BuddyLeeX

on my 305, will that be too much lift? If so, should I just get new performance 1.5 ratio roller rockers? Will the new 1.5s add more power?

Vader

BLX,

If my numbers are correct, the 262H (.450"/.480", 206°/210°, 112° LSA) should be O.K. for an LG4, except for the valve springs and valve guide clearances. The heads will probably need to be machined for larger springs, and the valve guide clearance may have to be increased. It's a really good time to go with screwed studs, too. The recommended Comp kit includes springs that are rated for 0.500" maw lifts, and your 1.6 rockers will exceed that. Those springs are 1.260" in diameter and might fit your heads without machining, but you'll need to measure to be absolutely certain. If you really want to use 1.6 rockers, you'll need the larger (1.43") diameter springs and machining.

The rockers alone really won't be worth a lot more power, adn the $$/HP gains really don't support it. You can spend almost as much as a new cam costs, and won't have anywhere near the change in performance.

BuddyLeeX

ok, well im buying the cam alone fo rabout 50$, and then I need new lifters, how much would the springs valves and machining cost? And actually the came is (.462/.469 lift 218/224 duration, 110 LSA) this info came off their site. Will porting my heads do anything?

Vader

BLX,

According to my numbers, the 262HR has the specs I listed. Since your car is an '87, it should have the factory hydraulic roller cam. The cam specs you have listed are for an XE262H, which is a flat tappet hydraulic cam. I'm thinking you should probabky stay with the roller lifters if at all possible.

As for head porting, it can always do some good unless it is done poorly. You'll want to start by matching the ports to the gaskets, then mathcing the intake passages to the ports. The valve bowls themselves are a good place to start removing material, and the runners can be blended from the bowls to the gasket-matched ports to maintain good flow and velocity in the tract. If you are going to that extent, you might want to consider larger valves on the intake side, and unshrouding the valve faces on both sides. Playing cards can make good templates for measuring the port shapes and matching them from runner to runner. They runner forms don't have to be a perfect copy from cylinder to cylinder, but the closer you can get them to uniform, the better. Elimination of flow impediments and overall port volume is more critical than the actual shapes of the ports, within reason. Of course you don't want any sharp turns or angles if at all possible, and all transitions need to be smooth and as straight as practical.

JRoy91RS

I strongly suggest staying with 1.5 ratio rockers in order to reduce wear on your valve train (especially valve stems and lifters) with that 305. Most of the HP gains from changing rocker arms are due to the fact that aftermarket rockers are just lighter and engineered better, not because of their ratio. The stock roller rockers from GM are actually pretty decent, does anyone else concur? Or is it really worth it to buy aftermarket 1.5's? I'm not referring to aluminum, but stamped steel, which seems to be preferable on daily drivers, since supposedly they are more durable.

BuddyLeeX

alright, well if I knew how to port my heads I probably would if I could do it by myself and it would take a max of one weekend without any tools that I woiuldnt already have. I saw a tech article of daniel burks ported heads but I dotn know if I understand all that crap. BTW, thanks Vader for clearing the cam thing up, I thought I could put a 262H on mine, is there an XE cam that is hydraulic roller cam? Ok so, Im thinking of getting the haudraulic roller cam with aftemarket aluminum 1.5 ratio roller rockers since jroy said it was mainly the how they made them not the ration that give yo more power, lighter better right? Aluminum. More help please, Thanks.

BuddyLeeX

ok, waht about the CompXE270HR (218/224 duration, .495/.502 lift, 110 LSA) now thats a cam, perfect LSA I want something that will lope just a little. I was looking at the 264, I want 3.73 gears but I saw 270, "High performance application, largest with stock converter, noticible idle" I want a noticible lope, but if this isnt right for my car, it will be going with new 1.5 rr, edelbrock intake, tweaked carb, headers and hooker cat-back, then is the 264 better? Note, Im not putting the cam in until I get my engine tweaked up a little bit more, like headers, cat-back, rr, intake, gears, ignition. But if I do put it on there with say jsut headers, will it be bad?

Sitting Bull

Buddy,

With your otherwise stock 305 there is NO WAY that you will want the troubles such a lumpy cam will bring your way. If and when you carry out your mods, THEN think of maybe an XE262 cam.

When these guys write their ads saying "noticeable lope at idle" they are talking about a 350 almost always. With a 305 the "lope" on an XE 270 would be plain unliveable. Those extra 45 ci make a lot of difference.

Personally, for a street car I'd stick with an XE 256. But hey, I like a car I can drive, not be forced to fiddle with day in and day out.

It has been said more than once, "After doing all of your homework and thinking you have found the perfect cam for your engine, pick one size smaller." Why? Because our eyes are always bigger than our stomachs, i.e., upper rpm horsepower is only attractive on paper--you drive on the street where torque is to be found.

RB83L69

I have Comp's XM264HR-12 in my 305 at the moment... people have stopped me at traffic lights to say it sounds good. The car passes CA emissions with it. With a set of 186 casting "double-hump" heads, that cam, Comp 1416 1.6 roller-tip rockers, Edelbrock TES, and everything else (carb, intake, cat, exhaust, all emissions devices, air cleaner) completely bone-stock L69 stuff, the motor does about 265 HP at the crank.



Red curve is RW HP, blue curve is RW torque, green is calculated approx crank HP.

BuddyLeeX

hiw much did the XM264HR-12 cost you? I was looking at teh 264grind under hydraulic roller cams on jegs since vader informed me that i had roller not flat tappet, and they are really really expensive. Also tell me more about the roller rockers, with the cam dont you have enough lift already with 1.5 ratio roller rockers, is there a need for 1.6?

MikeH

iTrader: (10)

Get steel rockers....Comp cam pro magnums are very good they will rebuild them for free. Or a set of the roller tiped Comp magnums. There cheaper than Crane golds, and will last longer imo. I know there are people who have used aluminum rockers on the street with no problems. But I will never do it again...Ive been chasing my tail trying to tune this new combo. What was wrong all along was the number 3 intake rocker broke right in half. It died a slow death I didnt realize it till it broke all the way.

I noticed a nice power increase with the 1416 1.6 Comp rockers over the 1.5 full rollers. Should find out for sure after the dyno tune weds.

Sitting Bull

Buddy,

A certain series of cam will usually be the same price. But unnless you are moving to a standard tranny, think smaller in terms of camshaft.

RB83L69 will tell you the same thing. For an automatic like a TH700r4, an XE 256 will make you happier.