Well, I spoke to Tim today, and found we still have a little hiccup that he's dealing with. Seems that there is a miss at about 5000 rpm, and it's driving him loopy. He's swapped the carb, still had the miss...he's swapped the distributor...still had the miss. I talked to him a bit and we decided it couldn't be airflow as it should be adequate. I asked if perhaps it was a voltage issue (that old air, gas, spark trifecta...ya gotta have all three), and he said he thought it could be possible that the battery he uses on the dyno might be weak. So, as we left it, he said he had the charger on the battery, and was going to keep tweaking on it until that miss is gone.
Originally, he was under the impression that the valve springs were too stiff, and were causing bleedoff, but he didn't sound as convinced of that today. Regardless, I know I'll keep at it until he figures it out. By the sounds of it, though, it seems that the plant is getting really close to making some dyno runs and getting dialed in.
What Tim did say about numbers was that before he backed off on the engine when he detected the miss at 5k rpm, the plant was still pulling over 500 ft/lbs of torque. That tells me that the torque curve on this thing has got to be pretty darned flat! That's okey dokey with me!
Anyway, I know it wasn't the update you guys were looking for, but it sounds like we're just about there. I'm sure Tim will pop in and give us the scoop when he's chased out the gremlins, and got it dialed in.
Oooooooo! This was my 500th post! I'm "elder" now.....wait.....is that a good thing? Do I get a discount at Denny's?
Ok, well, I'll respond to myself....or I'll just babble a bit more...
I spoke to Tim today, and he went into the shop on a Saturday to get my motor figured out. He swapped in a third carburetor...still had the miss...he tried another distributor...still had the miss...he and his buddy we're starting to think they'd have to pull the intake manifold to see if a lifter compressed or something, when it dawned on them. They had eliminated pretty much everything: carb, distributor, airflow, fuel, EXCEPT....the ignition box they use on the dyno.
Seems the MSD box they use had crapped out on them, and wasn't working well. So, they dug up another box and tried it out, and wouldn't you know it, my engine runs like a champ. According to Tim, the plant pulls over 500 ft/lbs of torque under 3000 rpm, all the way to 6000 rpm...I was NOT upset to hear that!
So, Tim said he'll be doing the fine tweaking on the plant on Monday, and hopefully we'll see some actual numbers on it then. I felt bad that he had to go through so much crap just to get it right when it was so simple, but I really appreciate the effort he's put into this build of mine. It's a rare thing to find someone that's really invested in their product like Tim is. You all could do a lot worse than to go to Tim for your engine build needs.
I'll give another update when I get more info. 'later!
Yes I am still alive. Here is what I am finding. Our miss is from the valve train. We have installed titanium retainers and it helped almost an extra 1000 rpm. I am also hearing that the "OEM spider and dog" system is ok to mid .500 lift or so. RPM range also affects this. We have found a new lifter to use. It has been around but new to us. It is a hyd. roller lifter with the tie bar set-up. We purchase them from Lunati, they are made by Morel. Sounds like they have worked great in high rpm applications and big valve spring pressure. We just received the set today, so I am going to make plans to get them installed soon. I will give updates as soon as I know them.
Well I ended the week with a victory!! The 434 made about 6 sample pulls without any missing issues. Bottom line is we originally had strong enough springs, but the OE lifter system just did not handle the lift and RPM.
I stated before that by adding the Titanium retainers, we saw the "miss" happen at a higher RPM. So this told me that the valve train was the issue.
We added the new lifters and did not see any results. But because of the better lifters, we were able to go back to the stronger springs. Now none of this was an issue until you reached about 5500 RPMs. Next week we will go back to setting the ignition and adjusting the carb. Even though the ignition is set low, I did record 516 torque and about 470 HP. Not a bad start. Finally!!
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