Nah you should,.unplug the vac line from the distributor then check the timing you should have around 30~34° in by 3k Measure 1.75 down from the factory mark on balancer and put a mark,.then use that mark to adjust your max timing I would worry about cam timing rite now ,..you are over advanced rite now sounds like.
If you have the vacuum advance connected, then there is vacuum advance degrees in that 44* total. A stock canister provides as much as 20* of advance at 16" of vacuum. If you haven't limited the canister to a lower number of degrees, your wide open throttle timing could be very low which would make a HUGE difference in power. That could be your problem right there. Any timing added by the vacuum advance canister DROPS OUT at wide open throttle. The canister has a spring inside that opposes vacuum pull. Vacuum overcomes the spring to advance the timing. When you go to wide open throttle, vacuum drops to very near if not 0. The canister spring PULLS any timing it contributed OUT, leaving you with your initial timing plus your mechanical timing. Simply disconnect your vacuum advance and plug it. Then measure your maximum timing. It will help to have the lightest springs inside the distributor so that you do not need to rev the engine beyond 3000 RPM before the mechanical advance maxes out. The stock springs will not allow that until as much as 4600 RPM.
Not to me Bob, but maybe to the OP, after all, he is in Germany, might be a bit of a language barrier or not. We need to stop monkey farting around and get a total timing WITHOUT the vacuum advance.
Sorry Bob, did not mean to ignore you. I wanted to answer once I have double checked the settings, which unfortunately I was not able to do over the weekend (can't do stuff like this on a Sunday in Germany). I have to confess, I am confused now about my timing. And I will try to double check and if necessary correct any wrong settings before I go back to the dyno on Thursday next week. Here is some more input: My distributor # is 1112110 which from reading should be a good base to start with. The mechanical advance sets in at around 1100 to 1200 1/min and is maxed out with 18° at around 2900 1/min I limited the vacuum advance to 7°, using the Vacuum advance Limiter Bushings from Ken G. Link: New product: Vacuum advance Limiter Bushings I did set the 44° with the vac connected and at 3500 1/min. Is this where I screwed up?
Yes it is,..dont worry about the time it takes to come in,..concern yourself only with how much max timing comes in and at what rpm it stops coming in with the vac line disconnected and plugged
OK, the 1112110 is a 1972 GS455 distributor. It has a maximum of 14-18* of mechanical advance at 2900 RPM. Is that what you actually observed, or are you quoting the specifications? If you actually have a full 18*, that is good, since it could be anywhere between 14 and 18*. What that means is if you want say 34* of total wide open throttle timing, your initial should be 16*BTDC. Forget about the vacuum advance, leave it disconnected. The only time it will function is at light throttle cruise. On the dyno, the vacuum advance will contribute nothing.
Here is what I measured today: 22° @ 880, no difference w/o or w/ ported vac. My new adjustment is (all w/o vac): 17° @ 830 28° @ 2000 29° @ 3000 31° @ 3800 34° @ 4600 I did not dare to rev the engine up higher. Does this curve (engine speed versus mech advance) looks ok? Also (belt and suspenders) adjusted the throttle cable to make sure that secondary really opens before the pedal hits the floor My conclusions are: Mechanical advance does not stop at 2900 like the distributor# suggests, but goes up to 4600 (or even higher), so I need some softer springs Do not believe paper-specs for a 50 year old car, unless you have confirmed it yourself. Probably the distributer was overhauled sometime and the settings have been changed Mechanical advance gives around 17°, maybe even 18°, will find out with softer springs The previous setting resulted in too much advance (about 5°). Had no pinging, maybe due to the good german gas I use (102ROZ). The dyno run on Thursday will tell if the overadvance killed the performance Theory is one thing, real world experience is better. Thanks to all your input I know better understand the setup of the distributor (at least I believe so ) Compression- and leak tester arrived today, but I will not get to using them in the next couple of days.
