I've got a chevy 350 in my car. It's from a 1970 corvette and it's got some standard cast iron 76cc chevy heads on it. In an attempt to get some extra umph, I want to swap those heads for some vortecs, mainly because they have 68 cc combustion chambers and better swirl characteristics so I'm anticipating a gain of 30-40 HP and better gas mileage.

I pulled some 062 vortec heads from a 99 Yukon and I'm in the process of cleaning/rebuilding/upgrading them. The goal is to get some more horsepower but I'm not looking for some screaming pavement pounder here. I just want to make the most of the opportunity whilst the heads are off the car to get them cleaned up and possibly mildly ported to go on my daily driver. I've never done this before so I'm looking for some general advice.

The plan is to get them checked for cracks and then hot tanked. But after that, I'm not sure.

Will replacing the stock springs with "beehive" springs, make any difference? What about z28 springs?

What are the advantages/disadvantages to getting stainless valves? Is it wise to just re-use the old valves?

Are there any alternatives to the stock self-aligning rocker arms that won't break the bank?

I read this in an advert for a 383 stroker: Heads angle milled 0.55. What does "angle-milling" mean?

I know you can get screw in studs instead of the push in ones but that involves a guide plate and non self aligning rockers which pushes up the price a lot (I'm guessing) which is something I'm trying to avoid. Same with machining them to accept 2.02 intake valves. It's just too much for my application and pushes the price up to high.

I want to keep the price down as much as possible and I'm grateful for any ideas on what to do to these heads. I'm open to any and all comments.

 

Beehives are a great choice. With a garbage stock 70's flat tappet, something like hte LS2/LS3/LS6 GMPP "Yellow" (now painted blue, pn is 12499224) beehive springs are a much more affordable option and will save you concerns about valve lift later when you move these heads onto a decent roller block with flat top pistons. Retainer to use is (Comp Cams)787-16 with the GM springs. Regular aftermarket beehive springs will fit too, but you dont need them. They will give you around 90 lbs seat pressure and 250-300ish open pressure depending on valve lift and installed height. Do some research on those springs and find out what installed heights they need to be at and invest in a valve spring height micrometer if you need to.

Other than that, have a machine shop do a valve job for you and test for cracks and you should be good to go.

Those springs will work well with an LT4 hotcam one day, but I wouldnt go with anything more aggressive than that with them.

The beehives give you much more guide to retainer clearance, around .050" more I believe. So your max lift goes from around .470 to .520 or so. This give you a LOT of extra breathing room to upgrade later. Beehive springs have less valvetrain mass due to the smaller retainer also. But the RPMs the factory cam is going to operate at... you wont really see a difference.

I'd honestly just let the machine shop pick valves for you. You dont need anything exotic. I would also recommend against larger valves, there's not much benefit (in fact you're a lot worse off) without porting in addition to larger valves. Treat larger valves as a repair operation in your case.

With the factory cam, you're fine with the pressed in studs. You may want to consider going the guideplate route later on if you ever want to put those heads onto anything serious or you want to make a big cam upgrade to that engine, but it's always something you can do later on. That pushes the price up considerably and it quickly becomes a better option to get some aftermarket aluminum heads instead. So handle that when the time comes unless you feel compelled to future proof it.

Angle milling and all that is to increase compression by decreasing chamber size. I would tell you to not do that. Depends on whether the pistons in that old 350 are flat tops or dished. There's no telling what that engine is really from and 60's technology wasnt that special, 70's tech was even worse. If you have flat tops in it, 64cc chambers is fine. If they're dished then you're in a pickle... But since you're not upgrading the cam while you're at it, even if it's lowish compression, the vortecs will be fine with ita nd you'll still make more power. Higher compression isnt going to help much without a cam upgrade, and just going from larger chamber heads to smaller chamber heads will be a nice boost. I'd avoid milling them at all unless they're warped (in which case I'd suggest looking at other options).

 

Thank you InfernalVortex for the awesome reply! I found a lot of useful info there. Just to clarify, the camshaft in the car currently is an "RV" cam.

 

"RV" cam...Is a term given to a camshaft that has a touch more duration and lift than stock, but the actual specs are anyones guess. I could think of about 10 cams off the top of my head that would work well in a "RV".

 

Then all the assumptions I made about the camshaft are entirely correct. You wont see the benefits of going crazy on these heads, so if you just wanna freshen them up on the cheap side you can get away with it.