Chevy Nova Forum banner

1 - 13 of 13 Posts

·
Registered
Joined
·
139 Posts
Discussion Starter #1
well i ended up with a scared feeling, my car is not doing so hot she is running rough and backfireing through the exhaust when the engine is under load as soon as i put it in gear and let it sit idle will just sounds weird popping out at the exhaust and rough hoping it is not the cam can any one that has had this happen help me out or had any one with experiance
 

·
Registered
Joined
·
265 Posts
honestly there is no way to tell if you have a cam issue right away like magic.. it will take some investigation.

start by pulling plugs.. plugs tell a ton about how healthy the motor is and will help you diagnose where the problems lie.

also.. we need more info.. did you install the cam? Did you break it in according to manufacturers specs? Did you use a zddp additive?

If all else fails... pull valve covers and yank the power from distributer ( so thengine doesnt fire) and look at the valves while someone cranks the motor over. If you see a valve not opening and closing thats your culprit.

could be a valve needing adjustment, flat lobe.. collapsed lifter..etc..

thats a starting point for you.
 

·
Registered
Joined
·
139 Posts
Discussion Starter #3
Stock 355 chevy jasper not sure of cam stock im sure the got the car this way not sure when il get the chance to do any tests tommarow hoping no rain
 

·
Registered
Joined
·
265 Posts
My experience has always been hit or miss with jasper engines. If its a stock 355 just replacing it with a mild grind and a double rolling chain isnt a bad way to wake that motor up.

Engines built on a production line do not have the attention paid to them like a custom one off or a motor built in your garage.. by you. Assembly lines tend to have "... its a monday" issues.

Follow the steps above, it could be a bad plug or wire... even the possibility of a rocker stud pulling out or a valve adjustment. Plan for the worst and hope for the best. Be patient and methodical and take each step. Youll find it.. youll fix it, you'll have pride in it I swear.
 

·
Registered
Joined
·
139 Posts
Discussion Starter #5
well got in the engine compartment to listen to it but even with car under load in gear under the hood all you hear is the belts no ticking but by the driver side door you can hear it thinking more exhaust problems but i may take valve covers off any way to check for sure like i said had no time lateley to do any thing will keep you posted
 

·
Registered
Joined
·
155 Posts
Ok auto mechanics 101...:) you say your car is "running rough" does it have dead miss? If it is missing (running rough) you need to isolate the miss to which cylinder it is. With the car running at idle, carefully (insulated spark plug pliers help) pull off and replace the plug wires one by one. You should hear the engine start running rougher or at least change as you pull off each plug wire. It should smooth back out as you place wire back on the plug. The one that doesnt change the engine sound..... there is your miss. Now things that can cause that range from a bad plug wire to a flat lobe on the cam. I was always taught "when your hear hoofbeats behind you, think of horses not zebras" While it is POSSIBLE you have a cam issue id rule out everything else b4 i started ripping into a cam change... just my opinion, what are you guys thinking?.. good luck :)
 

·
Registered
Joined
·
160 Posts
Check your timing.

Do the spark plug test, Pull the cap off and just fiscally look/check everything over real good.

As for the tick it could be a loose rocker arm but most likely if you have headers it's probably them.
 

·
Registered
Joined
·
139 Posts
Discussion Starter #8
Took off valve cover and watched the rockers with it running all were good all pushrods spibning like they should but did have crappy valve covers as near the valve cover rail on the intake was wet with oil had some ol stock ones I put on and also no baffle in the pcv area I was sucking oil in but funny thing my oil keeps reading past full on the dipstick kind of weird if you ask me
 

·
Registered
Joined
·
265 Posts
by the way there is an easy old school trick that is cheap and works well for adjusting and or just checking valves. Just take a pair of stock crappy sbc covers and cut the center out of the top. Then plop it on there and fire it up... you can see all the rockers and make adjustments without the smokey oily mess!:eek::eek::eek:

check your base timing in 2 ways. first use a timing light with the advance unplugged. Second, you can use a vacuum gauge and just adjust it till you see the vacuum hit its highest steady point then make tiny adjustments from there.

Personally, and It may be unfathomable to some people but I can get real close just by an "ear tune" cause I have built so damn many sbc's. After wards Ill double check with a timing light and Im almost always within 1-2 degrees. That comes from a LOT of shop time...lol
 

·
Registered
Joined
·
139 Posts
Discussion Starter #10
im always at 20 on vac and still need to get that dizzy fixed up so the vac advance canister wont hit the intake runner so i can get timing in better but also im running rich all the time i can always smell gas with it running or off checked for leaks no leaks the smell is coming from the carb now i have heard that carbs like to be around 4 to 5 psi fuel pressure im running around 8 to 9 psi with the stock pump i am thinking of getting a fuel pressure regulator is this a good idea
 

·
Registered
Joined
·
265 Posts
6 psi is the magic number for carbs I have found... more than that you blow past the needle and seats and run the risk of not only damaging your carb but also the engine itself. Use an inline regulator to get it down to about 6 psi and your golden.

also to get your dizzy turned back without pulling it... simply loosen the bolt and turn the dizzy back toward the driver side.. then take each plug wire on top of the cap and move them over one post, clockwise, one at a time... thus you have all the firing order right and your dizzy is turned and you keep your timing close to where it was so you can finish fine tuning from there.

good luck and toss some pics for us!!!
 

·
Registered
Joined
·
139 Posts
Discussion Starter #12
I will try if I can figure out how to get em from my phone to my computer and also have you had to run any regulators with stock pump
 

·
Registered
Joined
·
265 Posts
i did actually run a regulator on a carb set up i had a few years back.... but it was a 13 psi edelbrock racing hi po fuel pump and a halley carb.... ran richer than a pig till i dropped her down to 6-7 psi with a regulator and a jetting change.
 
1 - 13 of 13 Posts
Top