I have a set of LT1 Castings that has been ported by AHART of San antonio. The heads are going in next week to have a Competition 5 angle valve job done. They will also be cut for larger valves. I was going to go with 2.00 on the intake and 1.56 on the exhaust. Do you agree or would you go 2.02 I, 1.60 E?
Im looking to build a 383 for strip use, but it will also play as a daily driver for a little while. Would like to run mid 11's NA and possible add a little juice to run around a 10.6-10.7 once I have another car to get me from point A to point B.

 

i can't see how bigger would be detrimental... but watch out that they don't go too low on the angle

 

Until recently I thought that the 2.02/1.60 valves worked fine with the stock seats. Well I realized that even though they do fit and can be run on the stock seats (after machining, of coarse) but they do not sit correctly on the stock seats and they are sealing on the back side of the valve because the stock seats can not be cut large enough for the 2.02/1.60's to seat near the edge of the valve. Basically if you cut the stock seats as large as they can go a 2.00/1.56 works GREAT and if you use the 2.02/1.60 you are basically putting a larger valve in front of the same size hole and not helping flow but probably hurting it.

I have used 2.00/1.55's and 2.02/1.60's and they always seem to end up with the same flow #'s. I have never flowed the same exact port and swapped valves to see if there is a 3-5 cfm diff.

My opinion is go with 2.00/1.56 valves unless you want to change seats or if you ALREADY have the 2.02/1.60's than I would use them even though they do not sit correctly. Some might agree with that, most may not, but that is my opinion.

NightTrain66

 

Thanks for the info there NightTrain.

If I remember correctly you are a head porter in TX right? So I'm assuming that you've got a pretty good idea what you're talking about based on experience? Not being a ****, I just don't like "I heard this" and "I heard that" type of info.

With ported heads, bigger cam (specs unsure), 383 w/ 6" rod & 10.5:1 comp, long tubes...you think the bigger valves would be worth it?

I'm looking at the Silverline Premium line at www.sivalves.com thru Combo Motorsports, or the Manley Race Flo's right now from Scoggins Dickey.

 

Where would you recommend getting some 2.00x 1.56 valves from??

John

 

Ferrea makes the best ones but they are "about" $16 each ($250 a set) and Manleys, SI and REV all make 2.00/1.56 valves for "about" 10 each ($160 a set).

The Ferrea's are rounded on the chamber side of the exhaust valves and have more "meat" on them and seem to take a back cut better. They are slightly heavier either due to this extra meat or the stainless that they are made of ????? not sure why.

Ferrea's are the best though.

Ferrea's are tougher to buy and you probably need to get them through an engine builder. The other valves can be bought from Combination Motorsport, Jegs, Summit, etc.


NightTrain66

 

Thank you much!