Javier97Z28

Who knew they were so different?

These are a set of 643 casting I purchased on the left next to the 561 castings I pulled off my car on Saturday.

The 643's are on their way to Lloyd..

SStrokerAce

Huge diff huh....

On the bench they are way different in stock and ported forms as well.

bret

Javier97Z28

Go figure, that being said.. the 561's look more "finished".. not sure how that affects thing in the flow department really. I think I read a post before where either you or Lloyd mentioned about 10% more cfm out of the 561's in stock form.

Anywhooo, Bret I'll be contacting you later this week or early next week to order my supporting parts.

SStrokerAce

Cool... yeah the 561's flow better out of the box and they are lighter

redemn93

now i see why they say the 643 casting have more room to port. the design is completely different underneath. i can also see how they are lighter.

Javier97Z28

Well I wasn't really posting it as new information, I thought I'd let people see 'em side by side if they had not gotten the chance to yet

I hadn't run into a pic post of them side by side, I'm well aware of the search feature and use it daily

SStrokerAce

Actually it's really good that someone posted pics for guys finally... the cores have been discussed but not with pics to identify them.

Bret

CreatiVe2

pretty nuts, im glad i picked up a set of 93 heads to have lloyd port them ;-D

roughneck427

yeah i knew there was a light weight casting now im wondering you know people have claimed the aluminum LT1 head combustion chambers are 54 cc and other people said they are 58cc i have a set of 643 and before anywork was done they were 54cc im wondering if the 561 castings are 58cc's and thats where people are getting that # from hmmmm???

SStrokerAce

No they are all 54cc.

The big deal is to make sure you can tell the castings apart so you can get the right set to send to the porters. The internal parts of the port are hard to see the differences unless you have a well trained eye.

Bret

Colin91Z

So how much more flow are the 643s capable of over the 561s?
Mine are 561s and I thought they turned out nice:
http://web.camaross.com/forums/showt...highlight=Flow

SStrokerAce

The 561's flow less ported because they have less material in the areas where taking material out helps flow. I've seen 275-285 out of the 643's

Hotwire

Shouldn't it be the 561s flow less ported because they have less material?

SStrokerAce

Yeah I screwed up. Good catch

Hotwire

Was just making sure. Lightly read the thread, had to go back through and actually make my few leftover brain cells work for their keep to be sure.