building a 383

[TraceZ]

I'm kicking around the idea of building a 383 for my car in a couple years. I'd like to start building knowlege about it and ahve some questions that I have not been able to get answered using the <SEARCH> feature.

1) Balancing... Can I use my stock flywheel and balancer? Is my stock motor internally or externally balanced? I've heard people talk about a "balancing plate", what is that exactly?

2) Cam.... Everyone talks about a cc306 cam. Is this a Comp Cams grind? What is the exact part number? Is this a good choice for a street driven car? Will it totally destroy my fuel economy? Is this a good cam to use on a M6 car?

3) Rotating Assembly.... My car is street driven. It would rarely if *ever* see track use. Do I really need forged internals and a 4-bolt main block? Would cast be good enough?

4) Heads.... should I have the stock ones P&P, or buy different ones? What is the performance / cost difference between the two? What are your suggestions?

5) Drivetrain... Would this setup in my M6 car destroy the rearend on street tires? Would my SLP clutch be enough to hold it?

[Jeff_in_Atl]

1) Balancing... Can I use my stock flywheel and balancer? Is my stock motor internally or externally balanced? I've heard people talk about a "balancing plate", what is that exactly?

Externally balanced. Mine was balanced with a weight of 94.7 grams on the flex plate. You need to tell your engine builder that you want to use a stock flywheel and the best thing you could do is give him the flywheel to use when balancing the crank. FYI the motor builder could build the motor with a neutral balance so you need to talk to the builder.

My understanding is the harmonic balancer is for harmonics not for crank balance.

5) Drivetrain... Would my SLP clutch be enough to hold it?

Maybe not. I'm going to send my kevlar disc back for replacement. The SLP pressure plate will be fine. I'll make you a heck of a deal on a new kevlar disc.

[Joe 1320]

1) Balancing... Can I use my stock flywheel and balancer? Is my stock motor internally or externally balanced? I've heard people talk about a "balancing plate", what is that exactly?

It can be done either way. Netural balence is nice when replacing flexpaltes or flywheels.

2) Cam.... Everyone talks about a cc306 cam. Is this a Comp Cams grind? What is the exact part number? Is this a good choice for a street driven car? Will it totally destroy my fuel economy? Is this a good cam to use on a M6 car?

That's old technology and not really the best choice. There are more modern patterns even from comp cams.

3) Rotating Assembly.... My car is street driven. It would rarely if *ever* see track use. Do I really need forged internals and a 4-bolt main block? Would cast be good enough?

Cast is fine for non performance applications. If you want it to live a long life, don't scrimp on the rotating assembly.

4) Heads.... should I have the stock ones P&P, or buy different ones? What is the performance / cost difference between the two? What are your suggestions?

Depends..... ported LT-1s will outperform out of the box LT4s. Much depends on your budget.

5) Drivetrain... Would this setup in my M6 car destroy the rearend on street tires? Would my SLP clutch be enough to hold it?

If the tires are slipping, the rear end and clutch will live longer. If you start hooking, kiss them goodbye.

[TraceZ]

What is a fair price to pay for a bare 4-bolt LT1 block with a spun main bearing? it's got 20,000 miles on it otherwise.

[TraceZ]

the seller says he'll give me the block for $250. Is that ok? I've got pictures of it, and I cannot see any damage to the block from the spun main bearing.

[Jeff_in_Atl]

I can ask my neighbor about it but I may not see him till Saturday.

[TraceZ]

He came down in price to $225. It's a 4 bolt LT1 block with 25,000 miles on it. You can still see the cross hatches on the cylinder walls. It had spun the #3 main, but by looking at the pictures, I cant see any damage. I'm sure there is nothing wrong that a machinist cannot fix easily. He is including an oil pan, front cover and accessory bracket for no additional cost.

He says it is from a 1994 Z28 that had its motor replaced under warrenty. According to him, GM used 4 bolt blocks as warrenty replacements.

I'm going to inspect / pick it up on Feb 6th. Wish me luck. It'll be awhile, but the next step is an Eagle stroker kit for it... then a cam.... then heads...

This is going to take a while! I'm sure it will be worth it!

[Injuneer]

If the 4-bolt block is from a Corvette, the pan and the accessory bracket won't be of any use to you.

