Not something I would have checked as the lifter valley plate hasn't been off.

 

Yea, no one else would have thought to check under an installed cover.
A vacuum leak will make it run lean. Ya should notice that it ain't idling right.One way to tell maybe, would be to pull the vacuum line off of the reg and see if making it run richer at idle by boosting the FP will help it smooth out.Don't know,never tried it that way.

 

Well, just pulled the manifold, and as usual, things were oily. But not nearly as bad. I think the flat gasket and weatherstrip glue helped a LOT.

The plugs were there in the bottom of the manifold. So no dice there.

Didn't see any obvious signs of gasket failure other than the somewhat oily runners still. Not for sure if that's old stuff or new. I know that the three plugs I pulled today after a bit of idle tuning were all white on the lean side which hasn't happened before. But at a sitting idle if I enable the fuel trims the car will still try to dump rich at times.

Work in progress. I'm thinking about double stacking those metallic manifold gaskets with the weatherstrip glue and see what happens. The car actually felt like it was running pretty good today save for feeling a little weaker than I think it should and for the low vacuum on the idle.

 

Mines doing the exact same thing, so if you fix it before I do, let me know.

 

Hmmmmm......I needed to make an update yesterday but didn't get around to it.

I put the car back together on Monday/tuesday, and didn't fire it until Thursday. Fire it up and after some idle tuning and tweaking, I had it idling at 1000-1150 RPM quite steadily. The ve tables were up around 40-45% this time and the vacuum was much more stable, but still wavering from 6-10 in/hg. So I decided to take it for a spin, and it felt MUCH better. MUCH MUCH better. Kind of a slug down low, but that's what a big cam and stock 3.23 gears get ya with a six speed. Railed on it a couple of times and it felt pretty good, like it needs tuning to maximize.

So I bring it home and let it cool down. Pull a few plugs and what do I find???

White. Not carbon and oil fouled, but white lean. Ended up pulling the manifold anyway to check for the IAC port plugs to make sure they were there (which they were). Found no leaking or seepage marks on the intake manifold gaskets.

The ONLY thing I changed was the gasket itself. I switched from the Fel-Pro 1284 (paper gasket with raised bubble around ports) to a stock replacement Fel-Pro, the crushed metal kind. That's it.

I just got done putting the manifold back on and will be running the car again tomorrow morning sometime.

 

Right on!

 

Well...........


Finished it up today, and my buddy with a very nice 95 Z28 came by and we ran them.

His car has a VERY nice 383 wiht TPIS AFR heads and a 230/236. Makes about 405/405 to the ground with a KILLER powerband. He's also running an M6 with 3.73's.

I'm running the 355 with the head/Joe O cam setup, and a 93 M29 with 3.23's. Gonna be a bit of a slug until higher up in the powerband.

First run: From about 40 MPH, he put 1 car on me up to 130.

Second run: From 15 MPH, he puts 2-3 cars on me up to 120.

I hung pretty good considering it's a baseline tune and my bad need for gears.

Yeah, car seems to be on the right track now.

Unfortunately, I felt what seemed to be valve float at about 6500-6700 RPM. May have to look at a set of beehives in the near future.

 

If it lays down that high it's probably fuel or float or bounce. Check your FP with the guage taped to the windshield and run the P*** out of it.41-47psi

 

It didn't lay down that bad though. It was still pulling, I just felt a sharp drop off.

 

Ran it again today, and it just isn't idling right. I did a hot/running valve lash set on the Comp R's, it's nice and quiet now. But that caused a drop in my vacuum (Yes, I'm sure I set them right). Now the vacuum at idle, if left extended at idle, will throw a low MAP code. The car just won't pull crap at idle for vacuum.

I'm going to pull the manifold again and give double-stacking the manifold gaskets a try. After that, I think it's going to go to an engine shop.

Of note, I pulled plugs 1,3, and 4. 1 and 4 were white lean, while 3 was black. I may still have a leaky port.

