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Converting a Y engine to a 9 in 97 STS

3K views 26 replies 10 participants last post by  Starfire88 
#1 ·
This is a continuation of my other thread, but I figured I'd get better response with a new title.

I have a 97 STS that I have pulled the engine out of with bad head gaskets.
I found a real good Y engine same year. With the heads resurfaced and valves redone, inserts and gaskets already installed.

I don't want to put in the Y engine in my car.

Can I convert this new Y engine to a 9 engine with my existing parts??
If so, what do I need to swap over?


Thanks in advance. This forum has been very helpful during my Caddy ownership so far
 
#6 ·
Thanks guys.

Would you buy a used motor that someone else has worked on and do this, or would you insert your own block?

What's the chances of me coming across a cracked head or block?

Mine spewed exhaust gases into the cooling system. after 20 mins. of running it would overheat quickly.
 
#9 ·
Ask any engine builder if he would replace the cams and not the lifters on a non-roller engine.

Ask any engine builder if you can swap lifters around from lobe to lobe.

New cams get new lifters in my book.

In my book used cams in a different engine gets new lifters.

Napa has lifters for about $16 each that would be about $500 just for the lifters on used cams.
 
#10 ·
AJ is exactly correct: NEVER mix and match lifters; never replace them in different bores; new cams = new lifters or followers.

Swap lifters or mix them up and you're in for a real expensive mechanical mess.
 
#12 · (Edited)
probably kind of like replacing a chain without the sprockets.

I'm really torn. This Y engine I found is already got Norm's inserts in it. Everything is great except the lifter idea.

I can get the Y engine for like 450 bucks. (with some trades) The guy that did the work is reputable.

Can i just put my heads on this thing? He put the heads on the Y engine with new bolts to the First step in the torque process.

What would you guys do? I can do the work on mine. Thats not a problem, but is it easier to insert my engine or separate it from the tranny and change it? I already have the cradle out and in my garage on jackstands.
 
#13 ·
If you go back in Northstar Performance a few days you'll find a thread with pictures of the pre-2000 engine which uses hydraulic lash adjusters directly between the cam lobe and valve tip. You change cams, you must change all 32 lash adjusters (lifters). Megabucks. (The 2000+ engines changed to a roller cam follower setup. NO.)

The bottom end of the engine is bulletproof, so if you do a top overhaul/Norm's Insert job on your present engine you're good for at least another 150,000.

If you change to VIN 9 cam(s) you must change to a VIN 9 PCM program and final drive gear ratio. Different engine management and transmission final drive setups. Fuel, torque, and transmission control curves different.
 
#15 ·
The Vin 9 also has one other difference other than the cams. It has an oil cooler so you may want to swap that over. I have reground 272 Vin 9 cams in my Vin Y block, Norms inserts, cometic gaskets and hylomar sealer. Just getting the bugs worked out as I'm running on a different computer.
 
#18 ·
Hylomar is a proprietary name for a line of RTV (Room Temperature Vulcanizing) sealers and gasket makers. Sort of like the line of Permatex Red, Blue, and Black sealers in blister packed tubes at Trak Auto/Pep Boys, etc.

Different formula RTV's are used for different gasket applications, such as exhaust, oil, coolant all require different sealants.

GM has just gone to a more or less universal RTV which is sold at GM dealers only (so far).
 
#21 ·
This may be a dumb question but there is a lot that I don't know about the different year N*. If you can purchase a Y engine for a decent price, why don't you just put it in as is rather than converting it over to a 9? If it needs a different PCM it seems that would be easier to do than converting the Y engine to a 9 engine.

Confused....
 
#23 ·
I ended up finding a 9 engine.
The tranny is different on the 9 vs. the Y. that was the kicker.
I was a bit confused about which engine was the higher HP engine. I guess the 9 was the more powerful engine, is that correct?

If you don't mind me asking, whats the problem with the transmission, just a different type that you didn't want or did it have something to do with the mounts?
 
#25 ·
VIN "Y" is generally the 275 HP engine with a 3.11:1 final drive.

VIN "9" is generally the 300 HP engine with a 3.71:1 final drive.

I say "generally" because the GM/SAE flywheel HP ratings tended to change slightly during the years of FWD model runs. The PCM is set for each individual engine, transmission, and car VIN, so a swap is not quite as simple as a straight engine change. There are mechanical differences in the two engines, cams primarily, so there are problems with overall engine management if the PCM's (fuel and ignition settings) aren't swapped also. AJxtcman and Highlinecady are currently working on various PCM changes, but most of that is on indefinite hold for the foreseeable future.
 
#26 ·
davz. Go ahead & swap the heads. those vin 9 heads don"t know their sittin on a vin y block. did all the research and found out the lower half vin 9 & y share the same parts. I am in the prosess of doing this my self. Just put the heads on today and damm if i did"t strip out a time sert on the final pass. .Gonna switch to studs now. Good luck & get crusin..Rainboweed
 
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