gearhead0384

iTrader: (7)

I am about to buy a set of SDPC modified vortec heads. Now for my set up I only really need the .525 max lift vortecs but for an extra $5 I can get a set of modified vortecs that are good up to .600 lift. What is the difference between to two sets beside the obvious that one can handle more lift than the other. From searching around I keep hearing people talk about there vortecs can handle .575 lift with a roller cam. Which set of heads are they referring to? Either the roller cam allows more lift with the .525 or allows less lift with the .600?? I was just thinking that in case I decided to chance up my combination the .600 max lift heads would probably be the better bet, but I am not really sure. I just don't want to buy the wrong set of heads if I decided to go with a bigger cam in the future.

Below are the two sets of heads in question.

http://www.sdparts.com/product/SD806...25Springs.aspx

http://www.sdparts.com/product/SD806...00Springs.aspx


Thanks

Kevin

Supervisor42

Be honest with yourself about what the engine will be used for.
If it's going to be used mostly at the dragstrip get the .600 heads.
If it's going to be driven on the street the .525 heads are a better choice.
The shorter (.600 lift) valve guides will wear faster than the longer ones.
If you look at the cams with up to .525 lift with 1.5 rockers, they are more than adequate to get you below 12 miles per gallon on the road.
If you get the urge to use 1.6 rockers and go above .525 you can use offset locks and shim the springs.
When you come to your senses and put a streetable cam back in it, you will still have the longer-lasting guides.

gearhead0384

iTrader: (7)

So the valve guide hight is the only difference. I have been searching every where to find what the differences are between the two. What do you think the life expectancy difference of the valve guides is between the two?

jtrescot

I could be completely wrong here, but I would expect that there should be a difference in the valve spring specifications between .525 lift and .600. I see that they both mention "Z28 springs", whatever they are.

Also, all the head flow data that I have seen on Vortecs show them choking up much after .500 lift. If you are thinking about a cam larger than that, I would keep it in mind.

gearhead0384

iTrader: (7)

I am going with http://store.summitracing.com/partde...8&autoview=sku as my cam. Its not to o crazy just enough for me. I just want be able to go with a larger cam in future if I wanted to, that is after some decent head work.

Kevin

Supervisor42

To quote the SDPC, they cut the "stock" (.450 lift) guides down for the for .525 lift heads and put better springs on.
For the .600 they cut the guide down even further and change springs again.
If it didn't make a big difference in longevity they would put the .600 lift guides in all of their heads.

gearhead0384

iTrader: (7)

Thanks alot guys for clearing this all up for me.