demetri

[QUOTE=Iowan;135142]... not one had a bad damper on them!


[QUOTE]


When I had this car a few years back, the car ran very smooth, but based on the harmonic balancer, I had to advance the timing a bunch, like 20 at idle rather than 10. Low end torque torque improved substantially when I advanced it. As it was, the car also had an unusually good high rpm performance. At that time I had assumed that that the harmonic balancer may be off.


Summer of 2013.... The car was no longer running smooth, and I had some other engineering projects with that mechanic, so I took it to him. I had assumed that the heads were tired and the cam may have been worn. When he took it apart, he discovered that the timing chain was stretched severely and ready to jump a tooth, which explains why I could advance the timing so much, and why the engine ran strong at high rpm even though it had the basic cam 260-0.425 ... So, the harmonic balancer theory is no longer very high in the list of likelihood. It turns out that due to too much sitting, one or two valve springs got tired, and that helped wipe out the old cam.


Anyway, now I have the timing around 20 at idle, and another 16 by 3000 rpm. I think the timing is very close to optimum now.


What part number Hollies do you use? Do you have power valve to replace frequently? What gas mileage do you get with the Hollies. Any part numbers to suggest? Do you think 750 or 800 is enough? The 800 AFB certainly seems to provide enough air (based on vacum reading at WOT).


My immediate plans are as follows. I will drill out more the secondary jets. I have little faith on that, but its very easy to do. I also have a Q-jet sitting around, I have heard these run rich when the seconaries open. The Q-jet I have on my other 440 seems to do good at WOT, and gives me about 13 mpg without functional vacuum advance. These are low cost actions that I can take, and see what I learn from them.

Iowan

Don't guess or make assumptions, verify top dead center on the damper, verify the timing then work on the carb!!!! In that order!!!!

Chasing your tail............with your head up your butt!

Coronet 500

Your wasting your time Iowan, I've been down this road on other forums.

This guy thinks he has the answers and will defend his decisions over and over, and if it doesn't go well, blame others for not telling him what he wants to hear.

To Demetri, if you know what's right why do you keep asking questions.

I wouldn't let this guy work on my lawnmower.

demetri

Hmmm ... where did this come from? When did I blame anyone? I only said that I was hoping to find the tuning experience in the group to help refine my guesses. And you guys simply confirmed that this experience is currently in short supply.


There are many ways to do something, and the optimum way depends on the situation. For example, R. H. had suggested to me to do a plug cut. That is a good suggestion. But, in order for me to take 2nd gear all the way up and then let it coast, I would have to take the car to about 100 mph. I live in the middle of the city, and I cannot pull over on the side of the freeway and pull out a sparkplug. This is not R.H's fault or anybody's fault, this is the situation, and we have to adapt to it.


Another suggestion of dual carbs. Again, this is an expensive option. I may go that way, but that is not my first choice. Holley is a great suggestion too, but will get me 8 mpg. If the forum does not have the answer, that's fine, this is not an easy one (like my pinging, guessing the head gasket was not an easy one). But trying to turn everything into "I told you so" is counter productive.


I understand that some of you guys only know one way of doing things, and one way only. That does not mean that all other ways are wrong. You are stuck with the timing, when this really seems to be a mixture issue or electrical problem (it appears to not be electrical).


And ... by the way. You condemn setting timing by ear, but no matter what you say, if I have an engine that pings, even if the timing is set "correctly", I will still retard the timing.

Iowan

There you go.

Iowan

your so correct!

demetri

So .... I drilled the secondary jets further on the AFB 800 ... Max size from Ederblock is .119. I drilled them out to .135 ...


Up to 3500 rpm, the torque continues to improve, and in fact the throttle response in this range seems about the same as my other 440. But now the fuel pressure drops even faster as the revs go up ... result of increased fuel flow. So, it is hard to assess the effect on the hesitations. There are still instances, however, where the fuel pressure is still reasonable (i.e., around 3-3.5 psi) and I still have hesitations. Even though with this pressure range I may still have lean mixture, it should probably be sufficient for no misfire, as the engine has ran before in this fuel pressure range and did not have misfire ... I may have two problems fighting simultaneously.


I will try to address the fuel pressure issue, however. I have a spare electric pump, lets see what happens if I replace it.

Coronet 500

I know of one man who can tune an engines timing by ear, watch exhaust and diagnose/adjust a carburetor by odor.

