1970fbody

iTrader: (3)

Will they work with a stock bore 5.3?

BlackLS1Bird

iTrader: (2)

My 2005 Silverado with the all aluminum high output 5.3 came from the factory with 243 casting LS6 heads on it. Should be fine.

777

iTrader: (21)

Yes, heads are interchangeable. Just know that your compression ratio will change (will be lower) based on the difference in volumes.

1970fbody

iTrader: (3)

Thanks for the replies. I continued researching after I posted that question and found out all gen 3 heads are interchangeable. I guess the next question is more involved.

I want to install a 5.3 in my 1970 camaro. I have a set of 241 heads. I know now that simply installing these heads will drop compression a bit. (not sure how much). I also know using pistons from a 4.8 will bring it back up.

Is the drop in comp from the 241 heads enough to warrant replacing the stock 5.3 pistons with the 4.8s?
The plan for the engine is a cam upgrade, ls1 intake, and moderate overall performance improvement.

BlackLS1Bird

iTrader: (2)

I believe the 4.8 pistons are smaller diameter than the 5.3 pistons and therefore wouldnt work in the 5.3 block. I may be mistaken on that but im pretty sure. Anyone who knows for certain please chime in on that.

BlackLS1Bird

iTrader: (2)

^ Revise that. Did some research. The 4.8 pistons are the same diameter but the crank stroke is different. I think you will be ok as long as you take into account the difference in piston type between the two engines. And remember that the 5.3 has a total of .352 inches more stroke which equates to .176 inches higher at TDC. As long as you make sure you have proper PTV clearance, you will be ok running the 4.8 pistons.

1970fbody

iTrader: (3)

So considering the parts I have, or will have soon. A stock 5.3 iron longblock a set of 241 heads. Would you use the 5.3 heads or the 241 heads?

Maybe this is a better question, with the items above as a base, how would you build this 5.3? Street driven, auto cross, possibly open track events once or twice.
1970 camaro, manual trans, built to handle a road course. But mainly used for street fun.
I'd like to keep the efi.
What intake, cam, which heads from above, which injectors,
Would you change anything away from stock in the bottom end? Oil pump, bearings, rings, 4.8 pistons for better compression?

This will be my first ls build. Idle quality can be rough. But driveability should be good. No power adders,

Last part of this is that I really want to use as many factory GM parts as possible.

I'd love to hear opinions on this. Thanks!

garygnu

it mite be cheaper to leave the short block alone and just mill the heads .what head gasket will you use ?

1970fbody

iTrader: (3)

I have not decided on a gasket yet. It's going to depend on the condition of the shortblock I end up with. If I need to go through it I will swap the pistons. If not then maybe mill the heads. I still need to choose a cam, intake and TB.

BlackLS1Bird

iTrader: (2)

I would probably have the stage 2.5 work done to the 5.3 heads. Since it is going to be an NA street/auto cross Motor I would select a cam that has a broad yet slightly higher power band (2400-7000) or something like that since with auto cross you are in and out of the throttle some much. The only thing with that is proper gear selection as to not fall below the lower power band in the turns. If you can gear it correctly to keep the engine in the higher rpm range but leave some space for acceleration before the next turn that would be the ticket. Come out of turns at about 3K and get into it hard and be maxing out just in time to brake for the next turn. Definitely run a little higher compression so when you come out of a turn on the track and hit it, you have good power all the way through the rpm range. Im thinking something like 10.8:1 compression. It is premium gas friendly for the street yet will make nice power on an NA motor. For the pistons, I think stock 5.3 are slightly dished and the 4.8 are flat top. I would use the 4.8 to increase compression as long as you wont run into PTV clearance issues. Just keep that in mind. Might have to have reliefs cut in them. I would upgrade the rods since it will probably see a lot of high rpm, high power time on the track. The stock crank will be fine for the application. Stock piston will probably be fine but wouldnt be a bad idea to go forged. Along with the cam and head work, I would definietly upgrade the rockers as well as good heavy valve springs, Hardened push rods, and a high flow oil pump. I would personally do a rollmaster double row timing set as well. For an intake, for sure the FAST LSXRT truck intake. They may be a little overkill, but 42 lb. injectors just so you have plenty of fuel and leave some room for more if needed later. Couple all of this with some 1 3/4" long tube headers and a nice flowing exhaust system and/or cutout. I know that stainless works and american racing now make long tube for the GM trucks. Im not sure if anyone else does. I havent really seen a lot of companies make long tubes for the truck, mostly just shorties that replace the manifolds. I hope I was able to offer some insight. If anyone else has some differing opinions, by all means post them up and we can see what we can offer the OP for good sound advice. Oh yeah, Merry Christmas everyone.

