Rob, There is a big difference between advertised duration, and duration at .050 lifter rise. You quoted the advertised duration, which is not what Barry Grant was talking about. I noticed you gave us everything but which cam you have. What is the part # of the Champion plugs you are running?
more info I just spoke with the shop that timed my engine. I was told that the engine is timed a total of 35, and that because of the mallory distributor there is very little advance in the distributor, probably around 12 degrees. The guy from BG suggested a 4 hole, 1in spacer for my carb. The problem is that there is no way I can fit it, there is only about 1/4in in between the hood and aircleaner. Please keep the suggestions coming, I think Im actually beginning to understand all this. Rob
reply So here is what I have learned today... I spoke with mike @ TA ( hell of a nice guy ) and he tells me that the duration on the cam is actually 238-248 @ 50, and that the carb should be ok. I also mentioned to him that I bought my distributor from him as well, and he asked if I had him re-curve it ( I checked and I did not) he said from the factory the mallory uni-lites have about 22 degrees mechanical advance with an initial setting of 20-24. Im getting a little lost in the numbers here. If I understand the carb, seems ok, but maybe the distributor should be re-calibrated. He also asked me about vaccum pressure. I said I didnt know, but after I got off the phone, it occured to me that im having problems with my brakes, and I thought the two were unrelated, but maybe they are not. Does anyone have a suggestion for some things I can check to make sure that everything is correct with vaccum hoses and what not? I also recently noticed that the hose between the intake and the waterpump housing was kinked, so I am replacing it. Would that have anything to do with any of this? Thanks, Rob
Rob , Aren't cars great?! I know a lot of this must seem very foreign to you at the moment but don't worry, there are some wonderful people on this board that will help you so long as you are willing to ask. Before you get too deep into this it would be very, very wise to check the simple diagnostics of your car. Vacuum; what is your vacuum reading at idle, in gear? Is it steady or does it waiver? RPM; Also at idle in and out of gear. Steady or waiver (how much). Your plugs look as it the engine, or atleast those cylinders are much too rich. Before you tear into your carb I'd look over the ignition first. An ignition problem can be very misleading. I know because I spent a great deal of time blaming the poor performance of my car on a new carb when in fact I had a bad plug wire. CHECK ALL PLUG WIRES FOR CORRECT RESISTANCE AND LOCATION. It's very easy to connect the wrong plug and wire. I did it recently on a quick tune up and had the same symptoms you are explaining. This will take 10 minutes. Aubrey
Rob, If the bypass hose was a little kinked, it wouldn't affect the way the motor runs. All it does is provide a path for the coolant to circulate when the thermostat is closed. If the Mallory distributor has about 22 degress mechanical advance, then you need to run 10 degrees initial advance for 32 degrees total, 12 degrees initial for 34 degrees total, etc. Try reading this thread on timing. http://www.v8buick.com/showthread.php?t=58598&highlight=total+advance Do you have a timing light? If you want to learn to work on your engine, you need to have the basics first. Timing light, tachometer, vacuum gauge, good set of basic tools, and this Bulletin Board. That's all you need. It is possible you have low vacuum for one reason or another. Vacuum gauges are cheap. Low vacuum will affect the power brake unit. Incorrect initial timing will make your vacuum lower than it should be.
reply ok... Today i replaced all the plugs ( all 8 were equally burned) and fired the engine up without the aircleaner. I held the choke open, and it ran good. It idles too low ( around 900) but other than that its sounds better. I think it still needs to be dialed in a bit, but I am going to take that to be done professionally. I have a neat video that came with my carb that tells me how to tune it, but I am not sure about some of the things they are talking about. I think vaccum is an issue. I have blead those damn brakes three times now. The car stopps, but not like it should. My convertable had drums all around and stopped much better than this car with discs up front. I am going to buy a vaccum gauge this week. I hav been told that big cams sometimes cause problems with vaccum secondary carbs and brakes. i think this carb may be a vaccum. Im not sure how big is big, when they say that, but im sure a gauge will tell if thats my problem. This may seem stupid, but i have a hose going from my power brake booster, to the vaccum port on the manifold, and the PCV valve to the port on the back of the carb. Is that right? should i have any other connections? Rob
Rob, It looks like you have the TA 290-08H cam? With the 238/248 @ .050 duration, I'm guessing you're lacking enough vacuum to work the booster on your brakes properly. I've got the 288-96H cam, which is 4 cams milder than you have and I'm pulling a pretty steady 14" of vacuum. That's a 230/240 @ .050 cam. Get a vacuum gauge and see what you're pulling. I'll guess you're in the 10" range. Yes that is a vacuum secondary carb. You can see the housing where the spring sits to control the amount of secondary opening, based on engine vacuum. It's at the back, passenger side of the carb. There's a diaphragm and spring inside the housing. You can get kits to adjust when the secondaries come in based on spring tension.
reply Steve, I think you are right, I remembered it in their catalog as the "500 HP street cam"..but that sounds right. I bought a vaccum gage yesterday at sears. I am assuming I unplug my vaccum line from the power booster and place the hose from the vaccum gage on the fitting coming off the manifold? Also, the more I look at the carb, that must be correct, I believe it is a vaccum secondary. It seems to me that vaccum is probably a lot like amperage where if there is not enough to go around for all things it powers they will not work properly. Is that correct. I have tried bleeding my brake lines again and again. They are all clear with no bubbles. I definatly think its a vaccum issue. With that on the table, there is a shop down the road a few miles that does all sorts of fine adjustments, carb tuning, timing and that sort of thing. Would driving the car a few miles harm the engine running the way it is? The engine is definatly running too rich. The oil smells of gas, the exhaust stinks and the new plugs are a little black, but the engine sounds a hell of a lot better. There is no more hesitation, or coughing. I think that was a result of the choke leve hitting the air cleaner. Please keep the kelp coming, Rob :3gears: :beer
if the oil smells like gas you should change the oil before you damage the engine. have you tried adjusting the mixture screws on the carb. Demon carbs will run rich if you have the idle screw turned in to much. this uncovers the transfer slot causing it to idle rich. if your distributor has vacuum advance connect it to manifold vacuum, that should help clean up the idle a little.
