Broke In Cam Now Popping Sound [Archive]

toofun

06-06-2005, 04:47 AM

I have a 350 goodwrench motor. I recently copied the goodwrench quest power combo and used a 268 xe cam, 1.6 magnum roller rockers, airgap rpm manifold and trick flow 23 degree heads. I used the recommended comp cam springs and push rods for my application. Bolted it all together, removed the inner springs on the valve springs so I could break in the cam, set the valves and fired it up and broke in the cam. It idles great but when I raise the RPMS to set the total timing, it would pop and backfire. When I shut it down and tried to restart it, it was very hard to get it to start.

If I let it sit for about 20 minutes It would fire back up again without hesitation but as soon as it warmed up and you try to set the total timing same thing would happen. When I set the valve lash on the rockers(hydraulic) I tightened them until I could still twist the pushrod back and forth with my fingers lightly and then 1/2 turn more per the instructions. My buddy says that the reason for this problem is that when the engine is cold the lifters are not pumped up so it starts right up but when the engine is warmed up the lifters are pumped up and expanding so when you increase the rpms the valves are set too tight. He recommends setting the valves looser and let them tick and set them while the engine is running. Could this be the problem? I have checked the #1 position and reset the distributer and it is dead on correct. I also have the vaccuum advance hose connected. Could it be valve float due to the second spring not being installed? I plan on putting the second spring back in first since the cam is already broken in.

Sorry for the long post but really want to give as much info as I can with this post so I can narrow down the variables. ANY INFO WOULD BE GREATLY APPRECIATED. Fine Tuning has never been my forte so Ill leave it up to you experts to chime in.
Thanks in advance

Mark
TOOFUN

68protouring454

06-06-2005, 05:06 AM

sounds like you go ttoo much inital timing along with total, retard it some and see, that is usually what happens when there is too much timing, stater will not crank motor over, but when its cold it will, also like your buddy says, check valave adjustment again when its at operating temp, and adjust, but i would look at the timing, sounds like you got to much
goodluck
jake

toofun

06-06-2005, 05:15 AM

Thanks for the info. When I try to retard the timing the car will not start at all. It turns over like a dead dog no signs of wanting to start at all.

68protouring454

06-06-2005, 06:02 AM

how hot is engine getting?? the valves may give you popping, i would there i read your problem wrong i thought it sid it was hard to turn over when hot, so it turns over normally just will not fire, sounds like loose clearences on the valvs
jake

CAMAROBOY69

06-06-2005, 06:12 AM

Travis B

06-06-2005, 07:35 AM

Put the springs back in it and relash the valves....I hate setting them running I always roll the engine on tdc for each cylinder and twist the push rod until it just starts to drag and tighten in there if you aren't comfortable with that do 1/4 turn! Better to be a little to loose than to tight!

toofun

06-06-2005, 08:42 AM

So Travis,

Do you think the reason I am getting that has something to do with the fact that I am only running the single spring at the moment? Or is it a combo of both the spring and the initial setting?

chicane67

06-06-2005, 10:49 AM

This sounds wayy tooo familiar. This recently happened to me when installed my head and didnt have my rocker arms adjusted properly. Thats where I would start. Ive learned its better to have them too loose than too tight.

I gonna have to second this one. The heads will need to be retorqued after the initial break in AND the rockers will need to be relashed, when the engine is at operating temperature. If the lash is too tight, the valves wont seat long enough and you end up burning an exhaust valve.

Ask me how I know..... ?? Cuz it's been done before, trying to get a few more ponies by 'tight lashing' the cam at the track !! I cooked more than one exhaust valve that day..... but it ran killer. BTW, the way to check for this condition is to pull the PCV valve from the cover and place your thumb over the PCV's hole..... and you will get the same backfire.

Basically, just recheck the timing for-sure, re-torque the heads and re-lash the valves just to cover all the bases.

yody

06-06-2005, 08:33 PM

Heres what i say;
for one, you need to put the inner valve springs back in after cam break in, this could cause the motor to pop etc at higher rpm. Also you need to disconnect the vacuum advance when timing the motor, also when setting the valves, you need to turn the adjustment nut until you can't shake the pushrod up and down anymore, NOT by turning the pushrod. Wiggle it up and down , as soon as it won't wiggle up and down then give it a half turn. YOu could easily have the valves too tight which would definelty cause it to pop. Reset the timing with the advance tube disconnected and then readjust the valves.

toofun

06-07-2005, 03:13 AM

OK,

Two questions? I am assuming when I disconnect the vacuum advance tube I should plug both the tube to the carb and the canister?

Second question, why disconnect it? If I set the total timing to 36 degrees wouldnt the vacuum advance pull it past that once connected again? I guess what Im asking is what is the thinking behind disconnecting and plugging it?

