88' shelby Z quest for 11's (lots of pics)

[1984rampage]

I am having this same issue with a GLHS. Oil pressure is great unless you accelerate heavily. I have had wiring gremlins in the past so I assumed that the sending unit was bad....

Let me know what you find out as I don't want to lose this motor

[Shadow]

I am having this same issue with a GLHS. Oil pressure is great unless you accelerate heavily. I have had wiring gremlins in the past so I assumed that the sending unit was bad....

Let me know what you find out as I don't want to lose this motor

I've seen this a few times over the years and Both times it was indeed the sender. Can't remember if it was an aftermarket sender in either case, but swapping it out solved the problem.

I also seem to remember reading of something like this, that ended up being an intermediate shaft with excessive clearance. High rpm the shaft would walk around and left distinctive markings on the outer bearing surface. (I think it also took a few teeth of the shaft and pump)

[moparzrule]

Ouch lol. I did have the machine shop install new intermediate shaft bearings, so hopefully thats not my problem.

[acannell]

I've seen this a few times over the years and Both times it was indeed the sender. Can't remember if it was an aftermarket sender in either case, but swapping it out solved the problem.

I also seem to remember reading of something like this, that ended up being an intermediate shaft with excessive clearance. High rpm the shaft would walk around and left distinctive markings on the outer bearing surface. (I think it also took a few teeth of the shaft and pump)

I have also seen this. I basically ignore the stock oil pressure gauge, its too unreliable. I've confirmed in my case it was not the sender but the connector to the sender. I've since broke the connector apart and squeezed the terminals together to be tight again, but its still not very reliable. I would have assumed what moparzrule has observed was this sort of issue but he said he was using a mechanical gauge for those readings so apparently its real.

Moparzrule:

Could you make a simplified timeline of what happened with this engine so far? Its getting a little lost in the many pages here. Something like 1) assembled 2) went to track 3)noticed breaking up 4) seized or whatever 5) took apart saw bearing junk everywhere..etc..

[stormy69]

nice build, bummer on the bearings...

one thing i noticed about ignition break-up you never followed up on (i just read the entire thread for the first time) is something turbovanman mentioned, a bad tps. i have had the sames issue (on a fox mustang with a 5.0 and a procharger tho) with a bad tps, it even ohmed out good but replacing it fixed my problem...

good luck with the next build. i am doing a 2.5cb for my 89 csx, its coming slow but its coming... so many other projects lol

[moparzrule]

Moparzrule:

Could you make a simplified timeline of what happened with this engine so far? Its getting a little lost in the many pages here. Something like 1) assembled 2) went to track 3)noticed breaking up 4) seized or whatever 5) took apart saw bearing junk everywhere..etc..

assembled
noticed breaking up
dyno'd, got a/f dialed in and added a bunch of timing helped but still breaking up
changed to 3 bar calibration fixed top end break up 100%
took to track
at track, first pass broke shifter cable....tried to rig it, broke again on second pass anyway but engine seized up at the end of the track on the pit road
trailered home (thanks to cliff sebring), dropped pan and say bearing carnage
swapped in new bearings, running good and smooth with no knock
finally noticed oil pressure dip because I was specifically looking at that gauge now instead of boost and a/f

one thing i noticed about ignition break-up you never followed up on (i just read the entire thread for the first time) is something turbovanman mentioned, a bad tps. i have had the sames issue (on a fox mustang with a 5.0 and a procharger tho) with a bad tps, it even ohmed out good but replacing it fixed my problem...

Thats because going to the 3 bar calibration fixed everything. A bad TPS would make it break up at anything over 3000 rpm for our cars, and a bad MAP is anything over 2000 rpm. Those settings are in the calibration, you can actually change them if you want but I leave them go so that if it does break up over that specific RPM I know which one went bad.

[acannell]

assembled
noticed breaking up
dyno'd, got a/f dialed in and added a bunch of timing helped but still breaking up
changed to 3 bar calibration fixed top end break up 100%
took to track
at track, first pass broke shifter cable....tried to rig it, broke again on second pass anyway but engine seized up at the end of the track on the pit road
trailered home (thanks to cliff sebring), dropped pan and say bearing carnage
swapped in new bearings, running good and smooth with no knock
finally noticed oil pressure dip because I was specifically looking at that gauge now instead of boost and a/f

and whats the damage so far? all rod + main bearings or just one set? any other damage besides bearings noticed?

is it possible the rod squirter holes were pointed the wrong way?

what about bore and piston diameters just to confirm that there is no obvious issue with clearance?

same with wrist pin diameter and rod bushing id?

is there a possibility bearings are just the wrong size? any idea what the clearance was?

something about this whole thing bugs me...i dont think there is a solid explanation for all this yet

[moparzrule]

and whats the damage so far? all rod + main bearings or just one set? any other damage besides bearings noticed?

is it possible the rod squirter holes were pointed the wrong way?

what about bore and piston diameters just to confirm that there is no obvious issue with clearance?

same with wrist pin diameter and rod bushing id?

is there a possibility bearings are just the wrong size? any idea what the clearance was?

something about this whole thing bugs me...i dont think there is a solid explanation for all this yet

I did not remove the main caps, just tossed in new rod bearings. I don't know what anything you mentioned would have to do with low oil pressure besides the bearing clearance.

