Very true. I'm not 100% sure about all the burden, but you are right about it NOT being automatic. He should be documenting and backing up EVERYTHING.

RACE ON!!!

 

I doubt his 100K motor is in any worse shape than my 80K one. I'm not asking you to take my word for it.


Anyhow, valve timing affects the VE at cranking speed, which is what I was reading into, that you were trying to base it on how much air is entering the cylinder to be compressed. There are so many factors, I'd never say what's good or bad as long as the readings are consistent, but more often than not I see readings from 140-160.



On my Ford, I pulled 150 - 160 - 125 - 50 - 110 - 160 - 155 - 65

Clearly 125 isn't good on this car, whereas it might be acceptable on another.

Disclaimer: This statement is not intended to imply CFI does not know that consistent readings are important.

 

I wonder if the "mechanic" actually ran any of these tests. And I want one of his magic valve leak tool thingys.

I hope you didn't pay for these "tests." if so, oops. I would consider it a lesson learned and move on. I doubt you will win against him, unless he has had a lot of them.

 

Auto mechanic is a difficult fkng job. He could be making more money doing easier work if he went to school, but obviously he didn't. It doesn't take a rocket scientist (or even a mechanic) to figure out why he made that decision.

 

L98s are notorious for leaking around the rear of the manifolds, period. Chouldnt leak right away though.

I found the where the block meets the head (especially on the drivers side), you really have to look carefully as there is a very slight gap there that needs to be filled, your leak will start there in that corner every time.

 

Thanks for all your inputs. As far as the compression/leakdown test, I'm gonna be on the hook for that one--I was the one who ended up insisting he do it as he was assuming the engine was just worn--he charged me $90 for this, plus I got to use his own tests (however valid it really was) to prove him wrong about having a worn out engine. Actually my concern at the time of testing was the exact opposite, that he'd give me some BS low compression reading just to bolster his point. Instead, he's still arguing with me that the engine must be worn, even AFTER his "205psi" compression check, since the seal leaked in the 1st place. Anyhow, for now the car seems to have stopped leaking oil, who knows maybe 2nd time did the trick. This time around, the car sat overnight before being started and the seals got a chance to set in, maybe it'll help. To the shop's credit, they did pay for my rental car after the redo job took longer than planned and never balked at redoing the seal free of charge. My cc co will give 60 days leeway on this, will put them on notice, I have his own compression/leak down results in writing to back me up, if need be will have another Vette mechanic give written diagnosis. Vette shops here in South Florida are found a dime a dozen compared to most other parts of the country, but the trick is finding one that knows what the f%$k they're doing.

 

 

I see that this is probably already solved but I just wanted say that if the problem arises again , they have a crank case pressure guage that you put over the oil fill hole. That will tell you if your getting any pressure in your crank case.

 

If they used conventional RTV (Black, more than likely, I prefer Copper), it MUST sit 12 hours - MINIMUM, 18 to 24 hours is best - or else it WILL blow out. RTV must be allowed to set up.

The reason I prefer Copper RTV, it is much more resistant to oil and heat, and because of the colour, it is easier to see gaps in and/or leaks.

Many have used "The Right Stuff," but I have no experience with it yet.

 

Well, you should get it then. You can throw your rainbow spectrum of RTVs in the garbage. The Right Stuff replaces them all and does a better job than all of them.

 

Sounds like your mechanic may be honest, just stupid. Hopefully he lucked out this time around.

As Bogus said, the intake goo MUST be allowed to cure overnight for best results.

 

I wasn't thinking the words, "volumetric efficiency" when I made the comment, but I guess it applies. I wasn't referring to "how much air is entering the cylinder to be compressed", so much as I was concerned with how much air is pushed OUT of the cylinder as the piston rises on the compression stroke, before the intake valve closes. You can't start to compress the air in the cylinder before you have a closed cylinder. That is why I said that the cam timing was more important than the compression ratio. The compression ratio assumes that you start compression at BDC. You don't.



I think we both realize it is the difference in the numbers, not the size of the numbers, that is important.

RACE ON!!!

 

If I read CFI-EFI last sentence correctly , what I generally want is all the cyclinders compression to be within 10% of one another.I believe that's an acceptable range. Most my experience with SBC has been with 265,283,327-332, and 350's, the 332 had a ratio of 11.5:1 and I've never seen numbers at 200 plus, but since CC has, I guess it's possible. And as far as CC goes, I think he definetly has a ford that need alot of help at least in that area.

 

A cam with lots of overlap or advancing will lower your compression test readings. I'm guessing your 11.5:1 motor had a spicy little cam of some sort.

 

Take a few moments to reflect on this last post. Overlap has NO effect on the cranking cylinder pressures. Overlap takes place at the end of the exhaust stroke and the beginning of the intake stroke. Cylinder pressurization doesn't begin until the intake valve CLOSES on the compression stroke. There is no interaction with the overlap period.

Advancing the cam will cause all the valve events to occur earlier, including the closing of the intake valve, which will BOOST the cranking compression readings.

RACE ON!!!

 

Also, the sky is green.





What I should've said instead of that nonsense is that a big cam with a later closing intake will lower the pressures you read. Nothing else should matter on that end.

 

RACE ON!!!

 

I know I'm late on this but as a mechanic I highly recommend "the right stuff" to seal anything fluid related.....the stuff works great and contrary to what was said earlier in the thread it doesn't need to sit overnight....i've done plenty of intake gaskets, trans pan gaskets(only if manufacturer recommends silicone sealant etc..chrysler) differentials....and in the 4 years that I've been using it I haven't had a car comeback with a seal problem unless cause by mechanical failure....just thought I'd give my recommendation!!!

 

The most common problem is not using the right sealant for the application or misapplying it. It is absolutely essential that all traces of residual oil on the surfaces is removed with the appropriate solvent. It is also important to assemble the parts before the product has a chance to skin over which is usually within 5 minutes and sometimes much less than that for some sealants. In most cases you should not have to wait overnight for sufficient cure time but you increase your chances for success if you do. In my opinion it is not worth the risk to start the engine sooner. We use many of these in different applications:

http://www.dowcorning.com/content/pu...it/80-3258.pdf

I used the Dow Corning 832 on my intake manifold job and it worked well.

 

Its amazing to me how a lot of you guys bash the "dumb hick mechanic" as you call them, everytime something doesn't go right with a repair. I myself quit an electrical engineering field to mechanic on large natural gas engines, and i'm sure i make more money than most guys on this forum.My point is mechanics aren't stupid dirty people, they just have the ***** to work on stuff you don't. And by the way you can accurately measure the crankcase pressure(blowby) and compare with gm specs, but i'll leave it too the smart people to figure out how. This isn't directed at anyone in perticular, but maybe some of you should trade up to a c6 with a good warranty