Tim,

I don't know if you're long past the ignition timing issue but I found this link on Facebook and thought it may be of interest.

Ask Away with Jeff Smith: A Basic Guide to Ignition Advance - OnAllCylinders

 

Thanks very much for the link, I did see that post on FB the other day also. While I want to say I've got my timing set pretty well, as of last night, the engine is just not running the way it should be. I've had the Camaro up on stands all week trying to get the entire car one (well close to one) color. Of course, that's when we actually get some summer here and the humidity had made it extremely difficult to try and sling some paint. Anyway, my kids and I went for a little ride last night and the engine runs beautifully. There is still something not right though, and it's very obvious. Driving it like any other normal car at low, steady speeds it runs ok. I can tell by the way it sounds that it's not operating smoothly. Hard to explain of course but the blub blub blub sounds (increased with rpms) it's making just isn't right. It's not smooth. I can check timing and initial is at 17 btdc and right at 36 when timing is all in, by 2800 rpm. Vacuum still really low -4"hg at idle. Hate to keep repeating myself but I don't know what else to check? Had the cap/rotor off to check the springs and weights and they are working just fine. WOT just gives me nothing but bogging and not a delay, it doesn't stop until I pull my foot back. So to summarize, I would like to say that I've got the ignition timing taken care of but I don't know if that's entirely true. Not certain if my problems are carb issues or what? I also can't seem to get that darn shotgun scoop to stay in place when driving. I had gotten the linkage lined up perfectly so the butterfly's would open/close properly but the scoop itself keeps turning toward the linkage, badly! Last night I had to stop twice in 2 miles to move it back into place as the linkage had wedged the throttle open, which isn't exactly safe! Only having the one little wing nut to hold the filter element AND scoop in place isn't working. If I can't figure that out, it's coming off there sooner than I had planned but I wanted to use it for the remainder of summer. With about one month remaining to try and get some enjoyment out of this Camaro I really pray that I can get the performance issue(s) figured out now! Just don't understand it! Starts, idles and somewhat drives great that is until you put your foot in it a little. Thanks again for thinking of me Neil, very much appreciated sir!

 

Strange deal here. So the Gilmer belt has decided to start walking off the end of the alternator pulley?! The belt is NOT misaligned, there's absolutely plenty of space for the belt on both the crank and water pump pulleys and . Look what it's done to the belt? This just happened tonight and I didn't even know it had come off there until I got back home and things were a little bubbly in the radiator. Aren't these the belts that are supposed to NOT fall off? Guess I better get busy and get a new belt ordered.

 

The belt can be perfectly aligned, but if the alternator is even slightly cocked, it will try to walk off and tear up the edge. The alternator also needs to be rock solid, or engine torque on acceleration will try to pull it sideways, and also eat up the Gilmer belt. As I mentioned previously, I dumped mine after 3 belts, and numerous attempts to try and make it stop eating the belts. Not to mention the rubber dust all over my engine bay!
A close up of your shotgun scoop linkage, and how it hooks to the carb would help me diagnose it. I'd guess it's either the angles on the linkage, or possibly it might be slightly short for a full throttle hit, and pulling the scoop sideways when it bottoms out.

 

It must have something to do with the engine torque while driving as it's always been perfectly aligned on all 3 pulleys until now. Got a new belt coming but for now I think I'll flip the belt around and try to pay closer attention to what's going on with it.
The shotgun scoop is actually turning on it's own just from the wind while driving. I removed the linkage yesterday and just turned the butterfly's sideways (open) for a test drive. I had to stop and turn the scoop back after about 3 miles. With only the single wing nut holding it in place on top of the filter element, its not keeping it still. With the linkage connected, that only helps it turn faster. There's really no other way of securing the scoop to the carb beside the wing nut on top of the breather is there? Don't see how there could be. That's my problem though, I need to get a stronger fastener!

 

I took the scoop off tonight and just put the base plate, element and top plate on so I could try and really tighten the wing nut down. I now have it to where it won't turn so easily but think it's going to be tough to get the scoop part mounted back on there like that. Don't know, maybe that's the way you're supposed to install it? I had to tighten it so much that it's literally starting to smash the element down! I'm basically going to try securing the scoop one more time. If it turns sideways again, it's outta here. The looks of the scoop have actually grown on me, I'd like to at least keep it on there for now if I can. I don't even think I'm going to mess around with cutting a hole in one of these hoods to clear it since there's so little summer left this year. Not a big fan of driving around hood-less but again, not much driving left this year.


I'm going to drive it tomorrow if I can keep that belt on there so I can get a video clip of what it's doing at WOT. Doesn't really make much sense that it runs so well up until about 3/4 throttle and then just bogs until I pull my foot back. I went ahead and replaced the fuel pump tonight also. Had bought a new one a few weeks ago when I was trying to figure out one of the previous problems with pressure. Haven't had any low fuel pressure readings since then so I never changed it out. Trying to figure out if it's a fuel delivery problem causing the WOT issues. Hopefully I can get a clip of what it's doing. It's not a delay, have never been able to feel this Camaro truly accelerate yet and it would certainly be nice to!

 

Is the bog right when you hit WOT or is when you hit high RPM? I guess what i am trying to say is, when you punch the throttle at low rpm does it bog instantly, or is it only at high rpm under load that does it?

I would think that if it bogs as soon as you hit it, your carbs squirting too much fuel (i believe that is your accelerator pump? No idea) but if its at high rpm under load, i would assume that you are running out of fuel.

Can you take the car up to max rpm under no load? Can you get the car to go to max RPM while driving if you don't punch the gas?

One thing that may help is find a cheap wide band o2 and hook it up, will tell you if you are flooding the crap out of the car or if it is lean.

 

Haven't really tried WOT from a dig, it's always been from a higher rpm under load. I've even tried doing it gradually up to about 3500 rpm and then WOT and it bogs. Yes I can take the revs up under no load as well as under low, steady throttle under load. That's why I'm thinking it's more likely lean rather than rich. I've tried adjusting the accelerator pump to all 3 of the adjustment spots and still get the same results though? That's what's making this so strange. I'd very much like to get an O2 sensor and air/fuel gauge installed, probably next summer. I keep adding gauges, might as well get an a/f ratio one also. Just got the a new vacuum gauge and a-pillar pod so I can watch vacuum while driving too. Appreciate the suggestions very much, I'm trying like hell to get this figured out so I can finally have some fun. Don't want to complain, it's been nice to actually drive the Camaro after doing all this work the last several years, but I'm quite ready to have this thing act like it's meant to.

 

I ran Type F in my TH400 for 14 years. It works better than Dexron but you don't want to mix them. I put Type F in it when I converted from a 4 speed to the TH400 back in '91 and the transmission was freshly rebuilt. I went through the trans again in '05 and have been running Redline synthetic ever since. Not that I had any issues with Type F. Just wanted to try a more expensive race type fluid.

 

Appreciate the confirmation Steve. I've only driven about 10 miles since getting rid of the synthetic fluid and switch to type F. So far so good. If you've been running synthetic in yours for 10 years now, I'm assuming you haven't had any issues with it in your trans? I don't have an informed opinion either way and have to base my decisions on what I've heard/read from others. I heard that synthetic wasn't recommended for the TH350's and being that it was a fresh rebuild, I didn't want to risk any damage. That's when I started reading about others using Type F and decided to use that instead.