Thanks
Mark
TOOFUN

toofun

06-07-2005, 03:27 AM

Thanks for all of the info guys. I guess no matter what you read or think you know there is always alot more to learn. That is why I love working on these cars. I always learn something new all the time.(SOMETIMES THE HARD WAY UNFORTUNATELY LOL) I stripped off the covers, and loosened the lock nuts. On the valves that were completely closed I could see the lifter pushing the rod up as I loosened it so they definately were too tight. I usually pre soak the lifters in oil, then install them, put the rockers on and tighten it until I have no up and down movement, then I turn it another 1/2 turn.

But I always did this with the motor not warmed up. It has always been cold or a new rebuild. I guess like Bill said it is easy to have the lifter plunge down when it is new. I hear the lifters when new are in a NEUTRAL POSITION. So here is what I am going to do. I am going to retorq the heads, then install the rockers back on. I am going to take up the slack going up and down and turn the nut 1/8 of a turn. Then I am going to install the valve covers( I am buying new valve covers anyways so I am cutting the tops of these) Start the motor and after it warms up for about 10 minutes I am gonna adjust the valves while it is idleing. I know it can be messy but I am hoping with the valve covers on and just the nuts exposed it should eliminate a huge mess. This seems like the best way to go since with the engine running the lifters are pumped up so no false readings can throw me off.

Just hope I didnt damage anything during breaking in the cam. All of the pushrods are good. I pulled them out and table rolled them. Do you think I damaged anything?

Thanks
Mark
TOOFUN

CAMAROBOY69

06-07-2005, 04:06 AM

Im glad my advice worked. :) This just happened to me so I was quite certain it was over tightened rocker arms like I said in post #5. If you have hydrolic lifters im sure you are fine. Probably no damage.

SicMonte

06-07-2005, 06:33 AM

wow..im reading this thread and I/ve learned alot!! My motor is backfiring at high rpm's now and I just passed 1000 miles on it. Im gonna do this today and see what happeneds. If you burn a valve...what exactlly happends??

toofun

06-12-2005, 07:03 PM

Going absolutely insane now. Took the rockers off, checked all the pushrods, installed the second springs back in. Put the pushrods back in place, put the rockers in place tighened down the nuts until the rod does not go up and down any more then set the lock nut. Thought it would be better to have them too loose than too tight so I DIDNT even to the 1/4 to 1/2 turn. I was all set to start the motor and set the valves with the motor running. Even cut a notch in the valve covers to lessen the mess.... Well tried to start the motor and it would not fire up. Advanced it a little bit and still would not start. So I retarded it a little bit and W H A M!!! Got the biggest loudest backfire through the exhaust pipe I ever heard in my life!!! I couldnt hear for about 45 seconds. Scared the ever loving **** out of me and my neighbors swore someone got shot.

Besides being alittle embarrassed, I am extremely pissed off!! What the hell? At this point I am ready to take an axe to it but will try to sleep on it and let a cooler head prevail tommorrow. Could I have burnt an exhaust valve? How would I be able to tell without ripping the motor back apart again? Is it something else? ANY HELP WOULD BE APPRECIATED!! :banghead:

Thanks
Mark

yody

06-12-2005, 08:32 PM

FIrst of all, you don't need the motor running to adjust valves, i would actually advise against it. YOu really want to start over, do the EO/IC (adjust Intake valve when the exhaust valve starts to open / adjust exhaust valve right before the intake valve closes, you can do all the intakes first and then exhausts, go in the firing order 18436572) method of adjusting the valve, and check the pushrod like you are(just take the slack out of it right before it stops moving up and down) and then give the rocker arm 1/2 turn, no less no more.(if using poly locks, give it 1/4 turn, then tighten set screw, and then give the set screw and lock another 1/4 turn at the same time.

Once thats done, disconnect the ignition, take out the #1 spark plug, have a helper crank the motor over while you cover the spark plug hole with your finger. Have him/her bump the motor over a little at a time, until you feel the compression push your finger off. Then put the balancer timing mark at 12 BTDC on your timing tab(you usually have to back the motor up about a 1/2 turn with a breaker bar on the balancer bolt). Now pull your distributor cap off (you can really do this before also) and adjust your distributor so the rotor is pointing directly at the #1 spark plug wire terminal.(when you put the cap back on) Now you know that your timing should be REally close and your valves are just right. Then go from there. YOu could easily have a flat cam, but most likely you didn't give it tighten tthe rockers enough. But you need to get the basics 100% before you start going crazy.

Matt@RFR

06-12-2005, 09:00 PM

adjust Intake valve when the exhaust valve starts to open / adjust exhaust valve right before the intake valve closes
Cody, have you ever been to Built by "D" in Yuba City? I worked there for a year or so, and Cory is the only guy I've ever seen run valves like that. Works like a charm, and is by far the fastest way to do it. The only difference is he (and I) run each cylinder at a time instead of going down the firing order. Take the front end off, sit on the tire, and run each bank instead of jumping from side to side.

