The oil puddle under our Chevelle's...
The oil puddle under our Chevelle's timing cover was just the tip of the iceberg. There were also potentially serious problems lurking in the crankcase; oil pressure was unstable at cruise rpm, and pressure dipped to nearly zero under braking.
If you listen carefully, your car will talk to you. How you interpret what your car says to you, and what you decide to do about it, however, can mean the difference between happy motoring and an empty wallet. After dropping in our new 496 big-block last fall, we went through some pretty normal teething pains, fixing small problems, and sprucing things up as we went along. One of our tasks was to install a brace of Stewart Warner Maximum Performance gauges into our Street Sweeper '68 Chevelle. We had lots invested in the 496, and the SW gauges would help us keep it safe and sound.
Right from the get-go, something looked odd about the oil pressure. On start-up, pressure looked good, but dipped under braking, and fluctuated wildly at cruise. Full throttle, strangely, exhibited no problem. Could it be the new gauge? Could it be the pressure sender? We hedged our bet, took it easy with the car, and ordered a new sending unit. The results with the new sender were ditto. To the good, the SW gauges were right on the money, but to our detriment, it looked like we had some predictable and intermittent oil-starvation problems.
When we saw this street/strip...
When we saw this street/strip oil pan from Moroso (PN 20403), we knew it was perfect for what we wanted to do with the Chevelle. A built-in windage tray is great for mitigating the foaming action created by a stroker crank like ours, and it doesn't involve being bolted to the main caps.
Meanwhile, we were chasing down other oil-related problems, like leaky valve cover breathers (see "Breath Of Fresh Air," December 2007), and a really nasty leak from a cheap Chinese timing cover. (Yeah, we should've known better, but we were trying to save money, ya know?) The game plan became clear: we needed to take a look at the bottom end of our 496 to check for bearing damage, and find the cause of our oil starvation. That meant yanking the big-block from the Chevelle, so we might as well take the time to put a few fixes into place.
In the Captain Obvious department, we ordered a COMP two-piece aluminum timing cover (PN 212) that we hoped would eliminate the Exxon Valdez pool of oil collecting on the garage floor. The corner of the timing cover that meets the oil pan and block is notorious for leakage, and the COMP piece has the rigidity to hold up under flex. The added strength would also improve the accuracy of the ignition timing, which tends to scatter as the cam button pushes against a weak, flexible timing cover.
The source of our oil spillage...
The source of our oil spillage was this cheap chrome timing cover. Or was it our budget stamped oil pan? Hard to tell, since the leak came from where both were bolted together.
Another area of concern was the budget-stamped steel oil pan, which had no provision for windage control, or any trap doors to hold oil around the pick-up under g-forces. We browsed several catalogs and discovered that Moroso had exactly what we were looking for: a 6-quart street/strip wet sump pan with a built-in windage tray, crank scraper, and a kick-out sump with a trap door (PN 20403). Most windage trays are bolted to the main caps, and we liked that we could just bolt the pan on without tampering with the bottom end of the 496. The crank scraper was an added bonus, and this one would clear our 4.25-inch SCAT 9000 stroker crank, too. All three of these oil-control devices (windage tray, scraper, and sump with trap door) would increase our chance of curing the oil-starvation problem, which to this point hadn't been impacted by experimentation with different oil-fill levels.
To go with the Moroso oil pan, we needed Moroso's companion oil pump with integral pick-up (PN 22185). This was due to the pan's sump and baffle arrangement, which needed a special rectangular pick-up to physically clear the inside walls of the new pan.
The Moroso pan has a 6-quart...
The Moroso pan has a 6-quart capacity, and features a kick-out sump with a trap door. This effectively keeps oil surrounding the pick-up under hard braking, which was one area of concern for our 496.
As in past stories, we borrowed the facilities of Don Lee Auto in Rancho Cucamonga, California, to put the wrenching on the fast track. The 496 was yanked from the Chevelle's engine room, and put on a stand for the post mortem. Within seconds of pulling the oil pan, the source of our oil starvation was revealed: the small brazes that held the pick-up to the oil pump had cracked, and the pick-up had rotated out of the oil. It was a one-in-a-million fluke, and we'll never know how it happened, but the important thing is that we listened to what the engine was telling us. Our caution from the moment we noticed the problem is what saved our bearings, which looked great upon subsequent inspection. Our use of Pennzoil Platinum Synthetic since day one can't be overlooked either. The superior film strength of a premium synthetic can often mean the difference between protection and metal-on-metal contact.
We breathed a sigh of relief, bolted on the new Moroso pump, then buttoned it up with the new COMP two-piece timing cover and Moroso pan. After stuffing the 496 back into the Chevelle, a fresh 6-quart crankcase fill of Pennzoil 10W-30 Platinum Synthetic completed the fix. We got more good news when we drove the Street Sweeper around the block and experienced none of the pressure drop during braking, or the pressure fluctuation at cruise that we had before. For the next couple of weeks, we took it easy at first, then ratcheted up our street punishment on the healthy 496, and found no problems. Even better, the oil slick in the garage didn't return. As our date with the quarter-mile loomed, we were more confident than ever that easy 11s awaited us. Check back with us next month, as we give you blow-by-blow details of our first track outing. You won't be disappointed!
Our existing aftermarket oil...
Our existing aftermarket oil pump was more than ample for the job; however, Moroso's oil pan needs a specific pick-up to clear the pan's internal baffling.
Eliminating our big-block's...
Eliminating our big-block's oil leak was the original impetus for ordering one of COMP's two-piece billet aluminum timing covers (PN 212), but we later realized it would also improve the ignition timing accuracy of our 496.
With the 496 big-block out...
With the 496 big-block out of the car and on an engine stand, we pulled the old pan and quickly saw our problem: the oil pick-up had rotated out of the oil after the brazing holding it had broken.
After figuring out the cause...
After figuring out the cause of our oil pressure problems, we then checked the rod and main bearings. Thankfully, we had been using 10W-30 Pennzoil Platinum Synthetic, which provided sufficient film strength during the few moments of zero oil pressure.
Tim Lee of Don Lee Auto Service...
Tim Lee of Don Lee Auto Service helped us yank the engine, and swap the Moroso pan and COMP timing cover. If you live in Southern California's Inland Empire, Tim does great work for a reasonable price.
COMP's two-piece big-block...
COMP's two-piece big-block timing cover includes all the fasteners and gaskets you'll need for installation. It also comes with a nice timing pointer (not shown) and a peephole for checking crankshaft endplay with a dial indicator.
This is the shot a lot of...
This is the shot a lot of you want to see: how the Moroso pan fits with long-tube headers (Stainless Works in this case) and the stock Chevelle crossmember. We found plenty of clearance for the headers, crossmember, and our aftermarket Meziere starter.