[70ss396_kid]

hey guys, I just picked up a 64 nova wagon a couple weeks ago and its giving me fits. it has been swapped to a 350/th350.

When I bought it it ran ok, there were a few issues and it bogged when I stepped on it (q-jet, power piston was bad). I figured I'd do a tune up, but have had problems since.

I replaced the carb with a reman from autozone (i tried to rebuild the old one first but it was warped and wouldn't seal). I also replaced the plugs/wires/cap/rotor, fuel filter, and replaced a stuck open thermostat.

In park it idles pretty smooth, rpm wanders maybe 100 rpm but sticks close to 1100. When I put it in drive it drops to 600rpm and runs noticably rougher. Theres a small pop through the exhaust at idle in gear maybe once every 15-20sec. I figure this is just because of it being rich but I could be wrong. I tried adjusting the idle screws but I really can't get a feel of what the car wants as I'm pretty inexperienced. They are basically set at 2 full turns out from bottom. Also 1100rpm in park to 600 in drive seems like a big drop, am I right?

the main issue is a miss/pop through the carb under part throttle and through the exhaust too. Not once, but several times and as long as its under part throttle. Also If I step on it it doesnt pop, but the power surges. This is all based on a short test drive around the block. I didn't want to drive it too much incase something was really wrong.

I set the timing at 8* btdc at 1100rpm, plugs are gapped at .035. My dwell is at 20. Idle is 1100 in park, 600 in drive. Water temp is 190. Vac advance doesn't seem to work, how do I test it? Its just unplugged while I'm troubleshooting.

any ideas? could the carb just be really out of whack because of the altitude? The car didn't have any popping or driveability problems before I screwed with it, but it was also running at 100* because of the thermostat. I don't know if that has something to do with it or not. For the plugs I just referenced a 70 camaro 350 4bbl, could they be wrong? The threads were slightly longer than the ones I took out. I didn't get a number to cross reference off the old plugs before I tossed them like an idiot.

I don't know much about the engine. Its a 350, the qjet was off a 70 camaro, performer intake, ram horn exhaust manifolds and it has double hump heads (didn't cross check the #s). Cam and compression are a mystery but it isn't lopey or anything.

sorry bout the long post, but I've been fighting this for a couple weeks. If I can't make any headroom this weekend I'll probably take it to a mechanic next week and let them sort it out.

 

[Jim Mac]

I would eliminate the obvious first. number one I would make sure your firing order is correct. When you timed your motor, did you pull the vacuum adv hose off then set the timing? Did you set your dwell first then adjust the timing? if you did the timing first and adjust the dwell, you will change the timing. Are the heads the old style camel humps that take the 13/16 plugs? If not sure you might want to check. Check for vacuum leaks. spray some carb cleaner around the base of the carb, and anyplace else that the motor pulls a vacuum. Good luck. Jim

 

[Jim Mac]

Just looking at your post again. You did mean your points are set at .020 and your dwell is at 28-32 degrees correct? Jim

 

[BigFred66]

As Jim said...dwell should be 28-32 degrees.
Did the plugs that came out of the engine require a 5/8 or 13/16 socket?

13/16 = plug w/sealing gasket>>>>>> AC #R45S would be a good choice
5/8 = plug with "tapered" seat/no gasket(there are some 5/8 gasketed plugs,but not correct for an older Chev V8,threads are WAY too long!)) AC #R44T would be a good choice.
Re-check firing order.

 

[ToyzRMe]

Double check that #5 and #7 plug wires are not crossed. It's real easy to miss this.

Randy

 

[Steve Blok]

The dwell needs to be set at 30 . Im sure that is most of the problem. Take your time and set the dwell and slow the idle down to 600 or so and double check your dwell. Then set your timing. Now try to adjust your idle mixture you should be able to do it with the engine idleing slower. Try setting the idle to around 750 or so in nuetral. Now put it in gear and see what it will idle at. If it is just a plain stock 350 you should be able to make it idle smoothly at 600 rpms in gear.

 

[70ss396_kid]

the plugs are 13/16 just like I pulled out. The difference is the new ones have maybe 1/8" more thread. No interference problems though. Firing order is 18436572.

I reset the dwell to 30... it was 20. The popping out the exhaust at idle is gone. I had to re-adjust to 12* btdc at idle. It doesn't act real happy with any less.

I found another source of problems though. The #2 cyl. seems to have a random missfire. Possibly why the power was surging at full throttle on the last test drive? Maybe this is responsible for the big RPM difference between park and drive? At high idle it seems ok and it runs smooth (1000 or higher).

In drive it starts to missfire, and that i think is why its rough and hunting for idle a bit. When I pull the plug wire its not a constant/immediate rpm drop like it is when I pull one off the driver side bank.

I didn't drive it but it seems real responsive and sounds good when I goose it. In park (900-1000) it seems to be real smooth and sounds better. Just in drive its shudders and doesn't sound real even.

after it cools off I'm going to pull the #2 plug and inspect it. What should I look for?

thanks a million guys, I'm pretty novice at this stuff and this is my first SBC.

 

[charbilly2001]

Double check that #5 and #7 plug wires are not crossed. It's real easy to miss this.

Randy

Nope. Its exactly the opposite. Reason it out. #5&7 are the only two cylinders that fire in sequence AND are physically adjacent to each other. When #5 is firing #7 is just completing its intake stroke. If the plug wires are crossed the magnetic field collapsing around #5 doesn't get much interface with the #7 wire. If, however, the #7 and #5 wires run parallel to each other for a distance then the field collapsing around the #5 wire will also induce voltage in the #7 wire and that can cause a weak spark across the #7 plug and fire the uncompressed intake charge in #7.

