[RESOLVED] 1994 Firebird LT1 Optispark, Cap & Rotor replacement
Posted 14 July 2005 - 11:55 AM
I've got a 94 Trans Am with the LT1, and I've been trying to replace my Optispark unit for the past month. I've got the distributor replacement already, but I am having a LOT of trouble finding a cap and rotor kit.
$150 + shipping- Jeg's has an MSD kit, but it's not available until the end of July and they can't guarantee there will be any stock available after all the back orders are taken care of.
$130- Autozone carries a cap and rotor kit that is almost identical to the cap and rotor kit I have, except it has what appears to be a vacuum port molded into the side of the cap.
$230- Autozone carries a cap and rotor kit that is identical to what I have.
Can I use the $130 cap and rotor kit that has the vacuum port on the side? Can I use it if I plug the port, or run a vacuum line to it?
Any other parts store in my area charges atleast $230 for the cap and rotor kit. Other online stores and catalogs have stopped offering the MSD kit, or they have the same back order problem Jeg's has.
Thanks for any help
Posted 14 July 2005 - 01:38 PM
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1989 Formula 305 TBI----15.6@93 mph (March 2005)
soon to be 409 SBC and faster than 15's!!!!!
UPDATE: New 409 SBC 5 speed initial passes w/
2.76 open diff---13.64 @ 105 mph
1967 Firebird 400---------14.3@101 mph (September 2001)
soon to run with 461 and a tranny that won't grenade in a week!!!
Posted 14 July 2005 - 06:55 PM
I've been researching this so much I can tell at a glance the differences in the units. The main difference as I understand between Gen 1 (92-94) Optis and Gen 2 (95-97) Optis is the switch from a spline drive distributor to a clover gear drive distributor, and the venting on the cap. It's not the distributor I am asking about, but the cap. The only difference is the cap in question has a vacuum port molded into the top. Everything else on the rotor looks the same.
So would using the vented cap with a capped vent (I don't think that would be any different than a sealed cap which is what I originally had) or hooking a vacuum line to the cap (would it really vacuum anything?) be functional if mounted to the proper distributor (gear drive, no vents) on my 94 LT1?
Posted 14 July 2005 - 08:56 PM
Posted 15 July 2005 - 09:10 AM
Check out this link, this guy does a cool mod to make a 94 opti vented. I didn't read the article yet though.Opti link
That is a great link. I'm going to take a look again at both caps and rotors to double check that they are identical. Based on the pictures and the article, that guy is making the same thing I could buy. He just goes the extra step of vacuuming the distributor as well as the cap.
I'll let everyone know if this works or not.
Posted 20 July 2005 - 01:56 PM
The only difference in the cap molding from vented to non-vented is JUST the vent tube. For now, I opted to block mine until I can see how it runs. There IS a packaging difference though. The vented cap & rotor kit also comes with a new seperator plate (the plastic piece between the electronic distributor and the cap & rotor unit) which is has plug port molded onto it. As I haven't seen a vented distributor yet I must assume this is a difference from non-vented to vented. Fortunately I still had my old seperator plate which still had good seals.
As I stand now, the rebuilt electronic distributor (Autozone $175) and a new cap & rotor assembly (Autozone $130) are combined to make become a rebuilt Optispark unit. I have it mounted on the engine with all the other hardware. Tomorrow I should be able to fire it up and see if the electrical part of this experiment work or not.
By my math, I have saved atleast $45 off of the price of a new Optispark from GM ($300 special+ shipping or $350 no special+shipping), and I have a lifetime warranty on the electronic distributor. Seeing that my car has 125000 miles on it and the original cap and rotor were still working, I doubt, I'll ever be replacing the cap & rotor again.
We'll see how this turns out tomorrow!
Posted 22 July 2005 - 07:18 PM
Excellent information, thanks for the update.
I got everything hooked back up with the new cap & rotor installed, and it works fine. For the record, you can use a vented distributor cap on a non-vented distributor as long as you use the non-vented distributor seperator plate. I have the new cap's vent plugged for now, but it can very easily be hooked to a vacuum line.
Thanks for the help everyone. Hopefully once I gut my cat now, the car will be running as it should.
Posted 06 February 2009 - 09:03 PM
Hi, I am new to this forum my Name is Curtis and I have a 94 formula. I think my opti is going on it, It starts and drive's good but when you start getting into high rpm's it starts missing. Anybody have the same problem? So I am going to change it but my question is do I have to change the whole Distributor or could I get away with just the cap and rotor. Since it's at high rpm's would it not be the secondary ignition section of the optispark (cap and rotor).
Thanks in advace any idea's would help!!
Edited by 94_formula, 06 February 2009 - 09:22 PM.
Posted 12 February 2010 - 09:20 PM
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