I was thinking about getting a new cam so I called up Comp and got a recomendation of a 206 212 .425 .440 cam. I checked my stock cam specs and found out that in '85 the stock cam was a 202 206 .403 .415 cam. I wondered if I could just leave my cam, and change to 1.6 roller rockers. I know switching to rollers helps, and the 1.6 helps too. What do you think?
thanks

 

sounds good, i was gonna do it but decided against it because inorder to do it on my 88 (slef aligning) you have to be prepared to remove the heads to lengthen the width of the holes for the pushrods. so i decided against it at this point. i dont know about the 85 though but if so go for it

-Stell

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1988 IROC 305TPI MINT!!
Mods= Accell SuperCoil, MSD 6A, Ported Plenum, No MAF Screans , K & N, 160 Thermostat+ Temp Switch
And Always Trying To Go Faster

 

1.6 ratio rockers will give you .430/.443 lift, somewhat more than the recomendation.
What are you trying to achieve - is this a 305?
What other mods?
What gearing?
What trans?
If auto, what stall speed convertor?
Daily driver?
Cam choice is integral to overall performance envelope.
It must be matched to heads, compression ratio, gearing, etc.
A 4/6 degree, .022/.025 increase in cam specs alone won't produce much difference in performance.

 

I would say don't bother. 1.6 rockers help a little...but it's not much. not for what they cost. I'd say 10hp or less typically, depending on the combo.

 

It is my daily driver. My only mods are exhaust, K&N, and throttle body airfoil. I was looking to improve my times (15.4@89mph) and get more torque. I would want to know if I had to take my heads off.

 

sorry
3.23
700r4

 

Your heads and cam become restrictions to flow at about the same time - after you have eliminated the really big bottlenecks, the intake and exhaust tracts.
Start with the exhaust - cat back, high flow convertor, headers.
Then move to the intake side - K&N, porting, aftermarket runners, base.
Then think about a cam to maximize these mods - but do the breathing mods first.

 

Are you sure you have what you think you have? I don't have any TA specs in front of me..but that doesn't sound right to me. a 202/206 cam..in a 305 TPI with a 3.23 rear and auto...all stock?

 

yep...look at specs for '85 only. My rear end gear is calculated with rpm and tire size. It may be a little off, but not much.

 

If you did decide to go with the Crane 1.6:1 self aligning full roller rockers, you would not have to pull the heads to use them. The rocker arm alignment holes in the heads would simply be "redundant" alignment holes.

Tim

 

85,

The '85 had much better cam profile specs than the subsequent years. The best information I could find on the 1.6:1 rockers was an advertised 16.6 HP and 17 lb/ft torqye improvement on a 305. This of course would be the maximum, probably with many other modifications, and the valve train therefore would be the limiting factor. This is generally how the aftermarket works to create "verifyable" dyno HP gains with their products - make the rest of the engine as dependent as possible on your component(s), then show the differences with your component(s) installed. Regardless, the difference will likely be less than 16.6 HP in your case. I would suspect that some of the power gain would be from the additional lift and slightly longer effective duration, and some of the gain would be from the decreased friction provided by a full-roller rocker over a stock stamped set.

Personally, I would consider the self-aligning 1.6:1 rockers in your case, since they can always be used on other SBC engines you might build. Any gains you get now wouldn't be lost in the long term.

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Later,
Vader
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"Make Me Bad"
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