Easy Question, '91 5.7L TBI, interferrence?

[Rerock]

True or False:

This engine, in it's purest stock form; is designed as an interferrence motor.

[KWTMECH]

????????????????????????______________come back on tuesday

[cummins2nv]

This is FALSE. Technically speaking, I don't believe any engineer "designed" an interference engine. When a timing chain or timing belt breaks while the engine is rotating, some valves may be stuck in their full open position while a piston comes to TDC. This is an unfortunate circumstance than can not be avoided in some instances but I would say it is probably not the case in a low compression TBI engine with a stock camshaft.

[myojunk]

im with stupid ^

false

[cj8scrambld]

I say true.........the TBI motor "interferes" with good performance in it's inability to accept change!

[Rerock]

Originally Posted by KWTMECH

????????????????????????______________come back on tuesday

Ok... Its tuesday. Does the answer change?

[Rerock]

Originally Posted by cummins2nv

This is FALSE. Technically speaking, I don't believe any engineer "designed" an interference engine. When a timing chain or timing belt breaks while the engine is rotating, some valves may be stuck in their full open position while a piston comes to TDC. This is an unfortunate circumstance than can not be avoided in some instances but I would say it is probably not the case in a low compression TBI engine with a stock camshaft.

While determining why this motor won't run, I discovered that the timing chain was streched...bad. To the point that the chain wore off the teeth of the cam sprocket and was randomly slipping and gripping. If it were an interferrence design, than this motor is most definately fawked. If not, than there is another reason why this thing has 0 (maybe 5, the gauge doesn't read that low) compression and won't run.

Teh sirch was kicking my ass, couldn't find a definitive answer.

[KWTMECH]

Originally Posted by Rerock

Ok... Its tuesday. Does the answer change?

No, same answer. Not an interference engine such as a honda may be

[cummins2nv]

Originally Posted by Rerock

While determining why this motor won't run, I discovered that the timing chain was streched...bad. To the point that the chain wore off the teeth of the cam sprocket and was randomly slipping and gripping. If it were an interferrence design, than this motor is most definately fawked. If not, than there is another reason why this thing has 0 (maybe 5, the gauge doesn't read that low) compression and won't run.

Teh sirch was kicking my ass, couldn't find a definitive answer.

Well if the timing chain is slipping and grabbing like you say, then that there very well could be your problem. It is very unlikely the engine run if the timing chain is slipping as you suggest, and if it DID, it would run REAL bad!. The next step to take before shelling out money for parts, would be to perform a leak down test in each cylinder. Depending on how many miles the engine has, I would say that 20% leakage is acceptable if it has over 100K on the odo...almost all engines will have atleast 10% leakage. If you do not know anyone with a leak down tester (or a compressor to pressurize it) you can get a cheap one at your local auto parts store. It will not be the greatest quality piece but it will serve it's purpose in your case. Or, for about the same price you can just buy a stock aftermarket timing chain and gear set and throw it on. I can safely say that I seriously doubt any valves kissed any pistons in your TBI engine.

[Rerock]

I had another thread going,
but cliffs notes: (how's this for keyword searches)

165,xxx TBI 350. Originally pulled timing cover, crank was at 12:00, cam about 10. Way out of time. I put it back to TDC(50/50 chance)? Test run, sputters pops, won't sustain. Distributor, no dice. Cam 180 out. Flip cam 180, 0 compression. Flip back, 0 compression. WTF? Test compression gauge, seems to work. Huh. Interferrence motor? Nope. Try other cam combos. Found it, motor's timed. Compression test, 30psi+/-1 across. Consistent but low. Issue? Drop in distributor, oil pump's out of time. Obviously. Long screwdriver? Donor Distributor/drill? Put together, keep running, get warm/ lubed, compression back? If not, fried rings, parkr? Yes, time ingition, done.

Sound about right?