But you need to get the basics 100% before you start going crazy.
Exactly! Mark, where do you live? This would be SO much easier if we had a member close to you that could come for a visit and get you all set up.

yody

06-12-2005, 09:04 PM

no, never been to yuba city. I hate to bust by bubble, but that method is pretty widely known. The very best it gets. I guess you could go each bank at a time, but if you go in the firing order, its only about a 1/2 turn on the motor until the other valve starts to open or finish closing. if you do just one bank, you are turning the motor over more, which is a PITA. Especially if you have some compression! Also just for reference, opening is when the spring starts to compress, and closing is when the spring expands

Matt@RFR

06-12-2005, 09:09 PM

I figured Cory in Yuba City didn't have a patent on the technique. :slap: Just the only guy I've personally seen do it.

Regarding running valves on each bank, my experience is with full-effort race cars, on which most have remote starter buttons on the firewall, each side of the motor. :)

yody

06-12-2005, 09:12 PM

yeah, don't know why i never wired one of those in, painless sells them, i guess i just didn't want my Ahole friends messing around wiht me, with the hood up! Comp cams actually recommends that method in their manuals and instructions, they just word it differnetly. How is work going?

toofun

06-13-2005, 02:20 AM

OK Guys,

I will try it again and let you know how I make out. I live in Middleton Massachusetts about 20 minutes north of boston and about 40 minutes south of Manchester New Hamshire. I am getting so frustrated with this whole thing. I really is a pain in the ass. Dont know if anyone is around my area who has experience in this or not, but if you are I would gladly pay you for your time to come down and take a look.

Thanks
Mark
TOOFUN

toofun

06-14-2005, 04:58 AM

Here is where I am at. I loosened all the nuts on the rockers and reset them using the EOIC method. But I left them loose. Very little up and down play in them if any and DID NOT GIVE THEM AN ADDITIONAL 1/4-1/2 TURN. Figured better too loose than too tight. I ran a compression test on each cylinder (cold since engine wont start to warm it up) and here is what I got.
#1 210 #3 210 #5 200 #7 200
#2 210 #4 210 #6 210 #8 195

So I am assuming I dont have a problem with the valve hanging up or a bent valve since I would think I wouldnt get any reading with a bent or hanging valve Correct?

Also is there such a thing as having the valves too loose? Could this cause a backfire or a non starting problem? Once again thanks for all of the replys I really appreciate it.

Mark
TOOFUN

yody

06-14-2005, 09:16 AM

as soon as it won't wiggle up and down then give it a half turn

and then give the rocker arm 1/2 turn, no less no more.

why aren't you listening??? why do you keep leaving the valves loose?? that is not the correct way, you are doing it WRONG. If you listened you would see that you NEED to give them 1/2 turn. Your philosophy of too loose is incorrect. THey need to have the proper preload. Go back AGAIN and adjust the valves EOIC and give them 1/2 turn. We can't help you if you keep not listening, and doing it the wrong way time after time.

toofun

06-14-2005, 03:41 PM

I really appreciate you comments but here is why I have not done it that way. First of all , originally I did it EXACTLY that way. I tightened the nut until there was no UP AND DOWN play, then I gave it 1/2 turn. The engine started and then after a while when I tried to raise the rpms to adjust the timing it popped and backfired like crazy. I shut the motor off and tried to restart and it wouldnt start unless I let it cool down for about 30 minutes So everyone told me I had them too tight.

When I read the book they say to adjust the valves the same way that you did except they said to do it AFTER THOROUGHLY WARMING UP THE ENGINE. So you can see why I am a little confused. I am assuming that when the engine is warmed up or getting hotter the valves and engine will expand making the clearances tighter. So if you are suppose to take the slack out and then turn it 1/2 a turn while it is EXPANDED AND HOT then that would mean that the valves will be a little looser when the engine cools. BUT if you take the slack out and give it 1/2 a turn when the engine is COLD, when the engine warms up and expands it will be too tight wouldnt it? This is why I keep thinking that the valves need to be looser before I start it up. Dont mean to be difficult really appreciate the comments but need a definitive answer to help me make sense of it all.

