[gtofreek]

Originally Posted by dataway

I thought cast iron and powdered metal were the defacto standard in modern vehicles for unleaded fuel. Surely they are not installing bronze guides in new vehicles? This engine is probably going to have to get regular doses of race fuel anyway. Not going to be a daily driver.
Although, I have heard, don't know if it's true that the "spiral" was to allow lubrication .... I always thought you did not want any lubrication (oil) in the guides ... as it burns, fills up the guide, binds the valve.

There is a difference between factory hardened iron guides, and the replacement 1/2" thinwall cast iron guides. The factory aluminum heads with iron guides are a different deal all together. For what you will be replacing the bronze guides with, the cast iron versions do not last long unless you find the carburized versions.

I have installed bronze guide liners in bronze guides before, so it works just fine. The thing is when I worked at another shop we used K-line guide liners, and tooling. The K-line tooling had a very difficult time boring through the bronze guides, and would usually get stuck half way through. Where I work now, we use the Classic version of the liners with tooling from Goodson, I believe. The boring tool we have[straight flutes] cuts through the bronze guides much better. It will slow down halfway through, but not stop and get stuck. Bronze bores a little smaller than cast iron so that needs to be accounted for when sizing them.

The cast iron guides with the spiral give even less surface area to absorb wear, so they wear out faster. You will not find any factory aluminum head with iron guides that are spiraled. They are all solid ID. Those guides are hardened also, probably carburized. Most of that stuff is metric sizes, so good luck finding an OEM guide that will fit.

[dataway]

Some of the decision to use the cast iron guides was due to my machinist, he wasn't comfortable putting bronze liners in bronze guides ... for whatever reason, and he seemed confident in the iron guides .... so, yeah perhaps not the best choice out there. In all likelyhood this vehicle won't see 10,000 miles in the next 20 years ... so hoping for the best.

I'm still soaking all this info up for the next build where I will be more concerned with performance and will have more flexibility with both parts, funds, and machinist.

[GOAT WHORE]

Originally Posted by dataway

In all likelyhood this vehicle won't see 10,000 miles in the next 20 years ... so hoping for the best.

Your machinist probably has this same attitude.

[rtanner]

Originally Posted by dataway

Block was decked .012, heads not touched, this will be the engines second valve job, seats don't appear recessed at this point .... if things look too bad I'd just go with hardened seats.


Check on the shims ... figured those would be needed. (is there a big downside to shims?)

CC roller tips will have to stay .... my other option was OEM rockers and I had this box for free. Hear good things, hear bad things .... so that's a "season to taste" thing.

Pushrods easily changed if necessary ... so yes I'll look into this.

Guides .... already had bronze guides installed ... my machinist was hesitant to put bronze liners in bronze guides. So .... new guides required.

Will check out the Chevelle site, working out the push rod length doesn't seem to be that complex, I'll give it a shot.

Thanks folks.

push rods will be fine, cc rollers are fine, I personally have found (from my et slips) not the internet keyboard, that I like 1.6 on the intake and 1.5 on the exhaust, especially if you have headers, other than that, you have a very good combo, well chosen!!

[455hota]

Can some one answer this question:

Can the CC Magnum roller tip rockers be used on stock 389 heads, with the original 389 oil drippers, and original style 389 stepped valve covers with no interference /hitting /rubbing issues??

Thanks in advance...

[steve25]

Out of all the Pontiac motors I have had over the years with roller rockers on them I have never had a early 326, 389 of 421 motor with roller rockers on them, so I do not have direct experience to relay to you.

That all being said, I do have some of the comp Cams rockers you question on hand and when I compare them they are only .030 taller in the ball section then a factory rocker, so besides Comp saying they fit 265 to 455 motors they look like there should be no issue with running them!

At worst you might have to stack on another valve cover gasket and use 8 longer 5/16" course hold down bolts to gain clearance.

This assumes that way longer valves have not been used in the heads or the latter 67 and up longer push Rods are not used since that will kick the push rod end of the rocker up higher towards the valve cover then stock, both in the valve closed and open positions.

[STEELCITYFIREBIRD]

Holy Archive, a thread reborn from 2016!

[455hota]

No one can flame me for not looking through the older posts before I ask my questions!!!!! Lol


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[STEELCITYFIREBIRD]