New to this forum, asking for a little help.

I have an 89 rs and pulled the v6 out and was planing on doing a 350 carb swap... This is my first engine build and getting a little confuse on what cams to use, heads, pistons, etc.

I plan on have the block bored .030, and install vortec heads.. Now my question is what would be a good cam for the set up? I plane on using either a 600 cfm or 650 cfm carb and a vortec compatible intake. What would be a good cam and if need be what work should I have done on the heads? I'm use an 89 l98 block a ditch the tune port and would like to keep this block a roller cam set up.


Again inputs, opions and greatly needed!!! Thanks!

 

Flat-top pistons; regular head gasket; have the block decked to take up most of the deck clearance (how far "down in the hole" they are at TDC). Choose pistons that minimize that in the first place: virtually ALL cast ones, MOST hypereutectices (most notably, including the SPeedPro ones) and ALOT of forged ones (notably again, the TRW/SpeedPro ones) all add .020" of deck clearance to the already gigantic stock .025" or more; meaning with any of those, your pistons will be close to .050" below the deck at TDC.

A roller cam with about 218 - 224° of intake duration, and about 10° more on the exhaust. A Comp XR276 would be about right. Performer intake, Holley 6210 (650 CFM spreadbore... Holley performance with Q-Jet gas mileage), a good-quality NEW distributor, and of course, good headers, cat, & cat-back.

 

^^ What he said.

I'm running the xr276 in my 383 and its a bit small, but has a pretty nice idle to it. With the smaller cubes, it'll be a bit more aggressive.

I don't know how much reading you've done into Vortec heads, but there's a lot of hype out there. There's two casting numbers, and one is regarded as better than the other. This isn't true, they're both used to make the same assembly.
The xr276 is on the brink of the max valve lift that vortec's in factory form can handle. The valve stem seal boss may need to be machined a little deeper to accommodate the higher lift, or you may be fine. You might also make a little space depending on which retainers you use. Vortec heads need pushrod guides installed or you must use "self-aligning" rockers. Do a little reading on this, as some who have used the self aligning rockers have had the lip on the edge of the rocker tip break off on the inferior brands of rockers, and the name brand rockers are significantly more expensive than the non self aligning variants.

Figure out the compression ratio of whichever pistons and bore size you plan to use. On a 383 with flat tops and 0 deck, it ends up being pretty high, but you may be able to get away with pump gas on a 355, (otherwise, there's always e85)

This is all from my memory when I was considering Vortecs, so take all of this with a grain of salt, and DO YOUR OWN RESEARCH.


This next part is just my opinion, feel free to ignore it!
Ditch the Vortec idea, and pick up a set of budget aluminum heads (Patriot has come a long way). Once you get done pricing out the special stuff needed to make the vortecs work (new vortec intake vs. used edelbrock performer, SA rockers vs standard, cylinder head machine work, etc), you'll find out that new AL heads aren't so far out of reach! Also, don't be so quick to ditch EFI (notice I didn't say TPI )

 

Thanks! I forgot to say that I'm building thins on a budget too....all depends on what I get from taxes. I think I'm still going to go with the vortec head only because use their cheap, easy to find, and I heard their a good upgrade since they flow better then the l98 heads that I got, I had out the l98 block in my rs and got sick and tired of wording it in, hence is why I'm going carb... I still have the intake and all

 

Wiring, not wording....my bad lol

 

The relative new news is Patriot went out of business.That the Freedom series heads and all the problems with them finally caught up to them.Not sure if they where going to get bought out or not.

Careful piston choices is important.Especially when considering the chamber of Vortec heads.You need to keep below 9.5 SCR and 8.5 DCR.E85 in some places is hard to get.D-shape pistons over the deep dish ones is the way to properly build a stacked parts engine.Quench<a edit> should be set at .040 to .035 without exceeding 9.5 SCR or else your leaving alot on the table.

 

Thanks I will keep that in mind, I'm trying to get all my reaserch and inputs in before I start the build, as is this is my very first build....never was a mechanic but I wheat to school for collision so I do body work....just not engine!

 

I hadn't heard that Gary. Well it's AFR's or bust then lol.

 

Anything thing else that I would need to have to the block/heads for this setup? And with the vortecs, should I have them machine to accept the the comp xr276 cam? What about push rods? Will the factory work or should I get a new set?

 

Pushrods are cheap, replace them.

You can check clearance on the heads if you have them. They may or may not need machining.

 

I haven't picked up the heads yet, I will be here in a week or so, how can I check for clearance, and how should what size push rod to get, or how to measure the length I need?

 

When you mock them up on the block to check valve clearance, you will be able to see how close the retainer gets to the seal. You can mock up with the factory pushrods, and if the rocker tip stays centered on the valve stem, you're golden. If not, get the next step up or down in length. I think I ended up getting .050" longer. Yours should be pretty close to stock length too.

Keep in mind you will need bigger springs with that cam as well. I don't think the spring pocket needs to be clearanced, but if it does, consider beehive springs instead.

 

Cool man, thanks! Now another ? Is the distributer that is factory on the l98 (small cap) with that work? Or do I need to switch to the big cap?

 

The timing on that dizzy is computer controlled, I'm not familiar with what other distributors are available since I'm all EFI, but an OEM HEI would probably be the simplest.

 

Ok, for fuel, would I be able to run the factory pump (v6) but run it to a reagulator since carb motor don't need that high of a pressure?