Sooo, long story short I spun a rod bearing and I'm looking to rebuild the bottom end on this car once again... Anyways, what im wanting to do is build a mild 355 spray motor. Im planning on using 6" H-beam rods, .030 over forged pistons, oversized Clevite 77 bearings, and getting the stock crank turned. My mods are in my sig, and I don't plan on ever spraying more than a 150 shot. I just wanted to get a couple of things ironed out before I shell out about a grand and a half.

Should I be worried about the crank balance at all with new rods and pistons? The car never sees more than ~6300 rpm.

I have been looking at pistons on summit and jegs, and i'm not sure about which ones to get. Im pretty sure i should just get the flat tops w/ -4cc reliefs for a 6" rod, stock stroke (3.480 i think) and are overszed .030". But i dont know much about what compression distance they should have. Im not familiar enough about quench, deck heights, and head gasket thicknesses to make a decision. I dont want to pay to get the block decked either if i dont have to. Should I use a pressed or floating pin? Im also looking for suggestions on brand, alloy material, and a good place to them.

Should I use file fit rings and if so at what gap? or are total seal rings the way to go?

If there is anything else bottom end related that i'm overlooking please tell me.

Thanks in advance.
Dane

 

Good questions.
First get the crank checked out and see if it can be fixed or not. With any new setup (pistons, rods..) that attaches to the crank you will need to get the crank balanced. Im a fan of JE/SRP stuff. Full floating is my choice.

If you are not getting your get your deck "0" then those reliefs should be fine. Does not sound like you are running any type of radical cam setup. Just put some FelPro 1074 on it and call it good. If you wanted a bump in compression a little go with the LT4 Impala Gaskets.

When they bore the motor out it's a good idea to get the deck surface checked as well.

Did you figure out what caused the bearing to spin?

 

150 shot seams like alot for a mild 355. You should think about different pistons too, someone correct me if I,m wrong I dont spray but dont you want domed pistons if your spraying not flattops??

 

In the nitrous world, a 150 shot on a flat-top forged piston is child's play.

And the ring choice is more crucial than the piston type. Dome, flat, and dish affect compression more than anything else.

 

Not sure why you would want a domed piston, except possibly for a thicker, stronger top. But you can get "nitrous" flat tops from quality piston shops that will have no problem standing up to a lot of juice. I have a set of BME nitrous pistons, flat tops, and I'm spraying a 300-shot on a 381 that makes 500HP NA. I did opt for 5.85" rods, to keep the top ring away from the heat, and to minimize the pin intrusion into the ring pack. But that won't be as big an issue on a 355.

 

Thanks for the replies.

Im not sure why the bearing spun, i still havent yanked the engine yet, but i assume it was just time for it to let go, i have been pretty harsh on that stock bottom end for a few years.

I thought the stockers were flat tops w/ -4cc reliefs, I want to use a stock style piston that is forged instead. Also, I don't want to bump up the compression ratio any more than stock really, i already am using the impala head gaskets.

What is the best ring choice for a nitrous set up?

What about rods too? would I beams hold a H/C/I + 150? Or H-beams only?

 

I have a set of I-beams.... Oliver Billets. But you don't need those for what you're building. The shape isn't as important as the overall quality of the rod.

 

Thanks for informing me, I learn something new all the time. Do you have any answers to the other questions?

These are the pistons I'm looking at on summit:

http://www.summitracing.com/parts/HRS-HRC4583/

I noticed that they have a compression distance of 1.225", how would i go about figuring out if thats going to work with the stock deck height?

 

You have to match the pistons to the rod length. The compression height + rod length + 1/2 the stroke tells you where the top of the piston is. Compare that to the deck height.

1.225
6.000
1.740
====
8.965"

 

Hey man if your planning on building your bottom end youll have to eventually go to a mchine shop to get it balanced since they are internally balanced. So unless your doing this rebuild just because you want to learn for yourself i wouldnt do it. Basically all the parts needed would cost you more than what it would cost you if you had a shop do it. Thats if you pick the right shop. You shold go to the website carolinamachineengines.com they remanufacture short blocks and long blocks both factory specs and high performance. They charge 650 to remanufacture a short block which if your buying new rods and a crank and getting it balanced would cost you more i would check the webite out. I think personally you could rebuild the top end for cheap by doing that yourself but the bottom can get expensive.

 

The stock LT1 is externally balanced, with a weight on the flywheel or the pressure plate. The front of the engine is neutral balanced. A rebuilt engine can be balanced internally or externally, depending on your preference.

 

what would be better internal or external if your running a stock dampener and a zoom stage 2 pressure plate? sry for the intrusion

 

Thanks Injuneer, the stock deck height is 9.something right?

Slick-Z thanks for the recommendation, I checked the site out and I'm looking for something a little more than a stock rebuild, so in the long run i would save money by buying the parts myself, taking everything in to get machined, then assemble the bottom end myself. I've assembled engines before, and kind of enjoy it, so thats not much of an issue. Also, i plan on keeping the flywheel the way it is, so I want to go with the factory internal/external balance configuration. I hoping it will save some money in balance time too.

I still haven't gotten a solid answer for what the stock piston style is, flat top w/ -4cc reliefs right? I'm not trying to bump up the compression anymore than stock besides using a thinner head gasket.

 

If you are fixed on assemblying it yourself, get a copy of this book:

http://www.amazon.com/exec/obidos/AS...0target=_blank

 

Hey man hes right i have the haynes manual which is awesome. But when it comes to the details on the bottom end their really not clear enough so then you would have to go to the lt-1/lt-4 rebuild manual, good suggestion. Man im over here in kuwait right now cant wait to get back to my Z.