dre2013

iTrader: (7)

long story short, a friend of mine just put his 95 TA m6 back together, and keeps blowing up optisparks.

mods are:
comp xfi 292 (242/248 .589 113LSA)
LT's, ORY
heads are milled a little
EWP
and other boltons

after putting on all the mods he put on an msd opti. ran for one nite and then crapped out. returned it and got another, same thing ran for one nite and then went out. the 3rd one lasted about 150 miles and the car was running great, next day it went out too. 4th one lasted about 40mi.

all of this is without going over 5k rpm(car is untuned).
Dowel pin is .645"

anyone got any ideas? i've been out of the lt1 game for a few yrs now so i fig'd you guys would be able to help

Fastbird93

iTrader: (10)

What exactly went out in them? Did you open them up and take a look at the inside? Check valves still in the vent lines???

dre2013

iTrader: (7)

he did open them, and most of them looked like this:

Doughboy692

First the MSD opti sucks and even though they tell you the ones they are making now are better than the first ones they still suck. The only good use for them are trash can fillers and door stops. If you would like 4 more junk ones post your address and if they have not gone to the dump yet they are yours. Buy a genuine AC delco and you wont mess with it again for a while if everything is ok in the engine even if you are spinning 8K.


As for things to check to make sure its not something else look at the cam pin and make sure it is exactly the same length as a factory one. If its too long it can cause the piece for the optical sensor to run out of line with the sensor and will kill the sensor quick like you described. I have seen several with pins that are too long. Some times you can tap in a bit to get the right length sometimes it has to be cut. I cannot remember what the length is but I can check next week if you PM me monday. Leaving in the morning to do a little testing before the bracket finals this weekend or I would do it for you tomorrow.
Hope this helps
Rob

Doughboy692

Treed me with the picture. Check the cam pin it will cause that too because the rotor runs out of line too just enough to make it hit the pins on the cap. If the bearing in the opti has too much play it will cause this too.

dre2013

iTrader: (7)

i was wrong he has actually been through 6 opti's. 4 MSD's, and Accel, and a few hrs ago an AC Delco one went out.


thanks, the dowel pin length was .645 i believe. i also told him the msd's were junk so he tried an Accell, lasted 20 miles. Last night he put in an AC Delco, lasted 120mi and went out earlier today

Doughboy692

Ok you got me wondering give me 5 minutes I will run out to the shop and measure one of my cams.

Also I know this my sound dumb but mistakes can happen when you assemble an engine. Did he put the plate back on the front of the block? Also if you take it apart again measure the end of the cam that sticks through the cam plate. If the plate is missing or the cam was machined wrong the cam can walk to far forward and take the opti with it. Give me a minute and I will walk over to the shop and measure a pin. Be right back.

dre2013

iTrader: (7)

plate is on the front of the block, im not sure if he'll have it back apart anytime soon..hes pretty pissed off about all this . he said last nite that if it broke again he wasnt gonna mess with it anymore this year. If it will help him to diagnose what the problem is i'm sure he'd pull it apart again though

WS Sick

When the opti craps out is it just not running or does it run rough, throw codes ??

Doughboy692

The factory cam I have measures .620. I checked a brand new comp that is for the engine I am currently building and it is .635 but It will be 620 before it goes in as I saved a factory cam just for this reason. Way back around 96 or so when I put the first cam in a LT1 car it was a Crane and they had a little tag attached to the cam to check the cam pin length before installing the cam and it came with 2 pins. I will never forget that day as the one in it was too long and I broke it off trying to pull it out with a puller. What a pain in the **** that was LOL. He should be able to see how much cam walk he has without taking the timing cover off. Just remove the opti and set up a dial indicator against the cam gear. then push it too the back of the block and zero the indicator and grab a hold of a bolt head with some vice grips and pull it forward. Cant say for sure whats going on without seeing it in person but its hard to believe that many optis are bad out of the box especially when its 4 different companies. Please let me know what if anything you find out as its always nice to know things for future problems.
Good Luck
Rob

dre2013

iTrader: (7)

itll be driving running fine and then just shut off. he said one time something inside it literally popped, said it almost sounded like a gun. that was opti #3 i think, and going 30mph in 3rd gear

WS Sick

Are you guys just changing optis after that or do you check the pulses from the opti and the spark (just trying to be thorough)

Doughboy692

Just curious what timing chain is he using?

dre2013

iTrader: (7)

i know on at least two of them we tested and it had spark, and another he said the pulses were correct too. i havent been there each time so i'm not 100% sure

i will find out

dre2013

iTrader: (7)

said he is running GM timing chain. im guessing its just a new stock one.

96capricemgr

iTrader: (1)

Not going to be a popular answer but my guess is the person who made such a horribly incompetent cam choice, and drives it untuned is just as incompetent with a wrench.

Been driving and hammering on optis for over a decade and NEVER a failure, not even on my rather heavily modified car, has seen 7000rpms with a bone stock Delco opti.

Doughboy692

Ok that rules out too thick of a gear not allowing clearance between the opti and the gear. What about timing chain gear to cam bolts? Maybe if they are aftermarket bolts the heads are too thick and not fitting the recess in the opti. Also did he degree the cam in if so how much did he move it. If it was moved a bunch maybe its moved so far that the heads of the cam bolts dont fit the recesses in the opti correctly. Just trying to come up with some ideas for you guys to check as you definitly have a problem here. I mean what are the odds of that many going bad and all the msds that I have seen that are bad have had bad optical sensors

dre2013

iTrader: (7)

horrible cam choice, definitely. i told him to go with a cc503 or 230/236. They didnt have/couldnt find that at summit, so he ended up with this cam .
Only reason for driving it untuned is because he wants to get the bugs worked out before he trailers it 1.5hr and pays $500 for a tune, only to have the opti crap out first run? he already as an appt for the tune, car just hasnt stayed running long enough. After changing the opti on 4 LT1 cars i owned, i got tired of this opti bullshit, hence switching to the ls1. some last forever, some leave you stranded during rush hour traffic.

dre2013

iTrader: (7)

timing chain gear to cam bolts are new factory units. cam was just installed straight up. also i appreciate you trying to help bro, thanks much

hawk584

iTrader: (1)

4! for that much $$ you could have upgraded to the EFI connections LS1 cpu/coil pack upgrade!