OK my engine builder is making me very mad! I have a 95+ opti I just went out and tried to put on my new engine and it wont fit! The LT4 hotcame has a splined cam gear and not a recession for the dowel pin!

What can I do? I don't want to have to take everything apart or buy a new opti. What are my options?

 

It sonnds like you have the wrong cam gear. You need the one for a 95 and up. If your builder made this mistake you also need to check the dowel length in your cam.

 

I have a dowel out of a new one but my engine builder originally was going sbc style with an LT1 block. He was gonna delete the opti.

My question now is can I have that area drilled out for the new style opti? or do I need a whole new cam!

Also, will the timing gears and everything be set up correctly for a true LT1 cam? I may take this oportunity to upgrade to a better cam. Please advise!!

 

You will need the correct cam gear, correct length dowel pin and correct cam with the large hole in the front (the LT4 Hot cam should have this).

 

Well suposedly there is an LT4 hotcam in there. It does not have the large hole in the front. As you can tell I don't know a lot about the internals...

It has a smaller hole with teeth around it in the cam. But it is suposedly a brand new LT4 hot cam?!?!

 

I dont know what cam gear it has...the only real issue I notice so far is the hole being too small for the optispark. It looks like the opti would plug right in and line up correctly to everything if that hole was bigger.

 

Hmm...since LT4s did not come out until after there were vented optis, it would follow that it would have the larger hole. Perhaps it is not really an LT4 Hot cam.

 

i think his problem is the cam gear....stock a screw driver in the hole and see how deep it is or if it stops

 

So am I reading this right? I am contiplating putting in a hotcam in my 94. Will I have this same issue due to my opti not being vented. Will I have to convert to a vented type to fit? I am very interested in what you find out.

 

The timing set has to work with the opti
the hot cam will work fine
one is spline(non vented) drive one is pin drive(vented) ju

just make sure you get the right timing set

 

OK You guys are confusing me. Heres the run down.

Timing set - I dont know?? I will take pics in a few minutes when my batteries are charged. You have two main holes in the timing cover. The one for the crank snout and the one for the cam which has a dowel pin and 3 bolts. My only issue is that the cam's hole it has in the center of the 3 bolts and the dowel pin is too small for my opti to plug in to. What does this have to do with the timing and such?

Can I simply drill out the cam hole large enough to support my opti?

If not, JPAC24 I will sell you my oldder style hot came (once I confirm it is a hotcam via its model#) and I can go buy the correct one to save me a lot of trouble

 

Its not clear from your description whether you are talking about the center hole in the cam SPROCKET (gear), or the center hole in the cam itself. The 93/94 cam SPROCKET has the spline teeth in it to drive the UNVENTED Opti's splined driveshaft. The spline teeth are not in the cam hole. Sounds like they didn't change the cam sprocket to the one that provides the pilot hole for the 95-97 vented Opti pilot shaft.

These articles have some pictures of the differences. Just remember, the LT4 HOT cam is designed to work with the vented Opti, but will work with an unvented Opti.

http://para.noid.org/~muttvette/opti.html
http://www.automotiverebuilder.com/ar/ar99928.htm

 

So if I am understanding this correctly, The Hot can can be used on the 94 with the non vented opti.. If I wanted to do the cam swap and keep my non vented opti, what additional parts are needed? I don't want to go through the expense of changing to the vented type when I have replaced my opti and is in great working condition with < 6k on it. One other question would be can a stock replacement timing set be used on this set up without problems? This would be on a tame build up on a weekend cruiser. (sorry to hijack in this thread)

 

Here are some pics! Let me know what you think.

 

Click the thumb nail then click the image again when it opens in a new window to get a very large view.