Thanks
Mark

68protouring454

06-14-2005, 04:05 PM

you have adjusted and re adjusted thing so much i would start from scratch, pull distributor again, then slowly go around adjust valves so they each are opening fully, and so they each have 1/2 turn on them, then find top dead center on compression and insert distributor, now align #1 on cap to rotor and put wires on, now assuming you have the 2 other ingriedients to a running motor, spark and fuel it should run, there is something else going on, did the hei get unplugged or a fuse blow?? getting a chevy sb to run is pretty easy, compression/spark and fuel, now maybe the cam timing was messed with or installed off, i do not know but its not rocket science,also the static compression you are seeing the motor must have damn near 11-1 compression.
i just read your first post, maybe you got wrong pushrods?? its just time to check everything
jake

protour_chevelle

06-14-2005, 04:56 PM

The rocker nuts have to be adjusted when the valve is closed eh... then half turn. You can't just go over all the rockers without turning the engine.

-Matt

Charley Lillard

06-14-2005, 06:06 PM

The popping when you rev it might just be because your single spring is too weak to close the valve fast enough. I would put the second springs back on and try it again. If it doesn't want to turn over when hot you might have the timing too far advanced. Try backing it off a bit the next time it happens. If you have valve covers with the top cut out get some of the clips that snap over the rocker arm oil hole so it doesn't get too messy. With the engine running loosen a rocker till you hear it clacking, then slowly tighten it till it gets quiet and tighten another 1/4 turn. Do all of them that way. If they are all clacking so loud you can't hear the one you are trying to adjust just slowly tighten the ones you think are making noise. It will get quieter. I would set initial timing at 10-12 right now while you are adjusting.

yody

06-14-2005, 10:14 PM

Okay no offense everyone, but read his old posts, we have already gone over everythign just mentioned. He needs to do exactly like i said a few posts back. Don't worry about the motor being hot, yes that might be a little bit better but not much, you have hydraulic lifters, if you have aluminum heads the lash might expand .004. which aint squat on a hydraulic lifter. JUST ADJUST THEM WITH 1/2 TURN. Also that is not how you adjusted them the first time, you clearly stated that you were "until I could still twist the pushrod" not up and down but twisting it, which is not the correct way, you could give the polylock a full turn and still be able to twist the pushrod, you have go up and down. You also need to retime the motor like i said in detail. NOne of this could even be your problem but you need to get it down first before you start messing with other stuff or coming to conclusions. Get your valves adjusted right and then re-time the motor!! Don't reply until you have!

zbugger

06-15-2005, 10:31 PM

One last question here. What kind of locks are you using on the studs? Are you using Poly Locks?

toofun

06-16-2005, 04:14 AM

Yes I am using Poly locks.

Railing68

06-16-2005, 01:00 PM

After reading all the posts the EOIC method works very well and fast even for solids. ALso timing the motor prior to starting is the only way to go. One thing I noticed is that he had 1.6 ratio arm listed, did he use these on break in? I do realize that he removed inner spring, but could this contribute to a break in related problem even with out inner spring? If indeed the cam has lost a lobe. SS

toofun

06-16-2005, 02:49 PM

Yea I did use the 1.6 ratio rockers on break in. Also was very careful to check for coil bind and rocker arm interference when I installed them. I will be trying again this weekend on saturday with the help of a friend of mine so Ill keep y all posted on how it goes.

Thanks
Mark
TOOFUN

yody

06-16-2005, 06:39 PM

just make sure to follow the instructions we posted, then if that doesnt' work, we can begin trouble shooting, did you check your pushrod lengths?(not that it would cause any of these probs.)

toofun

06-17-2005, 05:51 AM

Didnt check the push rod lengths but can tell you this. I bought the cam and also bought the pushrods, springs and rockers all together. I called the tech at comp cams and told him what I was running what I was using and specifically mentioned that I was using 1.6 ratio pro magnum rockers with this application so that I could assure myself that everything in this combination matched each other perfect. Hopefully tommorrow I will be dancinig in the streets instead of crying on the curb.......

yody

06-17-2005, 09:04 AM

that doesnt' mean anything, but if you are using stock heads etc. it shouldn't be too much of a problem, although just for fun i would check them anyway, comp woulnd't be able to tell unless they checked it themselves, again that wouldnt' cause your problems, just a cool thing to check. Also don't be prepared for the car to be running after doing what was mentioned. You just need to do this stuff as prelimanry. It might fix it, but if it doesn't you know the basics are covered

toofun

06-18-2005, 06:40 PM

ITS ALIVE...YES ITS ALIVE...... Had a friend come over and help me out today. He went through everything and started from scratch. Seems I didnt have the valves too tight on this last setting just didnt have the distributer set right. I always tried to set it dead on the number one on the cap and he said that he always lined it up to the corner of the front of the head with a screw driver. Actually put it a little after the number one setting. Said I had it off about two teeth. Well what ever it was he fixed it. Started right up on the first turn of the key. Set the initial timing, then tuned the carb then set the total timing, again with the carb, set the idle and MAN this thing sounds mean now. Hits the throttle and it just erupts!! No stumble, no hesitation, it really comes alive!! Thanks again for all the help and comments. I am thrilled, cant wait to take it out tommorrow.