Hi--

1993 corvette lt1 40th Anniv

I recently had my engine rebuilt to a 383 stroker, 1.6 roller rockers, new valve springs, crankshaft, lt4 hot cam, polish and ported heads, etc... When trying to adjust the roller rockers the oil was spilling out way to much oil and as they were tightened it created knocking and scratching on the bottom of the roller rocker and on the top. The oil pressure was very high at first but not now after 250 miles. Not tightening the roller rockers correctly i'm not sure if it caused the oil to 10 or less psi at idle after warm/ replacing two oil pressure senders, warm when driving it goes to 40 where before it was over 80 when cold and idled at 60. I have a HV oil pump, also I believe blow by is coming out of the valve cover cap when engine is warm white smoke not a lot, nothing coming out of the back pipes but need to pay attention next time it's started attention to running. At the moment until everything is solved with the roller rockers issue and oil I haven't started the car. The engine has 250 miles on it at the moment because the mechanic said it would be okay to drive slowly just to break in the motor even with the noise from the engine due to the roller rockers. There is a knocking noise which has been there from the start and I hoping it is still the roller rockers. I have warranty for 6 months on engine rebuild from the machine shop.

Any ideas on why the oil pressure is low? Is the engine toast or does the oil pump faulty? Please let me know any thoughts you might have on the above issues. Thanks

PS: I forgot to mention I'm getting code 13 and code 16

 

Did the machine shop assemble the engine, or who assembled the engine? It seems strange to me that you are adjusting the rockers, rather than the shop that assembled the engine. Were there changes of plans about how the engine would be built after the machine shop started the project? Was it the original plan to use 1.6:1 ratio roller rockers? Are the roller lifters/cam followers hydraulic or solid? Full roller rockers or roller tip only? Are the roller rockers noisy because you aren't able to adjust them properly? Have you talked to the shop that assembled the engine? Several really strange things going on here, and it's very strange that your mechanic told you it's okay to drive the car with so much noise coming from the engine!

I've got another 100 questions, but I'll stop there!

 

If the shop built the engine, you installed it and "TURNED THE KEY" you are likely without warranty OR you will struggle with the shop. A certainty? No but unless the shop and you have a previous relationship OR an agreement on this build it's likely.

Most want to be the one that "TURNS THE KEY" and cranks it. I wouldn't have it any other way.

HRR asked many questions and others in addition to he likely have many, many more. HRR mentioning 100? That's likely not a stretch.

 

Drain your oil into a clean drain pan. Let it set for a few hours, then look for metal sediment in the bottom of the pan. Let us know what you find. Wishing you good luck! This doesn't sound good.

 

Cut the oil filter apart.

Metal trapped in the pleats of the oil filter will TELL ALL.
Will

 

You have removed the drip tabs or used new valve covers without them, correct?

The oil pressure is not necessarily bad. LT1's in general are low on pressure at idle. At 1500 rpm is a more indicative number

Some things to consider for low pressure...

--If the clearances weren't set properly (crank and main bearing)
--High Volume pump with not enough capacity in the pan (Did you install a bigger pan? the LT1 has crappy capacity stock and a High volume pump won't work well with one
--solid lifter cam? if so... you have to install oil flow restrictors if you went this route or all the oil ends up at the top of the engine.


It sounds like you have a custom valve cover cap, did you eliminate the PCV system? This is a no no on the LT1. You will hate it in the long run, I know from experience.

 

change the oil and change the oil filter

 

Any results?

 

Rule of thumb is 10psi per 1000RPM's.

I've seen a LOT of SBC's idle with about 5 psi.

FYI, HV oil pumps do NOT put out more pressure. Pressure is set by bearing tolerances.

I agree about checking for metal in the filter/oil.

 

Turns out there is a lot of metal in the oil filter. I'm forced to pull the motor out and have it rebuilt again by the same machine shop as they assembled the motor. The machine shop is covering the engine under warranty. They mistakenly assembled the wrong type of roller rockers caused metal to go through the entire engine. Not sure if I can get them to pay the mechanic the extra costs to get the motor out and put it back in working order but I'm happy they will rebuild the engine free of any additional cost to me so hopefully this time around it works.





valve covers: http://www.jegs.com/i/Proform/778/141-132/10002/-1

 

yikes, Sorry to hear this! yet ANOTHER "qualified" Shop Nightmare story. How do places like this survive? at least they are willing to re-build. This shop is going to re- hot tank? and examine everything?

