dobeluvr

I am thinking about replacing the valve covers with chrome ones. I have been contemplating replacing the heads either this year, or maybe next, depending on funds. I have read on here about taller covers and roller rockers, gotten confused, and am looking for what would be the best options. I am planning on keeping car for along time and do not want to buy something that limits what I can do later. May be looking for a little better performance, but nothing extreme.

So based on that, what is your recommendations.

This is what I have 1977 l48 with Edelbrock performer plus 2102 cam, edelbrock performer 2101 intake manifold, edelbrock 1406 carb, 333882 heads, true dual exhaust.

AboveTheLogic

A couple of quick searches tell me that the cam/intake combo you have should be good for about 320 hp/380 ft lbs with the right heads. I'm guessing a 180-185cc intake runner and a 64cc chamber should do the trick. Lots of options out there.

I'm not sure that you really need roller rockers with that cam. I'm guessing your engine doesn't see more than 6,000rpm, and that cam has under 0.45" lift. Maybe you'll get some long term durability with roller rockers?

REELAV8R

I have short chrome valve cover with roller rockers and they fit. It depends on what rockers you go with. Aluminum rockers are thicker and taller than the steel ones. Different heads have different height valve cover rails as well, so the valve covers will sit down lower on a lower rail.
I would agree that you don't need roller rockers with that cam.

MotorHead

You won't see / feel any gains until you lose those 882 heads

Bob E

I replaced my 350 CI with a 350 CI crate engine and Valve Covers were not interchangeable. Wait 2C what ur new heads take. Some have 2 center bolts and some are held on with 4 edge bolts.---boB

dobeluvr

Ahh, never thought about the fact different heads may take a different cover. So I will take that advice and look for the heads first, then the cover.

MotorHead, I knew about the 882 heads and thats why I am contemplating replacing them, just wont know if funds are available till later next month, lol.

AboveTheLogic...your assumptions are correct...maybe a little high...don't think it will see much over 4500 rpm, lol.

So with all that in mind, i will start looking at heads (instead of covers) with 180-185cc intake runner and a 64cc chamber..Anything else I should be aware of? And is any head a better quality for the money? I cant/wont afford the high end ones, but don't want junk.

Are edelbrock heads any good?

AboveTheLogic

I looked at a lot of options for heads for my '79 and recently pulled the trigger on a set of Blue Print H8002K heads. New aluminum heads ready to go for under $1000 seemed like a good way to go. I was looking at Pro-filer and some other brands too. Really, the more money you have the better head you can get and the more power you can make.

If you're going to keep that cam, look for a head that flows well at 0.450 lift. You don't need a head that keeps flowing well when it gets up to .500-.600 lift. If you look at the flow numbers for AFR heads, for example, they keep improving at super high lift. The Blue Print heads I bought seem to flow best right past .500 lift and I ordered a .510 lift cam so I think it should be a good match.

The guys over at the hotrodders forum helped me understand things a bunch.

gkull

That is failed old logic that continues on as modern myths.

True statement: A given head port has a max cfm flow at some valve lift. Lifting the valve higher does not create more flow. This point is know as stall.

True statement: As rpm rises the "time" that the valve is open. At 6000 rpm the cylinder is firing 3000 times per minute.

False statement: All I need is valve lift to peak cfm because of the stall!


Your little cam lobe spends very little time at that max valve lift which is only 1/3000 of a second for the whole compression and power stroke. So just because it stalls at a max cfm does not mean that you do not have more cylinder filling capability as rpm goes up.

poorly cammed motors with this low lift Myth are the ones that have drastic drop off on a dyno sheet at some relatively low rpm. Where higher lift with an equal duration will have higher peak numbers and then taper off in power... You are just not using the heads to their potential

AboveTheLogic

Thanks for elaborating on that. Its worth pointing out that the head flow at moderate lift impacts mid range power. The whole thing about how little time is spent at max lift is what convinced me to go from a flat tappet cam to a roller cam.

gkull

If you look at how dyno simulator programs work. They take head CFM flows from all .050 lift increments and they get an average total flow during the whole lobes lift. The higher the average CFM to more power up to a point

A roller cam lobe spends more "time" in the higher CFM valve lift.

But it is still a Myth that gets passes on and on by Cyber dummies to think that limiting lift to some low lift point is better. The motor doesn't care about statements like this "Its worth pointing out that the head flow at moderate lift impacts mid range power. It is the average flow from all lift points.

That is what convinced me to run extreme solid roller lobes with very aggressive lift rates and I have not had a motor with less than .630 lift in 20 years

dobeluvr

So with what Gkul said above,

Does that change what AboveTheLogic said?...

"A couple of quick searches tell me that the cam/intake combo you have should be good for about 320 hp/380 ft lbs with the right heads. I'm guessing a 180-185cc intake runner and a 64cc chamber should do the trick. Lots of options out there. And "If you're going to keep that cam, look for a head that flows well at 0.450 lift. You don't need a head that keeps flowing well when it gets up to .500-.600 lift."

or was they talking in details way above my head, lol?

AboveTheLogic

I think he's challenging the part of my statement where I said that you don't need a head that keeps flowing well when it gets up to .500-.600 lift. Those HP numbers were advertised on edelbrock's website for that cam with a decent flowing head. I'm guessing your heads are costing you somewhere between 30-50 hp.

dobeluvr

So, if I got this straight, I need a head that flows enough to produce the hp with the lift that this cam has. If it flows more with a greater lift, great, but all that means is that the heads can do more with a different cam.

gkull

I'm challenging the myth about low valve lift and stopping at the point of not more cfm. The CFM continues on at the same rate. Big low lift numbers do get the cylinder filled by having the air go in the right direction. Cams with less duration and overlap decrease intake reversion. higher lift is a better solution than additional duration for cylinder filling as is tuned runner manifolds. I'm all for roller cams

AboveTheLogic

Yeah I read that like 3 times and I'm going to come back and read it again when I'm not so tired. Matching heads/cam/intake/exhaust is really a science...

gkull

Tall valve covers can have clearance problems with stock accessories and bigger alternators. Stamped steel is not as ridged as the aluminum. The best valve cover gaskets are the Felpro blue with steel inserts.

I actually ran high lift 1.6 ratio steel Comp Cams RR's under my stock 79 L-82 covers. I had to remove the cover oil splash tabs

resdoggie

I once heard that you aim for the highest lift cam with the least duration you can get away with without detonation while maximizing your timing curve. I'm thinking this is what gkull is saying about higher lift cams. The nice thing about my AFR heads is that they flow more at lower valve lifts compared with other heads of similar flow rates i.e. better cylinder filling without the need for smaller runners. Is this correct? I guess its a trade off in how you want make power - higher lift cam or smaller runners to increase velocity. Or spend bigger bucks to get optimum. If I'm at 90% of peak power, I'm happy with that. I don't need to chase down that extra 10% unless I was to race professionally, which I won't be doing.

My oem finned vv covers fit my AFR's with my aluminium roller rockers due to the raised rails on the heads.

Jebbysan

"The ideal port is one that flows 0 cfm until .200 lift....of course we all know that is impossible...." Larry Widmer

Carry On,

Jebby