Does anybody know the exact difference between the timing covers of a 94 LT1 and a 95 LT1. I want to convert my timing chain from a stock to a cloyes along with some other major mods to my 94 Z28 LT1 (ported heads, LT4 hotcam, 58TB, roller rockers and more. I'm expecting 450 hp more or less.

I have read an article that states that for cloyes #9-3145 I have to do a 95+ opti changeover and go to an electric water pump. The article says I need '95 timing cover #12552426. I have found someone selling what they call a 92-95 lt1 cover-no crank sensor part #10214196. When I go to gmpartsdirect there is nothing for his part number. my question is that if there is such a part number for 92-95 why would I have to change from a 94? One other thing being that the article says 95+ opti, does this mean that I can use a 96 or 97 also? The article makes it sound like there is a big difference between 93-94 to 95-97 opti's. Here is a list of parts the article says I will need to run the cloyes with electric water pump:

95 GM Optispark 1104032
95 Opti elec harness 12130319
Opti vacuum harness 12555323
Opti vacuum fitting 14082470
95 timing Cover (incl all 3 seals) 12552426
GM timing cover gasket 10128293
95 Cam Timing Gear 10206039
Water Pump Gaskets (2) 10128343
Is there a similar cheaper way of doing this conversion, or am I doing this for nothing. I know I can grab more hp with the elec wtr pump but is it worth the price for the conversion. Please someone respond.

 

If the timing cover fits a 92-94, then it is used on a non-vented opti and it definitely wont work for the vented opti conversion - stay away from it.

The 95-97 covers are the only ones that will work. The vented opti's have a much larger drive, and the required timing covers have a larger hole in the center for the vented opti drive to pass through.

The 95 covers are optimal, but the 96 and 97 covers will work as well. On the 96 and 97 covers you'll either need to leave the crank position sensor in, or remove the sensor and plug/cap the hole (I used a used a 96 cover and 4 cent freeze plug when doing the conversion to double roller)

I dont know why the guy claims his cover will fit 92-95. Either he is wrong about the last year, or GM put a few vented optis on the early 95 cars (possible, but I've never heard that before). Regardless, you can't use it for the conversion.

 

If you are gonna run a cloyes double roller chain and electric pump then you don't need to change out timing covers. You only need to change the timing cover to a 95-97 if you want to convert to the newer 95-97 vented opti.

 

How's that possible? I havent shopped for double rollers in about a year. Did Cloyes start making a double roller with a timing gear grooved to fit the splined shaft on a non-vented opti? If not, you can't use a 92-94 timing cover.

 

nope you got me. I forgot all about the 93-94 opti's being spline driven. Sorry.

 

wait a minute....you mean since i am going to change to an electric water-pump and a cloyes timming chain i need to convert to a non-vented opti?? Tell me this isn't so. Even if i use the Delteg system right.....since it still uses the postion sensor.

 

I'm sure they did....just like some have dual cats, some don't.

 

Yep, that's the case unless they've started making a timing set with a slot for the splined opti shaft on the non-vented optis (which I don't think they have). Lunati makes an aftermarket chain set for the non-vented setup, but it's not a roller and I've heard a few horror stories. From what I've seen, I'd go with the stock chain over the Lunati, if you're staying non-vented. The stock chain set is actually pretty Heavy Duty, as far as stock chains go. One of my buds is still using a stock chain (not the orginal, but still a stock chain) on his TT LT1 setup, and it's been holding up fine.