EMC recap

[dan miller]

Some of the things we’ve learned this year make perfect sense, and that education allowed us to build a better performing engine. Some of the things we’ve learned, and more than most would suspect, do not make perfect sense. To put it mildly. lol

We had difficulty getting valves and pistons to clear. We thought that steel rods would allow for tighter clearances, but we didn’t find that to be the case. We ended up re-cutting valve pockets twice, grinding the combustion chambers, and de-stroking the crankshaft .005". We lost a full point of compression, got ourselves “locked in” on cam timing (couldn’t move the cam around as much as we would have liked), and were still hitting. Next year, we’ll put a little larger dome in, and not worry as much about quench.

We really goofed up on valve springs. Gene found some unknown springs (different ones for intake and exhaust) that were close to what we wanted, and seemed to work well. Until two broke on the dyno the day before we had to leave for Lima. Our only option was to borrow some from a customers engine, which were way stiff, undoubtedly costing some power. In retrospect, unknown springs were a terrible place to compromise (and try to save a buck). We bent two intake valves (which didn’t seem to hurt much), and resurfaced several valves that were hitting. Apparently, we got two mixed up (stuck in the wrong hole), and one of the valves that had been lightly hitting was really hammering on the piston. The lesson here is to make the number stamp on the valve deep enough to see clearly.

There’s a fine line between getting enough spring to control the valves up to the cut off RPM, and not getting so much that it costs power. And then, the cut off RPM is a variable, as a couple of times the engines were run to almost 7500.

The headers made zero sense to us. And, apparently to some other folks as well. We determined, at the very end of our last dyno session, that our combination seemed to like oversized primary tubes and a non merge collector. We’ll spend some “quality header changing time” on our FIRST dyno session next year. We thought 1.875" was the correct size, and 2.00" ran better. Will probably need to check out some 2.125" primaries (no kidding) next year. All pretty strange stuff!

It’s my feeling that the cast manifold rule penalizes non main stream engines, and that fabricated manifolds should be allowed. If the rules don’t (either directly or indirectly) prohibit IR, we’ll probably continue experimenting with it, as that’s the only viable manifold that’s available for our engine type.

We’ve been running a locked out ignition, and I believe that it might be worthwhile to do a little messing around with some form of a curve.

I’m wondering a little about oil. This year, we saw no difference in thick (10-30) and thin (05) weight oils. Also, our oil temp stayed lower (around 150F) than I would have liked.

Hopefully, others will chime in here, and offer their views and lessons learned this year.

Also, hopefully, we’ll see some of you guys at EMC next year. It’s a hoot. You’ll learn more than you could possibly imagine, and meet some REALLY cool dudes (and a lovely dudette or two).

Danny

[Ted]

Dan. I enjoyed meeting you and the other competitors. And thanks for sharing your thoughts. Although the Ford Y-Block I brought to the show was at the lower end of the scale for the scores, I was quite pleased with it as it was definitely a learning experience. I know now that I had too much cubic inch shoved under those oem iron heads. But going into this I was concentrating on good peak values and not the overall score. The small cubic inch version I had for last years competition was definitely a better player by way of the scoring but the peak values were nothing to brag about. And last years engine fit last years rules which just took some of the fun out it. Much more fun just seeing how much stroke I could shove into one of these older engines.

I was restricted to using cast low profile dual plane intake manifolds but ending up testing seven that were each modified internally differently. I also tested several sets of headers and ultimately settled on the stepped headers as I was able to tune out the dip in the lower end of the torque curve with that particular set. This engine combination was one of those rare instances where adding mufflers actually helped my overall score. Likewise I tested every combination of springs and advance limiters available for the distributor and my particular engine liked a short and lazy curve with all the advance in at 4500 rpms. I initially had some valve float issues and simply stepped up the over the nose valve spring pressures far beyond where I normally set these engines up. To the credit of the Isky cam and mushroom tappets being used, the valve train held up just fine without any signs of distress right up to 7400-7500 rpms even though the engine was essentially out of breath at 6700 rpms. I thought it was interesting that the Lucas 20W-50 oil supplied at the event was about 10 lbs less oil pressure that the Valvoline 20W-50 oil that I performed all my testing with. That’s something I’ll have to test here at the shop just to insure it wasn’t a difference in oil pressure sensors or was indeed related to the oil itself. Plenty to think about for sure.

The best thing about this competition was going into a testing regime at the shop that I normally would not have done for a simple race engine buildup. It was definitely a great learning experience for all that were involved. And rules and budget permitting, will look forward to doing it again.

