Since restoring my engine compartment, I have had quite a bit of trouble with idle and a bog during launch or kickdown (basically any time during WOT). The car cruises well but has trouble under load. And my definition of a bog is the car spits and sputters in the engine compartment and feels as though it is going to die. It actually died on me once from a stop sign. I think I am setting up the timing correctly. I have the vacuum adv off the distributor and plugged. I set the initial timing to 2.5 degrees. I have advanced the timing a little further and it ran a little better, but I don't feel I should have to run that much advance, and it was still very sluggish. When I set initial timingto 7.5, once I hook the vac adv the timing mark goes to almost to 28 deg at idle (about 900 RPM). The car sounds okay, but when I go to put it in gear, the RPMs drop considerably (~400 RPM) and it sounds horrible as if it may die, as though the timing is off. I have checked total timing at 2500 RPM before and it has always been high, around 34-38. That was before the carb was rebuilt. I haven't checked total again. First, things first, when I restored the engine compartment, I did replace the timing set with a stock set of Cloyes. Now I am second guessing myself. I am pretty sure I installed them the same way the old set came off. I think I had the engine at TDC, I know I installed with the arrows pointing at each other. I know how to work with tools, but do not have a great deal of experience with engines so please pardon any stupid questions. 1st stupid question ( :laugh: ): (Devil's Advocate)...Would the car run if I installed the timing set with the engine 180 degrees off TDC? In my mind, that is the only way the timing set would go on incorrectly....? The crank gear is slotted and can only go on one way, and the cam gear has only two positions it can be in. Like I stated before, The car cruises very nicely, but idle in gear and under load does not do well. Would this be the the logical answer? I already tried a few things: I thought I might try a new high output coil and pertronix unit to see if that would help at all. That did not seem to make any difference seeing how I did two test runs, first with Pertronics and then pulled that out and ran the old (they were new) points and old coil back in and it ran the exact same. I have done a new rotor, cap and plugwires. New ground strap. The carb was just professionally rebuilt/restored to factory specs. Installed it and low and behold the same problem absolutely no difference. What should my next step be. I am going to recheck all of my grounds, but then what...send in to the local shop. Is there anything else you guys can think of. Keep in mind the car was running good before I took it apart!!! I changed the timing set. What could I have done besides screw up the timing set and paint the grounds? AAARRRGGGHHH. :rant: Any help is greatly appreciated.
Are you running a stock carburetor? It sounds like you are on a non ported source of vacuum. My '67 has the original carburetor on it and at idle it makes very little difference with the timing with the vacuum hose on or off. I get full advance at 2500 (around 36 degrees). I have my initial timing set at around 10 degrees at 850 rpm. I am running a TA 212 cam advanced 6 degrees. BTW the engine would not run if you were 180 out on your timing gear set. Did you change the vacuum advance unit on your distributor? I tried the adjustable unit and could never adjust it back enough for the timing not to go to around 24 with the vacuum hooked up with the original carburetor. The 67 carburetor, 7027146 Rochester, has only the PVC valve hook up and the vacuum advance hook up on the carb. All of the other vacuum hook ups are on the manifold. You may have a vacuum leak somewhere. Did you put the stainless steel gasket back on when you replaced the carburetor? The later carburetors had more vacuum hook ups. If you are running a later one try hooking to a ported source of vacuum. One other thing, make sure that your secondaries are opening on your carburetor at WOT. There are some other adjustments that you can make for a "bog" condition but I don't remember them but they are fairly simple. Good luck!
Thanks LaMarr, It is the original carb. It was just rebuilt/restored, and I do have the metal plate under the carb. I have a gasket on top of and under the metal plate, is this correct? Everything is completely stock on the car in the engine compartment. Thanks for letting me know that the engine would not run if the timing set were 180 off. I was really second guessing myself. The vac advance on the distributor has not been replaced. 2nd stupid question ( :laugh: ): Should the vac advance not make a difference when the car is at idle? Is mine bad if it is. Like I said, at idle when I set initial timing, I have the vac line plugged and set it to 2.5-5. Then when I reinstall the vac line to the distributor, the timing jumps to around 25-28. I don't completely understand this vac advance stuff. Can you tell!!! p Can I get a replacement unit at the local auto parts? Again, thanks for any help.
I am going out on a limb here so in other words I am not completely sure if it should have that much advance at idle. When I had my engine rebuilt, I found that the vacuum advance unit in the distributor was bad so I replaced it. They are available at most parts stores. After the rebuild with the different cam I do not get the same amount of vacuum at idle that I did before and the amount that I do get is not enough to advance the timing at idle (about 12 in.). I do not know what it was before but it was probably 3 to 5 higher. That is certainly a good question that I am unsure of the answer. I will tinker with mine tonight or tomorrow night and see what more I can learn. I have another '67 distributor that I will also look at and put vacuum on to see where it starts to advance.
Jarrod, It helps alot if you tell us what year and size engine you have in the car. If you have the stock distributor in the car, and the stock timing is 2.5* BTDC, you should be running full manifold vacuum advance. The stock cannister will provide an additional 14-18* at idle, and some of your mechanical advance will be in, so 24-28* sounds about right. The stock distributor in that engine(66 or 67????) provides alot of mechanical advance(28-32* @ 4800 RPM). Combined with your initial timing, you'll have 30-34* total at wide open throttle, at 4800 RPM. That is optimal timing. To get the best performance, you need your advance in sooner, no later than 2500 RPM. To do this you have to replace the stock springs in the distributor with lighter ones. When you do this, you now have to restrict the amount of degrees in the vacuum cannister to avoid overadvance at lower RPM's This has been discussed alot previously. Do a search under Crane Adjustable Vacuum Advance, and read up. I have a feeling that this may not be your problem. It isn't possible to install the cam gear 180 out and have the engine run, BUT it is possible to install it backwards. Can't remember the effects of this, but I know Rick Martinez(9secstage1) did this on his Centurion Tow car, and John Csordas(Skyhawk) fixed it for him. Might be your problem. I gave Rick a call and left a message asking him to post on this thread, he could tell you more.
Thanks Larry, I will watch out for Rick to post here. The car is completely stock. It is a '67 GS400 with the stock '67 400 Block. Original Carb and distiributor, etc, etc. Stock Cannister??? Is that the vac advance unit on the distributor? Do they put the arrows (to line up the gears) on both sides of the cam gear? I know I installed the arrow facing out. They were lined up. I just thought I might of had the engine 180 out from TDC. Again, Thanks,
Jarrod, Yes, the vacuum advance unit provides an additional 14-18* at idle, when hooked to the full manifold port. Combined with your 2.5* initial timing, that gives an idle timing of 20+ degrees. Automatic transmission cars really like that kind of timing at idle. When you go wide open, the vacuum advance drops out, and you get 28-32* of mechanical advance peaking at 4800 RPM. You can really wake up the motor by changing the springs so that your advance is in by 2500 RPM. Then limit the vacuum advance to 10*. It would also be good to limit the mechanical advance, so you could run more initial. If you limit the mechanical to 18-20*, you can run 12-14* initial, plus 10* vacuum advance. You would then have 22-24* at idle, 30-34* at wide open throttle, and 40-44* at light throttle at cruise for gas mileage. Yes there are markings on both sides of the cam gear. I believe that is how Rick made his mistake. Can't remember though whether the engine wouldn't run or ran poorly. Rick should post tonight, keep an eye on this thread
Sorry Larry been busy, I did get your message. In my case the engine wouldn't run at all, at most sputtered once or twice. The timing gears had marks on both sides which in my dumb luck used the wrong marks. 180 off it wouldn't run.
