BCinDC

I recently purchased a 96 LS400 in near mint conditions, EXCEPT, it doesn't run . I thought/hoped that the problem was the ignition system (it didn't appear to have spark when I looked at it). However, it turns out that a mouse took up residence in the motor and filled the timing belt area with debris (almost like sawdust). As a result, the timing belt slipped and the valves bent (in case anyone still isn't sure...95-97 ARE INTERFERENCE).

So, rather than rebuild the heads, which is pretty expensive and requires a bit more time, I have been looking at heads on eBay. However, none are 95-97. They all will fit 95-97, however, after reviewing the parts lists at Sewell I found that the cams and valve springs (and valves, actually) have different part numbers for those years, vs 90-94.

So, I am wondering if anyone with a shop manual for 90-94 could look in the Cylinder Head Removal section to post the cam lift specs (they are there for the 95-97, so I'm assuming that they'd be there for the earlier years as well).

Thanks,
Bob

PureDrifter

iTrader: (10)

why not just buy used heads from a yard...

www.car-part.com to help your search.

BCinDC

Thanks for the link. That could be handy.

Effectively, that is what I am doing on eBay. But none available are from 95-97. SO, I am trying to figure out how different the cam lift is. I'm contemplating swaping my 96 cams (and maybe my springs, if there is a lift difference) for whatever comes in the heads. Going this route would, be much more of a pain, as I then have to measure & possibly/likely change (and order new) shims.

cgawelko

Dont buy heads for a 90-94 to put on your 1996. But the cam specs from Alldata are as follows:

Camshaft Journal Diameter 1.0612-1.0618 [01]
Camshaft Bearing Clearance .0012-.0026 [02]
Camshaft Endplay .0016-.0035
Lifter Bore Diameter 1.2205-1.2211
Lifter Diameter 1.2191-1.2195
Lifter To Bore Clearance .0009-.0020

[01] -- Exhaust camshaft thrust portion: 1993-94, .9433-.9439 inch;
[01] -- Exhaust camshaft thrust portion: 1995-96, .9433-.9539 inch.
[02] -- Exhaust camshaft thrust portion, .0010-.0024 inch.

BCinDC

Why are you saying don't use the 90-94 heads in a 96? They are supposed to fit, though I get the impression (which is why I'm looking for the lift specs) that the cam is ground to different specs.

Thanks for the ALLDATA info, which is interesting. The only difference I see is slightly looser exhaust cam thrust clearance is allowed in 95-97.

Unfortunately, this doesn't include the lift/lobe height data. Which I'm also interested in (to see if there is any likely power difference due to the cam and whether the springs are likely to be different pressure (actually the spring PSI is listed in the 96 manual, so it's probably in the 90-94 manuals as well).

PureDrifter

iTrader: (10)

the heads/intake are different for '95 M.Y. the heads will bolt on but they are different castings. Unlikely to work unless you swap to '89-94 pistons and complete valvetrain, at which point you'd need the '89-94 management too.

cgawelko

well 1990-1992 is different than the 1993-1994 by some sensors for cooling, and then 95-97 is different and then 1998-2000. 95-97 you guys have interference engines which you found out, I dont in my '93. so thats different. 98+ has VVTi which is different heads, just because someone says something fits, doesnt mean 100%. I can bolt 350 heads onto an LS block, or a suzuki swift efi head onto a suzuki samurai, doesnt mean it is the perfect fit.

BCinDC

I thought I posted this earlier, but somehow it didn't make it...

FWIW, this has been an interesting and informative thread for me. (HT to PureDrifter for the car-part.com link. I had never run across that before.) Ultimately, I haven't gotten all the details about how the heads are different, however, I have learned some things that are helpful to me, and possibly to others who might have bent valves or, for some other reason, need heads.

In particular, I was told by a salvage yard rep that if a salvage yard is selling the heads alone, that means the engine they came from was bad, otherwise they would never have taken the heads off. For that reason, they do not warrant that the heads are funcitonal at all, only that the castings are not cracked. If you want to be sure the head assemblies are good, you need to either get them from a complete, running engine, or get the entire engine.

Given the very particular way the timing belt needs to be aligned to avoid valve damage during removal, (and the liklihood that the guy removing the heads isn't using the shop manual procedure to do it) it's very easy to imagine that good heads would/could easily be damaged as they were removed in the salvage yard.

For that reason, I went ahead and bought a complete engine (127k miles from a wreck...only $300) so HOPEFULLY, I will be able to get good heads from it....we'll see over the next few weeks.

PureDrifter

iTrader: (10)

lexus redesigned the runner layout(or length, i forget), valve sizing, and lift on the '95-97 heads over the earlier ones, as well as upping the compression.

They are significantly different, this isn't really up for debate as it's been documented on numerous forums.

BCinDC

No debate here. I understood when I made my initial post that there were differences (reviewing Sewell's parts catalog revealed that...but it doesn't reveal the specifics/magnatude of how they are different). I had already searched existing threads and found no cam nor any other valvetrain or head specs.

I had two goals in starting this thread (maybe I should have titled it differently; and I didn't really state my most immediate objective; I thought it would resolve with the other):

1), most immediately, to identify whether a pair of rebuilt heads being offered on eBay were 1st or 2nd Generation (actually, there are/were several there that don't indicate year); and

2) to find out if 1st Gen could be used on 2nd Gen (in the event that the eBay heads...weren't 2nd Gen), even if they weren't identical (i.e. to get an idea how great the differences were).

Subseqently, as noted previously, I've found a 2nd Gen engine, so I really don't need the info. However, for purposes of closing out the thread, I will add what I've learned. I remembered the website address that had the specs - http://www.lextreme.com/misc.html. I had seen that before, but I couldn't remember what the link was (I'm not sure how I missed it when I "Googled LS400 Engine Specs" ).

So, to get back on topic....After reviewing the specs, the lift difference is small (assuming that the lobe base circles didn't change; which is not specified): +.5mm intake (41.710 vs 42.210); +.05mm exhaust (41.910 vs 41.960).

I didn't see any other spec differences that are substantially different (the valve spring specs, & cam journal specs are identical, minimum permitted valve length is .1 mm shorter for the 1st Gen intake, no change for exhaust minimum length; and no info is given on the diameter of the valve heads).