But the oil squirters are facing the correct direction, piston to wall clearance is .0035'', wrist pins are .901 (the next size up is .912 and they would literally slip right through and have so much slack that any moron would be able to tell that was wrong), and like I said earlier I only checked one crank journal for rod bearing clearance and that one was in spec....and since I was in a hurry building it I did not take the time to check all 4. However, I still think all 4 were fine, see explanation below-

As discussed, the fact that the bearing damage gets worse progressively to the number 4 bearing indicates loss of pressure. A bad relief valve completely explains it, and also to the reason why I had no issues for the first 500 miles (because of the 4 bar cal screwing with my top end I wasn't revving it high at all really) until I swapped in the 3 bar and the top end power was restored....after I did that, the engine was destroyed in just those 2 passes at the track because I was pulling high RPM's for a long burst of time.

[bakes]

I know when i try to run BoostGeeks SC on the 4 bar Cal it miss fired so violently i though it was going to spit the rods out . Now saying that is it possible you bent /twisted the rods ???

[moparzrule]

Nah it was never what I would call violent, just breaking up. After I replaced the bearings, it runs perfectly smooth. It's actually smooth past 5000 rpm but I've only tried taking it there twice because of the oil pressure dropping. Other than that, it drives around perfect and purrs like a kitten.

[Ondonti]

Bent rods will often cause odd wear patterns (like only wear on one side) on bearings.
This is more about oil pressure being there one moment, then dissappearing, based only on RPM. Clearances being bad usually causes the most problems at low rpms where your pump is barely making any pressure, and hot oil makes that issue much much worse as it thins out.

[acannell]

I did not remove the main caps, just tossed in new rod bearings. I don't know what anything you mentioned would have to do with low oil pressure besides the bearing clearance.

But the oil squirters are facing the correct direction, piston to wall clearance is .0035'', wrist pins are .901 (the next size up is .912 and they would literally slip right through and have so much slack that any moron would be able to tell that was wrong), and like I said earlier I only checked one crank journal for rod bearing clearance and that one was in spec....and since I was in a hurry building it I did not take the time to check all 4. However, I still think all 4 were fine, see explanation below-

As discussed, the fact that the bearing damage gets worse progressively to the number 4 bearing indicates loss of pressure. A bad relief valve completely explains it, and also to the reason why I had no issues for the first 500 miles (because of the 4 bar cal screwing with my top end I wasn't revving it high at all really) until I swapped in the 3 bar and the top end power was restored....after I did that, the engine was destroyed in just those 2 passes at the track because I was pulling high RPM's for a long burst of time.

I ask because the order of failure might have gone like this:

1- oil pressure normal
2- assembly/machining error (clearances, OD/ID fits) causes MASSIVE bearing failure due to extreme mechanical stresses at very high power
3- bearing failure causes oil pressure loss
4- oil pressure loss causes remaining bearings to fail

By relief valve are you talking about the one inside the oil filter?

I forget, is that adapter thats screwed into the block that the oil filter screws onto, also a valve? Could it be in backwards or something? Or maybe RTV got stuck in it somehow? You could probably inspect it without having to drain the oil, might be a little messy but not that bad.

[moparzrule]

An assembly/machining error that would cause that kind of pressure loss would have shown such loose clearance that there would have been slop on the rod big end and cause immediate rod knock.

Relief valve in the oil pump. The valve in the filter is the bypass valve, would have no affect on oil pressure. The only thing the bypass valve does....is bypass oil and not filter it (in the event that the filter would get clogged). The only way a filter could possibly cause low oil pressure is if it got clogged and the bypass valve failed...extremely unlikely, especially since the filter has about 10 miles on it now.

Adapter into the block is not reversible, and it's not a valve it's hollow just to allow oil to pass through. It's literally a 5/8'' ID hole. I didn't even use RTV to put the pan on I used the rubber gaskets only.

[acannell]

When will we see some more updates with this???

Have you driven it around or dynoed it using the band-aid bearings??

When do temperatures warm up so you can get everything fixed?

[moparzrule]

Haven't touched it, way too cold. I think we had one or 2 days that hit 40 in the last month lol.

[OmniLuvr]

When do temperatures warm up so you can get everything fixed?

remember, he doesnt live in California, the weather is way to nice out here, hes got at least another 2 months... there still doing race legal here, pretty crazy, why cant we have a real track other than barona (which I wouldn't really call a real track...)


so what are the plans though, swap the pump, or pull everything?

[moparzrule]

Yeah it just snowed 3'' today as a matter of fact lol.

The plan is to pull everything and rebuild the engine all over again. Most likely swapping to a G head, and also swapping in a 568 that I'm taking to get freshened up (new pads and bearings etc).

[moparzrule]

The high temp for today.....11 degrees, and -4 is the prediction tonight. I could only wish I was talking celsius here, or wind chills, but I'm not.......Who wants to come help me pull the engine today? We might need to pull an all nighter

Some global warming please This is the coldest winter in awhile here, and last year was very cold too.

[OmniLuvr]

ship that thing out to san diego, the temps have been in the 80's for over a week...

[moparzrule]

ship that thing out to san diego, the temps have been in the 80's for over a week...