327_TPI_77_Maro

iTrader: (8)

Hi guys, I just wanted to give some first impressions after converting my 1967 327 that is MAF EFI'd from a flat tappet hydraulic cam to a retrofit comp cams hydraulic roller. Here are the before and after cam specs:

Before: Comp DEH275 0.462/0.482" 219/229 @0.05, 272/275 adv. duration, 110 LSA, w/ matching comp flat tappet hyd. lifters.

After: Comp XM276HR "Extreme Marine" retrofit hydraulic roller cam, 0.503"/0.510" 224/230@0.05, 274/276 @0.05, 112 LSA

HOLY CRAP. The car idles similarly (choppy muscle car sounding idle), but the idle is cleaner and a lot more stable w/ the roller, with NO tuning changes. I have my own custom burned proms but I have not re-done the tune yet since swapping to the roller cam. I have gained a TON of vacuum at idle w/ the roller cam, even though it still chops along at idle. I had hard brakes in gear w/ the flat tappet cam, but now my brakes are totally normal in gear at idle.

What I can not get over, is how SMOOTH the engine runs cruising now. Even with the engine up in the power band w/ the flat tappet cam, the engine still transmitted some vibration through the chassis. W/ the roller cam, even winding it up hard, the motor is just dead smooth. The throttle response is massively improved over the flat tappet cam.

The engine sounds a whole lot different w/ the roller cam -- you'd swear the car is now twice as loud, even though the headers, exhaust, mufflers, everything are the same. It has a much more modern smooth but powerful tone.

I don't even need to mention the power increase -- it's substancial seat of the pants and on the rolling burnout o-meter.

I guess the bottom line is that, people who say, converting to roller won't gain you much at all and isn't worth the cost, are probably just too cheap to do it themselves. The engine drives totally different being rollerized. I really can't put into words how much more smooth and responsive the car is.

Cost:
Comp retrofit roller camshaft: $250
Comp Pro Magnum Retrofit roller lifters: $350 on Ebay, very lightly used (these are $600 new, these are not the cheap retrofit roller lifters that are $350 new)
Lunati 7.290" hardened pushrods: $40-ish

Total cost: $640-ish

Is it worth the cost to me? Hell yes. Best money I have spent in a long, long time.

Damon

Smoother idle with the wider 112* LSA I can understand. More power I can understand. Smoother through the rev range is a new one on me. Can't say I could explain that.

Sometimes it's best not to question when something works better for unknown reasons- just enjoy it!

Glad to hear it's working well for you.

Toehead

By the way, that is one of the most beautiful cars I have ever seen.

Glad its running well !

Orr89RocZ

iTrader: (20)

awesome man glad u liked it. why the "marine" cam?

327_TPI_77_Maro

iTrader: (8)

I wanted a 112 LSA to keep the O2 happy. Comp grinds all their "car" retrofit cams on a 110 LSA for NA motors. The XM276HR marine has the exact same lobes as the comp extreme 276 retrofit roller cam, but on a 112 LSA instead of 110. The cam is otherwise identical. Marine is just a suggested application for that grind.

I have run the same hydraulic grinds on 108 and 110 LSA's in this car, w/ the EFI, with no difference in idle quality or vac. 230+ duration flat tappet cams are just dirty running because the ramps are so lazy.

Thanks for the compliments. The paint is 20 years old and chipped and scratched but looks good from more than 10 feet away. It's due for a repaint some day.

cc 82Z-28

iTrader: (7)

I really like your car and I too am doing a retro hydraulic roller cam in a 400 I am building. My cam is a little more aggresive coming in at .528"/.539" with 110 LSA and .230intake/.234 exhaust. With 64cc heads I will come in at about 9:75:1 compression. I think I am going with 1.6 roller rockers which will push the lift higher. I've run flat tappet cams forever and decided to take the leap and spend the money on the roller this time since there has been been so many failures due to the change in formulations of motor oils. I am really looking forward to getting it together and in my car this spring.

327_TPI_77_Maro

iTrader: (8)

cc82, thanks. My 0.503/0.510" cam is probably "bigger" than yours because mine is in a 327 with like a very short stroke!! Supposedly the same camshaft in a 327 and 350 will support the 327 to roughly 400 rpms higher, due to the shorter stroke taxing the heads/valvetrain less. So extrapolate that out to a 400 ...

I am running 64cc iron 200cc runner heads 2.02/1.6. On the little 327 they are more than enough head for probably like 7000+ rpms.

KrisW

iTrader: (5)

he he...

My favorite measurement of performance...

Do you figure that your roller lifters are far superior to factory pieces? I'm asking because it makes a difference if you're going to start an engine build up with a newer roller block or not. I have a newer truck block. I could have it machined for the factory roller lifters or just run a retrofit kit like yours.

I'm wondering if there is an advantage either way...

zipfast

iTrader: (2)

327, what are the valve timing points for that cam?
IVO, IVC, EVO, EVC.
Or if you could, just post up a pic of the cam card if you still have it.

IROC406

Hey 327_TPI_77_Maro


Can you tell me how reliable those retro kits are? Any issues?