tylercamaro

iTrader: (1)

so ive been hearing vortec heads are the best flowing stock heads gm made, or something like that, so while i dont know much about them so any different years/or makes of vehicles flow better than others?

zraffz

Stay away from the 3/4 ton and 1 ton vortec heads that end in 906 casting. They are supposed to flow worse then the other casting.
Vortec heads are great but the problem with them is they can't run cams larger then like .420" lift without having the valve guides cut so your flow is limited in stock form.

tylercamaro

iTrader: (1)

what years?

stealthroc89

906s from the HD and 1-ton have a single angle grind on the exhaust side, which hurts flow, 3 angle on the others. The castings are the same though .460" lift is the highest you can go safely. Theres a "ghetto grind" method in which you grind the bottom of the stock retainer up to 3/32" to free up some lift, about .530" safely. This also requires you to remove the spring dampner.

vetteoz

iTrader: (13)

http://www.chevymania.com/tech/vortec.htm
http://www.chevyhiperformance.com/ho...458/index.html

GM vehicles with L31 engine

* 1996–2003 Chevrolet Express/GMC Savana full-size vans
* 1996–1999 Chevrolet/GMC C/K full-size trucks
* 1996–1999 Chevrolet Suburban/GMC Suburban
* 1996–1999 Chevrolet Tahoe/GMC Yukon
* 1999–2000 Cadillac Escalade

vetteoz

iTrader: (13)

Without mods

https://www.thirdgen.org/forums/post...681-post1.html

stealthroc89

Never posting from my phone again lol. Thank for finishing what I couldn't vetteoz.

tylercamaro

iTrader: (1)

so i can basically put these on any size sbc, correct?

zraffz

Yeah. you will need a vortec style intake manifold though... I saw a build somewhere of a 400 small block with vortec heads and it made unbelievable power; like 450 horse and 550 ft lbs.

ncracer409

Comp cams makes a bee hive springs and retainers to run a large cam with mo heads mods a bit pricey about 275 i run these springs with 480 lift cam and still have retainer spring clearence

stealthroc89

Vortecs have a lift limit, depending on the casting it can be more or less since each head may be slightly different from another. Most pro's suggest keeping it below .510" so you get the most out of the combo, otherwise the ports may stall and lose power. I'm running a .489" lift cam with 1.6 roller rockers (.521" total) and I dont feel any drop in power up to my 5800rpm redline, I've taken it to 6100rpm and let off because I'm not comfortable with going over the cams suggested redline. It's actually 5600, but the 1.6's gotta add some rpm, right? Either way, its a street head and should be paired with equal parts.

89redliningRS

If they are going on the 305 you have listed then you should mill them down atleast .030 to keep the compression ratio close to what you have now. I paired mine with a used LT1 cam and an Edelbrock performer rpm intake and have pretty good results. Only thing I did was mill them down and use the .010 thickness stainless head gasket. Kinda wish I would have done the beehive spring mod while they were off to go to a larger cam later but I'm still pretty happy with them.

tylercamaro

iTrader: (1)

actually they were gonna go on a 307, but that im building, then later on id use em on the 305 or somthing bigger down the road