383 not sealing up well oil reports

[Michael Joslyn]

383 Plate honed, very lttle core shift.
XE276 retro roller Comp Cam
Wiseco dish pistons floating
Vortec 64 cc heads standard gasket
5.7 rods
130-135 PSI cold comp. in each cyl. (seems low to me.)
Leak down is 10% in 6 cyl. on a 100 pound scale. 5 and 6 are leaking 18 and 22%.

First oil change 10-40 Dino. 950 miles
Alu. 8
Chro. 7
Iron 36
Copper 31
Lead 108 Leaded gas
Tin 8
Moly 42
Mang. 1
Silicon 91
Sodium 16
Calcium 1556
Magnesium 5
Phos. 826
Zink 850
Barium 1
Sub visc. 59.8 Values 65-76
Flashpoint 365 Values >375
Fuel 0.5 Values

Second oil change 1,051 on oil 2000 on engine
M1 15-50
Alum. 9
Chro. 9
Iron 53
Copper 19
Lead 65 Now running unleaded
Tin 2
Moly 126
Nickel 1
Mang. 2
Potassium 1
Boron 112
Silicon 63
Sodium 7
Calcium 2320
Magnesium 521
Phosphorus 948
Zink 1216

Sub visc. 78.3
Flashpoint 385
Fuel Insolubles 0.4

Still looking for input on if I can get an oil in this engine that might seal it up better, or some input on weather the engine is still seating, eating itself, etc.

Thank you, Mike

 

[sbc350gearhead]

When you did the leakdown test, did you listen for where the air was going? Are you running a PCV valve? Are you running dished pistons?

 

[Chris142]

I wouldn't be too concerned with the compression test. Many things can affect this test such as cam overlap and cranking speed.

You need to find out if it's leaking past the rings or valves. I'd guess valves since you don't have alot of fuel in the oil.

If it is past the rings drain the oil and dump in 5 qts of 5w-30 and give it h*ll!

 

[drive it forever]

Engine doesent have enough mile on it yet? Chrome moly rings? If so those can take a while to break in. I bet the cam has a 110 degree lobe seperation like most comp cams. That can make for a low compression reading with a low to begin with compression ratio. If the cam was installed straight up, I would retard it back a few degrees. What is your compression ratio? I think your cam choice might be wrong with your dished pistons. I would say overall that the best advice is that the engine needs more miles on it to seat the rings in. A engine with vortec heads can allow for more compression without preignition knocking then old/crap heads of the past.

 

[Steve S]

The dirt is still washing out of your engine don't waste money on oil anaylsis for a few more oil changes or syn oil.. Check Valve adjustment.

 

[DSteven]

I can't give useful information on the engine; however, I can state experiences, like yours, with regard to oil. I had a 94 Corsica 2.2 that used oil, due to a previous overheat. I switched to Castrol High Mileage 5W-30 and 10W-30. With that oil, it didn't 'puff' out smoke and never consumed any oil. I suggested the Castrol HM to my grandpa, who repairs small engines. Some engines had very worn rings, etc. The Castrol HM nearly cured the problems, without even using 20W-50. I would suggest using the Castrol High Mileage oil from these, and other, experiences.

 

[Michael Joslyn]

Good information, thank you.

Yes, the pistons are dished to 20 cc if I remember right. I believe I should be around 9.5 to 1.

I believe it has Moly rings, I'll ask the guy. Are there both Chrome moly and just Moly rings?

I did the leak down at 2000 miles. It was leaking past the rings, very loud in the crankcase.
At this time I introduces a PCV valve and put in a light grade dino oil 5-30 I believe. Since then i have been loading the engine as much as I can but the weather is getting crappy here and I have M/T on the back.

I was thinking valve adjustment too, although with a hyd. cam it is probably alright.

If anybody else has any comments I would welcome them.

Thank you, Mike

 

[novadude]

quote:

---

If the cam was installed straight up, I would retard it back a few degrees.

---

This is backwards. Retarding the cam will result in a later intake valve closing event, which would cause cranking compression to drop, not increase. Comp seems to like 110 LSA and they usually "grind in" 4 deg advance, so the cam is on 106 ICL when installed "straight up". If you want cranking compression to increase, you'd want to advance it to 102-104 ICL, not retard it.

If the dishes are big enough, and you have stock ~0.025" deck clearance, combined with a thick head gasket, it is very possible your static C.R. is too low for that cam, causing low cranking numbers.

I wouldn't sweat the cranking compression readings too much though, provided the thing seems to run good. Cranking compression can be affected by a lot of variables (thottle open? Air temp, etc, etc).

 

[BlazerLT]

You need to stick to dino oil for longer than 950 miles for a proper and complete break in.

 

[Michael Joslyn]

I was thinking that maybe I switched to early in 20/20. As has often been the case, I followed the recommendation of the builder that 500 miles was enough for the dino oil.
My concern now is that the walls might be glazed a little and that those cylinders might not get any better.
Ah yes, the pride of ownership.

Thanks again for all the replies.

 

[Ford358]

You should do a leakdown prior to running the engine, and a leakdown periodically for health checks. Leakdowns have nothing to do with compression checks as it is not relavant to cam events. The test occures with both valves closed, and with the piston at your desired position, most folks like it at TDC.

The leakdown is given in percentages of air coming in, and air exiting past the rings/valves/gaskets if there is a problem.

 

[novadude]

On that note (not to drag this too far off topic) dies anyone know where to buy a cheap leakdown tester?