[1989TransAm]

Thanks for the reports. Interesting reading.

Dan, Troy thought that the headers you had built may have been over scavenging and that is why the larger diameter primary tube helped. Maybe a stepped header in your future?

Ted, from what I read is that you were not able to get the heads in time that you wanted to run. If so next year should be a lot better.

[gmrocket]

Some of the things we’ve learned this year make perfect sense, and that education allowed us to build a better performing engine. Some of the things we’ve learned, and more than most would suspect, do not make perfect sense. To put it mildly. lol

We had difficulty getting valves and pistons to clear. We thought that steel rods would allow for tighter clearances, but we didn’t find that to be the case. We ended up re-cutting valve pockets twice, grinding the combustion chambers, and de-stroking the crankshaft .005". We lost a full point of compression, got ourselves “locked in” on cam timing (couldn’t move the cam around as much as we would have liked), and were still hitting. Next year, we’ll put a little larger dome in, and not worry as much about quench.

We really goofed up on valve springs. Gene found some unknown springs (different ones for intake and exhaust) that were close to what we wanted, and seemed to work well. Until two broke on the dyno the day before we had to leave for Lima. Our only option was to borrow some from a customers engine, which were way stiff, undoubtedly costing some power. In retrospect, unknown springs were a terrible place to compromise (and try to save a buck). We bent two intake valves (which didn’t seem to hurt much), and resurfaced several valves that were hitting. Apparently, we got two mixed up (stuck in the wrong hole), and one of the valves that had been lightly hitting was really hammering on the piston. The lesson here is to make the number stamp on the valve deep enough to see clearly.

There’s a fine line between getting enough spring to control the valves up to the cut off RPM, and not getting so much that it costs power. And then, the cut off RPM is a variable, as a couple of times the engines were run to almost 7500.

The headers made zero sense to us. And, apparently to some other folks as well. We determined, at the very end of our last dyno session, that our combination seemed to like oversized primary tubes and a non merge collector. We’ll spend some “quality header changing time” on our FIRST dyno session next year. We thought 1.875" was the correct size, and 2.00" ran better. Will probably need to check out some 2.125" primaries (no kidding) next year. All pretty strange stuff!

It’s my feeling that the cast manifold rule penalizes non main stream engines, and that fabricated manifolds should be allowed. If the rules don’t (either directly or indirectly) prohibit IR, we’ll probably continue experimenting with it, as that’s the only viable manifold that’s available for our engine type.

We’ve been running a locked out ignition, and I believe that it might be worthwhile to do a little messing around with some form of a curve.

I’m wondering a little about oil. This year, we saw no difference in thick (10-30) and thin (05) weight oils. Also, our oil temp stayed lower (around 150F) than I would have liked.

Hopefully, others will chime in here, and offer their views and lessons learned this year.

Also, hopefully, we’ll see some of you guys at EMC next year. It’s a hoot. You’ll learn more than you could possibly imagine, and meet some REALLY cool dudes (and a lovely dudette or two).

Danny

didnt your ignition box have a built in limiter to prevent the operator from just buzzing it up? last year i had mine set at 6600 just to be sure.

[Ted]

There’s a fine line between getting enough spring to control the valves up to the cut off RPM, and not getting so much that it costs power. And then, the cut off RPM is a variable, as a couple of times the engines were run to almost 7500.

Danny

didnt your ignition box have a built in limiter to prevent the operator from just buzzing it up? last year i had mine set at 6600 just to be sure.

I had my box set at 7500 rpms just to insure that it wasn't going to shut off early. I didn't have the tester here to check the new box just prior to installing it on the engine to insure it was indeed going to be accurate in regards to the rpm cutoff. I'd rather it overran just a bit than have it coming on early.

[dan miller]

Hello GM

We did not have a rev limiter, although we had springs good for well over 8K (a last minute "upgrade" after we broke a couple of springs).

The MSD 8 box requires an add on box to utilize a rev limiter, but when we plugged it in, the ignition broke up at a very low rpm. Unplugged it, and all was well.

I was told that the DTS dyno has a built in rev limiter. Yes/no?

Danny

[gmrocket]

i have no idea how it was set up this year but considering every pull,between competitors, should be as identical as possible, wouldnt they have it set up to run in auto mode? isnt it an add on option on most dynos?

[dan miller]

Some of the engines were very difficult for the operator to get loaded at the bottom end. I doubt that an automatic function would work - at least on the bottom.

Danny

[gmrocket]

isnt that the whole purpose of the auto load servo? to take the "crankiness" out of the loading. as i understand it, the low rpm loading is where its most effective?