Timing problem

[8upZR1]

After fixing a blown head gasket on my 90 it has been unable to start. Many good suggestions were made on the other thread I started. Today I cranked the car with the plenum removed to check out the injector spray pattern and I was greeted by combustion from the injector housing ports. All 8 cylinders are firing, its just that the combustion occurs in the ports and not the chamber. Can anyone tell me if this is an ignition timing issue or if this is a cam timing issue? I am stumped.

[ZR1 MK]

Based on information here and your previous post, I would check the combustion chambers with a scope viewer to see if any valves arent fully closed or bent at TDC due to a slipped cam. Or check compression and or leak down if you dont mind cranking the engine, but Id go with the other option first. If all checks machanically, start diagnosis on the ignition timing again.

[8upZR1]

I have a boroscope, just need to find all the pieces. I dont think any valve damage occured, before firing the motor spun nicely by hand, and while cranking I have never noticed anything that would be worrisome. I cant think of anything that would cause my timing to be so far off though. For combustion to exit the ports, the spark is occuring sometime while the intake valve is open. About as far as you can get from correct timing. Compression has always looked good, leakdown I have yet to do.

[ZR1 MK]

If all checks mechanically, it should be an electric issue. What is the MSD box you mentioned in your other post?

[8upZR1]

I use an MSD DIS 4+ box. It converts the ignition to a cd setup and ups the voltage from the coils. It has some nice features like multiple sparks, rev limit, 2 step, high speed retard, tach output. IMO it is a necesity if you are running nos. I have been running this igntion on my mustang for years now and have no complaints about it. I am surprised that more ZR1 people do not know about this box. I mentioned it to Haibeck and he kept asking me how I run an MSD without a distributor.

I am beginning to think that it would be impossible for the timing to so far off from an electrical problem. I am going to pull off the valve covers and recheck the cam timing. I was told that when using a crank locking device that it would only fit into one of the slots machined into the reluctor wheel, but now I am thinking that this advise was BS and that I locked the crank down in the wrong location. I did not even think to check this because the info came from a source who has always received the highest praise from the people on this forum. I am beginning to think this was a load of bs.

[ZR1 MK]

My engine builder uses that same ignition box.
The crank has a variety of slots, but only one that is deeper than the rest. It lets the crank locating tool make contact with the block, where the other slots wont let the tool set 100%. Its at 51 degrees. This could be the problem. Do you recall?

[8upZR1]

That is what I was told so as soon as the base of the locking pin went all the way to the block I figured I had found the one deep slot. When I bolted it down it was sitting pretty, flush against the block with no gaps or space whatsoever. I am now thinking though that this is a crock. Any of the slots is deep enough for the crank tool to fit into. Today I am going to redo the cam timing and I will find TDC on #1 and then rotate backwards 50 degrees and look for the nearest slot. I should have done this the first time, but hey, this is the first time I have played with an LT5. This time around though I will set the cam timing as the factory does it. No degree wheel and no hassle, just line up the holes, pin the cams and torque down the bolt. I do not want to do this crap a third time so I will go with what I know the car runs with. If my wife does not come home from work early I may be done by sundown.

[8upZR1]

BY the way, who is your engine builder? What combo are yuou running in your ZR1? ARe you happy with what you have?

[ZR1 MK]

I would have confirmed the crank position at 51 degree regardless and checked everything many times. I was thinking of doing the cam timing on my own, but probably will have everything assembled by the engine builder.
My current engine only has ported plenum and injector housings with modified exhaust. Pics and list of mods is shown in my webpage. This link http://www.cardomain.com/ride/418999/4 will take you to the specs for my new 427 engine.
Good luck with the cam timing. I heard its a pain with the engine installed. Or maybe you plan to pull it. I have info on doing it with a cam coder if do it installed and your interested.

[8upZR1]

427 sounds like a monster, that should be a hot ticket. I am doing this with the motor in the car. It is semi painful, but I am married and have therefore an amazingly high threshold for physical and mental abuse. I have already started the process, in fact the cams are already timed to the factory settings. All that is left to do is put back the valve covers and all the other pieces and do-dads. I decided to not mess with degreeing with a wheel cause I would only degree to factory specs anyway since this has been such a nightmare. I checked about a million times that I was in the right slot this time. If I put this motor back together and it still does not run I will be extremely angry that I gave up my performance cam settings for factory specs and still nbeed to hunt down some ignition gremlin. What is a cam coder? I have never heard of this. Do you mean the cam specs? I have those, the cams look cute on paper, very gentle. Anyway, time to play with the little one. I will update on tomorrows starting attempt.