Best Valve Combination to run on BT Chevy Ext. Port Head

Getting ready to replace valves on Heads, right now Im running a 2.25 int. 180 ext. on a 521-13/1 compression
roller cam 752 int 756 exh. Dur 270I 276 e at .050 just wonder if I could benefit going to a 1.88 exh. and leave
the intake alone......also who make a 1.88 the right length to match my combo?

Several manufacturers make the 1.880" exhaust in the correct Blue Thunder length. R E V, Manley. and Ferrea for example. However, you may want to consider something smaller than the 1.880", such as a 1.850". Have you had the heads flowed? Are you needing to improve the exhaust flow?

Charlie

Just got paperwork when I first purchased heads 341int. 275 exh. just wondering if theirs a better
tried and true set-up since I need to purchase valves. I'm also going to do a Manifold up-grade and sell
the Victor Jr. to go with new Trick Flow model...that should be worth about 17-20hp. The 1.85 valve a
std. model?

smackjack wrote:Just got paperwork when I first purchased heads 341int. 275 exh. just wondering if theirs a better
tried and true set-up since I need to purchase valves. I'm also going to do a Manifold up-grade and sell
the Victor Jr. to go with new Trick Flow model...that should be worth about 17-20hp. The 1.85 valve a
std. model?

No, the 1.850" valve is not a std. model. However, if those flow numbers are accurate, then your money would be better spent on reporting your intakes and seeking better flow out of them. If all they are flowing is 341 cfm, then comparatively speaking your exhaust flow is good enough and your intake flow needs help. I'd rather see something like 375 cfm/275 cfm out of Blue Thunder heads.

Charlie

Thanks Charlie, Not sure how accurate no. were and going by a est .700 lift...so valve combo might
be a keeper just do some work on the intake side...maybe even a better valve profile..any recommendations
of what (class-style) and vendor should used with the most luck of economical gain?? I know its hard with
out seeing accurate data.

I'd work on the intake flow, thats where the power is at.

Maybe even consider reducing the diameter of the exhaust valve and putting bigger intakes like 2.300's in and do some more work on the intake port.

I, too, think you stand to benefit from more power with your general combination if you work on the intake side and/or increase intake valve size. Further with the BT CJ heads, should to go with an exhaust valve size larger than 1.80" over a 4.39" bore then you really need to evaluate the exhaust valve-to-cylinder wall clearance when using a roller cam the size of yours.

Paul

not only can the Intake work help but that Cam is less than what I would have figured, I think you duration is way lacking for that head, I agree with Charlie your intake should be in the high 375 to 400 range and a custom cam would help with the upgrade.....

smackjack wrote:Getting ready to replace valves on Heads, right now Im running a 2.25 int. 180 ext. on a 521-13/1 compression
roller cam 752 int 756 exh. Dur 270I 276 e at .050 just wonder if I could benefit going to a 1.88 exh. and leave
the intake alone......also who make a 1.88 the right length to match my combo?

With the Chevrolet exhaust flange BT heads, I prefer a 2.300" intake and 1.800" exhaust.