Since the head gasket looked like it was about to blow through again, I took the engine completely apart. I then took the block in to have it decked flat. It wasn't far off, but I was going to make sure that block wasn't going to be an issue. Since the head had been rubbed on extensively by Verne Colvin of BRE history, the compression was already high. I had the machine shop check it and we couldn't see light between it and a stright edge.
Then it was down to reassembly, which I thought was pretty straight forward. And yes, I put everything back where it came from (rods, valves, pistons, bearings, etc.). Although I did fix the maxed out dizzy advance by putting it in one gear back as it should have been before. This would give me more adjustability.
Refilled fluids and cranked the engine for 20 seconds to build oil pressure. Plugged the coil in and hit the starter. It started right up and purred like never before. A slight tweak of the timing and carbs settings and it was running smooth and had quick throttle response.
There's a race this weekend so I packed her up and dropper her at the track so as to have a good pit and pit layout. AND, it's supposed to be 100degrees Saturday. O joy!!!
I will update with details of how she runs. Wish us luck.
Friday, August 13, 2010
Engine Tear-down
After the lousy engine performance at ORP, I felt there was nothing to lose by tearing apart the engine to get to the root of the problem. Taking the head off revealed the effects of the unstable timing, carbs challenges, and eminent head gasket failure.
It didn't take long to locate the root cause of the poor performance. Removing the timing cover this time revealed heavy gouge marks. Not only was the cam gear grinding on the cover, but the timing chain was getting into the act too and over an 1/8" of the reinforcing rib on the inside was ground away. "Why?", I asked.
I took hold of the cam gear and the whole cam shaft would move in and out of the block some .130". I'm no pro engine builder with countless builds under my belt, but even I could see that that wasn't right. Since there's a helical gear on the shaft that drives the distributor, it was easy to understand why the timing wouldn't remain stable.
Some more disassembly revealed that the woodruff key was forced out the back of the slot when the cam gear was jammed on. This kept the cam gear from bearing against the block as it should. Thus, the shaft would slide in and out at random, and take the distributor setting with it. Flat on the ground without load, the engine would time and run well. Race it up or down a hill, and it would crap out.
And now, the train wreck picture show......
Woodruff key jammed half way out of the slot
Should the side of the cam bearing be ground into like this? I doubt it.
Another angle. And pistons 3/4.
Pistons 1 and 2
Another head gasket for the trash. And the buildup on the valve area.
It didn't take long to locate the root cause of the poor performance. Removing the timing cover this time revealed heavy gouge marks. Not only was the cam gear grinding on the cover, but the timing chain was getting into the act too and over an 1/8" of the reinforcing rib on the inside was ground away. "Why?", I asked.
I took hold of the cam gear and the whole cam shaft would move in and out of the block some .130". I'm no pro engine builder with countless builds under my belt, but even I could see that that wasn't right. Since there's a helical gear on the shaft that drives the distributor, it was easy to understand why the timing wouldn't remain stable.
Some more disassembly revealed that the woodruff key was forced out the back of the slot when the cam gear was jammed on. This kept the cam gear from bearing against the block as it should. Thus, the shaft would slide in and out at random, and take the distributor setting with it. Flat on the ground without load, the engine would time and run well. Race it up or down a hill, and it would crap out.
And now, the train wreck picture show......
Woodruff key jammed half way out of the slot
Should the side of the cam bearing be ground into like this? I doubt it.
Another angle. And pistons 3/4.
Pistons 1 and 2
Another head gasket for the trash. And the buildup on the valve area.
Sunday, August 8, 2010
Oregon Raceway Park June 18-20
The engine wasn't right, obviously. It had a knock in the front of the engine since the day the engine builder did the initial run-in of the new build. $1500 and a whole race season lost netted me a rebuilt engine with no power and an ominous knock. Gee, thanks man! I was determined to race this year and wasn't in any hurry to give up. I ran the engine once out of shear frustration with having missed the year before. The knock didn't improve or worsen. I figured a rebuild was the worst I would have to face and was rolling the dice.
I spent time after that last race to go over the car and look for what might be causing the lack of power and the odd knocking that had been present at the front of the engine since I got it back from the engine builder.
