Addicted To Boost Posted November 22, 2011 Report Share Posted November 22, 2011 I'm 95% certain I have a headgasket leaking or a cracked head on my 91 GTP. I'll confirm this first before moving on, but if this is the case, I'm going to remove both heads and do some work. Now, that said, I was contemplating maybe swapping on 96-97 LQ1 heads... is this a worthwhile change? I'm new to the LQ1, so any discussion on this topic is welcomed. Whether I use the 91 heads or the 96-97 heads, I will be refinishing them with new valve guides and seals, seeing how them leaking seems to be a common LQ1 issue. Any benefits/drawbacks to each? If I swapped to 96-97 heads, would I have to use the cams from that engine as well, or can I use my 91 cams? Were the cams changed at all? Quote Link to comment Share on other sites More sharing options...
GOT2B GM Posted November 22, 2011 Report Share Posted November 22, 2011 Seeing as how the 96-97 motors are interference, I would look into what component(s) make then interference motors. If you just swapped heads, you'd need to also swap exhaust manifolds. For this option I would compare the lift of the 91-95 cams to the 96+ to make sure you aren't going to drive valves into pistons. If you did heads and cam carriers, you'd also need to change the cam gears on either the intermediate shaft or the cams because the 96-97 belt is different from the 91-95 I'm not sure if there are any piston differences..... Quote Link to comment Share on other sites More sharing options...
jman093 Posted November 22, 2011 Report Share Posted November 22, 2011 96-97 heads do flow better and have high compression to make a little bit more power. 96-97 intake and exhaust manifolds also flow better. 91-95 pistons are different than 96-97 pistons, and although 96-97 pistons have valve reliefs in them, 96-97 heads are a common swap and no one has had any trouble in this using them with 91-95 pistons. Although it might be more likely that if a timing belt did break that it would contact the piston. It's rare for that to happen on any year stock LQ1. Ben at WOT-TECH one CC'd the heads and pistons and I think 91-95 284 pistons like yours are about the same as 96-97 pistons, so your compression ratio should increase about a 1/4 point to around a stock 96-97 (which is 9.75:1) with the newer heads. If you were also looking to squeeze everything possible out of the swap, when looking for the newer heads, find a 97 engine as it has smaller lighter lifters than 96. Quote Link to comment Share on other sites More sharing options...
Addicted To Boost Posted November 22, 2011 Author Report Share Posted November 22, 2011 Are the cams themselves any different on the 91-95 engines versus the 96-97s? If I could use my current cams, that would save me the trouble of swapping cam gears. Also, the engine in the car now is out of a 92 Lumina automatic car, so I will have the automatic pistons in this engine. Quote Link to comment Share on other sites More sharing options...
Addicted To Boost Posted November 22, 2011 Author Report Share Posted November 22, 2011 I think I remember reading somewhere that LQ1s have hydraulic lifters as well... is this true, or do they use a shim under bucket design? Also, if using the 97 heads and lifters, does that necessitate using the 97 cams as well? Quote Link to comment Share on other sites More sharing options...
GOT2B GM Posted November 22, 2011 Report Share Posted November 22, 2011 (edited) 91-95 PISTONS (even the auto ones) have valve reliefs in them that look very similar to the 96-97 Edited November 23, 2011 by GOT2B GM Quote Link to comment Share on other sites More sharing options...
jman093 Posted November 23, 2011 Report Share Posted November 23, 2011 Are the cams themselves any different on the 91-95 engines versus the 96-97s? If I could use my current cams, that would save me the trouble of swapping cam gears. Also, the engine in the car now is out of a 92 Lumina automatic car, so I will have the automatic pistons in this engine. I think I remember reading somewhere that LQ1s have hydraulic lifters as well... is this true, or do they use a shim under bucket design? Also, if using the 97 heads and lifters, does that necessitate using the 97 cams as well? Cams are different, but yeah, I think they swap just fine. I'm not sure if they fit in the 96-97 cam carriers or if the carriers are swapped onto 96-97 heads (or maybe either is possible), but this is not a rare swap and I haven't heard of a problem, so I'm guessing it's not an issue. The difference I know is 91-95 cams are actually more aggressive than 96-97 ones. Lift is the same at .370, but they have more duration and overlap and I think timing was also changed a couple degrees. The tamer cams is the reason attributed to the 96-97 only being rated a measly 5 more hp despite more compression, better heads, better intakes, and a better exhaust manifold, and its also the reason attributed to 96-97's generally idling a bit better. There should be some power to pickup though to using the older cams. Lifters are hydraulic. 97 differs from 96 only in the use of the lighter 33mm lifter vs 35mm in 96. So 97 lifters require 97 carriers and obviously 96 with 96. However, either year of carrier can bolt on either year of head, and either year of cams can be used in either year of carrier. So you can mix-n-match there. Quote Link to comment Share on other sites More sharing options...
AL Posted November 23, 2011 Report Share Posted November 23, 2011 Wow... lots of good info in that post Quote Link to comment Share on other sites More sharing options...
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