I am asking this dumb question out of laziness, not stupidity.

'92 RS, 305 5 speed, stock except for exhaust and open element.
90k miles. T-top coupe.

I have two oil leaks (that I know of)---the one in front I'm pretty sure is from the intake manifold end-----at least when I cleaned the front of the engine, then ran the car awhile, it got wet around the junction of the manifold and the block. I'm new to these 305's, I thought there used to be a rubber gasket with locating pins in it between the intake manifold and the block----I'm told they just seal 'em up with silicone now.

It's the rear leak I'm concerned about. Getting oil drops on the bottom of my bellhousing. Kid I bought the car from seemed pretty straight, and he and his mom told me they had the clutch replaced less than a year ago. The clutch does feel pretty solid.

Of course I'm hoping it's an oil pan gasket or some stupid thing like that, but that ain't where the oil is.

Would a (nooooo!!!!) rear main seal leak be unusual for this engine? One of the mechs at work says it's a waste of time to do a rear main---he says the seal failure is usually caused by play in the main bearings, so the crank will just jump around and ruin the new seal just like the old one. I'm only doubtful because the car is not beat and has "only" 90k miles----with all the 150-200k cars I see out there, why aren't they pouring oil out?

Your 2c???

Thanks,
Dean

 

It could be leaking from the back of the intake manifold as well.

 

Thanks, Danny---

You got me all cranked up here, thinking that not only isn't it the rear main, but that I might be able to fix both leaks by re-sealing the intake mainfold.....I'll take a good look down the back of the engine tomorrow---see if there's a trail.

If and when I pull the manifold, anything I should do while it's off?
Car is TBI, and as I mentioned, pretty well stock. I'm not in a rush to make any major expenditures on the motor at this point, for now focusing on the body, rims and interior.

 

Dean,

Other possibilities are the distributor base gasket, oil pressure transducer connection, rocker covers, or the oil gallery plugs at the rear of the cam bearing and LH top side of the deck (not likely).

The block should be prepped for either the rubber "China Wall" gaskets or may have been assembled with nothing but RTV silicone. I like to use the "China Wall" gaskets with a bead of RTV on either side, but a pyramid of small (approximately 1/8") beads of RTV can work just as well.

As for the elective work you might do while the intake is off, there isn't really much you can do for improvement without a cam change or head removal. It sounds as if you're not quite convinced that it's time for that yet. Your '92 has a roller cam and lifters, so removing them for wear inspection isn't really necessary. There are a few step you can do to insure reliability:

1. You could clean up all accumulated sludge.
2. While the distributor is removed, check the lower bushing and shaft for excessive play.
3. While the intake is off, remove the EGR valve and thoroughly clean the EGR passages. Clean the pintle and seat on the bottom of the valve as well.
4. Clean the IAC passages and bores of the throttle body.
5. Thoroughly clean the intake surfaces on both the heads and intake. Apply a thin layer of RTV sealant around the water passages if there is any surface rust or pitting near the passage openings.
6. Use an anaerobic sealant (like LocTite PST) on all fasteners that enter the water jackets when you reassemble.
7. Use anti seize compound on all other fasteners.
8. Plan on a cooling system flush and oil change shortly after assembly to remove any contaminants.
9. If you're concerned about temperature, you can install a 180°F thermostat when you reassemble. That is about as low as you can go while still satisfying the the highest ECM temperature-dependent parameters (at 176°F), and still retain adequate heating in colder ambient tempertaures.
10. If you're really bored, you can check the port sizes of the intake and heads, and match the intake openings as best you can.
11. You could convert the fuel pressure regulator to an adjustable type while the throttle body is off - if you plan on any future modificationos that might change the compression or intake flow.

If you really want to dig in, the sky's the limit, and we can find lots of things to take your time and money.

 

I took a look at what I could see at the back of the intake.

I know the best way is to clean it all off first and see what's fresh, but I'm encouraged to see some oil in the area of the base of the distributor. Clean-up and recheck will be next.

Vader, out of the list of things you gave to check (thanks!!), a wet distributor base would kind of take everything except the base gasket out of the picture, no?

Next question: Not being familiar with the distributor base gasket---I vaguely remember a squarish o-ring-type of rubber gasket under the flange beneath the distributor body---but please refresh my memory---does it sit in a recess cut into the manifold, and what puts the pressure on it to make it seal? Just the c-shaped, one-bolt distributor clamp? What usually goes wrong with the gasket when they give up?

Thanks so far for all your suggestions. I'm seriously thinking about making a cam my next "big" move, and I guess it'd be foolish to tear the intake and TBI off twice, I really barely have the time to do this stuff once, might as well make it count!