I ran a compression check and one cylinder was higher than the rest by 30psi. Loss of compression is one thing, but increased compression? What the hell? I had the carbs running both even and balanced. Timing seemed stable. Valves were adjusted and checked at the track last time. Just the knock, compression imbalance and lack of power. I took off the bottom end and checked everything I could see. I took off the timing cover and checked the chain and tensioner. All looked fine. I decided to forego the PIR race and get ready for the very fun ORP races.
I started a new job on 6/1, but was sure to arrange being off Friday the 18th for the HDPE at ORP to test the car before the race. All I needed was the car to be right.
I asked a new friend from the track to come by and look over the car and help me see the problem that the car had... I couldn't see the problem having stared and prodded over it for so long. The extra set of eyes, and more importantly experience, would be a great help.
After messing with the timing it didn't seem to improve anything. He called his friend and we came to the conclusion it had to be the valves. We rechecked them, and sure enough, one was very loose. We readjusted it, checked the compression, and all 4 were spot on. Yeah!
I'm going to ORP.
I spent time after that last race to go over the car and look for what might be causing the lack of power and the odd knocking that had been present at the front of the engine since I got it back from the engine builder.
I ran a compression check and one cylinder was higher than the rest by 30psi. Loss of compression is one thing, but increased compression? What the hell? I had the carbs running both even and balanced. Timing seemed stable. Valves were adjusted and checked at the track last time. Just the knock, compression imbalance and lack of power. I took off the bottom end and checked everything I could see. I took off the timing cover and checked the chain and tensioner. All looked fine. I decided to forego the PIR race and get ready for the very fun ORP races.
I started a new job on 6/1, but was sure to arrange being off Friday the 18th for the HDPE at ORP to test the car before the race. All I needed was the car to be right.
I asked a new friend from the track to come by and look over the car and help me see the problem that the car had... I couldn't see the problem having stared and prodded over it for so long. The extra set of eyes, and more importantly experience, would be a great help.
After messing with the timing it didn't seem to improve anything. He called his friend and we came to the conclusion it had to be the valves. We rechecked them, and sure enough, one was very loose. We readjusted it, checked the compression, and all 4 were spot on. Yeah!
I'm going to ORP.
Grass Valley- Still No Power
The excitement of the first race in Grass valley's new Oregon Raceway Park was the most anticipated race of the schedule for me. I headed out for the 3 hour drive to SouthEast of the Dalles. Got there at Friday after the drivers training had completed. Unfortunately, the other drivers had anticipated the race as well and parking was at a premium by the time I arrived. I dropped the trailer and car off in my assigned paddock space and found myself a camping spot 1/8-1/4 mile away down a gravel road.
I learned that in Eastern Oregon it gets pretty cold at night. Being in the high plains with the 30mph winds got things quite chilly. It carried into the morning. Sweatshirts under jackets with a head cover was necessary all day. The car wasn't quite running right, but I sensed it was all a function of the carbs needing adjusted.
The first run was frustrating in that I had almost no power up the hills. But, the car did run and the track was a blast.
The organizers see to it that the Novices get screwed on run times. We're the last before lunch (practice), a mandatory lunch meeting and the first run ("quals") after lunch. Since the car ran like crap, I had no time to work on it between runs. I skipped the quals to save what I did have in a car for the race. After all, it is my 4ht year trying to get through the novice program.
The race saw me run dead last with the car having almost no power to pull up the many hills of the course. But, I did get another race logged. YEAH!!!
I learned that in Eastern Oregon it gets pretty cold at night. Being in the high plains with the 30mph winds got things quite chilly. It carried into the morning. Sweatshirts under jackets with a head cover was necessary all day. The car wasn't quite running right, but I sensed it was all a function of the carbs needing adjusted.
The first run was frustrating in that I had almost no power up the hills. But, the car did run and the track was a blast.
The organizers see to it that the Novices get screwed on run times. We're the last before lunch (practice), a mandatory lunch meeting and the first run ("quals") after lunch. Since the car ran like crap, I had no time to work on it between runs. I skipped the quals to save what I did have in a car for the race. After all, it is my 4ht year trying to get through the novice program.
The race saw me run dead last with the car having almost no power to pull up the many hills of the course. But, I did get another race logged. YEAH!!!
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