DOHC Cam Swap

[farley463]

As I recall, in 96, when GM switched over to OBDII, the LQ1 was completely redesigned. The heads were redone to bring the compression up from 9.25 to 9.75, the intake was redone with longer runners and the removeable TB, but that only gave a 5hp increase. From what I remember, is that they redesigned the cams to a much milder profile. Now I have access to both the 95 and 97 engines, so what I'm thinking about doing is a cam swap. What I plan on doing is swapping the four 95 camshafts into the 97 cam carriers with the lighter 33mm lifters. Basically what I'm asking is, has anyone else done this before? I've read a lot about it but I've never seen any results pertaining to it. I'm hoping it'll net atleast a 25-30hp gain but I'd like to see what everyone else thinks before I dive into it.

[1988GTU]

As I recall, in 96, when GM switched over to OBDII, the LQ1 was completely redesigned. The heads were redone to bring the compression up from 9.25 to 9.75, the intake was redone with longer runners and the removeable TB, but that only gave a 5hp increase. From what I remember, is that they redesigned the cams to a much milder profile. Now I have access to both the 95 and 97 engines, so what I'm thinking about doing is a cam swap. What I plan on doing is swapping the four 95 camshafts into the 97 cam carriers with the lighter 33mm lifters. Basically what I'm asking is, has anyone else done this before? I've read a lot about it but I've never seen any results pertaining to it. I'm hoping it'll net atleast a 25-30hp gain but I'd like to see what everyone else thinks before I dive into it.

IIRC you'd have to swap all the cogs out to match the rest and then I think you run into belt issue. Also, the cam locks are different from the older cams, basically check to make sure you can even use the cams in your carriers or if you can swap just the carriers on your newer heads without much issues. I'd just do the 6,6 timing adjustment and while the heads are off, do some port clean up/polishing to make up for any possible cam gains you might* even net from cam swapping. Cost vrs effectiveness

[farley463]

Yeah, I was planning on using the 97 cam cogs. I had one of the 95 cogs crack on me when I was trying to pull it off, so unfortunately I won't be able to use those. I'm pretty sure the 95 cams will fit in the carriers, as the only difference between those years is that the 95s have 35mm lifters, and the 97s have the lighter 33mm lifters. Other than that I don't see any issues. I was actually going to throw the 95 carriers on the 97 just for the simplicity, but the 95 engine had a bad lifter tick due to being starved for oil. I checked the cams, and they are in good shape, with no noticeable damage to the journals.

[farley463]

Slight update. I pulled the rear cam carrier off the 97 engine today, and decided to tear it apart to see the differences between the two cams. As you can see in the picture shown below, the 97s exhaust cam (left) does appear to be a bit less aggressive than the 95 (right). I've since proceeded to install the 95 cams in the 97 carriers, so I can still retain the lighter 33mm lifters and the 96-97 cam cogs. I have to reinstall the back carrier tomorrow, then swap the 95 cams over to the front carrier. I should be putting the engine back in soon, and I'll be sure to share my results.

[timg]

Very cool. I'm looking forward to seeing your results.

Tim

[SappySE107]

Looks the same to me. If you want to know for sure, send an intake and exhaust cam out to get speced. I have the 91-95 specs already and it was 25 for each cam plus shipping. I seem to recall the 96 and 97 engines only having a timing change, not a lift or duration difference.

Also your 95 cam looks pitted.

[robertisaar]

isn't a lift change more or less impossible without shimmed/different lifters?

oh, and here is info from when i was doing research on the subject.

                        96-97:   94-95:   91-93:
cam max lift at(crank) 108/115  112/111  112/111  *
springs                 65/160   75/180   75/180  lb
96-97 intake hits it's peak 4 crank degees earlier than 91-95
96-97 exhaust hits it's peak 4 crank degrees later than 91-95
so latest setup has it's intake advanced and exhaust retarded compared to 91-95, which increases overlap.

[SappySE107]

I probably wrote it down somewhere or posted, back when I was really into the 3.4 DOHC. Sounds right, the springs got weaker and the timing changed and that sounds right to me on the degrees it changed. Lift could have been changed if the carriers were different and the base of the lobes were smaller. You can go ahead and measure lift pretty easily.

[robertisaar]

i did some research there too.... 91-96 right-side cam carriers are one part number (10127482), 91-93 left side(10127481), 94-96 left side(10162137).

then of course, 97 has it's standalone parts. 24503321 for left, 24503318 for right.

[pocket-rocket]

i did some research there too.... 91-96 right-side cam carriers are one part number (10127482), 91-93 left side(10127481), 94-96 left side(10162137).

then of course, 97 has it's standalone parts. 24503321 for left, 24503318 for right.

So they consider left and right from behind the engine. Odd. I guess that means they think in rwd. I wish they would have carried that thinking over on the w platform.

Sent from my HTC One X using Tapatalk 2

[farley463]

Well I know its been a while but I figured I'd give an update on this. The car is finally back together and for the most part running as it should, I still need to do some tweaks, but anyways, here are my results. Its hard to tell after having the car apart for 4 months but it seems like the low end isn't too bad. Its a bit doggy below 3500 but if I powerbrake I can chirp the tires. The top end feels like its definitely improved, I can definitely tell when the power comes on, after it hits about 4 grand it just takes off and pulls hard all the way up to 6500. Cam timing was kept stock on the intake but I did a 10 degree retard on the exhaust. Idle is somewhat smooth, very steady when warm right around 1000rpm. I haven't filled it up all the way yet to figure out my fuel economy due to a leaking filler neck, but I'm estimating about 15-17mpg with my heavy foot.

Overall it seems like the swap has broadened the torque curve a bit, but I didn't get the big power increase I was hoping for but I'm satisfied with the results. If anyone has any questions on this swap be sure to ask! This was done on a stock 97 LQ1 using the 97s cam carriers with the 95 cams.