With compatibility with the rest of my stock parts the major issue, and price close behind, what should I be looking at as far as a cam? Manifold? I'm pretty well committed to not changing over the TBI or the heads---and I realize that will limit me in the power dept, but am I headed in the right direction?

 

All the distributor gasket is is a small round paper gasket that slips down over the distributor shaft. I have never used any type of sealant on this and I have always been fine, and yes the only thing holding it down is the c shaped clamp. As long as you have a timing light, it is very, very simple. One tip though, just make sure the #1 cylinder is at BTDC before doing this. A cam would be a good idea while the manifold is off the car, but I would suggest header to go along with it or you will most likely be dissapointed with your cam results due to how much the stock manifolds choke even a stock engine.

 

You should have only the flat fiber (paper) gasket under the upper flange of the distributor. I vaguely recall the square rubber ring on some Pontiac engines from days past (or maybe some of the old Ford Clevelands). If you have an oil accumulation at the distributor base, you may have found the culprit.

As for the cam swap, this might be a good time if you can spare the car for a few days. Since you have a roller cam, you have the option of using your original roller lifters if they are in good condition. One caveat is that your cam selection will determine whether or not the ECM will require a different EPROM or not. Changing the profile to the point where idle vacuum is significantly altered will likely require a PROM change. The TBI system is heavily dependent on manifold absolute pressure/vacuum to meter fuel flow. There are easy methods to tune some of that out of a less than ideal combination, but only to a point before reprogramming is necessary.

Try to select a cam profile with similar duration and lobe separation to what the factory installed, or longer duration and a wider lobe separation, mainly to keep the valve overlap about the same as stock. Your performance advantage will have to be made with gross lift increases and ramp design, and not through a longer overall duration. There are some good aftermarket cams that will accomplish that. Of course, the more aggressive ramp of most aftermarket cam lobes will require a change from the stock valve springs nso that the lifters stay compliant with the lobe surfaces without floating. Then there is the consideration of the reliability of the factory press-fit rocker studs used with the higher spring pressure. It's a vicious cycle of "Where do I stop?"

If you'd be happy with a bit more performance, you'll have to limit your cam selection.

If you want to go in head-first, plan on different springs, rocker studs, probably valve seals, better rocker arms, ad infinitum. And when you're in that deep, the question of the heads and valve sizes becomes more an issue, and chamber volume, port volumes, etc.

25th makes an excellent point, but since your repair project already has you removing the intake, you lose nothing by installing a better cam grind now. To take full advantage, you'll likely want to address the exhaust issue at some time, but that is largely external engine work that doesn't need to be done immediately.

If you decide to improve the cam, plan on a new timing set at a minimum. You may also need a different length push rod set if the cam grind changes significantly, but standard oversize (+0.100") is usually about the limit for most aftermarket street cams with stock heads. With a mild aftermarket cam, standard push rods are often suitable. The rest of the work is already going to be nearly completed in your current project, with the exception of removing the water pump, harmonic balancer, and timing cover. A fresh timing set is usually a good thing at around 100K miles anyway.

If you determine that a new cam and timing chain are the proper thing to do, I'm sure there are a few suggestions for a good street grind just lurking out there.

 

OK, guys---I'll bite.

I'm not looking to get 300hp outta this mill. Just a little real punch.
The right cam sounds like the ticket.

Not looking to do any more than I have to as far as changing over my existing parts, either.

So, let the sales pitches begin - LOL - somebody tell me how you
bolted on a couple of hundred bucks worth of cam and maybe intake without either: 1/ tearing apart the whole engine, or 2/ destroying its streetability.

By the way, you didn't mention anything about having to remove the radiator or A/C condensor. I'd love to hear that's because they don't have to come out!!!

 

If you wanna get 300 hp out of your 305 tbi then you're gonna need a descent sized cam and some way better flowing heads, not to mention all of the bolt ons. It can be accomplished a lot easier with a power adder though, but if you want to do it NA then plan on doing heads, cam, headers, intake manifold, and tb. With the right combo it can be accomplished, but I would bet it is a lot more work than you are willing to do.

 

25th:

You'd definitely win that bet---but I'm <not> hung up on HP numbers at all. I just want a little more seat-of-the-pants punch.

At this point, I don't want to remove the heads, or scrap the TBI.

Looking for recommendations re: a cam and intake which will do something for the punch while I make the most out of the other parts I already own. Stuff which won't cause me any hood clearance, EGR compatibility, or other of those kind of headaches.

 

Sorry, I tried to use brackets around the word NOT, as in NOT hung up on horsepower numbers at all.

I forgot that it would delete the word!!!

Duh.

 

Go search on the tbi board. They can be very very helpful and know what they are talking about when it comes to tbi.