Switching to Crate Class 604/602 witch one???

[1bbmft]

I'll be running (30 years driving experience in Street Stocks, Sportsman and a limited LM) in the Crate Class next season just wanting to know is the 150# weight break with a 602 (the track I run at gives this) worth the savings on price of a 604 motor or should I just get a 604 motor (the car i'm looking at has a 602). I have been told that the 604 has a big HP advantage vs the 602. Also does the motor as it comes from GM need the upgraded valve springs or are they already on it, like I said I'm new to this Crate deal.

[MM90]

My local track runs both in the same class but they only give the 602 a #100 weight break @2275# minimum weight. They seem to be all competitive with each other, I know of at least one 602 that won several features this year against the 604. I would think your track make-up might be a determing factor. If it's a momentum type track then the 602 should be fine, if it's stop and go the 604 might be a better choice. I think for the 602 to be competitive though it needs to be at the minimum weight allowed.

[Racer63]

I would spend the money and get a 604. All the new motors should have the new valve springs on them. If it's actually a new motor that is.... Brad Hibbard who is on here or Hendren could tell you what to look for on the heads to identify the new ones.

[brad hibbard]

the new engine has a new part # 19318604 VS the old at 88958604

also the new engine will not say GM Performance on the end of the heads it will have the chevy bowtie

only difference is the valve springs though

Brad

[1bbmft]

Thanks, yes it's a hammerdown (Kankakee County Speedway in Illinois) you only lift a little going in to one and hold her down outta 2 run the wall in 3&4 and then do it again for 20 laps. 2250# for 602, 2400# for 604 per UMP rules. Motor must have (never seen 1 car checked last year, I raced my UMP Sportsman against the Crates) GM seals so I'm guessing that these Hendren, Fast track and others are not legal??? Think I'll just keep the 602 and see how I do then If needed I'll get the 604.

[Matt49]

Another thing you need to consider is that the 602 motor itself is about 70 pounds heavier than the 604. You might have a bunch of trouble getting the tail weight back in the car and taking advantage of the weight break.

[ohsomthin]

small track the 602 is fine but remember there is no replacement for displacement, the 602 runs great with alot of gear and no carb spacer, with spacer its a little to get it off the corners and keep up. we ran a stock 602 at a 5/8 mile with all 604s and couldnt pull off better than a 9th. bored it 30 put flat top pistons in it done a little cleaning up in the heads and ran 5th first night out in a stock 604 ran 3rd upgraded the valve springs to still "stock" and ran 2nd but know that in a 18 lap feature with a caution at lap 9 the guy that won . "in a stock" crate was right behind us ready to lap us as we took the white flag he took the checkered directly behind us. I know set up is everything but is it really everything??? QA great (expensive) set of shocks make
s everything faster too

[lindsey97]

I would get a 604. You really need a 300# weight break to make them even. You usually can't get your car weight % to where they need to be with a 602. If you are running a slick track with hard tires you mightt have some luck, but still a legal 604 can get its power to the ground on a slick track.

[Matt49]

but remember there is no replacement for displacement

The difference between a 602 and a 604 has nothing to do with displacement. They are the same. It's better heads, better cam, roller rockers, better manifold, etc.

All that being said, I wouldn't buy a 602. It's pretty much a throw-away motor. It can cost almost as much to have one rebuilt as it does to buy a new one.

But again, the biggest factor to me is the weight. It's very difficult to get the balance of a car right at 2300 or 2200 with that all-steel motor up front.

[ohsomthin]

also the 602 has dished pistons and bigger cc heads . The 604 has flat top pistons and smaller cc heads so Bigger displacement? Maybe I figured that wrong but 9 .75 compression compared to 10.56 ,,,,more hp!! check That Matt49

[Matt49]

The 604 has flat top pistons and smaller cc heads so Bigger displacement?

No.
The compression ratios are different. The displacement is the same. Displacement of an engine has nothing to do with the heads or the pistons. I understand what you meant now but you're not using the right terminology. The 602 and the 604 have the exact same displacement.
http://en.wikipedia.org/wiki/Engine_displacement

[bowtech]

I've ran both and had sucess the biggest factor for me has been track condition dry slick I felt the 602 was fine but remember u can't beat the extra hp as u will soon find out crate is all about momentum if u can drive smooth and consistant lap after lap your gonna do well with either choice