I did forget to mention that I found top dead center of the #1 cylinder last year and confirmed that the timing mark is lined up correctly. I believe that my initial 14*, 16* mechanical for a total 30*, vacuum plugged, is accurate. I also made a timing tape last year and taped it on as I had a basic timing light. This year I bought an advanced light with dial back and nothing has changed. I've read Larrys power timing post a dozen times, it was more fun than cleaning the house. I'm pretty confident that the timing can be eliminated. This texting is poor communication on my part, as all you readers don't get the entire picture unless I write everything, but then you'd have to read for 10 minutes, and that would be terribly boring. Took it out again and no pinging. Hoping to test static compression next; that'll be a little wait before I get to that. I'll keep posting as things develop. You've all been very helpful and thank you!
In the "old days" there were speed shops with distributor machines that could spin up your distributor and dial it in. Practically every one I did needed major re-curving. Often over 4000 rpm 3-5 degrees more advance came in just when you want it the least. So, often we had to make a positive stop by brazing the advance slot up some. Also you have to consider the barometric pressure. A 29.80 day vs a 30.50 day is a vast difference. 3 tenths of a second in the quarter. Basically like raising the compression AND leaning the motor out. Say someone maxed out their timing for a muggy cool 29.80 day, if they went back to the track when it was hot, dry and 30.50 it WILL detonate all the way down the track unless race gas was put in. One other thing, who knows what octane you are really getting at the pump. 93 might be 90 or worse. You think they really care? Most every car now has a knock sensor and all that would happen it the timing would back off and no damage. Basically it's like trying to run a 70 Stage 1 on regular gas in the 70s....good luck. Today's high test is only slightly better that regular gas of the 70s plus in most cases it has ethanol that leans the motor out. Bottom line is carb needs to be richened up and/or some timing needs to be taken out. Regular pinging and detonation will pound the rod bearings out and the motor will be junk......
I emailed Ken. He thought a CK secondary rod would be great for a mild 455. It approximates the stage1 AU rod profile. An AX might be too rich but it wouldn't hurt to try it. This was before i sent him the cam specs; I just described the engine as mild. Quadrajetparts.com carries them. Sent from my iPhone using Tapatalk
I checked cylinder compression today. 6 revolutions per cylinder. Tests results below: 1. 165psi 2. 169 3. 170 4. 172 5. 170 6. 175 7. 170 8. 166 psi Warm engine, plugs removed, carb wide open for full air, coil disconnected, gas line removed. Sent from my iPhone using Tapatalk
The fuel pump looks like a standard model, not a stage 1. The hose going to the carb is in a sharp 180 degree bend and could be resricting flow. (should be 3/8 steel professionaly bent) If neither of these are causing fuel starvation, they still need fixing if 400 HP or more is on your menue. Also check fuel tank venting. Old ones get clogged. No air in, restricted fuel out.
You are correct, it was standard but I now have a stage 1 pump installed. Didn't make much difference. Still getting good fuel pressure at wide open throttle, never goes below 5.5 psi. Also switched to stage 1 secondary metering rods, CK. might try the AX rods next. Sent from my iPhone using Tapatalk
had the exact same problem 455 w/ 68 430 heads rattled at high rpm , a little 110 fuel cured it , and turn timing down on the street.
Yep, I mixed a little 110 race fuel and total mechanical advance at 30 now. Seems to run just fine. Thanks! Sent from my iPhone using Tapatalk
That's a great article. That's why I was confused by the cranking compression to dcr relationship. There's probably a general relationship but you can't calculate one from the other.
You can with some tribal knowledge and experience. Altitude and starter crank speed change things (different engine families or gear drives), for example. Understanding the relationship to your local fuel and your specific engine's ability to resist knock based on combustion chamber shape and size is a good starting point. A good way to assess a metric value for your engine from another design without a way to visually judge or test things is to watch the trend for total timing in similar builds (but different families). It's a good idea to follow similar spec'ed builds closely and conservatively...meaning, creep up on timing and carb. More importantly is to realize that differing altitude and heat conditions move that line.
I can appreciate anyone's willingness to work on their own stuff and learn to tune. It's what the hobby aspect is all about. Any experienced tuner can solve this stuff quickly, without dealing with months of posts and stolen time internet searching or dealing with opinions and confusion from other hobbyists (no offense to anyone good at tuning their own stuff). Some basic books on performance and tuning would be a gift of time saving for anyone new to this (not directed at any individual, just a general comment). Way back, an old house I'd purchased had issues with an oil burner furnace. I had the old timer for the area do the maintenance after the purchase. After showing interest and asking him if I could pay him to explain a little bit about it's needs, the kind fellow spent a few hours with me and showed way more than I expected. Over a couple years I'd made minor adjustments that led to cutting it's consumption in half! Better than only charging me for 1 hr., I gained a lifetime of knowledge from that starting point.
Regardless of whether or not there is even fuzzy math to relate DCR and cranking compression, you can't do a compression test on the motor you are PLANNING to build... The calculator is invaluable in that situation.