1970fbody

iTrader: (3)

Fantastic info! Thank you very much.

I will look into the heads and intake and cam.
You mention truck headers, are they made just for the 5.3 heads? Or for a truck chassis? (the engine will be in a 1970 Camaro).

BlackLS1Bird

iTrader: (2)

You know what, I forgot you were transplanting the engine. The ones I mentioned are for the truck chassis. You will need ls style headers built for your year of camaro. There are a lot of companies that do swap headers as well as standard ones. Look around on the internet a bit and see what you can find. I'll look around too and let you know what I find.

1970fbody

iTrader: (3)

Stainlessworks has or will have soon a set. Edelbrock stopped selling the set they had. And I thinkDynatech has a set through summit. Plus Holley/Hooker offers them to I believe.

gearhead67

I'm also doing a build of a 5.3, and I'll be putting mine in a 67 Camaro. So I've been researching ways to build it on a budget. From what I've read, the 5.3 heads flow as good or better than LS1 heads. So with some porting, you can get better performance and not have to buy another set of heads. I didn't know about the difference between the 4.8 and 5.3 pistons - thanks for the info. I may use 4.8 pistons in mine if PTV clearance is good. For a cam, I'm going to use a z06. Nothing as aggressive as a lot of the guys on here use, but should be a decent cruiser. I also picked up a used LS1 intake, but still keeping an eye out for an LS6. Like you, I'm trying to use oem parts. And I'm trying to keep the cost down, so I'm constantly on the hunt for good used parts. You mention a manual trans in the Camaro. Is it going to be an old 4 speed or a t56?
pd

1970fbody

iTrader: (3)

There was a great build on a carb.'d 5.3 in camaro performers, chevy high performance or super chevy mag. I need to find it.
Anyway,.they used the 4.8 factory pistons which have coated skirts to bump the comp up a bit. With a ls1 carb. intake, trick flow heads and a small cam they hit over 490 hp.

I'm going a little different on mine. Ls1 heads, ls6 intake, moderate cam, 4.8 pistons, stock bottom end, not sure what TB yet, although I have a brand new one from a l92 but have no idea if it will fit. If not it's going up for sale.

When I find that article I'll get in touch and get you the details.
There is no reason I need to go aftermarket anything on this. I know I can build a decent, reliable and strong street motor with factory parts. Plus if anything ever breaks or wears out I can find parts everywhere easily.

I'm not sure on the trans. Maybe a tko or a new RS500 from Kiesler if they ever release it. If I find the right deal on a t56 I would use that.

BlackLS1Bird

iTrader: (2)

Yeah, buying parts on here and running LS1/6 parts will definitely be a good budget minded way to do things. People get rid of that stuff dirt cheap. It will still make plenty of power if set up correctly. Good luck with ya'lls builds. If you want any more opinions or advice just let me know.

1970fbody

iTrader: (3)

Thanks, I appreciate that. My engine plan just took a turn. Well the budget for it did. The tranny in my truck gave up reverse, second and overdrive last night. So after I pony up for that I can move forward on the camaro. It's a 4l60e. It made it 220k! Amazing!