Man my mechanic ability must have gone out with the Trash...I have been over the firing order at least a half dozen times. It wants to Idle fine..But It is backfiring on the side that has 2,4,6,8 cyclinders. Could I posssible have a valve to tight? Please Help me before I throw in the Towel..Lol...Thanks, Scot
They are on all the small blocks I have had,run the valves,also are you running a single or dual plane intake?
Motor has less than 500 miles on it. Ran fine before..Just put roller rockers on it and a new high performance HEI...I know it is something simple..I am missing something? I did the TDC thing then located #1 on rotor...Then on to then firing order 1-8-4-3-6-5-7-2...And by the Way 2468 are on one side of the Motor 1357 are on the drivers side 2468 are on the passenger side. I am having a little problem...I am not completely Stupid...Lol
If the valves are right,then check your connection in the new cap,sometimes they don't snap in all the way
X2, also check the timing advance with a timing light, both mechanical and vac to make sure they are both working like they should.
That's what I am thinking..I bet I will have to take the Valve covers off tomorrow and go through all of the valves and check the push rods and re-adjust the 1/4 turn on the rockers.
Assuming you have a backfire out the exhaust. Check plugs again. Look for cracked insulators around the electrode on the threaded end. Look for a plug wire acring out to ground. Was it HEI before? What brand is the new one? Check inside the cap, and the rotor. Be sure you have 12 + volts at the distributor. I had a backfire problem once that drove me crazy. It turned out to be a hairline crack in a spark plug insulator.My old ass eyes couldn't see it without a magnifying glass. Like the others said check your valve adjustment again. If it starts and idles ok, then the ignition timing is close. If it ran ok before check what you changed and remember that new doesn't always mean good. Keep us posted
Check the valves and pull the dist. try re-stabbing it it could be a couple teeth off, or maybe 180 degrees out!
For what it's worth this is my thought also. I actually had this happen on a dodge 318(same firing order and cylinder orientation as SBC). It was retarded too much. Everytime I would hit the throttle it would cough and backfire.
It would not run at all if the ignition timing was 180 out, and most likely blowing giant fireballs out of the carb. As long as the engine was with #1 cylinder @ TDC and the rotor was pointing close to #1 on the cap the ignition timing is close enough to run.
I will suggest valves .One of them is not closing tight.When that cylinder fires,,bang.Ether out the tailpipe of into the intake manifold.
start with the vacuum gage, it's easy, then the timing light. if the needle bounces then go for the valve covers, if it doesn't but the reading is low, turn the distributor till the vacuum comes up. then try it.
Good advice. I'd say it is probably a tight valve or maybe the distributor a tooth off (advanced). See how the timing marks line up with the timing light on it. Bob
Ok Guys...Here is the Verdict...Who would have thought that a push rod could collapse...I took all the push rods out on the 2,4,6,8 side..Found a piece of the ball end of the push rod broke off up inside the roller rocker ball pocket...I guess for one thing I could say I am lucky that the pieces stayed in tack..At least they did not fall down in the motor..Off to get another push rod...I think this will take care of the matter...Thanks for the Help Gentlemen... Happy Here...Scot
Put the old distributer back in and try it again. A little history here. A friend brought me his small block powered car when his mechanic couldn't figure out what was wrong with it. fresh engine built by a fella with good reputation. If backfired and poped through the carb etc. I checked the firing order several times. Called the builder and quized him, wanted to make sure it didn't have a 4/7 switch. Nope everything checked out just fine. the car had a brand new Accel hei, that I pulled and took to the local distributer shop. It checked out just fine. I ran the valves, frustrated I pulled the dizzy again. took it to a different shop and it checked out just fine. Finally after pulling my hair out for at least a week, I grabbed a distributer off the shelf in my garage and dropped it in. Ran like a top. Took the accell to the band saw and the fella picked up a Mallory HEI and lived happy every after.
Glad you found the likely problem. I really get a chuckle out of the "distributor 180 degrees out" comments on any thread where there is a question regarding an engine that runs, but has suspect timing problems. I think Ryan should add rule #7 to his list in the new members "Read This First" sticky. Rules: 1. No profanity in subject lines 2. No political/religious/racial posts 3. No Porn. 4. All personal information listed on this board is private and protected. The HAMB does not sell this information and you are not privy to use it for your own reasons. Test us on this one and we will bite. 5. New Users must fill out thier profiles. Every bit that you can. Simply click on "User Cp" above and get to work. 6. New users must introduce themselves in the intro forum. 7. An engine will NOT run if the distributor is installed 180 degrees out. Guidelines: 1. If in doubt, don’t post it 2. Stay on-topic and relevant with your posts… OT posts aren’t generally appreciated by our membership. 3. Gotta easy question? Try using the search function first. 4. Your life here would probably be easier if you complete your profile and introduce yourself before jumping into the deep end...
There is a reason that the push rod broke/collapsed like that . Since you installed a new roller cam , did you make sure the push rods are the correct length ? Also if you have one bad push rod I would be checking ALL the other push rods as well . Honestly anytime I change a cam to a bigger one and change the rocker arms , I ALWAYS install new push rods ! As cheap as they are it isn't worth the trouble of using old push rods in a newly build engine . That just doesn't make since . Also do like Porknbeaner said and Double Check that distributor and timing ! That also might be why you damaged a push rod ! It only take 2 mins to pull a distributor and bring up to TDC and drop it back in . Also back off ALL the rocker on that bank just in case they are too tight . That will cover the idea that the rockers are too tight . A little tapping isn't going to hurt the valves that fast until you adjust them . Did you adjust the rockers with the engine running or not running ? Retro Jim
I have to agree with you on that one . 7. An engine will NOT run if the distributor is installed 180 degrees out. If it's out 180 degrees , You will more than likely set the insulation under the hood on fire or you will not have to worry about trimming your eyebrows for a good while ! Now I guess you know who NOT to take your engine to for work ! Retro Jim
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