BBC 335cc Single Spring for Hydraulic flat tappet camshaft

Perfect performance upgrade for your 454 to 540 Cubic Inch Big block chevy good performance curve great for maximum 6500 RPM.

Premium quality aluminum cylinder heads assembled with only the best components from american Dart and Manley for your Big Block Chevy, cast in Alsi7mg and hardened to the best industry standards, assembled, tested and flowed on our own flowbench in our cylindershop right here in Denmark https://www.engineshop.dk/pages/about

Price is for a set of 2!

Fits Big Block Chevy 454 block gen V, VI and IV (4,5 og 6)

• 122cc Chambers (Can be milled down to 100cc at .009" or 105cc at .006")
• 3-angle valve job
• Intake runners 335cc
• Exhaust port 140cc
• Port opening 2.510"H x 1.820"B x 3/8" Radius
• Exhaust port location 0.357" raised, standard bolt pattern
• Manley Springs and spring-retainer 1.550" single spring with damper
• Manley stainless Racemaster series valves for both intake and exhaust, 2.250" & 1.880" w/ 30 degree back-cut & swirl polished
• Manley 10 degree valvestem locks
• ARP 7/16" Rocker studs, must be torqued to 55 – 60 ft./lbs. after installing
• Manley Vitron® Valvestem seals
• Dart adjustable hardened guide plates
• 4140 Chromemoly hardned spring locators
• Diamand honet and crosshatched manganese bronze valveguides, crosshatching retains oil film better and ensures longer servicelife of the valveguides
• 1.550" Single springs with damper are suitable for use with Hydraulic Flat Tappet Cam w/ max lift 0.660" 145 lbs seat pressure @1.900"
• Requires block with minimum bore 4.25"

Flow data on 28" Water Column Height with 4.350" bore, no exhaust pipe or intakemanifold fitted

Lift- Intake / Exhaust

.200” 167/107

.300” 225/136

.400” 270/159

.500” 303/178

.600” 351/194

.700” 365/204

• Designet for 3/8 push rods, heads will require pushrods that are longer than stock length. The most common lengths are a +.200” to a +.250”; however, due to a large number of variables (deck height, cam base circle, lifter height, etc.) ALL pushrod lengths must be physically checked to achieve proper valve train geometry.
• Check rocker has minimum 0.15" clerance to retainer
• Head gaskets Gen IV Block 4.540” Bore Felpro #1017-1 NOTE: 1017-2 is .051” compressed
• Gen IV Block 4.630” bore Felpro #1057
• Gen IV Block 4.625” bore Felpro #1093 OBS: 0-ring perfectly round, .051” thick, Typical “pro-stock” style gasket
• Gen V & VI 4.540” bore Felpro #1047 or #17048
• Gen V & VI 4.630” bore Felpro #17049

There is an increasing trend for people to compare cylinder heads and select based solely on highest CFM flow achieved, even though the cylinder heads have the same intake volume and same size valves. But the numbers don't always give you a comparable data point because it's affected by so many variables like

What size is the water coulmn height (WCH) on the bench. 10" ? 25" ? 28" ?

Is the flowbench calibrated? What is the temperature, humidity and air pressure? these all affect the flow numbers, did they add a correction factor?

What flowbench was used? Superflow SF110 is calibrated to 10" WCH, all other Superflow benches are calibrated to 25" WCH, this gives big differences here is an example. An SF750 calibrated at 25" WCH would show 264,5 CFM, where as the same bench calibrated to 28" WCH would show 250 CFM the

CFM * (square root of 28” / square root of 25”) = 250 CFM x (5,29/5) = 264,5 CFM.

Is there a pipe fitted to the exhaust when flowed? a pipe typically provides between 5 and 12% more flow because of the pressure difference

What bore size was it flowed on? The bigger the bore size, the bigger the CFM number will be

All our products are tested on fully calibrated PTS flowbench right here in Denmark and on 28" WCH