Sorry Ladies and germs,,,I know,,, I've written another novel!
Quote:
Originally Posted by johnjzjz
most think expensive shops are stuffing their pockets with money when on real side it is all the extra time and effort it takes to make it right the first time you only get what it is you pay for -- jz
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Excellent point!
That's exactly why when I'm getting machine work and the inital assembly done I leave it to the true engine builders. I'll freshen a bottom end, but when everything is new I think you’re better off having a builder that will spec everything out and make sure it's perfect!
You might be amazed at the differences it makes when a good shop does the work, making sure the cam is true and indexed, deburring the block, pinning freeze plugs and cam bearings etc. Most companies don't list this type of work, it's somewhat hidden in the cost. But it can be the reason you do pay that little more! This is where doing your research and talking to the builder you'll learn about their knowledge and how their work is done.
As far an LT1 spinning bearings, beside the fact these engines have low oil pressure to start with, I see a few things thT I think people do wrong with the install:
1) Not keeping everything clean, getting dirt and debris in the engine. From reading on other boards it appears scotch brite pads seem to be a common problem, pieces getting into the oil system.
2) Using a BFH to install parts like the crank hub! Do not beat the crank timing chain gear and crank hub on!
3) Using high volume oil pumps with stock pans, yes you can suck the stock pan dry and starve the engine of oil.
4) And the big problem I see!!!, people spinning stock bottom ends too high. The big cams people install need RPMs that the stock bottom end can't support. 6400 RPMs should be the limit.
There are allot of LT1 out there with 70,000+ miles on them making 400HP, BUT with RPMs limited! I built a few using 306, GM847 and custom grinds and they all run fine but I tell everyone to limit RPMs to 6400. Yes, there are guys out there spinning the motor higher, but they are the exceptions and not the standard. Remember you using an assembly line motor, not something that was carefully balanced and assembled.
Upgrading the oil pump is good, but you're going to have to make a call on this. There is currently allot of talk about problems with the melling stock replacements (Melling makes GMs), so you would need to go up to a HD the "M: series. But that's too much for a stock pan's capacity. I don't know of which other brands to use, some are using GM's white spring to add a little pressure and still run a stock pan. Again, people say the aftermarket HD pumps won't sucking the pan dry, but go look around on boards like CZ28 and see how many people burned up motors with high volumes pumps and stock pans! And here again, during assembly check the clearance between the pick up and the pan. You never want to assume anything, like the clearance between the pick up and pan is right, check it.
Alex, ( Here is where I go and start spending other peoples money again )
This is one of those areas where I suggest doing it right the first time and be done with it. Spend the extra dollars and get a bigger pan with windage trays and control flaps and a HD pump.
Before you buy the LT4 block you need to do some more homework. You might be better off just having your block rebuilt with better parts!
The LT4 is out of production, you are most likely buying a remanufactured engine. The LT4 block is nothing more then a Corvette 4 bolt main LT1 with a few upgrades. The LT4 was designed to be spun higher then an LT1 by way of a different machine process to the crank that made it stronger. But is the same material, upgraded bearing caps and the HD timing chain, and differently cut piston valve reliefs ( for higher compression). But you still using stock material rods and pistons and bearings. I would not consider an LT4 block a high HP unit, it's fine for 400-425HP, but if you're really shooting for 450HP or more then I would not buy an LT4, Just build a block with better internals then the LT4.
Now, I'm not trying to scare you or tell you this will happen, just that it COULD happen! So this is something else to try to research. The LT4 had a .4 higher compression then the LT1, by way of a smaller valve reliefs in the pistons. Since your looking at a block that has zero deck and I assume your heads were milled and with 570 lift of the 306 cam
you need to be very careful to check every cylinder for your piston to valve clearance! You may need to either go to a smaller cam, pull the piston and get them cut, or go with thicker head gaskets. Only thicker gaskets I know of for the LTx motors are the Cometics and you will pay a premium for them. Comectic gaskets cost $125ish each and require the block and heads to have a special finish in order for them to seal. So if you have problem you'll need to tear the block apart to have it and the heads refinished.
This is another example of where an engine builder knows to check and can adjust it during the assembly. Because I talked with the engine builder and he knew all the specs of the cam and heads I was using, he was able to determine the clearance was going to be tight. So he modified the reliefs in the pistons and finished the block to the smoothness required for cometic gaskets before he assembled it and shipped it to me. And he was right, I need .055 gaskets to get the clearance I wanted,
JB