I'm having a problem with my 292 Chevy. After warming up, it misfires while holding a speed on level ground, when I accelerate, the miss goes away and it pulls very strong, level out at speed and the miss comes back and gets worse. Some info , the engine has about 3000 miles since a rebuild, it has a very small comp cam, offy 4 barrel intake, Clifford headers and points distributor. Everything ran fine until a couple months ago. any help would be greatly appreciated.
Installed a new condenser, did not fix the problem, in fact it's misfiring more, not because of the new condenser. the miss has escalated now at low RPM , accelerating and holding speed. smooths out at higher RPM. Might not be electrical, but maybe dirt in the carb.Any suggestions?
Still sounds like ignition to me.
Are you saying it is missing at all conditions?
Any noises?
Maybe check compression.
Vacuum leak on manifold or carb base? Vacuum advance? Cracked distributer cap. Coil? Bad plug wire? Point gap?
Sticky valve?
I agree with most of what Beater said ,I'd also look very closely at the inside of the cap and the rotor for cracks Or Cross arching in the cap. I think a lean out would more at the higher rpm then at low. You can check the carb for dirt as you may think it being a issue, it can't hurt to look. You may also want to check the Valve lash. With the Up grade on the cam their could be???? a slit chance your pulling on the press in studs and loosing valve adjustment?? If you did not change over to screw in studs.
This is what I have checked, vacuum advance is good, removed vacuum line at carb and used my vacuum pump. cap and rotor have no cracks flash points, pulled the plugs, all are of good color and uniformly. I did pull the valve cover and no problems with valve lash. I rattled the PCV valve to make sure it's free.Unless somebody has any other ideas, it's back to the carb. my thoughts are if the only times it doesn't misfire is at idle and hard acceleration, then it points to the primary (low speed) circuit in the carb. I have to finish a small project and then I will work on carb and let you know if the problem is solved...Thanks for all the help
In my experience, if more throttle always makes it worse, it's electrical.
If it "cleans up" at some point, it's fuel delivery.
Yep, seams logical to me, will let you know after I clean up the carb
found a lot of black flakes in carb bowl,went right through glass in-line fuel filter(worthless). Cleaned carb twice, because of e-15 fuel, went 2 steps rich on carb. Still runs bad. Checked fuel pressure again, 5-6 lbs , doesn�t look like I�m getting enough volume . Back in �97 when I restored the truck, I used a fuel tank sealer , been told the old sealers don�t hold up to ethanol and can break down and clog fuel systems so going to clean or replace tank,clean lines and replace fuel pump. Not going to be able to work on it until first of year. Hope it works
E fuels are hard on many things. I hope you get things all cleaned up on the low-cost side of things and back on the road.
Keep us updated.
Finally thawed out,got back to work on truck, gas tank was rusty, bought new tank, installed electric fuel pump, cleaned lines, engine has occasional miss from 2500 rpm up. About to give up on points distributor, has anybody had any experience with the cheaper HEI distributor like TSP or am I better off using a pertronix ls igniter. I would prefer to use HEI because it�s all in one unit, I know clearance is problem, but you don�t need to move the distributor much for timing.
My preference is a HEI over a pertronics kit. The P kit is like putting makeup on a PIG. The point advance unit is very hard to adjust and probably worn.
Have used of these recently and like them.
https://www.12bolt.com/store/p574/Distributor_New_Small_Cap_194-230-250-292.html
Thanks for the link, I was hoping to spend a little less money, Langdon has one, a rebuilt off a 216 Pontiac, also JDM speed, with so so reviews. Has any body tried those?
I have NEVER been totally let down by a points setup. I have had to dig into my under seat & glove box stash for a coil or condenser. HEI side? I've walked home or called for help a few times even with a new module in the glove box. Pertronix & Mallory Unilite let me down but only once with a GM HEI. I carry a complete distributer under the seat along with other likely to fail-hard to find parts for my 270 GMC. Points might take a bit more attention.
I found out that �78-�80 292 chevy�s used a HEI distributor, that are reasonably priced and should fit. They have three wires, red,yellow,black coming out from the distributor and going into a two prong plug. Do you know what these wires should be hooked to. Also would this be a good distributor. Trying to keep the prices down�retired and in my late 70�s
Hi, hope this reply is helpful. Those later HEI distributors have the coil on the distributor cap. That 3-wire, 2-prong plug plugs in to that coil. I've been using one in my truck for years. First one was a junkyard pull, worked, but took slow-me awhile to recognize that the centrifugal weights were partly frozen; I thought at first it was just a weird smog-era advance curve. Bought a new aftermarket one a while ago - I think these are a one part-number fits all, so could probably use some advance curve tuning, but works well enough for now. Nice not having to replace and adjust points. If you go this route, you'll need a full 12 volt supply (the stock ignition supply has a resistor). You may need more initial timing advance as well. Good luck!