 

To be honest I looked at the oil today again and I can't make a definite on whether or not the engine is toast which is somewhat good news to me. It might be the scrap metal from when I removed the oil filter that might of fell into the container I let the oil drain into. At this point I'm not 100% on whether the huge metal pieces came from the filter removal or the engine.

I'm going to remove the oil pan and find out if there is any large metal pieces and replace the roller rockers, check the compression and replace the oil pump. Then proceed if necessary to have the motor rebuild.

As of right now I have the following items:

- check oil pan for large metal pieces, there definately is small metal pieces in the oil.
- Check compression
- Check oil pressure with oil pressure tester
- Replace roller rockers with correct roller rockers
- Replace the radiator
- Replace oil pump

Thanks for your input and suggestions

 

I'm getting the following error codes: H72 H74 for 1, H16 H33 H44 for 2, H64 for 9.

The oil pressure sender unit I've replaced now three times with no resolution. I hooked up a mechanical gauge and during cold start both show the correct oil pressure which is over 80. When the engine warms up the mechanical gauge shows 40 at idle and the cluster shows 0-10 at idle. Not sure how to fix this.

The good news is my engine oil looks normal and typical for a break in. However, I'm shooting out black smoke as the car is running very rich and when I put it into reverse it shuts off at times. The car overall runs like crap right now sucking up gas like nothing and the machine shop keeps postponing to have a mechanic look at the car under warranty. I've been told it will be this coming Tuesday or Wednesday.

Please help.

 

Cut open your oil filter.

 

I cut the oil filter and it looks fine. I made a mistake previously taking it off while scraping metal off the oil filter and landed into the container i was draining the oil into which I'm happy about.

 

Hi,

I replaced the map sensor and both o2 sensors which seemed to fix the idle problem. I'm still dealing with the oil pressure sensor not accurate when engine is warm as well as the car quickly getting up to 240 water temp when couple days ago it was running low temp around 100 before changing sensors. When fans kick on at 240 temp goes down 10 degrees at idle. Why is the engine blowing black smoke? What is the best resource for datalogging cords and program to date?

Thanks for any input

 

One source of excess gas is a blown fuel pressure regulator.

 

Okay, thanks for all your help guys through my problems with the rebuild!

Now I'm at the point where I've finally been able to get my engine rebuild once again by the same shop under warranty with no additional cost. The machine shop verified that the cam and lifters were trashed and after multiple requests gave me the information on all the parts he will install this time around.

Parts for engine from shop:
- Scat 9103750L - Scat Cast Pro Stock Crankshafts - http://www.jegs.com/i/Scat/942/9103750L/10002/-1
- Scat Pro Stock I-Beam Connecting Rods 2-ICR5700 -
http://www.summitracing.com/parts/sca-25700
- Rod Bearings - 8CB663H (unknown)
- Main Bearings - MS909H (http://www.jegs.com/i/Clevite/695/MS909H/10002/-1) ?
- Cam Bearings - CHP-8T (http://www.summitracing.com/parts/dur-chp-8t)
- Melling Lifters - JB2079 (http://www.autozone.com/external-eng..._459767_12404/)
- GM Hot Cam - 24502586 - (http://www.summitracing.com/parts/nal-24502586)
- Pistons - 8H860CP (http://www.ebay.com/itm/Speed-Pro-Ch...-/191176332666)
- Rings - E-251K (http://www.summitracing.com/parts/slp-e-251k)
- Engine Pro Push Rods - 581-7200
- Engine Pro 1.6 Roller Rockers - 07-1102-16

Questions:

1. Are the parts above quality? For example: I originally requested lt4 hot cam kit with 1.6 roller rockers (http://www.summitracing.com/parts/nal-12480002)

2. The machine shop said I would have 11.12 compression and have around 410 horsepower. The heads are polished and ported? Is this correct?

3. I plan on watching them rebuild the engine again in person. I want to make sure they replace all the parts that need to be replaced so I don't run into another motor needing to be rebuilt. How can I tell if the pistons or please let me know anything that can help me identify flaws while they are performing the work so if I need to make sure they do something I can.

Thanks again

 

Double check everything I'm about to say, but this is what I think happened, at least in part.

I believe your engine originally was equipped with self aligning rocker; you know where there are little tabs on the end of the rocker where it fits on top of the valve stem....my LT4 uses self aligning roller rockers;

now I went online and looked at "Engine Pro Roller Rocker 07-1102-16" and the photo shows, and nothing in the accompanying literature says different, that these rocker are a conventional unguided style rocker which require the use of guide plates and hardened pushrods.

If this is an issue, i.e. a mismatch of valve train components, until this is resolved, nothing is going to work properly...not saying that there may not be other issues