Choosing Roller Cam - F-Body Road Racing and Autocross Forums

Seeking advice from those that are/have use a hydraulic roller cam in a Gen1 350 SBC

Car is a '84 Pontiac TransAm - Mecham MSE. This is not a daily driver as I use mainly for autocrossing & car shows. My skill level at autox is 3 years and improving. I place in the top 1/3 of our local CAM-T group (typically 1.5 seconds behind leaders). The engine & drivetrain was overhauled 6 years ago and at the time built for car shows... then I stated autox! I recently had a mishap with my cooling system that I believe has created a compression pressure leak at the head gasket. Under high RPM runs my coolant overflow tank will raise above HOT level and not return to proper level when cold. I have tested several radiator caps & thermostats and get the same results. Under typical daily driving conditions the system acts correctly. There is no coolant loss under any condition as there is not smoke or mix into oil. So I guess the engine is coming out and i'm getting rid of the hydraulic flat tappet cam & weak valve springs.

Current drivetrain setup (suspenion ungrades not listed) :
Sniper EFI, Sniper Hyperspark distributor, Sniper sparkbox & coil, manual WC/T5 5-speed, McCloud balanced lightweight flywheel & pressure plateDana44 housing w/ Eaton TruTrac 3:31 gears. (I know the gearing is to high but that's going to stay for now) Car weighs in at 3400 +200 driver. Best 1/4 mile time 13.05 @ 107mph.

350 SBC 4 bolt, high nickel & tin block, blueprinted
Forged crank
+.060 forged pistons
Compression: Static 10.01:1, Dynamic 8.28:1
Total Seal rings- gapless 2nd
Prepped steel rods
ARP hardware
Comp test (yesterday) = 193-197 psi
Leak down test (yesterday) = 99-99+ & 100 psi
Rotating assembly balanced
CompCams - Hyd Flat tappet 12-242 (224I/231E @ .050, )
@ +4.125 advance
Cloyes true roller chain

Dart Pro1 aluminum heads, 72cc, 2.02 & 1.60
Ported & cc'd
7/16? rocket studs
5/16? chromoly Heat-treated pushrods
Chromoly roller rocker arms
Polylocs
Felpro 1003 Head gasket
ARP hardware

Dart dual plane intake
Felpro 1025 intake gasket

FlowKooler 1773 machined impellar water pump
BeCool radiator
Becool electric dual Spal fans

ETC. Etc. etc.

If you got this far... thanks for reading and look forward to your comments.

HYPR 84 View Member Profile	Apr 20 2025, 04:47 PM Post #1
newbie Group: Members Posts: 10 Joined: 26-April 22 Member No.: 234,990	Seeking advice from those that are/have use a hydraulic roller cam in a Gen1 350 SBC Car is a '84 Pontiac TransAm - Mecham MSE. This is not a daily driver as I use mainly for autocrossing & car shows. My skill level at autox is 3 years and improving. I place in the top 1/3 of our local CAM-T group (typically 1.5 seconds behind leaders). The engine & drivetrain was overhauled 6 years ago and at the time built for car shows... then I stated autox! I recently had a mishap with my cooling system that I believe has created a compression pressure leak at the head gasket. Under high RPM runs my coolant overflow tank will raise above HOT level and not return to proper level when cold. I have tested several radiator caps & thermostats and get the same results. Under typical daily driving conditions the system acts correctly. There is no coolant loss under any condition as there is not smoke or mix into oil. So I guess the engine is coming out and i'm getting rid of the hydraulic flat tappet cam & weak valve springs. Current drivetrain setup (suspenion ungrades not listed) : Sniper EFI, Sniper Hyperspark distributor, Sniper sparkbox & coil, manual WC/T5 5-speed, McCloud balanced lightweight flywheel & pressure plateDana44 housing w/ Eaton TruTrac 3:31 gears. (I know the gearing is to high but that's going to stay for now) Car weighs in at 3400 +200 driver. Best 1/4 mile time 13.05 @ 107mph. 350 SBC 4 bolt, high nickel & tin block, blueprinted Forged crank +.060 forged pistons Compression: Static 10.01:1, Dynamic 8.28:1 Total Seal rings- gapless 2nd Prepped steel rods ARP hardware Comp test (yesterday) = 193-197 psi Leak down test (yesterday) = 99-99+ & 100 psi Rotating assembly balanced CompCams - Hyd Flat tappet 12-242 (224I/231E @ .050, ) @ +4.125 advance Cloyes true roller chain Dart Pro1 aluminum heads, 72cc, 2.02 & 1.60 Ported & cc'd 7/16? rocket studs 5/16? chromoly Heat-treated pushrods Chromoly roller rocker arms Polylocs Felpro 1003 Head gasket ARP hardware Dart dual plane intake Felpro 1025 intake gasket FlowKooler 1773 machined impellar water pump BeCool radiator Becool electric dual Spal fans ETC. Etc. etc. If you got this far... thanks for reading and look forward to your comments.

Catmaigne View Member Profile	Apr 22 2025, 01:01 AM Post #2
Member Group: Advanced Members Posts: 66 Joined: 26-June 19 From: Philadelphia Member No.: 224,118	Do you have more details on the heads? Specifically the intake runner cc, flow numbers, and max lift for the springs? The size cam you have at the moment seems perfect for a 350ci with a 200cc head. I'm unsure if you want to go bigger, but my guess is that the Dart dual plane might run out of steam at 6k+ RPM and you'd end up with a peaky powerband. It's probably best to keep the duration around 224/230, 108-110 LSA for good midrange, and lift in the 0.55" range if the springs will support it. Going with more lift means more power but it requires lighter, expensive valvetrain parts to handle the faster ramp rates. That's probably fine for an auto-x car, but I would keep it more on the conservative side if you ever plan on tracking the car. I would talk to Lloyd Elliot as he can probably hook you up with a custom grind and help you pick out the right retrofit roller parts.