My vortec heads currently have 1.94 int /1.50 ext valves what kind of gains could be expected from 2.02/1.60 valves in these heads if any or is it not worth the time and machining. if any of you guys has done this to your vortec's already please respond.

thanx

"KB"

 

My understanding is it's not worth the money and time to put in larger valves in vortecs. All the testing that I have seen done says to do a 5 angle valve job and back cut them 30 degrees for the best flow. That is what I ended up doing with my vortecs. I also pocket ported them before I stuck them on.

 

I have a set of vortec heads that I had punched to 2.02/1.60 approx. 4yrs. ago- before they were popular or cheap. These unfortunately have not yet made it onto an engine. I have another thread under "Aftermarket Prod. Review" about Vortec heads. These heads were also bowl blended to unshroud the back side of the valve. I wish I had the money at the time to have these flowed, but I thought at that time I was the only fruit-loop around even screwing w/ these and well who cares how they work besides me. In my opinion (take it or leave it) bigger valves and bowl blending will always help some...unless you're dealing w/ 305 heads (there is no room to unshroud) . I can't prove my heads are better than stockers but if I was a betting man I'd bet on mine. As far as if its worth it $ wise- just depends on how good you and your machinist get along. I'm in pretty tight w/ my guy but the entire conversion for bigger valves, springs, studs, guideplates, and machine work was in the $500 range. I know that sounds crazy to do today- but remember these heads were selling (w/ these mods already done) for about $1200 back then and I only had $250 in my castings to begin w/, and I needed to purchase new valves and have a valve job to even get them usable. In todays market at slightly over $400 a set complete- I doubt I could justify the extra expense.

 

94-6spd did you notice a significant difference after you did your work to them or were the gains so small it was better left stock?

 

KB,

Just remember, that if these heads with 1.94"/1.5" valves are on a 305, then you literally CAN'T put 2.02"/1.6" valves on it. No way! The valves will hit the top of the cylinder. The smaller valves had to be there because they "fit" inside the diameter of the cyl. Larger valves will only work with the larger bore 350.

Good luck!

Poncho

P.S. I've heard there is somebody making canted valve heads that will angle the valves into that small space, but they would be prohibitively expensive, I think!

 

Well, I did all of the work before I put the heads on. I could tell a huge difference between the old heads and the vortecs. The old heads were from my GM Goodwrench crate motor. They had 76 cc's and from what I understand were a smog type head. Similar to the 882's.

 

Here's food for thought. With 305 vortecs with 1.84 valves my car would run deep 13's uncorrected. My friends firebird with stock 350 vortecs with 1.94 valves didn't run any faster at all, in fact most times I beat him! Also...those 305's I had had REGULAR chambers, no heart shape.
Chris

 

Poncho TA I'm using a 350 .30 over would this be concidered a large enuff size.

 

KB,

Sure! 350 w/ 2.02's good!! Only with 305's bad!

Sounds like a nice build up, keep us posted on the results!

On a different note, has anybody had any experience with the 305/331 stroker kit? I'm thinking about doing this but would like some feedback from those who have actually done it!

Thanks guys,

Poncho