Build link is here.

http://forums.corvetteforum.com/show....php?t=1539561

1 Question:

The vendor said he internally balanced my engine. Does that mean I need to have a completely neutral balanced flywheel? Shortly before I got the new engine I bought a new steel single mass flywheel and had it matched balanced to the old dual mass flywheel, The machine shop took off a bit of weight from one side by drilling a couple small holes. Do I need to then go back to the machine shop and have it neutral balanced again by drilling a couple holes on the opposite side?

2 Question:

Given my build do I need a new oil pan? Or can I reuse the stock one? I'm confused on when you need a new oil pan with a 383 and when you don't?

 

If its internally balanced it should take a "neutral" balance flywheel. Even though you bought it as a balanced assembly, its good practice to take the rotating assembly AND the flywheel AND balancer to a machine shop to have the balance checked. That way there are no questions. Good for piece of mind...

 

the oil pan only needs to be replaced if the crank counter-weights are hitting it. The odds are with a 3.75 crank no you will not need a new pan

 

Question 1.
Your engine builder probally "Dynamically" balanced your rotating assy. In other words he spun it on a balancing machine with bob weights. Some engine builders refer to this process as internally balancing an engine, but that is not really the absolute correct terminology.

External banced engines can still be "dynamically" balanced.

Internal and External is determined by which Harmonic Balancer and Flywheel he used in the balancing proceedure (Internal=no counterweights/neutral. External=counterweighted balancer and/or flywheel). He could have also used a combination of a neutral harmonic balancer and counterweighted flywheel, all stock 1pc rear seal SBC engines use this combo. The only flywheel you can get without a weight on it for a 1pc rear seal SBC is the aftermarket Alum ones (like my Fidanza), and you have to unbolt it from them.

Bottom line is call the engine builder ask him specifically what harmonic balancer (counterweighted ot neutral) and what flywheel/flex plate (counterweighted or neutral) he used. And your all set.

Question 2.
If I rember correctly your engine has Eagle SIR rods and they should clear the stock pan on a 3.75 stroke crank. Just slide the pan down on the engine and turn it over by hand, have some one listen really close to hear if the rods are hitting the side or the crank counterweight is hitting in the front. Also be aware that if you are re-using the stock windage tray (a very good idea if you keep the stock pan) you may need to space it down a bit with a few washers to clear the crank and rods.
Will

 

If you use a stock oil pan make sure you DO NOT use a Melling High Volume pump. Quite a few Camaro guys have had their stock pans sucked dry and their engines go KABOOM.

Their is still some debate about wheter this is true or not but just to be on the safe side: stock oil pan = stock oil pump.

If you want to use a high volume pump then use a high volume pan like the Canton.

BTW My engine builer told me my 396 shortblock was dynamically" internally balanced." So I took my stock dual mass and had it nuetral balanced. When I started my engine I had a bad vibration at 3,000 RPM. I called the engine builder and said WTF? It turns out my 3.875" crank was externally balanced and he forgot to tell me.

I ended up getting a new McLeod flywheel and having it matched balacned to the flywheel he used to externally balance my engine.

The moral of my story is be carefule and make sure you know exactly how your engine was balanced and what flywheel and damper you need and hold your builder to his recommendations.

 

1.) See posts #14 and #16, HERE.

RACE ON!!!

 

"Dynamic" balancing is the process. Internal or external refers to where its counterweighted. The pre 85 SBCs that everyone refers to as internal, they actually had the weight on the outside of the crank on the back, right where you bolt up the flywheel or flexplate. For most mild street applications, it doesnt really make much difference if it internal or external.
To take that one step further, the lower quality cranks require mallory plugs to internally balance them. The higher quality cranks, they actually lighten the conn rod throws, and move the counterweights slightly, there by resulting in an internally balanced crank without the addition of heavy metal.
We use Eagle cranks almost exclusively (not a sales pitch). They never have any added weight, and are usually pretty close to dead on. We always have them spun to be checked, and of course all the machined surfaces are checked for accuracy.
If you really want an internally balanced engine, I would spend the extra $$ and get a crank that doesnt require mallory slugs. Or, just build an external balance motor, and save the added weight on the crank.
As far as the pan clearance. If you set the pan on the motor with no gasket and turn it over you'll prolly hear it hit in a couple places. You can turn the motor over without the pan on and mark where the conn rods come closest to the rail, and then put the pan back on and mark the pan, and then ding it just slightly in with a ford carb adjusting tool, i.e. hammer

 

Okay

I called the vendor up and asked him. I'm not sure it helped. My vendor told me that the block was balanced to the standard GM flywheel and harmonic balancer for my year vette, and so he told me I should be able to just put my stock stuff back on there.



Though I'm not using stock stuf, I'm using a steel mass aftermarket spec flywheel that was match balanced to the original dual mass flywheel.

Fine, outstanding ----means no more money spent.

Except......for a I have a couple concrens. I thought I read on here one time that there were different balance weights/locations for the weights on all GM corvettes, that each flywheel was different and balanced specificaly for that motor? Is that true? If that's true then I'm in trouble because with this motor I got a differnt block so they wouldn't be matching. If GM used the same wieght on each flywheel then it won't matter.

My next question is this. When I got the new steel flywheel match balanaced to the dual mass flywheel I remember the shop saying something like 15 or 18 grams had to be taken off one side. Which he did by drilling three small holes in the side of the flywheel, but in talking with the vendor today I heard him mention 30 grams or so. I'm not 100% sure I remember the 15 or 18 grams correctly, but i guess my question is do all 1990 Vette L98 motor's have the exact same weighted flywheel from the factory assembly line?


One more thing...I can't just 'easily' take the rotating assembly in. What I have now is a long block, minus all the externals and intake. IE no flywheel, no crank pulley, no water pump no intake etc.....Can a machine shop do a balance check with the whole engine assembly? If I bring in my flywheel and haronic balancer/crank pulley?

 

You should be fine with your factory stuff....
If the engine is assembled, no, it cant be balanced without taking it apart.
If any (substantial) weight was removed from the flywheel, I would probably get another and install it as is. If its off by a few grams, no big deal. It'll run smooth.
Ok, rereading your post....If the steel flywheel has been MATCHED to the OE flywheel, I would go ahead and install it.

 

another question.....

Where on the block can I hook my hoist to? I used the head bolts before because I had removed the heads when I took it out, but now I need to lower it back in and the heads and it's a completed long block at this point. What is strong enough on the lower intake/heads to allow me to hoist the engine into place?

 

Run a chain from the pass side head(rear) to the drivers side head (front)