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Tbi454 w 69k issue

B

bad larry

1/2 ton status
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May 16, 2010
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Location
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Evening fellas, I had an issue today that I'm hoping isn't catastrophic, I was hoping some of you may be able to shed some light on it...
My truck has been real healthy up until today when I was driving down the road @50-55 and the ol-girl just quit... No smoke, no radical sounds, I had plenty of oil psi.. I costed to a stop, popped the hood checked all the vital signs went back and tried to turn it over and it was like she had no compression.. It's like I broke the timimg chain or something.. Does this happen to tbi 454s regularly? Anybody broke one before? It's a bone stock 88 tbi 454, anyways running mobil 1, I've owned the truck since 30k w no issues.. :dunno:
 
Have you checked for spark?

First thing I'd do on a TBI that just died, is check spark. No spark=no fuel. No spark is most likely an ignition module, BUT the pickups go bad, magnetism is lost, etc. Just narrow it down first.
 
"IF" it broke the timing chain..I have seen it happen...if I remember correctly 454's are a no clearance motor. Meaning when the timing chain breaks valve's touch pistons. Hope its not a broken timing chain, you'd think though if it broke the chain it would have back fired through the TBi or exhaust.
 
Sounds like the cam timing gear has sheered off the plastic teeth and the timing chain jumped a few teeth. This means the cam and crank timing are out of sync and most likely you have bent valves. Usually you wont know the valves are bent until you replace the timing set and try to start it again just to find it cranks the same.
 
And yup it is.... I rounded the cam gear, and bent a bunch of valves... At this point I'll be looking for some advise as to what direcection I should go from here. I had planed to do a 12v this winter so I don't want to dump a ton of $$$$ into getting her back up and running. I'd like to to a cam, intake, heads, and exhaust. I have a build that Brian from Herris performance emailed me, I asked him for a suggestion because I have one of his chips in my truck and he's firmilure with cams for tbi motors. This is what Brian sent but I really don't want to spend the $$$$ that is involved here..

http://www.summitracing.com/parts/lun-90454lk* is the cam GM should have put in those motors. You can however convert over and run the roller cam like www.tbichips.com/Jim454.htm which is about the same specs but roller is going to give you about 15 more horsepower over flat tappet cam with same specs and you don’t have to worry about wiping a lobe off the cam.* As for heads, can’t argue with the power numbers Jims 454 made but for my money on 454 heads, I would use. http://cgi.ebay.com/ebaymotors/AFR-...r_Truck_Parts_Accessories&hash=item2c5df23c9c which aren’t cheap but you get what you pay for on heads and 454 engines aren’t cheap to mess with no matter what.* With a bored 54mm throttle body from www.tbiparts.com and some nice exhaust that 454 should make 454 power and that torque number will compete with any of the diesel trucks and Jims truck does surprising well on gas mileage.
 
Check out all your ign components first. Check for injector spray at TBI, spark, check rotor, etc.

I've had a bunch of ign problems, same symptoms. Good luck!
 
I found a 1990 tbi 454 w 500 miles on a reputable rebuild I'm going to pick up on Friday. $900 seems pretty lucrative compared to the cost of specing a rebuild. I'm gunna order a set of decent headers and drop it in. I'll play with the old lump this winter. Thanks everybody for your help.
 
Good deal! I picked up a "mystery" 454 TBI engine for my build, haven't popped the heads off it yet but I naturally suspect the worst. It was fully dressed minus the throttle body (which I already have) so that was a plus. You still thinking about a Cummins conversion?
 
bad larry said:
I found a 1990 tbi 454 w 500 miles on a reputable rebuild I'm going to pick up on Friday. $900 seems pretty lucrative compared to the cost of specing a rebuild. I'm gunna order a set of decent headers and drop it in. I'll play with the old lump this winter. Thanks everybody for your help.
Click to expand...


Do yourself a favor, and thoroughly check all the ign components, injectors, etc.

If the problem is external to the motor itself, a new one won't run either....
 
I appreciate it but I've got bent valves, stripped cam gear, and bent pushrods... I'm gunna build it up this winter, drop in the rebuild for now...
 
bad larry said:
I appreciate it but I've got bent valves, stripped cam gear, and bent pushrods... I'm gunna build it up this winter, drop in the rebuild for now...
Click to expand...

Missed the verification of the internal damage, my bad.

Not good! Motor replacement as you are doing is the way to go!
 
Yeah Greg, with all hope I'll pull the front clip this winter and slide a 12 valve in there.. That's y I just wanted to get-er up and running and not sink a bunch I'd Ching into it now...
 
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