Crate motors

[hipower17]

if you bust a block 604 or 602 is there a gm block that is a legal replacement or can a bare 604 an 602 block be bought from gm?

[brad hibbard]

both engines use the same block and both engines came from the production line so to answer the first part of your question ---YES you could possibly find a block from another application that will be legal
the problem is usually they are wore out and crate engines have no provision for an overbore.

second part of your question is also ---YES
here is a link to a new block from GM ---they are finished and ready to assemble after a quick wash---and they come with cam bearings
http://race-1.com/i-18113602-1010512...main-seal.html

don't be confused by the description noting 4.00 to 4.030
they are 4 inch and can be bored to 4.030 for other applications


Brad
www.race-1.com

[dirty white boy]

brad what production blocks can be used? any one piece rear seal block??? our track owner encouraging teams to build up there own 602s and local engine builder check them n seal them! seems that would cost more in parts than buying a new one from gm

[brad hibbard]

the 602 block was commonly used in pick up truck applications (late 80's thru the 90's) is what I have been told by dealership parts people

look for casting # 10243880 on the back passenger side of the block (below distributor)

basically the entire engine is a production engine with the exception of the intake, oil pan, valve covers
I am not sure about the camshaft but it may also be the same in some applications

Brad
www.race-1.com

[dirty white boy]

thanks brad!

[hipower17]

do these only come with 4 bolt main caps?

[MLR19]

The crate motors are 4 bolt main caps, the 880 block from a production car could be either 4 or 2. GM makes a replacement block & also a replacement short block for the 604 (search ZZ4 Short block) I think the complete short block is available in the $2200 range.

Short Block Part # 12561723

[a25rjr]

Heres one from pace performance at $2149,free shipping, and $250 rebate.

http://paceperformance.com/i-6255345...ck-engine.html

[dirty white boy]

why wouldn't this zz4 work for a 602?

[MLR19]

I believe the 602 uses a different piston

[brad hibbard]

The 602 has a different crank and different pistons

GM just dropped the price of the 604 short block and it has changed our thought process going into rebuild season
any time an engine needs pistons it just makes sense financially to use a complete short block

MLR19---thank you for the heads up on the casting number possibility of being either a 2 or 4 bolt main block
I did not realize that

Brad
www.race-1.com

[hipower17]

what are the difference between the newer alum. head and the older, and are there any hp to be gained with the newer head?

[brad hibbard]

Depends on what you call the "newer head"
the 604 aluminum head has always been casted and finished with the same specifications and dimensions
with the exception of the spring package there has never been anything intentionally changed
many people talk about the logo change on the end of the head----it was exactly that---a logo change
nothing else was changed

if you go back before 2009 the valve job was not real good but that is fixable

the heads certainly look nicer these days but we do not see any gains

the bee hive valve springs are certainly a plus but other than that they are all pretty close

Brad
www.race-1.com

[hipower17]

thank you again brad for the info

[brett4]

Brad,after how many races do you suggest new pistons???

[hipower17]

i wondered that to and whats the max bore for this.

[MLR19]

Here's what I have found with the 604 pistons, keep RPM 6800 or lower (or more importantly no valve float) and stay away from detonation and overheating ,they will last a long time.
Over 6800 leads to valve float and also loads the wrist pin bore excessively and the piston life is shortened considerably. Unfortunately the racing is getting close enough that someone willing to over rev his engine has an advantage on corner exit & restarts (but shortened engine life). I would love to see all tracks institute a RPM rule .
This is similar to the tire problem, at the tracks where we race if you aren't bolting a new RR on for every feature, and LR every other ,you are giving up speed, because there are multiple guys doing it. Same with engines, abuse & replace as necessary. These cars are so hooked up on soft tires that they are working these engines beyond their designed purpose. It's not uncommon to run a 10 lap heat race without lifting. I'm amazed they last as long as they do.

[brad hibbard]

Have to agree with the statement from MLR19
the guys that insist on running 7000 to 7200 or actually anything above 6800 are significantly shortening the life of the entire engine

let me add this to be more direct about the question
top ring land wear is overlooked by many rebuilders
top ring lands will wear more quickly with high timing, low grade fuels and poor air cleaner systems
a piston can look perfect---the skirt can measure perfect---but once the top ring land is worn it will have what is called ring flutter
when the ring flutters it wears the ring, block and piston at a very quick rate
I am sure many folks can remember having an old worn out engine rebuilt and the thing runs great for 5 races or so and then it is back to lacking on RPM, using oil and over all down on power.
this was because the ring flutter wore the parts quickly.
the GM piston used to be $100 each which made it a hard choice as to whether or not to replace them
They now are in kit form and price out substantially less
In our shop we find that almost always on the second rebuild the engine will need new pistons due to top ring land wear

hope some of that helps
Brad
www.race-1.com

[CCHIEF]

Ring flutter = poor sealing at max RPM too.

[hipower17]

on the rockers can u run anything other than 1.5's ratio?