[TraceZ]

If the 4-bolt block is from a Corvette, the pan and the accessory bracket won't be of any use to you.

I was wondering about that, and asked him specifically about that. He insists it is all f-body stuff. We'll see next Sunday. Wish me luck.

I'm thinking about making a 396 instead of 383. Eagle has tha kits for those too, and they arent much more expensive. Am I missing something? Is the 383 better?

[AmericanZ28]

What about clearance trace? Im pretty sure the LT1 block will need some grinding in some areas to accomodate the longer stroke. Im pretty sure a 396 set-up would need it, but I'm not too sure about the 383. Im in the process of buying a cam from Combination Motorsports, and they're very good at helping you chose the right cam for your set-up. And from what many people can attest to, their cams are far better than the cc306, cc305, etc. For a little over $800 they're giving me my choice of cam, CC 1.6 RR's, Springs Kit, guideplates, lifters, 7/16" studs, pushrods, and gasket kit. Im sure they'd give you an even better deal if you let them do your head work. What kinda headers are you planning to go with?

[TraceZ]

What about clearance trace? Im pretty sure the LT1 block will need some grinding in some areas to accomodate the longer stroke. Im pretty sure a 396 set-up would need it, but I'm not too sure about the 383. Im in the process of buying a cam from Combination Motorsports, and they're very good at helping you chose the right cam for your set-up. And from what many people can attest to, their cams are far better than the cc306, cc305, etc. For a little over $800 they're giving me my choice of cam, CC 1.6 RR's, Springs Kit, guideplates, lifters, 7/16" studs, pushrods, and gasket kit. Im sure they'd give you an even better deal if you let them do your head work. What kinda headers are you planning to go with?

no headers. This is going to be a completely stock appearing project. After it is done, you will be able to look under the hood and not see any sign it has been built. I'm planning on getting an SLP y-pipe and catback, but no headers. I'm sure the sound of the exhaust will give it away to people who know a little about lt1s.

[Injuneer]

A 383 will generally require some clearancing of the block. The stock oil pan will fit, but may take some light hammer work. When you go to a 3.875 crank for the 396, you need to do more grinding on the block, and run a greater risk of getting into a water jacket. Also need to check cam/rod clearance more closely, particulary with a high lift lobe and long duration. You will probably need an aftermarket oil pan.

[TraceZ]

A 383 will generally require some clearancing of the block. The stock oil pan will fit, but may take some light hammer work. When you go to a 3.875 crank for the 396, you need to do more grinding on the block, and run a greater risk of getting into a water jacket. Also need to check cam/rod clearance more closely, particulary with a high lift lobe and long duration. You will probably need an aftermarket oil pan.

And that is why I love this place. Thanks fred, I'll stick with a 383. I'll do it internally balanced, and have my stock flywheel neutral balanced, with otherwise all external stock parts. I'm think I'm going to have the stock throttle body bored out too go with the ported heads and intake.

I still need to find a cam.

[Injuneer]

My setup is neutral balanced at the front, using a neutral balanced damper, and externally ballanced at the rear, using a weighted flex-plate (or flywheel when it was an M6). Generally less expensive than internal balance, where you get into issues of adding mass to the crank using a very heavy metal called "Mallory metal".

I didn't mean to scare you off of the 396... experienced builders have no trouble avoiding the water jackets. Not sure how often you run into the need for a small base circle cam though, with the 396. I guess it depends on the choice of rod length.

[TraceZ]

My setup is neutral balanced at the front, using a neutral balanced damper, and externally ballanced at the rear, using a weighted flex-plate (or flywheel when it was an M6). Generally less expensive than internal balance, where you get into issues of adding mass to the crank using a very heavy metal called "Mallory metal".

I didn't mean to scare you off of the 396... experienced builders have no trouble avoiding the water jackets. Not sure how often you run into the need for a small base circle cam though, with the 396. I guess it depends on the choice of rod length.

I'd like to use the stock flywheel and damper. What is my best route for balancing in this case? Our stock dampers are not keyed, so I assume they are neutral? And my stock flywheel is couter wieghted, correct? Should I just have the machinist externally balance the 383 using counterweights on the flywheel? Or, would it be better to have it internally balanced and have a neutral flywheel? I would think that having it internally balanced would result in a smoother feeling engine, and it would be easier to replace the flywheel in the future?