He is a licensed auto mechanic with over 40 years of experience repairing cars with all types of diagnostic equipment, built and raced super modified cars.

A man who can do these things and it's NOT YOU!

demetri

True ... may be one day ... I did not claim I was ... There are people in my area that can tune this in a few days, and may be $2-3K ... I do not want to go that route, I am learning and having fun in the process while keeping my $ in the bank.


In the mean time, my observations is all we have.


Suggestions such as the one from Iowan is what I am looking for, even if most happen to be incorrect (without the adjectives and rudeness would be better, but whatever...) I want people to challenge my assumptions.


I do not see this as a competition to see who knows more. In fact, I am fairly certain that many here have more knowledge in certain areas than others.

demetri

Made some progress ... finally.


First, I replaced one of the electric fuel pumps on the back, as I said before. That raised fuel pressure, to the point that I could hold almost 5 psi at 4500 WOT. But hesitations remained.


Then, I looked at the dwell again, set about 300 miles ago before the head gasket. It was on the low range. Suspecting my dwell meter over reading, I increased the dwell 4 degrees. The hesitations are now almost gone. Power delivery is now smooth in two runs I did, with the exception on one brief occasion in the 4600 rpm range. Unfortunately, the fuel pressure dropped a bit too.


So, as I suspected, there is more than one issue going on here, but the major issue was weak ignition. Not sure what's next, but at least now the car is much more enjoyable and faster.

RacerHog

........

64Imperial

When doing my 64 imperial with the 440 i was looking into these manifolds i used my imperials stock manifolds cause how the imperial is built and all the things on the car one manifold exit is on the very back half of the passenger sides and the str8 down the middle exit wouldn't fit on mine cause the suspension is there the manifold would be like 1/2" from the A arm part, but i'm not sure how different your imperial is from mine.

demetri

I have not even attempted to look into these. There is a website somewhere that has a dyno test of a low compression 440, and when they replace the regular manifolds with the HP, they get no difference. I think these HP manifolds were a gimmick for muscle car guys to make them think that their 440 is "special". THe reality is just replacing the cam you can convert any 440 to an "HP440". I am not sure how different our Imperials are. The 67s and 68's are a lot more like the regular C-bodies, with the radiator moved about 4 or 5 inches further ahead than in a regular C-body. You can tell, the radiator shroud is a lot longer.

demetri

More updates. I made some ignition upgrades, including a 45,000 volt coil. All these helped some, but power above 4000 and especially above 4500 rpm was always inconsistent and not smooth.


Based on discussions with Ederblock and other fellows, I suspected that I over drilled the rear jets, to the point that my fuel flow went down, probably due to fuel flow turning from laminar to turbulant. So, I installed larger jets on the primaries (which I had never touched, in fear of making my mpg terrible), and went back down to .125 on the secondaries . That almost eliminated the high rpm hesitations, but, as expected, the engine is now running rich at cruising conditions (I can smell it trhough the exhaust leak as I am cruising down the freeway). But the engine is still not rich enough at WOT.


So, what I learnt here is that the primary circuit seems to be delivering fuel for most conditions unless very high rpm and WOT. The bigger (drilled out) jets on the secondaries were helping getting my mixture richer at WOT and low-medium rpm, but as the fuel flow rate increased at over 4000, the hole was too big for laminar flow on the fuel side. That is the theory at least, but seems confirmed by the testing. At very high rpm, my fuel flow went down, making it leaner yet, and misfiring. Lets see what happens if I replace the .125 with the max size sold by elergblock, .119.


I am wondering if I can get better than 10 mpg with this setup on the freeway. Normally, a car like this can get up to 14-15 if you don't drive much over 80.


All these are temporary fixes until I prepare my Rochester or Demon (will try Rochester 750 first, because I arleady have a core). All the above is just playing around and learning about carburetors. The conclusion remains, AFB does not work for a 440 ...


Anyway, some may be interested in what I am learning.

Iowan

You just don't know what your doing!!!!........

demetri

As said on the previous post, I wanted to try going back to the maximum jet size offered by Ederblock, 0.119. The result was that the hesitations expanded down in the rev range, from about 4200-4300 and up with the 0.125 down to from 3500 and up. As you recall, when I reduced the hole size from the 0.135 to 0.125 helped smooth down the upper range a lot, but did not completely cure the problem.


