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I should also Preface that I do this on the side for fun.
I don't build on the level Scott does in terms of volume of motors built. But me experience with both brands has been the same. I always end up needing to purchase 2 sets to get the clearance right.
I keep a drawer full of multiple sets of mains…up and down, and rods…up and down. On average I’ll go through 2 boxes of each to get my numbers. I did a build last summer that I found my mains numbers in one box, and I was floored. I opened 3 boxes to get the rods right, but that’s normal with China rods. Fwiw, I find much more consistency with Molnar cranks and rods. For every build I bring in, I simply order another set of std mains and std rods, and mix them in the drawer to replenish my stock. I’d imagine there’s $2500 in bearings in that drawer.
I keep a drawer full of multiple sets of mains…up and down, and rods…up and down. On average I’ll go through 2 boxes of each to get my numbers. I did a build last summer that I found my mains numbers in one box, and I was floored. I opened 3 boxes to get the rods right, but that’s normal with China rods. Fwiw, I find much more consistency with Molnar cranks and rods. For every build I bring in, I simply order another set of std mains and std rods, and mix them in the drawer to replenish my stock. I’d imagine there’s $2500 in bearings in that drawer.
Well the TFS 235 heads sold. When I CCed the intake port runners they where 229cc on them. I've made up my mind and im ordering the new BTR canted cathedral port heads. Those have 250cc intake runner and im hoping the intake port openings are wider than the old TFS 235 so my holley split intake port alignment to head port is better.
Since this is a carb setup with a 1050 cfm 4150 on top i didn't want to totally kill drivability and lose carb signal with a large rec port single plane and rec port heads.
Im also changing the rear gear from 3.42s to 4.10s to help with drivability since im going with a larger port head and a larger cam.
Well the TFS 235 heads sold. When I CCed the intake port runners they where 229cc on them. I've made up my mind and im ordering the new BTR canted cathedral port heads. Those have 250cc intake runner and im hoping the intake port openings are wider than the old TFS 235 so my holley split intake port alignment to head port is better.
Since this is a carb setup with a 1050 cfm 4150 on top i didn't want to totally kill drivability and lose carb signal with a large rec port single plane and rec port heads.
Im also changing the rear gear from 3.42s to 4.10s to help with drivability since im going with a larger port head and a larger cam.
You can't go by the port cc to really determine anything. The CSA and airspeed of the port will determine the carb signal. I doubt the intake will be wider than TFS heads, but you might call them and get a dimension.
You can't go by the port cc to really determine anything. The CSA and airspeed of the port will determine the carb signal. I doubt the intake will be wider than TFS heads, but you might call them and get a dimension.
Most of time when you have a wider CSA low speed port volecity suffers which inturn effects carb signal at part throttle. Another reason why im switching to 4.10s. In overdrive ill be cruising 400 rpm higher at 70mph to help, IF these larger heads and cam turd out part throttle cruise like i expect them too.
Most of time when you have a wider CSA low speed port volecity suffers which inturn effects carb signal at part throttle. Another reason why im switching to 4.10s. In overdrive ill be cruising 400 rpm higher at 70mph to help, IF these larger heads and cam turd out part throttle cruise like i expect them too.
I wouldn't sweat it, I don't think the CSA is going to be radically different. You are going from a 2.08 int valve to a 2.125, I'm sure the CSA is more, but nothing like a LS3 head size. I think it'll run good, love to see the heads when you get them. Who is porting them?
I wouldn't sweat it, I don't think the CSA is going to be radically different. You are going from a 2.08 int valve to a 2.125, I'm sure the CSA is more, but nothing like a LS3 head size. I think it'll run good, love to see the heads when you get them. Who is porting them?
calling GPI in the mornin, hope to have good news tomorrow. Brian Tooley said ill have to flycut the pistons most likely with the canting of the valves. Plus im sure the pushrods will be quite different.
You will absolutely have to cut the pistons for the valve angle (canting), if your previous setup was even remotely close. I feel like a lot of people are going to try and throw these heads on a flattop bottom end, and run into valve clearance trouble. The canting puts the valve a lot closer to the piston.
Finally got the heads delivered. Just mocking them up with 1 head bolt installed and intake manifold just sitting on top, the new heads port alignment is way better than the old tfs 235s.
The port width at the entrance on the old 235s where 1.069 wide vs the btr heads have a 1.1150. New btr head along with holley split single plane Holley single plane with tfs 235 heads
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