 

One last thing: Anyone have any pointers for double stacking a flat stock replacement gasket??? anything specific I need to know?

 

Well, may not be as close as I thought. Today, after a valve lash set with the car running, the vacuum dropped and the car started to surge at idle. The vacuum dropped so low actually that it threw a low map code (DTC 33) and wouldn't do anything.

On a whim, I threw in a tune that the only other mod was a little bit more idle timing, and it started surging even worse!!!

So.....off came the manifold. Surprisingly enough, there was only a faint hint of residue on the head intake runners, but the inside of the intake manifold on the other hand.....it was SATURATED. With what, I don't know. But directly WTF is going on with my car?????

I found an engine shop familiar with late model (Gen 2, Gen 3) motors about 2 miles from my house. Called them today and the guy spent 20 minutes on the phone with me just going over the motor specifics. I'm probably going to swing by there tomorrow and have a look-see and talk to him some more. At this point, I can only see the motor coming out of the car and having it gone through.

I'm going to try two things before it comes to that though: I've got those stock replacement Fel-Pro gaskets on order, going to double stack them. In addition, I've also got a set of stock lifters that I'm going to put in the car just on the off chance that it likes those better. I had a couple of my Comp R's that REFUSED to stock ticking today no matter how much pre-load I put on them.

 

Just for S&G put a stock set of lifter's in that thing and try them. It sounds like ya are holding the valve open after an adjustment.
Try that before ya get all excited and yard it out.

EDIT: I just read the last paragraph,Daaa

 

ive been following your thread because i have the same problem. i have a 93 ta with a 383 and a solid roller. what you see in the intake is fuel, but its normal for our 93's because they are batch fire. they fire all the injectors at half the commanded pulse width twice per engine cycle. 93 manifolds always have fuel residue.

my problem is i had a hack (car pro motorsports) port my heads. they are AFRs, after, they surfaced them to return them to 55cc's . by doing this they had to take a ton off them to the point that my acc. bracket holes didnt line up and i had to hog the holes out to make it work. also my manifold didnt fit at all. so, car pro talked me into sending them my intake (saying it was no big deal and it happens alot) to cut it down to fit. it did work until ihad to rebuild the motor a couple years later and i forgot about this. the machine shop cut my block decks after a line hone. now my intake leaks so bad, i get blue smoke out of my exhaust.

ive had my intake cut 2 more times, and it lines up okay, but it will not seal. ive tried several different gaskets and sealer (not weather stipping glue) but i will try it next. im almost to the point where i will buy new heads and a intake just to be done with this crap. so i feel for ya man!

im thinking of making a plate to bolt on the intake where the tb goes, with a hole for a air chuck to pressurize my intake and see where it is leaking.maybe 10 or 20 psi. if i take my intake rockers off it should be a sealed area right?

summit sells different thickness intake gaskets for a standard small block. i wonder if it is possible to use them with some mods on a lt1?

if your car is idleing with 6-10 inches of vaccum it is not going to run right because it will be useing the high side 75 kpa or more, of the fuel map which is where the motor runs with more throttle so it will be rich and when you tune you wont work there because it would be lean after you get on it some, 93's are speed /density so they need vacuum to run. the map sensor is the main player here. it kinda sounds like you have a cam with too little lsa or alot of duration that is not building any vacuum. then the intake leak is compounding this. i have gen 6 dfi on my car, it is more forgiving than a stock ecm but it still needs vacuum for it to know how much fuel to put into the motor.

one thing you can try is to take the map sensor off the intake and plug the hole. get about 10 inches of vacuum hose and put it between the sensor and the intake off one of the vacuum ports. this will isolate the sensor from the cam reversion so it wont surge as much. im thinkin that your cam is too aggressive for this setup though.

 

Yes ya can use them. Got to cut new bolt holes and possible trim the port holes if they don't come big enough for your heads,but order the ones that fit the port's and they will work.