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!

[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.

[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

[toofun]

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

[Railing68]

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]

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]

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]

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