When I built the motor for Wally it was intended to be a cruiser, not a race motor. The motor is standard bore with stock 70 cast pistons. No cutting on block or heads. I imagine compression is probably standard 9.5 to 1. The cam was degreed by Dave Hemker and Stage I cam. Heads had big valves put in and the chambers were cut for the big valves. So you have pretty much of a stock 70 Stage I motor.
Herman, many thanks for the information. I do not want the engine to be a racer either, but I am concerned that something is not right, as the power is not even close to the spec for a 1970 455 / 455 Stage 1. I guess you built the engine about 10 years ago, so many things might have happened since.
Second run on a different dyno confirmed the previous numbers. Peak HP 193.4 @ 4270 1/min and peak lbf-ft 280.9 @ 3230 1/min. Will do compression test next.
Hi Ralf In your first post you wrote that your "butt Sensor" has felt the power loss. Did it come suddenly or over time? Did the car feel more powerful when you got it? If yes I just cannot believe that the distributor went off that much by itself (I hope you all get what I mean). You did so many changes to your distributor now. If you would've just gotten the car and power were off I'd go and check everything starting with timing. I am curious about the compression test. Do a leak down as well. No need to buy that stuff. you can go to every VW Dealership and let them do it. They have excellent digital compression testers and leak down testers. (Ask me how I know )
Did you get your timing curve fixed before that second dyno? You should NOT have advance still coming in at 4600 rpm. That'll kill it right there, you need your advance in by 2500-3000 rpm on even a mild performance engine. I'd stop wasting money getting it dyno'd until you fix that ignition issue. You NEED to recurve it. You can rebuild that engine over and over and you're not going to get good results no matter what you do with an advance curve that slow. Fix that, and you're going to be shocked.
Before I would start making major distributor changes I would check the advance plate bushing. Appears its probably gone or worn out, stock its nylon and gets beat out over time. Most advance kits include a bronze bushing.
I bought the car last year and by the time it arrived in Germany and got street legalized it was late automn. So I did not have a lot of opportunity to drive it. This year I started right away with the TH200-4R swap and it was July when I did the first rides. I would not say that there is much difference in between last year and this year. My "butt sensor" uses as comparison the 200HP car my wife is driving, and my 326HP daily driver. Bought the testers for compression and leak test already, will most likely not be the only time I am going to use them. Well, I guess not . The measurement was carried out with the ignition timing curve as listed in my post #28. I have only very little, to none Buick experience, thats why I am depending on all the great input/feedback from this board. I was not able to interpret the data I measured, but based on the feedback of greatscat something seems to be worn out. I will check that out. Any recommendations for an advance kit, preferably from Summit or Rockauto, as they ship internationally? Along that line: Currently a Mallory Performance Module 6001M is installed Is that sufficient, or could that (of course along with the mechanical issues concerning the advance curve) contribute to the lack of power? Overall drivability of the car is excellent, rock solid @ idle cold and hot, good throttle response, just not at the level of performance one expects from 300ish HP. The second dyno run was performed on a different dyno and was more meant to be a confirmation of the first measurement. But you are right there won't be another run unless I really found something to fix / adjust and unless my "butt-sensor" feels some gain in HP.
Did the dyno shop have an air/ fuel ratio gauge on your car? If not; Not sure if it has been mentioned or not but if the compression and leak down tests come out ok then perhaps test your fuel pressure and or your air/fuel ratios. Order yourself an air/fuel gauge while you're putting your order in @ Summit if you do order from them. I think Larry may have a link for a good one? Larry?
The place I went last has the equipment, but my car is not yet ready for the sensors. I need to weld in threaded piece of pipes to the two pipes from the exhaust manifold to the mufflers. I will have that prepared for the next run, but I need to check / fix some more stuff until then, so that it will be worthwhile doing another dyno test.
If you're going to have the bungs installed, buy a gauge for your own use before you go to the dyno shop to make sure your air/fuel ratios are even close before you spend more $$$ at the dyno shop.
This is the one JW recommended to me and the one I use. https://www.summitracing.com/parts/avm-30-4110?rrec=true
