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Discussion Starter · #1 ·
After sending my intake manifold and heads off to get cut to make SURE that I was going to get a good seal, I finally put the motor back together and spent the past couple of days idle tuning. And......

Ended up on a whim pulling the manifold today because I just wasn't comfortable with what it was taking to get the car to idle.

http://community.webshots.com/album/460272038haJSmQ

Still having them fail within 1-2 minutes of the fresh start up after a new gasket swap. I just don't get it.

Anyone think double-stacking gaskets is worth a shot?
 

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I've had the same problem for over a year but I just live with it. Have you tried RTV'ing around the ports before assembly? It seems to help mine.
 

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Discussion Starter · #3 ·
Yep, RTV and all. This is something I can't live with because it's BAD. I'm talking 6 in/hg vacuum, fouling plugs out in minutes, detonation, ect.ect.ect. It's not just a minor leak.

I'll explain it this way, big cam and I had to lean the VE out to 25-35% at idle to get it to hold without surging. All the burning oil was throwing everything that far off.
 

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What oil are you using? Mine was horribly bad with Amsoil, and I went to 15w-50 Mobil 1 and its still leaking but not nearly as bad.
 

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Discussion Starter · #5 ·
Chris 96 WS6 said:
What oil are you using? Mine was horribly bad with Amsoil, and I went to 15w-50 Mobil 1 and its still leaking but not nearly as bad.
I've been using Mobil 1 10W-30 as was the recommendation from the shop that built the bottom end.

This was leaking on dino oil also though.
 

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Discussion Starter · #6 ·
Just talked to Chad @ Golen Engine Service earlier. It was proposed that I may not be getting a gasket failure moreso that I could be building up crankcase pressure and essentially putting so much pressure inside of there that I'm forcing the oil into everything.

Let's see......static CR of 11.7:1, dynamic I haven't a clue on because I never got a cam card. Cam is healthy with extremely agressive lobes, so probably going to have a relatively high dynamic.

I pray that my leakdown test comes out good when I do it in the near future. That shortblock is brand friggin new (<600 miles).

I'm going to try the trick of running a valve cover breather and using 3M weatherstripping adhesive on the intake gaskets first. We'll seen.
 

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Breathers might help alot, or the EVAP system connected to say the AIR pump or exhaust to get that pressure out of there....

Got a buddy that did the AIR pump thing, it worked but man, it sounded like a jet running, he took out the sound deadning stuff so it would not break off and clog up...
 

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Discussion Starter · #8 ·
Shon Herron said:
Breathers might help alot, or the EVAP system connected to say the AIR pump or exhaust to get that pressure out of there....

Got a buddy that did the AIR pump thing, it worked but man, it sounded like a jet running, he took out the sound deadning stuff so it would not break off and clog up...
I'm going to be test running the car again tonight, using a breather on the passenger valve cover.

I've also swapped in a new set of manifold gaskets, regular old Fel-Pro (NOT the 1284's, but the crushed metal GM style gasket) and used a light bead of weatherstrip adhesive around the intake ports. We shall see.....
 

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Discussion Starter · #9 ·
Update!!

Well........ran the car last night..........

Other than the still low but a lot more stable vacuum (wavering from 6-10 in/hg, averaging about 8 in/hg) and some slight smoke at idle/driving (hopefully attributed to excessive carbon build up), the car ran.

I actually got it on the road and railed on it pretty good. Felt a lot better than it had before, felt REALLY dang strong up in the 6000+ range, but I still feel like it's got more left.

Afterwards, I let the car cool and kept an eye on things. Idling at about 1000-1150 RPM, it's still only pulling 75-80 KPA on the map. I'd like to see that lower, but don't know how to get it there. Once the car had cooled down, I pulled plugs 1,3, and 4. All three had a pretty good shade of white, which is what I wanted. It's FINALLY burning lean, instead of getting all carbon fouled.

Noteworthy: I had closed loop enabled, but I also locked the LTerms and STerms to 128, so fueling corrections weren't happening.

Then last night someone on CZ28.com mentioned to me about checking to see if the IAC passage plugs were in place on the bottom of the manifold. That's something I'd never checked, and I bought the manifold without the lifter valley plate on it. So, on a hunch, I yanked the manifold again. Did it in under a half hour. Sadly, the plugs were in place, so my vacuum issue still seems unresolved. But, the good news is that those flat GM gaskets were holding up REALLY well. I had some oil residue in the runners still, but I'm not so sure it's completely fresh as it is just residual.

