Maybe it is just me, or maybe I have not found the right thread yet, but I seem to be confused as to what is NECCESSARY and what it RECOMMENDED when switching to a csi or mezz. electric water pump for example. I have yet to make any purchases, but if the water pump is off, I want to go ahead and do the timing chain also.
SO....Is it neccessary on an OBDI car to swap chains? If so, what brand is recommended for this specific application (namely a 1994 firebird)...Cloyes? If Cloyes (for example), how many different chains do they actually make - double roller vs. true roller? I want to modify the timing cover as minimally as possible. So with that being said, what would be best?
And lastly, are there any special tools needed for the chain swap?


Thanks guys...

BRIAN

 

Anyone?? I know you guys have done water pumps swaps already....just want to know whats up with the timing chain during this whole process....

 

The 94 setup is different from the 95 OBD-I, which is different from the 96-97 OBD-II setup. I don't think anyone makes a decent aftermarket timing chain for the 93-94 setup. The problem is the way the distributor is driven on the 93-94 cars.

You have three options:

Just use an electric pump and do nothing to the timing chain. In this case, you leave the waterpump drive shaft in place, sticking out of the timing cover. This option allows you to convert back to a mechanical water pump at a later date if desired.

Replace the timing chain with a stock replacement unit and add an electric water pump. You can remove the waterpump driveshaft and plug the hole in the timing cover if you wish.

Change the cam, timing chain, timing cover, opti, etc. to 95 style. This gives you the option of running either the LT4 extreme timing chain, which will work with the stock mechanical water pump, or an aftermarket chain like the Cloyes with an electric water pump.

Unless you are running a lot of RPM, the stock chain should be OK.

BRAD

 

awesome thanks for the info, last minor question, how would the hole on the timing cover be plugged up? is there any "nice" way to do it...I have heard several things included the dollar coins! odd but true...

thanks

 

Lets clear up something here.


To use a Cloyes Double Roller:

- need a 95^ timing cover (prefarably a 95 version, since there is no provision for the crankshaft position sensor)

- need a 95^ optispark unit, and its vaccum harness

- need a 95^ optispark harness, (old one will not work), and you might have to modify one of the ends (its easy as pie) to make it work.

Other things to keep in mind.

- you do not need a 95^ camshaft. You should just have to grind or push the pin a little (search for exact measurements).

- if you decide to stay with the stocker, you do not have to keep the waterpump shaft. It can be removed and will not leak.

 

Cloyes is a very expensive option, the gm double roller timing chain is almost identical to it, an can be had for signifcantly less. I run 7K rpm on a regular basis with nitrous and no problems to date on the gm performance double roller chain...

 

The Cloyes True dual roller chain that I put in my car cost me $75 from Combination Motorsports. It is much beefier than the stock set. I don't see how that is very expensive. I have a 95. Now if you have a 93-94 car, then it is an expensive option because you have to change all the other stuff out.

 

great info guys, thanks a lot, i think the easiest thing for me to do is to replace the chain, but with a stock chain, to keep some cash free for other projects. although the vented opti conversion would be nice since my formula has gone through a couple optis already. ill try to diagnose a potential leak when i rip the pump off i guess....maybe this is causing some opti failure?

Brian

 

Grind or push the dowel pin in? Why? A pre 95 pin would already be too short. It needs to be longer.

I guess that point might be moot anyway, because you must replace the cam (or have the existing one drilled). The 95^ opti needs the larger hole in the front of the cam to accomodate the protrusion of the opti drive.

 

well guys I have finally gotten around to ordering parts and what not. the stock chain it is!

there is no way i see the need to switch to a vented opti. however i do have 1 question.

**Will any leaks develop if a) i leave the waterpump driveshaft in place or b) only remove it or c) remove and try to plug it with something??

i figure from here on out i will probably always run electric pumps, so i doubt i need to worry about being able to convert back to a mechanical one. i do not want any leaks whatsoever though, so whats recommended???