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Officially time to look for my new 402.

4367 Views 23 Replies 6 Participants Last post by  slims00ls1z28
Not the way I wanted to end up doing it though and definately not in this time frame.

Decided yesterday to check plugs on the car since it has been running rough lately. As expected they were blackened from the rich fuel mixture of pretune. No problem expected it. got everything put back together and fired it up. Sounded real good. Much better than before and no miss. So lets get ready test it right? I get in and start it up and notice the low oil light is on. K normal Fbody stuff. Its 1.2 qt low. Top it off. Low oil light gone oil pressure 45 psi. Cool. Go to drive everything feels normal. Taking it easy though just cruising. About 3 minutes from the house cruising about 45 mph I some noise, a loud fast clicking and the car is dead. Didn't sound like anything blew. No loud obvious bangs clanks etc. So I get out check under the hood nothing seems out of whack. Look under the car still nothing wrong no fluids. I get back in to crank it but the starter just whirrs making a grinding noise. ****. I then noticed white smoke emitting from the MAF. ?!?!?. Pull the lid off and notice fluid in the bellow that I can reach. SO I pull off the bellow and low and behold dexcool and metal fragments are sitting on the lip. Not Good. Open the throttle body blade and the whole bottom of the intake is covered in dexcool and metal fragments. ****. Eventually got it home to start a teardown. So far I got the vavlecovers off and no problems there all valves are still there (haven't pulled the rockers off yet though). Started pulling plugs off and cylinder #5 sparkplug has no electrode left on it. Definately got smacked and hard. No fluids on it. Checked the oil level and it is about 3 inches up on the dipstick over the full mark with the tell tale signs of water droplets but its not mixed so the crank hasn't frothed it must have all fell into block after whatever let loose. will try to finish up the autopsy in the next few days to see what exactly went but as of now the leading theory is a rod bolt letting loose. Given the recent symptoms. But its officially dead and I'm officially broke to fix it until around Jan/Feb once I get all the Birthdays/Christmas out the way :'(
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Oh man that sucks. Sorry to hear that.


I am praying that all goes well with mine when it I get it back running.
Man that sucks. :(

Perhaps a rod bolt let go and flung the piston into the plug.
That's the only thing I can think of.

Sucks when something so little as a rod bolt can cause so much damage.
Sucks,

A 402 will get you back on the road.

You buying or building your 402?
Haven't decided yet still looking at options and $. Wondering mainly how long it will take for them to make stroker kits for the L76/92 whichever is the aluminum one I forgot. Going to take a few months to recoup from this latest round of mods.

Yep **** cheap insurance rod bolts would have more than likely did it. Won't know for sure until after I pull it apart but thats my leading theory as of now. As they say horsepower always finds a weakness. :BangHead:
Yeah there's already a nice 416ci L92 stroker out there.
Pretty affordable too.
Worth a look. :)
**** did some searching around and found them even cheaper. I can get the same 402 shortblock as TSP for 3200 :roxor:.

Also....took the head off the drivers side and discovered what happened. How exactly still unsure, but it appears that the exhaust valves were hitting the pistons (all of them) and the #5 valve head broke off which in turn exploded the piston. Every piston has a small indentation on the valve and every exhaust valve shows sign of contact with the piston. Still unsure how this happened as I know 100% I had the cam installed straight up as I triple checked it and rechecked it again when I had to redo the oil pump o ring. I never looked inside the chamber to check clearance but I did rotate it several times and it didn't feel or sound like there was any contact. I don't think they hit all the time as I did put almost 600 miles on it andran it quite a few times as well as being dyno'd. If they hit constantly I'm sure it would have gave up the ghost earlier (maybe?). Guess they just contacted when she started to turn up in the rpms. The valve springs are the dual springs that were matched to the cam from TSP I wouldn't think that they were not strong enough. The rod didn't go through the side of the block but it did bust the sleeve and the aluminum wall behind it so its definately toast. Head got smacked a few times with the freefloating valve head so I don't know if its repairable or not but I'll probably not worry about it anyway. Oh well was planning on making a pass tuesday to see where I stood i know it was at least a full second faster. She put 347 to the wheels with the valves smacking and all the plugs had alot of carbon buildup (running untuned for a while no doubt) on them, one wire was fubar'd, and was slipping too much and not locking properly. Man It was going to be a beast. Oh well income tax time time to build another. Hopefully the cam, pushrods, valvesprings etc will all check out fine and will find their way in my new engine along with relief'd pistons.
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If it was just the smallest amount of contact it hardly could have been noticeable from those tests, but would break a valve over time as what happened.

Very strange, I wonder what caused it.
ouch man, im sure most of us were grinding our teeth when reading your story. GL with the 402 or w/e you plan on doing. like they say, "if your not breaking **** your not going fast enough" and "breaking **** is the only way to go faster". if your positive you put the cam in correctly and see the valves are bent or imprints on the piston, maybe a valce lock slipped?? i had that on the prix, had a cam put in and there was a recal on the valve locks i ordered and on the way to the shop for my free replacment of valve locks i had one slip and hit the piston. :BangHead:

but GL and build it right.
You had a MS3 right?
You had stock heads right?
Yep along with the dual springs, titanium retainers, hardened pushrods and seats etc and everything else in the cam kit. Supposedly a matched set.
Do you remember the exact specs on your MS3? Mine vary a slight bit from what is posted on the web site. Hell the specs off the cam card are bigger than the MS4 according to the website as well my card said 238/242 and .605/.612 lift. Smaller than the MS4 on the intake side but more lift.
What was the pushrod length?
Do you remember the exact specs on your MS3? Mine vary a slight bit from what is posted on the web site. Hell the specs off the cam card are bigger than the MS4 according to the website as well my card said 238/242 and .605/.612 lift. Smaller than the MS4 on the intake side but more lift.
I will check but if they gave you the MS4 then that is your problem. The MS4 has to have the heads flycut I am pretty sure.
If it was just the smallest amount of contact it hardly could have been noticeable from those tests, but would break a valve over time as what happened.
Even though I don't think it hit all the time the indentations on the pistons are more than just a slight tap theres 1/16th in indention, and the valve face smacked it covering 40% of the valve diameter came in contact. At first sight I actually though it was valve reliefs until I saw the jagged edge and remembered LS1's don't have this.
What was the pushrod length?
Gotta check when I get home stock length I think. Like 7.4 or whatever comes with it.
MS3 are 237/242, .603"/.609", 113 LSA
I think they may have just cost you your engine.
MS3 are 237/242, .603"/.609", 113 LSA
I think they may have just cost you your engine.
holy cow, thats a freaking insane lift

:eek::eek:
holy cow, thats a freaking insane lift

:eek::eek:
His cam card said his had even more lift:
238/242 and .605/.612 lift

I have 5.3L heads on mine and a MS3 on 112 LSA and I had to have the pistons flycut for clearance. I would guess that .612 lift would put it really close even on stock heads.

and on 114 LSA I think that makes it even worse.
I am 99% sure your cam did the damage.
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