The car felt good, but it also was pretty sluggish down low. I can't tell if it's a vacuum issue, tuning (still needs a LOT which I hope helps), or just needs gears. I will say that on a hard 1-2 and 2-3 shift the car was making enough power to make the thing REALLY floaty on the stock 108K suspension. I mean REALLY floaty too. :devil:

Sooooo.......getting new gaskets today and putting it back together, and going from there tomorrow.
 

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I didn't have any luck with the 3m adhesive. If the issue is mating surface alignment, the 3m stuff isn't thick enough to take up the gap between the head and the intake. I went back to RTV and ran a small, like 1/16th inch bead of RTV around the BOTTOM HALF of each port, both on the head and the intake...let that set up for a little while so it won't completely mush when you bolt it together.

So far that's working for me. My oil consumption is down and the knock is gone. The heads and intake really need to be re-milled.
 

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Discussion Starter · #11 ·
Well......after yesterday, aparrently..........
































It runs. :eek: :eek: :eek:

Finished putting it back together yesterday afternoon and threw a new PCM For Less baseline tune in it that had some "out of the box" thinking in it. Ran decently, vacuum was holding an OK 75-80 KPA (fresh valve lash so I know I'm not hanging one open).

The tell-tale sign things are moving in the right direction: I did a couple of runs against my buddy's 95Z28. His car is running a VERY nice 383 (callies/Lunati rotating ass. I believe), TPIS AFR heads, 230/236 cam, dialed suspension, and M6 with 3.73's. GOBS of power everywhere, starting at like 2K rpm. Makes 405/405 and is completely streetable/driveable.

Then there's me, and my 355, Joe O cam and Joe Prince heads, M6 with 3.23 rear (M29 93 M6), completely stock suspension, and baseline tune. Car doesn't really come alive until almost 4000 RPM, but pulls like a raped ape up to the end of the tach!

First run from a roll get get me by a car from 40-130. Second run he put 2-3 on me from 15-130.

Once I get some gears and tuned in it should be VERY close. I'm pretty happy for the time being, but I already see more engine work in the VERY near future. At about 6500-6700 RPM I felt the car nose over a bit, and went "Uh oh, there's my valve float." Not good when the cam is supposed to PEAK at 6500-6700 and not drop off after that.
 

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Fastbird said:
.....
Once I get some gears and tuned in it should be VERY close. I'm pretty happy for the time being, but I already see more engine work in the VERY near future. At about 6500-6700 RPM I felt the car nose over a bit, and went "Uh oh, there's my valve float." Not good when the cam is supposed to PEAK at 6500-6700 and not drop off after that.
Are you sure you aren't just hitting the rev limiter? Do you still have the stock OPTI in it?
 

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Discussion Starter · #13 ·
jpsartre12 said:
Are you sure you aren't just hitting the rev limiter? Do you still have the stock OPTI in it?
Ummmmmm........yeah. I'm not hitting the rev limites. I KNOW what that feels like, and why in the would would I have it set of that kind of RPM when I know the cam should peak at about 6700???

I'm also running a vented opti conversion. The nose over wasn't an ignition thing, there was no popping or anything going on. Just felt a quick drop in power. And given the extremely aggressive nature of the cam lobes, it's most likely valve float.
 

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Fastbird said:
Ummmmmm........yeah. I'm not hitting the rev limites. I KNOW what that feels like, and why in the would would I have it set of that kind of RPM when I know the cam should peak at about 6700???

I'm also running a vented opti conversion. The nose over wasn't an ignition thing, there was no popping or anything going on. Just felt a quick drop in power. And given the extremely aggressive nature of the cam lobes, it's most likely valve float.
Do you still have the stock injectors in it? It could be starving for fuel if that's the case. Just another possibility to consider.
 

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Discussion Starter · #15 ·
jpsartre12 said:
Do you still have the stock injectors in it? It could be starving for fuel if that's the case. Just another possibility to consider.
SVO 30# injectors, racetronix 255 LPH pump, Hypertech AFPR. Injectors have 1K miles, pump has 400 miles, AFPR has 1K miles. Fuel system is good.

I'm almost 100% positive it's valve float. It was just too distinct a feel.
 
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