Is the 2.8l really what I want?

[caffeine]

I've always had success with the stock chain and 986 springs. I believe the 986s are easier on the chain than the 915s. IIRC the 915s will support higher revs but not as much lift as the 986s. That being said you probably won't be spinning much past 7k anyway and the 986s are fine for that.

[Ghosteh]

Here's another question, only slightly related to the cam/spring issue...

Will the brand-new timing chain on my old 2.8l fit & be a stronger unit than the stock LX9 chain? I saw a few old posts which recommended a pre-99 timing chain & gear swap for any LX9 build involving a performance increase.

No, valve float is just that, valves that are "floating", not really floating as in the general sense, but they are are not really sitting on their seat and are more bouncing off the seat, because the spring does not have enough pressure to control the bounce or closing of the valve, especially at higher RPM, where the time spent on the seat is short. This short period of time makes it seem as though the valves are floating, since there isn't enough time to allow the valves to regain control with the weak valve springs. Increasing the valve spring pressure, increases what is called "seat pressure", which is the force applied by the spring when the valve is closed. Increasing this pressure is what reduces the possibility of valve float. The trade off is the increased open pressure, that can cause problems with hydraulic lifters and even cams sometimes.

This is where the balancing act of a strong enough seat pressure, without too much open pressure comes in. This is part of the reason I went with the 915s instead of the 918s in my current build. I'll likely step up to the 918s in the future when I need even more seat pressure.

[Ghosteh]

* found the answer to a question I had. Disregard this post

[1988GTU]

PM Ben for a cam then pick up 26915's. About 15hp increase at a guess.

[caffeine]

Is the 2.8l really what I want?

You might want to talk with WOT-Tech about getting a cam that suits your wants/needs. I don't believe they charge extra for custom cams. That with some 26986 springs and you should be looking at a 30-40hp gain at least with a cam more on the wild side.

[Ghosteh]

ok Caffeine, so what cam could I get away with using, without having to worry about valve clearance with stock pistons? I really like the idea of eliminating any potential valve float. I'd go with either the LS6 or the Crane springs... whichever has been used and proven by you guys, and whichever best matched the cam.

I really don't want a radically lumpy idle... just something marginal. And what HP differences are we talking about this making?

[1988GTU]

Cam+Spring swap it. Don't look back.

[caffeine]

You can cam the engine while keeping an OBDI ECM it just needs to be tuned (which it will need anyway, or at least a swap chip).

Or maybe LS6 springs would be a slight bump in performance without being too much with a stock cam.

The problem with the stock springs is that they float sometimes even above 5200 rpm. I've run a 3500 with stock springs to 6300 rpm before and never had any problems result but the power completely disappears above 5200. I only ever revved higher when doing a burnout.

In other words you won't have longevity issues with stock springs but springs/cam are an easy bump in performance.

[Ghosteh]

Comp 26986 are the most common ones used afaik. I did read somewhere to be careful using aftermarket springs with a stock cam though. Something about how the stock hollow cam lobes tend to spin on high mileage engines and how stiffer springs could cause this phenomenon earlier.

That makes sense.

So if you were planning to run a stock cam, would it be better to stick with stock replacement springs? They may be a "weak point", but on an otherwise stock build, are they ever really going to be an issue? These motors should be good for a couple hundred thousand miles as-is, correct?

The other option is to go with an aftermarket cam (which I wouldn't mind if it made it sound like Caffeine's car), and the Crane 26986 springs. If I do that, then I'm looking at using MegaSquirt ECM instead of OBD, correct? What would be a nice MILD bump cam? If I decide to go this route (and what the hell... I'm jumping in pretty deep at this point anyway), is there anything else I'd have to change or be aware of? This route might be the snowball growing into an avalanche.

Oh, and I did get a 65mm TB and adaptor, which should be here next week. Everything else being stock, will I see any benefit from that size of a TB vs. stock?

[caffeine]

Comp 26986 are the most common ones used afaik. I did read somewhere to be careful using aftermarket springs with a stock cam though. Something about how the stock hollow cam lobes tend to spin on high mileage engines and how stiffer springs could cause this phenomenon earlier.

[34blazer]

Sub'd!


I like where this is going!

I installed Crane Cams 26915 springs on my LX9 recently. I have no direct comparison to a running LX9 before hand, but I can tell you that the Crane springs are by far stronger than the stock springs.

[Ghosteh]

I've decided to go through the heads while they are off... mostly because they really needs to be cleaned. I'll have the valves ground, seals, ect.. Seems I recall some mention that the LX9 weak spot was the stock valve springs, but there were better replacements available. Who makes the ones to get? (Was it Crane cams?)

[Ghosteh]

I think you may be talking about the protrusions on the 'passenger's side' of the intake? In which case they're used to attach parts of the wiring harness/plug wires IIRC. You could cut them off or use them for the same purpose in a swap.

Yep, that's it. I might as well leave them & use them again for that purpose.