So, apparently what is happening is that the oversize drilled jets help bring the mixture richer as the secondary flapper is not completely open in the mid rpm range, but at the upper end, the real big hole hurts fuel flow.


So, back to the 0.125. This is as rich as I can make it in the 4200-5000 rpm range while the rest of the rev range is strong and smooth. Until I have my Q-jet ready, that setting will have to do.


I was also considering to increase the weight on the secondary flapper and make it open slower. That would bring more air through the primaries which seem to do a better job in delivering fuel. But that will cost me a bit in airflow. Right now there is a bit less than 1" vacuum at the high speed range. May be adding half more inch of vacuum is not a huge deal if I can get the mixture richer, but adding weight to the flapper is not easy.

demetri

I finally got some time the past few weeks to attend to this car's issues. I got a Q-jet that works well and installed it. I had to use a large spacer below it, which may have improved the flow of the carburetor. After I took care most of the new vacuum leaks that appeared, I gave it a test. I could not time the acceleration to compare with prior runs, but it feels like it is more powerful throughout the speed range, more on the upper end though. And that was, without any tuning attempts (as you recall, the AFB was tuned to the max richness I could get). Also, the 750 seemed enough, as the vacuum was nearly zero in the 4000+ range at full throttle.


So, we are moving in a good direction, but not completely done.


While I was working on that new carburetor, I got shocked by one of the plug wires (very humid day). I had a suspiction of an electrical problem, but these plug wires are new and copper based, so this is very weird. During my testing, I could in fact feel some misfire, but that was now spread in the whole speed range instead of just on the top end.


Anyway, I will check the boot contacts again. But ... do you guys have experience from copper plug wires going bad?

demetri

I need no help. The path is clear. New plug wires. Crazy that this was a problem, but I suspected multiple problems.


It is good to see that the carburetor was the problem in the lack of upper end power. The sound of the engine also changed under full power.


I also have to chase vacuum leaks, but I will replace plug wires first for another acceleration test that I can time with the stop watch and see where I am.

demetri

As expected, new plug wires fixed the misfire, and the Q-jet fixed the high rpm lean condition. The car felt faster than ever ... but.


The stop watch, especially at the high rpm 2nd gear where things happen slow enough that the stop watch can capture them, the acceleration is not as high as I hoped. It is no better than my other car, same weight, gearing, and milder cam. In the 4-5K rpm range, I was expecting this engine to be noticably stronger. I still cannot smell any hydrocarbons from my exhaust leak.


I have now reached the point where a plug cut is worth trying. I suspect that even with the Q-jet, I am not sufficiently rich at WOT, especially at the higher rpms. Too bad that Q-jet is not adjustable. On the other hand, I only paid $80 for it. And I can use it as a spare to the other car, if I decide to try something else. But I need to get some driving behind this carburetor first.

demetri

As expected, new plug wires fixed the misfire, and the Q-jet fixed the high rpm lean condition. The car felt faster than ever ... but.


The stop watch, especially at the high rpm 2nd gear where things happen slow enough that the stop watch can capture them, the acceleration is not as good as I hoped. It is no better than my other car, same weight, gearing, and milder cam. In the 4-5K rpm range, I was expecting this engine to be noticably stronger. I still cannot smell any hydrocarbons from my exhaust leak.


I have now reached the point where a plug cut is worth trying. I have to find a good spot out in the country ... I suspect that even with the Q-jet, I am not sufficiently rich at WOT, especially at the higher rpms. Too bad that Q-jet is not adjustable. On the other hand, I only paid $80 for it. And I can use it as a spare to the other car, if I decide to try something else. But I need to get some driving behind this carburetor first.

demetri

No plug cut yet, but have done some road testing and some research ... In particular, I made some rough calculations to compare the performance I am getting with these road tests and more. Simple, but revealing. I am focusing on my 80-100 mph acceleration of about 6 seconds, which is done between just under 4000K and just under 5000K rpm.

I am looking at cars with similar gearing and known horsepower and performance. An example I found is the Jag 5.3 V12 (285 hp net) from the 70's with 3 sp auto. That car has about 60 hp requirement at steady state 100, my big boat needs about 90 hp (assumed a conservative 0.45 drag coefficient and 2.4 m^2 frontal area). Lets ignore power train losses. In the 80-100, both engines run very close to their peak power range. The Jag has about 285-60=225 hp available for acceleration. Since we happen to have the same rate of acceleration, my excess power would be proportional to weight difference. I.e., 225 hp*5200/4000 (ignoring payload)=292. Add my 90 hp in total drag, and we have 382 hp. So, that looks about right. It turns out that an extra 25 hp would take out 0.5 seconds out of the 80-100.

