I didn't notice any difference?!!?!?! My car is running so rough, that when i took a plug out to read, i forgot to put the wire back on and took the car for a drive shifting hard, sitting at stop lights...yet i didn't even notice anything. What does this tell me??? I know my engine isn't running right, but damn! I need help in all ways.

 

How old are your plugs and wires? I found that my daughter's Acura was running so poorly. A simple wire and plug change and it ran like a scalded ape. If you don't know the history of this car as it relates to tuneup intervals, I would start there. If you still have a rough running engine, then a compression check would be in order.

Gary

 

plugs are 2 weeks old..wires are about 6 months...things are fairly new...your right, i really need to breakdown and do a compression check.

 

You should take that motor to someone local that knows how to tune and setup a small block chevy preferrably with a chassis dyno, you spent enough already a couple of hundred more will be money well spent

 

Gary,

Not sure if I've ever heard this expression before. Quite a good mental picture.

Redshark,

Not surprising at all. Before replacing my heads, I had one exhaust valve so badly burned that the cylinder had no compression. It didn't run great, but it still ran at highway speed.

I remember using an engine analyzer that allowed you to shut of the spark to any number of cylinders. On a well tuned 350, I remember that it would still run for a short time with 4 turned off.

 

there is no one around local is the thing....
i'm just going to borrow a compression tester and find out for myself.

burned exhaust valve is my fear..but what causes it?? thanks for advice guys.

 

That was always an old mechanic's trick. For a motor that seemed to be missing, pull one wire at a time and see if the motor idled worse. When you pulled a wire and got no change you were reasonably certain that the problem lied with that cylinder.

 

i accidentally left the wire off...i didn't mean to, so i don't know if that cylinder was narrowed down to the miss, however, the plug looked like it had been firing.

 

I'd make sure the plug wires aren't crossed as well. You said the plugs are two weeks old so maybe wires got crossed, not hard to do. BTW stock firing order is 18436572. I would check this first. Then as mentioned above make sure the wire then the plug are firing. I would definitely look at the simple things before looking for burnt valves and such.

ltlevil

 

my dad started an engine once with only 1 side of the engine hooked up. i think it was a 305(?) .

 

I did this on my current setup and did notice it running a little rough but only found it after tracing the wires out. Made me feel kind of silly after discovering my mistake. Shiz happens.

 

Using wire shields? Just 1 more concern but tiny grounds can happen in no time if wires are cooked by headers.
Had a brand new Chevy PU once with 350 that i tuned-up myself the first schedule. Used the wrong tool to remove the plug boots and started having misses that grew worse. Under warrenty took the truck in to dealer and they found the bad boots/wires in 1 day - tiny holes cut by my Lesle boot removal tool. How they found the grounds/cuts? I really don't know but suspect they monitor all 8 cyls on a big scope and can see misfires somehow - maybe a ground short spark looks different than a plugs spark?
Also wires too close and running parrallel can misfire - #5 & #7 are next to each other in the firing order and one will induce a spark in the other too soon. Smokey said 1/2" min spread between wires and cross at 90* where possible.
Suspect more like a ign/spark problem since i know that mtr is brand new. Did it just start to run bad or has it been this way since start up?

Well hang in there Red. I'm kind'a teed with my lifter noise and suspect the rocker arm lock nuts. Found my #3exh and #5intk rocker arms loose after cam break in. Installed back-up nuts on top of the brand new CompCams nuts, adjusted vlvs for the 3rd time and now the lifter/tappit noise is on the p-side/bank.
I'm praying the cam isn't wiped. cardo0

 

Thanks Cardo, my plug wires are parallel, and yes the problem just occured...heres a symptom. When i hook my vacuum line up to go to all my main vacuum system for the wipers and headlights..the wiper doors and headlights try to barely open. I have that plugged off now, and suspect a vacuum leak, but have no idea where. I"ll check on the wires tomorrow...the problem occured out of nowhere. Sucks about your cam..hopefully its not the lobes. thats such a fear.

 

Well that may not be much of a symptom as a larger cam produces less vac. Vac gauges are cheap and very easy to use - just connect to a manifold tee and read. I forgot but i think u need 12-13" vac to operate accessories. Any ways if u plug them off and take a reading should be same as hooked up but if the roughness returns when u reconnect access u would have a vac leak outside engine. For a bad leak inside eng they don't normaly start them selfs - i mean a intk leak would make rough running on start-up not just appear later.
Rough running out a nowhwere really sounds like a burnt plug-boot too close to a header.

Ya i hope my cam is okay and my Crane new rocker nuts may be the cure. But i'm soo happy with the rest of the car. lars rebuilt my carb chokeless and it runs great without any adjustment, not even the idle mixture screws - just bolted on. I just hold 1200 rpm for 30sec to w/u and it idles fine all day. Cooling system now works great too. All my rebuilt gauges track fantastic, getting 6-9psi fuel press reading from the cockpit gauge panel and my temp guage climbs to 200*F then stays there like a rock.

Hey post ur cam duration and c.r. so i can look up what ur vac should read at idle. I have an old D. Vizard graph that has worked before to estimate vac. This might help identify a major vac leak.
cardo0

 

It only takes a minute to melt a spark plug wire on the headers. That happened on my engine while it was on the dyno at the machine shop! then very recently a boot melted on the #3 wire causing it to run like crap. I wasted a lot of money replacing other stuff 'til I found the real problem. At last I have a pretty new MSD distributor now

I wrapped the the new wires in an adhesive heat sheild plus added Accel boot protectors in hopes that the plug wires will stay in tact.

~Jay

 

I'll check my plugs carefully to see if theres a problem there.

cardo, my cam specs are
Duration at 050 inch Lift: 240 int./246 exh.
Advertised Duration: 284 int./296 exh.
Valve Lift with 1.6 Rocker Arm Ratio: 0.541 int./0.544 exh. lift
Lobe Separation (degrees): 110

Final compression 10.1:1

 

On the D. Vizard graphs i can only approximate but would u have less than 12" (10.5cr) vac but at least 11" (9.0cr) vac. Thats with 70* overlap. And that really is the top end for a street cam and still have steet manners.

Some times u can see the grounded wire spark at night when u open the hood. Maybe idle inside the garage at night with the door open of course and have a look for sparks at the boots.

cardo0

 

Thanks for the help Cardo! Let me know how your engine runs after you get things sorted out.