head rebuild hardware, where to buy?

[guibo09]

does someone sell a nice complete hardware kit to rebuild an m20b25 head?

- valve guides, seals, etc
- rockers, ecentrics, etc
- replacement SS valves?
- etc etc

looking at pelican, they sell parts individually... want more of a complete package deal.

[nando]

nobody sells a kit that I know of. You'll just have to order everything at once.

also have your valve guides checked before you replace them - they're probably fine. the valves are also rarely worn to the point that they need replacement, unless the engine was running poorly and they are burned or bent. new ones aren't that expensive of course..

[guibo09]

when i removed the head, i didnt think too much, and i rested the entire head (with exhaust and intake mani still on) on a drape + carpet that was on the floor valve side down. so the head was resting on the valves that were sticking out. is that enough to bend em?

[nando]

maybe, but not certainly. they should all be measured for wear and straightness anyway.

[guibo09]

alright, ill have it all checked.

where's a cheap place to buy rockers? i searched and people talk about a full set for under 200$, however, i never see rockers under 20$.

[thereisnoyun]

when i removed the head, i didnt think too much, and i rested the entire head (with exhaust and intake mani still on) on a drape + carpet that was on the floor valve side down. so the head was resting on the valves that were sticking out. is that enough to bend em?

actually... very likely. Depending on the duration you left it the way it is sitting. Also how hard the surface it is under it. If you rest the thing on concrete fo a week. I can guaranttee that thing will be bent. But if you left it on a carpet with lots of padding and the floor is wooden, it will be unlikely it will be bent.

order the rockers through bmw, they should cost you 200 for the entire set. All the components should cost you around 400 dollars. if you buy a new febi camshaft with it.

I take that back, BMW hike thier price, rockers are 27 a piece now even with CCA. a set of 12 would run you damn... I dont even want to know. 325 dollars ... daaaaamn.

- Yun

[guibo09]

actually... very likely. Depending on the duration you left it the way it is sitting. Also how hard the surface it is under it. If you rest the thing on concrete fo a week. I can guaranttee that thing will be bent. But if you left it on a carpet with lots of padding and the floor is wooden, it will be unlikely it will be bent.

order the rockers through bmw, they should cost you 200 for the entire set. All the components should cost you around 400 dollars. if you buy a new febi camshaft with it.

I take that back, BMW hike thier price, rockers are 27 a piece now even with CCA. a set of 12 would run you damn... I dont even want to know. 325 dollars ... daaaaamn.

- Yun

the head only rested for about 5-10 minutes on a softish carpet floor (concrete under). however, i dont see how time is a factor really, since steel doesnt creep at room temperature.

yeah the prices of the dam rockers are alot more than i expected! real piss off. i dont think it will be less than 400 for a full rebuild in materials.

[jlevie]

You won't bend the valves by gently setting the head on any surface. Now if you drop it onto a concrete floor...

You appear to have a '90 engine, which would have the improved FEBI rocker arms that aren't prone to breaking. So unless there's obvious damage to the rockers I don't see any reason to replace them. I would suggest mike'ing the cam to see if there's enough wear to justify replacement.

[guibo09]

You won't bend the valves by gently setting the head on any surface. Now if you drop it onto a concrete floor...

You appear to have a '90 engine, which would have the improved FEBI rocker arms that aren't prone to breaking. So unless there's obvious damage to the rockers I don't see any reason to replace them. I would suggest mike'ing the cam to see if there's enough wear to justify replacement.

is there any visible clue to confirm that i have the improved rockers? i thought this was a wear item?

what's mike'ing?

[jmc1590]

mike'ing: as in measuring with a micrometer....

[jlevie]

To some degree, the rockers are a wear item, but unless you have a lot of mileage on the head (300k or more), or the engine has suffered extreme abuse, there's probably not enough wear on the cam followers to matter. In either of those cases the cam will have suffered similar or more wear.

Mike'ing the cam means precisely measuring the diameter of each journal at several points and measuring each cam lobe and comparing those results with the measurements of a new cam. Wear of the cam is far more significant than a bit of wear on the cam followers of the rocker arms.

I sort of think that the improved rockers became a part of normal production along with the "weight improved" pistons, which started with 6/88 cars.

[nando]

I don't know, rockers fail from fatigue - I'd rather have new OEM rockers than old ones that have been through hundreds of millions of cycles and thousands of warmups/startups. and honestly there will be quite a bit of wear by ~150,000 miles, aside from the fatigue.

[guibo09]

I don't know, rockers fail from fatigue - I'd rather have new OEM rockers than old ones that have been through hundreds of millions of cycles and thousands of warmups/startups. and honestly there will be quite a bit of wear by ~150,000 miles, aside from the fatigue.

that's what me was thinking.

[jlevie]

Replacing the rockers isn't a bad idea, but it isn't strictly necessary. The majority of the wear on rockers is at the cam follower, an if there's significant wear there you can be pretty sure that the cam is worn enough to need replacement. The only down side to worn followers is that over sized eccentrics might be needed, which are available for this purpose. I suppose enough wear on the followers might make a tiny difference in how far the valve opens. But it would be a very small affect.

Broken rockers are not uncommon for the early design, but even race engines that spend a lot of time near the redline don't experience that failure very often. And there are Spec E30 engines out there well north of 150k...

I personally would not replace the improved design rockers on a head I was rebuilding, just because. And I think I heard that new OE rockers are up near $27 a piece now. Which quickly turns into a sizable expense.

[guibo09]

Replacing the rockers isn't a bad idea, but it isn't strictly necessary. The majority of the wear on rockers is at the cam follower, an if there's significant wear there you can be pretty sure that the cam is worn enough to need replacement. The only down side to worn followers is that over sized eccentrics might be needed, which are available for this purpose. I suppose enough wear on the followers might make a tiny difference in how far the valve opens. But it would be a very small affect.

Broken rockers are not uncommon for the early design, but even race engines that spend a lot of time near the redline don't experience that failure very often. And there are Spec E30 engines out there well north of 150k...

I personally would not replace the improved design rockers on a head I was rebuilding, just because. And I think I heard that new OE rockers are up near $27 a piece now. Which quickly turns into a sizable expense.

if i take pics of the rockers, can you ID new vs old design?