Alright, how does one switch to a larger valve? Do you just plop them in there, or do you need some machine work(I figure)? If so, is it possible to do at home or can it be done without paying $2000 for a friggin CNC job.
And yes, I know, why not just spend 2 grand here, 2 grand there, well I don't have it.

I decided to go with the home porting job, and I am going to get some aftermarket valves, so I figure, why not get bigger ones to flow more air. :D

 

2.00 / 1.56 are the largest valves you can put in there and still use the stock valve seat. They also perform the best on most 350 applications. You can gain a little more high lift flow by going with 2.02/1.60 valves, but it comes at the cost of a lot of mid lift flow. Since your performance will really depend on the area under the flow curve it's best to maximize the mid lift.

You will have to have a shop do the valve job for you, unless you have a valve grinder. I could tell you how to cut the angles for peak mid lift performance in your application, but unfortunately it's a trade secret from my days of working at Total Engine Airflow. I can't give up their methods like that.

In any case the valve job is very important, so is the type of valve. Stay away from Manley for LT1 applications, they just don't flow as well. Get some Ferrea valves if you can, stainless, swirl polished, undercut stems.

To install anything larger than 2.00/1.56 you will have to pay a shop money to make it work and you will likely see a flow decrease for your trouble. Oh and a helpful hint, don't go trying to hog out the ports. Bigger is NOT better. Get them as smooth as possible for airflow dynamics while retaining the smallest port possible. If you have two different size ports that flow the same volume of air, the smaller port will have higher velocity which will mean much better driveability. :cheers:

 

So, to put in the 2.00/1.56's I'll need a valve job, ok. I guess that is what the 3-angle/5-angle stuff is all about. Cool, I can afford one of those.


About what else you said, I was going to gasket match the heads, should I not even do that then?

And, I was going to go with Manley valves, where does one get Ferrea's?

 

Gasket matching is alright, just make smooth transitions and don't try to open up the entire volume of the port to the size of the gasket. You can open it up to the size of the gasket right near the edge, but it will need to taper it in to the original port and do so smoothly. If you try to make the entire port the size of the gasket you'll not only kill your velocity but you'll ruin your heads when you cut into the coolant passages. I don't know if that makes any sense or not. I could show you real easily, but it's hard to visualize.

I'm not sure where you get Ferrea valves. I don't know if TEA went through a vendor or if they ordered direct. I do know thats what TEA uses almost exclusively. They did find a Manley valve that flowed better for a particular head but I can't remember what it was, I know it wasn't the LT1.

TEA would sell you a set of valves, and everything else you will need, such as springs, retainers and such. Call 270-782-6397, durning normal businees hours, 8-5 central, and ask for Brent. Tell him that you're from the forum and that I sent you. He'll get you fixed up for a fair price. Above all he knows exactly what you would need to make a working combination. Nothing is worse than a bunch of mis matched parts.

 

Cool, thanks alot. I get what you are saying. Thanks for the reference.

I already have springs retainers and all that mess though, just need some valves and new seals.

oh, what would I do without this forum.... :cool:

 

Nathan you explained that well. If you are increasing your airflow through your heads then it is good idea to consider using another cam to take advantage of this. Not to mention exhaust modifications.

 

Oh yeah, defnitely. I already run a LT4 hot cam, a bit big, but I am building a 383 this time. I wish I could run longtubes, but my sidepipes will not allow it unless I double back the exhaust, and that eliminates the gains from going with long tubes.

 

Brent will glady sell you valve seals too :)