Dave, I havent touched the carb since it came out of the box. The question is how do you know how much to adjust it? I do have a vaccum secondary carb, previously in this post I said it wasnt, but I was mistaken. I have connected the carb vaccum fitting to the vaccum port on the manifold through the PCV valve ( small crackpipe looking thing that sits in the rubber grommet in the intake behind the carb ). Is that correct? Also I bought a vaccum gage at sears. I have been told by TA that any less than 10 on the vaccum gage and the brakes and secondaries will not work properly. Rob
Rob, There should be at least one fitting on the carb itself that you can hook the distributor advance to. They may be capped off. A full manifold vacuum fitting will hiss at idle when you uncap it. Look around at the base of the carb front and rear. The advance shouldn't be connected to the PCV (not sure how you did it). TA is correct, you need at least 10 inches of vacuum for the brakes to work.
Also I bought a vaccum gage at sears. I have been told by TA that any less than 10 on the vaccum gage and the brakes and secondaries will not work properly. Rob[/QUOTE] Low idle manifold vacuum has nothing to do with the vac secondaries opening. The secondaries open via a vac draw through a very small port in the passenger side fron carb venturi. As air speed increases, it causes a vac at this port which allows the secondariies to begin to open. By changing the tension of the spring in the secondary vac. dashpod, this will change when, how fast, and at what rpm range the secondaries will open at. Typically the stock spring that comes with the carbs don't allow the secodaries to open till too high of an rpm. Jim Burek
reply Jim, Oh ok...this was explained to me once before, but I must have misunderstood. I get it now. Yes, I need to get in touch with barry grant and get a different spring kit. The way I understand it now is that if the spring tension is too high, then the secondaries will open up too late ( too high in the rpm range ) for example right before I shift, therefore offer0ng no advantage. Is that correct? If so how do I know what spring kit to ask them for? mike at TA mentioned that there are many to choose from. If I had to guess id say you'd want the secondaires to kick in around 2500 rpms when your cam powerband begins to hit, also since I shift around 3500 rpms it would be right in the middle. Would you say thats a good idea? I am not sure if I have the right terminology going here. On the top of my intake manifold, in the back, by the firewall, there is a grommet that has the PCV valve in it. I have a hose attatched to that that goes to one of the inlets on the carb. It is the same size. My distributor is not a vaccum advance. It is a mallory uni-lite, and has no provision to connect it to and vaccum port of any kind. There is an L shaped fitting coming out of the manifold that goes to the brake booster. I originally had these switched, and was told that it was wrong, and I attatched the way they are depicted above. Is this correct? I can take a digital cam pic if that would help anyone. Thanks, Rob P.S. I will change the oil, but Im just curious, why would that damage the engine?
With a big cam you really need to dial in the ignition. Initial advance will vary but you should be in the 16 to 20 degree range with enough mechanical to get to 32 degrees total. 12 degrees will not give you enough vacuumn. By the way it is ok to run 900 rpm at idle. I doubt the jets are too rich on the carb, or at least rich enough to run black sooty plugs. If your ignition system is not working properly you will get the blackened spark plugs!!!!
reply Doug, I have a MSD 6AL...its brand new. How would I know if thats the problem? Does it get calibrated? Thanks, Rob
If the engine runs dead rich at idle or if your ignition is poor, you'll end up with gas in the crankcase. It can be as much as a couple of quarts of gas. This will wash out bearings and result in really really bad things. Change the oil.
Rob, The spring kit comes with quite a few springs. You will want to go with a fairly weak one. The demons have a quick change dashpod so changing the spring is very easy. It will just be a trail and error thing with the spring, you want the secondaries to open quickly, but not cause a bog. Jim Burek
reply John, Thats enough for me, I will do it before starting the engine again.....Thanks for the info.... Jim, Ok, so all the differet springs come in one kit. Got ya. The vaccum hose from the brake booster, where should it be connected to? I just want to say thanks for all the help here guys. I know I am being repetitive, and I appreciate everyone's patience with me. Because of all of your help, I am finally beginning to understand this stuff. Rob ou:
Carbon fouled plugs. Have you done a leak-down test? With you deck milled so much & your adjustable valve train, it may be possible you have 1 or more valves not fully seated. When its warm is it harder to start? Also the gas -smelling oil is an indication of leak-down also. If the valve train is too tight, when heat expands it could be holding intake or exhaust valves open very slightly at (TDCC)when warmed up & your plugs will look like what you've got. You could pressurize the cyl(s) with air at (TDCC top dead center compression stroke), open your butterflys on the carb & listen for air leak, & or listen at exhaust manifold/header opening for air leak. If you dont have the tools, your shop can do it for you.
Rob, I think you're either running too rich, or the plugs you are running are too cold. The MSD will fire almost anything, and the multiple sparks at low RPM keep the plugs nice and clean. Try introducing a vacuum leak into the engine at idle. If the engine speeds up alot, it's too rich. RPM's should increase a little, but not alot.
