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.

Can't offer much tech, but please post pics!! The only other Mecam T/A I've actually seen is Art Martinez' CP car, which I've driven and actually have the 302 shvrtblock out of when he went big. It was a beast of a car with the 302!!

Looks like a healthy setup you have. What, exactly are you wanting, better drivability, lumpy idle, more power? I've always been one to build torque into my engines, letting the HP take care of itself. It's paid off a couple of times.

That car you mentioned was most likely a 2nd Gen "MACHO T/A", those were pretty bad ass in the late 70's. Mine is a 3rd Gen, they produced the Motor Sport Edition (MSE) in 82-84, they sold these to support their SCCA TransAm racing habit.

I would post pics but when I click on the "insert image" button it list "Please enter the URL for this image" ? I do not have a website just a bunch of .jpg files. so I am unsure how to add them.

Here is a video of the car on the track (i just posted this)

https://youtu.be/XCPZ69BsDtQ

As for what I'm after with the engine... TORQUE before RPM. The car is strong even with the current cam but the flat tappet setup just scares me with the oils of today. I use Valvoline VR1 for the added ZDDP and been happy with it. The car was not built to racing or autoX and now I find myself thinking it would be better to move toward the roller cam & lifters for less wear & tear on those parts... but the high dollar expense to switch would be nice to avoid. I just figured if someone out there had some good recommendations I would seriously consider the swap since the engine will be removed in the next 2-3 weeks. Planning on the car being ready in Sept for the start of our next race season... so I have some time to plan this.

As for the car... I am the original owner, so I have had it for 41 years, I refurbished the car 2016-2019 for car shows and cruising. I didn't list the suspension mods as I was trying to keep this focus on the engine/drivetrain. If you are interested in seeing what the car looks like below is a video someone did of the car at one of the local carshows here in Phoenix, AZ from a couple years ago. I had it all spiffed up for the show with my street wheels on it.

https://youtu.be/f_aogMBdSvQ?si=tClojdKpQ6O1KJbL

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.

Very nice!! That car looks new!

The car I was talking about is. a 1982 MSE T/A. It belongs to Art Martinez. I believe he said the car was a race car. It has some pretty bit fender flares (only way to fit 14" slicks in the bodywork on a 3rd Gen w/o a lot of suspension and tub mods). I don't know if it came to him with the flares, or he added them after he got the car. The old CP ruleset was kind of restrictive on what body modifications you could make. They've gotten better, but still. kind of restrictive.

Let see if I can get some numbers for you. I had to dig back in my notes and pics from 2017 to come up with these:

Dart Pro1 Platinum 180 SBC 23* Aluminum Heads
p/n 11221111P (fully assembled head)
Brochure specs if not noted
Material: 355T6 alum alloy
Chambers: 69.4-70.1cc (after cleanup & polish)
Intake Valve: 2.02 (dykem & lapped)
Intake volume: 188.0-188.8cc left head 190.8-191.2cc right head (full porting with extra work on inside floor around valve seat)
Intake Dim: 1.190w x 2.075h (full size gasket match to Felpro 1205)
Exhaust Valve: 1.60 (dykem & lapped)
Exhaust volume: 75 unmeasured (full porting with care to valve seat & guide hump)
Exhaust Dim: 1.375h x 1/325w ( port matched perimeter .030 undersize of gasket)
Flow Intake: 257 cfm @ .500 lift / 28?
Flow Exhaust: 172 cfm @ .500 lift / 28?
Retainers: Steel 7 deg (machined keepers)
Spring pockets: 1.550 OD
Springs: options
1.250S = 110# @ 1.700 / .520 max (my setup)
1.437D = 130# @ 1.800 / .620 max
1.550D = 195# @ 1.900 / .690 max
Rocker Studs: I upsize to the 7/16
Intake Manifold : Dart dual plane 42811000 (port matched perimeter .030 undersize of gasket)

I didn't use the installed Dart springs when I found that I received grossly different build date heads, they appeared to be different brand springs. I purchased the CompCam recommended #981 springs, 1.250 single with dampener coil. I acquired an older RIMAC spring tester that I modified with a dial indicator and purchased a calibration spring to set my pressures.

(I have updated the following on 4-23-25 after reviewing old data)
I had originally used some Felpro MLS head gaskets and did not notice that one of the head cooling holes had a slight coolant seep after 2000 mles due to the old block not having enough surface to adequately seal the MLS gasket. So I switched to Felpro 1003 gaskets. I retested all my valve springs on the RIMAC tester and found them to be light by .040-.050 on all valves and reset them to 105# seat pressure.

Now I have noticed that the springs have lost more tension during after another 6000 miles since re-assy. I removed the #1 intake & exhaust springs using a nylon rope thru the spark plug hole to support the valves and retested them and found the intake needed an additional .024 & .014 for exhaust to meet the original 105# setting. So these springs are junk and nearing the possibility of floating the valves and know if I stick with this cam setup, I definitely need to go to dual springs or just scrap this and go roller style? oh but the cost!

This post has been edited by HYPR 84: Apr 23 2025, 11:37 PM

Sounds like Art Martinez had something very special.
1982 Mecham Racing won Pontiac their very first SCCA Trans Am Championship! Mecham supported their racing habit modifying new TA's into their street version MSE's.

This was the first new car I bought, still has the original paint and looks the same as the day I purchased it with 186 miles. All the MSE?s were serialized with mine being #84-0022, one of 50 built in 1984. Very few I was told had 5 speeds (mine didn't last very long). It had all the Mecham options; 300hp 350 4bolt replaced the stock HO engine, HD 4 core radiator, front & rear coil springs lowered the car 1.5" (unknown spring rates), Koni adjustable struts & shocks, gold Enkei 92 rims with wider EagleGT?s tires, MR gauge package, steering wheel, rear wing, war-paint scheme & MR graphics, rear droop limiter, front frame stiffener, etc. It was very attractive and fast for 1984. I have upgraded frame & suspension items, along with drivetrain and interior. And with 76K orig miles... it is a new car again!