Roller rocker debate
 

I am finishing up my 489s. Cam is .547 .547 112lsa 230/236 with eq 320 heads. My debate is what rockers to go with. I am looking at comp pro magnums, harland diamonds, and scorpion marine. Also up in the air on 1.7 vs 1.8 or even a combo of both. Whats your take??

Go with the Comp Ultra Pro Magnum Rockers. They are better than aluminum rockers for the following reasons- Better fatigue resistance, rebuildable, lighter over the nose, less bulky, and I'm sure a few other good reasons. Also the price will be on par with the better aluminum rockers.

On my old engines I broke a Crane Gold and I didn't have that many hours on the rockers. My new engines have the Comp Stainless Steel rockers, which are no longer available. Either way after my experience with Golds and what I've discussed with a few guys, I'll never run aluminum rockers again!

I have very little expertise on the matter, but after some research I went with the Comp Cams Ultra Pro Magnums. I'm just more comfortable with steel as all.

:food-smiley-007::food-smiley-007::food-smiley-007:

This is like asking if fords or Chevys are better.

Whatever you decide, make sure the setup / geometry works out correctly. I'd bet that lots of valvetrain failures are due to poor setup as apposed to aluminum vs. Steel or brand vs. Brand.

For some reason I think I remember that day. Never gave it much thought though. I've ran cranes golds for over 30 plus years and never had a problem but that's certainly not to say there's much better out there now. I've just never had an issue with them in fact just bought a new set of 1.8's for dyno testing only. I've looked at the ultra pro mags for new builds and seem pretty nice.

What ever OP does just stay away from the import 125.00 set of rockers. I wouldn't recommend those to anyone. Amazing how many of those big hp engines you see on the net selling cheap use all those components though. Buyer looks at price and power. Not cool. OP your cam is on the small side but should help save your drive among other things. You propping for 5200-5400.

I read an article from a reputable builder the other day and they said 80-90 % of engine failures stem from poor valvetrain geometry and stability.

of the three the comp pro magnum is the best imo.edit in,for your application any of the three will work ,also i wolud go 1.7 ratio.

Part number #1826. I see they come in 1.6's also. Hmmm. Might be worth buying a set and installing on your intakes while your out of town.

I was thinking comp ultras myself for reliability standpoint. I hear 1.8 causes more sideloading. Should i stay away from those or chase the power

If you want 1 mph go for it but the extra load on the lifters won't be worth it.

1.8's are a tool for me for the most part although have run them in the past. In some cases build depending they work well and worthy. Others not and gain not worthy. Never had valvetrain issues with them. It like 14 apache mentioned in your application gains would more than likely be minimal. I'd seriously consider 741 cam in your build.

If I could find a couple used 741 cams I would. I am opting not to mill my heads which will affectively put me at 8.6:1 compression. I dont want to hurt flow. I will be bore notching the cylinders though. Is compression too low for that cam?? Figure the .5 im giving up by not milling is only 20-30hp max and if i want to do blowers later compression wont be too bad

You have a 4.25 stroke engine. 8.6:1 is low, but pretty much same thing mercury used on the 525efi, 502 mags,, etc. Those were 4 inch stroke. A 4.25 stroke will require more camshaft.

I personally think that cam is going to be small in that build. Mercs 525efi, had a 236/244 cam with fairly low static. They run great. If you wanna make some power, youll need a cam that doesnt die at 5000-5200rpm.

I bought the comp ultra pro mag XD rockers last winter. So far so good. They look very beefy compared to the old cranes I had. I too ran cranes for years, had good luck, only 1 broke a trunnion. Then again, years back, we were running alot less spring psi, lot less rpm, milder cams, and so on.

Do those rockers clear the stock valve covers on gen vi

Im guessing you are running a flat top piston? If the block was 0 decked, with the eq heads, should be right about 9:1 off the top of my head with a .039 gasket

is that what you have ?

I have not tried that . Cant say.

I too would stay with the 1.7 rockers. The 1820-16 have billet pushrod inserts, those are the ones i am running. The 1620-16, do not, and go for around 300-320 bucks if i recall , 100 bucks less than the 1820-16.

The lock nuts did not clear my stock genvi valve covers. Close, a thicker cork gasket might of worked, but I bought the Hardin units instead.

Flat tops. 020 in hole. 3cc reliefs 119 heads. Gonna run steel shim gasket to keep compression up and quench in check.

Good to know

Its official. Gonna have rmbuilder do my cams. Hopefully we can ramp my dynamic compression back up to maximize the gains

^ Here we go lol

You gonna go smaller on cams ?

Buy motors from KidApache. :party-smiley-004:

^ Cobra or Big Johnson are also great choices I have read!

What do you mean

Id rather put a sail on it

Not sure how you can increase "dynamic" compression with a larger cam.

Tighter lsa. Should increase cylinder pressure. I have dry exhaust so I can get away with a little bit.

Maybe im *ss backwards here

put a 741 in it. From Crane

At 480 a piece for cranes dont you think i would better better off getting a cam custom made for my specific application for similar money?

$411
http://crane.carshopinc.com/product_...d/16145/168741

yes

Works great... I'm using that cam from car Id.

The 741 will carry better in a 502, than it will in a 4.25 stroke 489.

Where is the peak tq and hp of that cam in a 525 and whats is the estimated peak for the 489

Do you have a stroker motor??

An OE 454 and 502 are stroker motors. To name a few :)

Yep. Most dont realize the 454 was a stroked 427. And back in the muscle car era, those 427's made some serious power.