Maybe, some of you Pure Stock guys or F.A.S.T. guys can throw out a suggestion of two. Tonight I went over to a friends house to try and figure out why there was no oil comng up on the right bank of cylinders in his '73 Challenger. The engine is a combination of Mopar Performance short-block 360, warmed over 340 heads, crane cam and roller rockers, Air Gap intake manifold, Demon carb. It is backed by a 727 and a 8 3/4 with 3.55:1 gears The engine was put in about 3 years ago and has about 500 mile on it since. It's last outing was when the owner was driving it about 8 months ago and heard what he thinks is valve train noise and it began running rough while on the highway at about 70mph. The roll back was called in and it took the car back to the garage to sit unit time permitted. A couple of days later I took the right valve cover off and cranked the engine over for several minutes with no sign of oil getting to the valvetrain. So today, the distributor was pulled, the intermediate shaft removed and the oil pump spun with the oil pump priming tool. Now there is oil getting to the valvetrain on the right bank. Great! get the #1 cylinder to TDC and put the ignition back on and fire it up. So I think, lets do a compression test on the engine while the plugs are out and see how the engine is doing inside. All is well with the comprissions ( 110 to 140 ) except the #1 cylinder. It's at 40 psi. Could it be the rough running was related to a cam or lifter issue? Any thought?
Time to get the heads off.Speculation won't help. You need all the information in front of you.With 40 lbs you are gonna need to pull the heads.To start are the rockers all burned up? Few ideas jump out at me 1 the rocker shaft is upside down 2 If the cam bearing was installed without care
Are you thinking spun cam bearing is the reason for no oil to the rockers? And by pulling the head I can determine what exactly? Are you thinking bent valve or valves being the reason for low compression? If I want to check the camshaft for lobe lift I can do that with a dial indicator. A collapsed lifter or bent push rod would affect the total numbers but by comparing the numbers from on of the other cylinders it would tell me what the difference is.
Are you thinking camshaft valve, piston, rings or...? There has been bench racing about getting rid of the 340 heads and putting edelbrock aluminium heads on it.
I think what Tommy is trying to say is quit guessing what it is and pull it apart. All questions will be laid to rest when it is opened up. Once you find out the problem, then you dive into what caused the problem.:idea2:
Close the valves and pump that cylinder with air. If it's escaping from the cylinder you'll know where and if not it's probably valve train.
I'm borrowing a compression/leak down tester from a neighbor when he gets back from a business trip. I wish I had my own still it would have made this a lot easier to dignose.
One step closer. We put oil directly in the cylinder and let is sit a while to see if there was a possibility of the rings not sealing. I think that was the issue. Compression was 30-50psi before and now its at 90 after setting about 15 minutes with oil in the cylinder. We'll add some more oil back and let it soak a while longer and recheck. I thought we would have gotten oil to the rings as much as we primed and cranked the engine- quess not!
so here's the latest update. After getting it running there was a noise from the bottom end. So drained the oil and ccut the filter. It's got a lot of bearing material in the oil and filter as well as some aluminimum and iron. The engine stand awaits.
Got the engine torn down and the #1 rod bearings were spin and have taken out the rest of the rod bearings. We'll be contacting Mopar Performance to see if they are willing to help. The engine has less that 500 miles on the short bolck from them.
Talked with the parts rep at the dealership where the engine was purchase in 2004; I was pretty sure he would say, 12months/12K miles whichever comes first. And that is what he said. So now the choice of wha to do with it really starts. Put a crank kit in it; send it out and have it balanced along with a crankshaft, or what? I'll let the owner decide. All I can say is that I'm not very impressed with the quality of the product that Mopar was selling at the time. I would have preferred to have built it from the block up in the beginning. It wasn't my call and isn't really now. Updates to follow.
So the short-block went to the machine shop along with the rotating assembly. Also sent the cam and a core crankshaft. After close inspection by the machinist he found that the oil galley plug that is behind the oil filter adapter plate had come out of the galley. This would explain the oil pressure problem and the resulting oil starvation to the mains, rods, valvetrain,etc. And the fluctuation of oil pressure on the gauge. So the machining is done and it's now a balanced short-block as well.
You have to remember that the M/P short block is built by the lowest bidder. The M/P Crate engine program has plenty of problems. Hemi's (that you just paid $15,000 on) having finger tight main caps. OOPS! They lined up all the ring gaps in a nice straight row. OOPS! Oil Galley plugs?? Who needs 'em?!? I have a friend that is the parts manager at a local Chrysler Jeep dealer. He sends out his crate motors to a local shop to inspect the engine before it is delivered to his customer. Cheap insurance of that $150 inspection fee vs. replacing a $15,000 engine. :dollar:
Thanks for the verification that the Mopar Create Engine program isn't trusted by anybody that works as a Mopar Performance dealer. If I had people wanting to buy $15K create engines from my inventory I would gladly spend the $150 and have my machine shop check it out as well.
Thanks to all who chipped a thouhgt or two about the engine problem. So here's the update. As of tonight the engine is rebuilt and back in the car running. It needs some tuning but it all works and started after about 5 seconds of cranking. All is well with oil pressure and no leaks either. The valves need adjusted but thats about it, A tweak to the timeing most likely too. The bill at the machine shop and the other stuff was about $1200.00 so far. The light at the end of the tunnel!!!
It's alive and running better than ever. It's been to a couple of car shows and on a short trip or two to take car of other items on teh to do list. So far no problems. Now for the tuning and working some of the other bugs out.
So I thought I should update this thread. So the tuning went on and on with no consistant ability to get the carb adjusted for more than a few minutes. So we decided to do a compression test and see if that would help the diagnosis. And it showed that one cylinder had almost no compression. A leak past the exhaust valve seemed to be the issue. Air out the exhaust pipe and also blowing back through the car on the sister cylinder. So after pulling the head and having the cracked valve seat replaced and the guide replace it appears that whoever did all the work on the 340 heads missed the valve seat problem. The head has now been reinstalled and the car made its first trip the the strip and a few passes without any sort of issues and is back home with only minor tuning to be done. Now it's on to the rest of the list of minor issues. Finally!!!
