I am planning on rebuilding a 350 ('89 block). I am looking at the vortec zz5 heads (up to .550 lift), 64cc Chambers, 170cc Intake Runner, 1.98" Intake, 1.50" Exhaust

1.)What cam would be a good choice?
2.)What ratio RR's?
3.)Best size carb?


Rob

 

Assuming a stock converter and your existing gears:

1. Vortec heads in general like an asymmeteric cam, with a larger exh lobe, because the int port has all this great flow but the exh port is the same old sucky stock SBC exh port. For the gears and converter you have, use a Comp XE262 or Lunati Voodoo 60102. If you have the roller lifters, look at the Comp "503" grind except have it custom ground on a billet core with 110° lobe separation, or the Voodoo 60121.
2. 1.5
3. 650-750. My personal fave to just up and buy new is the Holley 6210 (spreadbore 650 man sec) which willr equire an intake that accomodates spreadbore carbs. You might also consider a 3310 or a Street Adventure in that size range. DEFINITELY NOT an Edlebrock.

Use pistons that DO NOT add the usual "rebuilder" extra .020" of deck clearance (eliminates virtually ALL cast pistons, most hypereutectics, many forged including TRW/SPeedPro). Have the block zero-decked to the rotating assembly. VERY IMPORTANT.

 

Is zero-decking the block to the rotating assembly not standard practice? What potential harm can be done if not done this way?

 

No unfortunately it isn't.

Stock, the pistons fail to reach the top of the block, by about .025", with about a .010" tolerance from front to rear on either side or from side to side. It is almost never less, and may be as much as .010" more (.035" total). This HUGE variation in deck clearance is one of a very long lits of reasons why some factory motors just seem to run better than other, supposedly identical, ones.

Aftermarket "rebuilder" pistons standardly add about .020" to this. (pistons fail to reach the deck by .045" - .055") They do this because if a block has been heavily decked, for example to replace severe scouring due to a blown head gasket that was driven anyway for thousands of miles, the piston runs the risk of hitting the head. This is commonly considered bad. Much worse than the opposite error; parts don't break and motors explode if the compression is a little low. Usually nobody even notices.

Needless to say, most people fail altogether to take this into account when "calculating" their compression. But the effect is MASSIVE: as much as A FULL POINT sometimes. If you see some n00b posting that his CR is "9.87:1" or some such, you can almost bet your paycheck he didn't include it, because if he was knowledgeable enough to have done that, he would probably also be knowledgeable enough to know that it can't be "calculated" that precisely in the real world.

"Measure with micrometer, mark with chalk, cut with axe"; except in reverse.

Most corner parts store machine shops will deck a block by shaving x .001"s off of it. They won't know how "tall the rotating assy is (i.e. how far the pistons are from the deck at TDC), won't know how skewed the block is (they're usually pretty horrible), and so on. This is a racing machine shop type of thing.

It is worth EVERY PENNY if you care how your engine runs. It's one of the reasons that some people spend giga$$$$ on a wonderful parts list, and can't outrun a stock 305: their machine work was sloppy. Covnersely, it's why some people can take a bunch of nothing and KICK YOUR A$$ with it. Which one of those types would you rather be?

 

What's your budget? Do you want wild or mild? His cam suggestions are good for a very mild setup, but those vortecs can push out some power and you've got 550 lift springs as well to help that factor. The only thing that bothers me is the runner size, but that's not by any means the most critical factor as it matters how the air flows, and not necessarily how much. Great start though by all means. What casting are those heads?

Mild?Comp XE268, longtubes, 3.42's-3.73 gears, 1.5 rollers, Holley 650 mechanical or vacuum secondaries, Airgap RPM intake manifold, stock stall will work with the 268.

Wild (street/strip)? Comp XE284 (the XE274 is what I have and mine is not mild at all.. check that one also), longtubes, 3.73's-4.10's, 1.5's or 1.6's (check lift #'s) Holley/Proform/Quickfuel/AED 750 with mechanical secondaries. I suggest annular boosters - but it's not a NEED.. just a really nice addition. Airgap RPM or one of the nice Single planes.. I still think the Airgap RPM is tough to beat all around, though. Run a 3000 stall converter and make sure you absolutely get a transcooler REGARDLESS of mild or wild. Heat = death.

For what it's worth - there are many cam vendors here that can custom tailor a cam for your application and you'll be paying the same amount. I'm sure one of them will chime in at some point.

Oh, and I forgot to ask - do you know what compression you're sitting at? That will also help narrow down what cam you may want to choose. Forgot to mention - don't be afraid to go with a solid cam, either. I went with a hydraulic flat tappet but my next will be a Lunati solid.

 

I am looking for a mild build, hoping to spend 2500-3k, including intake and carb. I also need to rebuild the 700R4, so yeah, money needs to be spent wisely. As far as CR, how would I calculate that?

 

Alright. Another thought. What kind of power gains would one hope for with the 12530282 crate engine (stock vortec heads) and a Comp cam # 08-411-8 (210/214, .474/.474, 111)?

 

When picking a cam, always make sure to double check the maximum lift your heads can accept.. I went with the 60101 from Lunati, and my 083 heads needed some clearance issues clean up.

 

Comp cams recommended this one. Are you saying to manually check the clearance?

 

I would do a 224/224 duration minimum with less than .550" lift obviously.

Do a 1.6 rocker if it gets you closer to .550".

Have a custom carb built by pro systems carbs. its the best money spent.

Air gap rpm vortech is an awesome intake. port match it as best you can.