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#16 | |
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The coalescing filter media (brillo pad) is going to hold quite a bit of oil under steady state condition of low rpm cruise, due to the large amount of surface area. At higher rpm, the velocity through the filter media is going to pick up a lot of that oil & carry it through to the PCV system. The restrictor/baffle design (essentially an orfice), restricts flow rate with increasing back pressure as crankcase vapor volume builds during higher rpm conditions. Adding coalescing filter media (brillo pad) adds surface area & tortuosity for good extraction but would do little to impede flow volume as vapor volume increases. Caveat: WAG requiring empirical test data to confirm or deny, highly theoretical opinion. ![]()
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Jerry Downey JERRYS LT5 GASKETS & PARTS http://www.jerrysgaskets.com 1994 ZR-1, Black/Black, Lingenfelter Aerobody, 416cu in, 3.91 gears, coil-over susp, Brembo brakes, etc. 2016 Black-Red, 3LT-Z51 Auto 8-speed. Last edited by A26B; 01-02-2011 at 11:33 AM. |
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#17 |
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Thanks Jerry.. now I understand I could plug the holes of my late IH too right? are all 3 open currently? your one pic blocks the 3rd. if I have to do that now is the time for me since it is winter and I need to pull the plenum to swap the AC compressor.. what is a few more bolts and a set of gaskets.
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1990 Corvette ZR-1 #1051 Watson Headers (2" Primary) - Borla Catback Late Model IH - Plenum Coilovers - 4.10s Custom Interior NCM Lifetime Member #978 |
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#18 | ||
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Jerry Downey JERRYS LT5 GASKETS & PARTS http://www.jerrysgaskets.com 1994 ZR-1, Black/Black, Lingenfelter Aerobody, 416cu in, 3.91 gears, coil-over susp, Brembo brakes, etc. 2016 Black-Red, 3LT-Z51 Auto 8-speed. |
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#19 | |
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Location: Bartlett, IL
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Yes by plug I mean restrictor/ Baffle although 2 are baffles 1 is a Plug correct?
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1990 Corvette ZR-1 #1051 Watson Headers (2" Primary) - Borla Catback Late Model IH - Plenum Coilovers - 4.10s Custom Interior NCM Lifetime Member #978 |
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#20 |
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Location: Jacksonville, FL USA
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Okay, I knew if I waited I would not have to start a thread about using late I/H's on 90 heads.
![]() I've tried to find the correct diameter freeze plug that I could insert into the late I/H so I could duplicate the restrictor hole size on the 90 I/H's.....so far no joy in finding a plug that fits the opening. My question would be would it be something that a machinist, ![]() ![]() ![]() ![]() Tom Jeff, the hole that is completely "pluged" is the coolant passage in the I/H that exits coolant from the block thru the I/H and then into the tubes.
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1990 ZR-1, Black/grey, #2233, stock. ZR-1 Net Reg Founding Member #316 & NCM member Last edited by tomtom72; 01-02-2011 at 08:06 AM. |
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