Broke In Cam Now Popping Sound

[toofun]

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]

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]

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]

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]

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.

[Travis B]

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]

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]

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]

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]

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]

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]

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]

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]

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!!

Thanks
Mark

[yody]

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]

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]

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]

I figured Cory in Yuba City didn't have a patent on the technique. 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]

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]

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