Having said all that I haven't heard of that happening since copper core wires disappeared in the 60's. Now-a-days its no more than an old wives tale. Much like 70 LS6's and Dana rear ends.

 

[70ss396_kid]

ok, now I really don't know what happened.

I pulled the #2 plug, it looked new. so I cleaned it anyway and re-installed it. The car ran like a million bucks. I drove it for probably 10 min or so around the neighborhood without any issues. The choke worked great and came up to temp just fine. I was so freakin happy.

well in the process of troubleshooting I found the throttle linkage was opening the carb only about half way. Well I stepped on it to see how fast this little wagon really is at full throttle. Its fast enough to lay a little rubber, and scoots pretty good. I let off after it went into second and the car died.

I pulled over and it wouldn't start. It does start if I give it some throttle and keep the RPMs up.

Now its missing out big-time, and barely runs. I have to give it a good amount of throttle just to keep it running. It doesnt idle and it wont run unless my foot is in the gas. What the *&%^!!!! It doesn't make any bad noises, and I didn't hear anything when I was nailing it before it died. It will run at a lower RPM if I constantly pump the throttle. If I keep my foot in one posistion it will stumble/missfire and slow down untill it dies.

The car did sit for a while before I bought it. Could the sloshing fuel have stirred up some junk? I haven't put gas in it since I bought it, and its down to about 1/4 tank now.

Ugh, I'm starting to hate this car.

 

[charbilly2001]

sounds like you might have a sizable vacuum leak.

With respect to fuel sloshing and stirring things up in the tank if thats happening and it has plugged your fuel filter I would think that idling would be easier to obtain than high speeds due to fuel starvation.

 

[Jim Mac]

Again check the simple stuff first, you said you set the timing, is it possible that you didn't completely tighted down the distributor? did you leave the rotor loose? (ive done that). Try those first. Jim

 

[ToyzRMe]

Nope. Its exactly the opposite. Reason it out. #5&7 are the only two cylinders that fire in sequence AND are physically adjacent to each other. When #5 is firing #7 is just completing its intake stroke. If the plug wires are crossed the magnetic field collapsing around #5 doesn't get much interface with the #7 wire. If, however, the #7 and #5 wires run parallel to each other for a distance then the field collapsing around the #5 wire will also induce voltage in the #7 wire and that can cause a weak spark across the #7 plug and fire the uncompressed intake charge in #7.

Having said all that I haven't heard of that happening since copper core wires disappeared in the 60's. Now-a-days its no more than an old wives tale. Much like 70 LS6's and Dana rear ends.

I DID NOT mean crossed, as in routed crossed. I meant that it's easy to connect #5 and #7 to their incorrect cylinders since they are adjacent in the cap and in the engine. If the wires are routed in a bundle,and you're not paying close attention, it can happen. Novices (and sometimes experienced guys in a hurry) do this often.

As far as crossfiring being an old wives tale, I have a flyweight small block sprint car piston sitting on my desk with major meltage of the top ring land and a large hole in the top that would beg to differ with you. This happened on the dyno and NOT with solid core wires. And, YES, it was definitely from ignition impulse-induced crossfire at full load at 8000+ rpms.


Randy

 

[70ss396_kid]

well I found the problem. The butterflies above the secondaries were stuck open. I opened them by hand a bunch of times and they stuck open several times. I guess this carbs going back for an exchange.

The idle is out of control too, and the idle screw backed all the way out. 1200-1400rpm. The throttle linkage doesn't go all the way back to the stop even when the fast idle cam is off, but I don't know if thats normal or not. I don't know if its the carb or a vaccum leak, but I guess I'll be able to narrow it down when I get a new carb on there. I did spray starting fluid all around the manifold, and plugged all vaccum ports, but I didn't get any real results. Somethings amiss though.

Thanks for the help guys, I'm learning as I go. I'll let you know how it goes when I get a new carb on there. Geeze, I thought these things were simple! :clonk:

 

[dreinecke]

Get rid of the reman'd carb and pick up an Edelbrock. Very easy to setup, won't screw around with you. A little more pricey, but should work well for you.

 

[70ss396_kid]

well I got the new carb on there. Works great. Apparently alot of the problems were from a junk carb. Now it idles just fine at 800 in park, 600 in drive, nice and smooth. Its rich, but I expected that at this altitude. Drove well and makes good power... ALOT more than I thought it had when I bought the car (due to the linkage not fully opening the carb).

It does load up a bit after hard acceleration, but clears up with a tap of the throttle. I think it just needs tuned. I'll probably let a pro dial it in since I'm not real confident in my tuning skills.

I really gotta thank you guys for helping. This car was driving me freakin nuts for the last couple weeks and I wasn't making any progress, getting really really frustrated and beginning to think I had gotten myself in way over my head. I owe you all a cold one :beers:

 

[dreinecke]

Just took a look at your site - the Chevelle is gorgeous! One of the places the Rocky Mtn. Chevelle Club has gone is the Carb Shop in Denver. They tune and dyno. Might help you get the rest of it dialed in.

Also, we're meeting in Castle Rock on the 21st and touring Legendary Motorcar there. If you're interested, send me a message.

 

[70ss396_kid]

I looked at the carb shop website... definately looks like they are the ones to take it too. Thanks for the reccomendation and the compliment!

My dad's b-day is the 21st so no can do. Do you guys have event schedule posted somewhere?

 

[dreinecke]

No problem, hopefully we'll get to meet you soon. The club website is: http://www.chevelles.net/rmcc/ There is a link with the calendar of events on it.

BTW, we do run an ACES Chevelle Regional in August!