Another example, look at this Ford Mustang road test:

http://media.caranddriver.com/files/...g-gt-specs.pdf

He did 80-100 in 4.5 seconds (I am 6 seconds). He did 80-100 in 3rd gear, reaching his peak power at 100, which is 300 hp. His drag is about 50 hp at 100. So, his excess power for acceleration is around 250. He is faster than me though, so I have to adjust my excess power for both weight and acceleration rate. So, my excess power is

250hp*5200/3500*4.5/6.0=278 hp. Add 90 for my drag and we get 368 hp. The lower number may be justified because this was a standard gearbox with less power train losses, and we have an automatic.

This indicates that my current acceleration is very close to what this engine is expected to do. I think that I may be able to trim that 80-100 down by another 0.5 seconds if I optimize everything else, i.e. exhaust, mixture, or timing. But I am very close.

By the way, 380 hp, 15% driveline losses, 0.45 drag coefficient, and 2.4 m^2 frontal area (the Cd is a bit on the high side, the A possibly on the high side too) give me a top speed of 155-160 mph, which would correspond to about 5300 rpm. But in the USA roads, this is not an easy thing to do.

I compared this performance with other cars too. A 1977 Mercedes Benz 6.9 Euro version has also 285 hp. This car had 80-100 in 8.0 seconds. I would beat this car some from 60-100 as well. I also found a road test of a 1967 Impala 427 SS with a claimed 386 hp gross and a 3.07 gearing, 3 sp. They would rev 2nd gear up to 100. It was about the same as the Benz 6.9, even though much lighter. That 385 hp rating is obviously BS, real hp must have been closer to 250-275 hp.

Anyways, car is doing well, but I still have to take measurements. I may go to a chassis dyno and see if I can measure A/F at WOT, and play with timing some, but not in the near future.

RacerHog

This was with the 750 Q.J.... ??

demetri

Yes, that Q-jet is working great at WOT, without any adjustments, which are impossible anyway. The vacuum at WOT is under 1 inch, so the restriction from the air side is low, at least up to 5K. I think the carb may be benefiting from a spacer between it and the manifold.

It feels a little weird, as the huge secondaries open at the last half inch of pedal movement ... but goes well. Funny thing is, now with the repaired head gasket, it seems happy with 89 octane. At least, now in winter.

I am having problems with low vacuum, which are at least in part due to a persistent vacuum leak in the base. Only after 2 or 3 miles does the vacuum start to be normal, but it is still a bit lower than I had in my 750 and then 800 AFB.

The funny part is the following. I visited a speed shop that I have some other business with. They had a bright flashy Chevy with 427SS budges on it. Turned out it had a 454. These cars came with the Q-jet that I have, yet, ironically, he had an AFB, just like the one I could not make work for the 440. But apparently, was good enough for the 454.

One more thing I forgot to mention. I have calibrated my tach to GPS speed, and do not rely on speedometers. Old car speedos had terrible errors.

One more thing. I had found a road test of a 70 440 Cuda with 3.55 rear. That car was 80-100 in 5.3 seconds or something. But, this was with 3rd gear, their 2nd gear expired at 75 or so. Obviously stock 440HP, but 3500 lbs rather than 5200.

RacerHog

Not sure if you have look at the H.P. Rochsester book.. But they do have some good areas to help in... I know there is a newer version, But I liked the old version... Just food for thought....

https://www.google.com/search?q=Roch...g7GyY2h3QFM%3A


This might help with the lean spot....

Iowan

��

demetri

Update and quick question.

I think that by better spark plug wire insulation, I got the 80-100 to about 5 seconds, so I have improved a bit the performance. But even the second set of plug wires are problematic, I need to replace them, and that may help further. However, the 750 Q-jet is a bit restrictive. I have just under 1 inch of vacuum at 3600 WOT, it probably grows to 1.5 inches at 5000 (not easy to observe that when revving up that high).

Question is the following. I had not started the car in about a month. I heard the lifters clicking right after fire up (took some cranking). Is this normal for stiff valve springs with the hotter cam? Lifter noise disappeared 15 or 20 seconds later.

Thanks