Guest zfan Posted July 23, 2005 Share Posted July 23, 2005 Last night I went to Denton, Tx. to race at the 1/8th mile track. On my second run after heating the tires I thought I heard noises from up front but could not be sure. To make a long story short I ran anyway and felt it drop off on the big end. The engine sputtered and acted like it was loaded/flooded but with a miss. I took it into the pits and when I checked it out I found valve train noise. Sounds like a bad lifter maybe a flattened lobe on the cam? I have good oil pressure, I pulled the valve covers and found no loose rockers. But start it up and it sounds like it is having a slight miss and I have noise coming from the valve covers. I am not that sharp when it comes to roller cams but I have heard it is possible to flatten a Hydraulic roller cam with a bad roller lifter. Has anyone had any experience with this issue. I had to get AAA out as my friends trailer got left at home. Didn't get in until 7 am this morning...gosh I hate life on 2-3 hrs sleep. Any imput would be appreciated. Mike Quote Link to comment Share on other sites More sharing options...
DaleMX Posted July 23, 2005 Share Posted July 23, 2005 Pull the valve covers and inspect for a broken spring or loose rocker. Could be a bent pushrod too. Pull the pushrods and roll them on a mirror to check for flatness. Quote Link to comment Share on other sites More sharing options...
jt1 Posted July 24, 2005 Share Posted July 24, 2005 Possibly a collapsed lifter- i.e. the plunger in the lifter is stuck down and not taking up the slack in the valvetrain. Run thru the valves like you're adjusting them, trying to shake the rockers. When the intake starts to close, check the exhaust, when the exhaust starts to open, check the intake. If you find one with a lot of clearance, that's the one. Sometimes you can take apart the lifter and clean it good and fix it, sometimes it takes a new lifter. Also, when you checked for loose rockers did you run the the valve adjustment sequence, or check with the motor in one position? If a rocker is slightly loose, it might not show up unless the lifter is on the base circle. Might recheck that as it's the easiest fix. John Quote Link to comment Share on other sites More sharing options...
Guest zfan Posted July 24, 2005 Share Posted July 24, 2005 I tend to think it is a collapsed lifter. I did bump it over and checked the rockers in different positions but due to a lack of light I could not really get a good look or feel for the problem. I will pull the covers and see what I can come up with. I had a heck of a time adjusting valves the last time I assembled things and that is not usually the case. So could be time for new lifters. What sucks is these lifters are the Comp cams Magnum retrofit hydraulic rollers and they are not cheap. Maybe just maybe it will only be one and I can call Comp about a single replacement. Well I am at it I am going to check the springs and get seat and open pressure. Maybe time to go solid roller and not have this issue again. Thanks, Mike Quote Link to comment Share on other sites More sharing options...
Guest zfan Posted July 25, 2005 Share Posted July 25, 2005 I have heard that Comp will rebuild the roller lifters for a price. I am going to call them today and see what I am looking at. If they do rebuild them its got to be cheaper than 400-450 for a new set of their roller lifters. If they do not I am going to seriously look into going solid roller and just go all out and have a custom ground cam made and do the Comp solid roller lifters and Comp magnum roller rockers and spring upgrade. Damn Hydraulic lifters are not cheap. Mike Quote Link to comment Share on other sites More sharing options...
jt1 Posted July 25, 2005 Share Posted July 25, 2005 Comp will rebuild the lifters, I don't know how they charge. Find the culprit and take it apart first. It may be just a piece of crud in the oil passage or plunger. If so, clean it up and reassemble and you're ready. Be careful taking it apart, sometimes the plunger springs are pretty stiff. Usually the only time you need to rebuild lifters is when you're running mega spring pressures and the axle bearings start getting rough. John Quote Link to comment Share on other sites More sharing options...
Guest zfan Posted July 27, 2005 Share Posted July 27, 2005 Well live and learn. I was told by a friend if you trash A motor you should have them replaced or rebuilt because of all the metal trash in the oil when lets say you spin several rods bearings like I did. I never even thought about it honestly. I called Comp and they said they do not rebuild them but my friend said I must have talked to a Noobie as they do. So tomorrow I will call them again and get the real story. I don't want to pay 450 for another set if I do not have to. May just retard the cam 4-8 degrees while I am at it. On the dyno It is missing the peak torque curve due to my high stall torque converter. I just new the engine builder was wrong when he said to put it in straight up which with a Comp cam is 4 degrees advanced. It is making peak torque at 3500 rpm just when my converter begins to work. It hits at 35-3700 rpm's. I really want peak at 4-5k. Mike Quote Link to comment Share on other sites More sharing options...
jt1 Posted July 27, 2005 Share Posted July 27, 2005 Your friend is right in that if you get a bunch of metal in the motor, they should at least be cleaned really good, but you can do that yourself. A rebuild would mean new bearings, bearings, and axles, which might not be necessary. Have you been able to isolate the problem to a certain valve? John Quote Link to comment Share on other sites More sharing options...
Guest zfan Posted July 27, 2005 Share Posted July 27, 2005 Well talked to Comp this morning and they only rebuild Mechanical roller lifters. CRAP! I believe I found the culprit and it is the #8 cylinder. Pulled the plug and it is very wet and thats where the noise is coming from. Today I will probably start to pull it apart and see what I can find. Also I guess I will take the hydraulic roller lifter apart. May just do them all. Talked to Crane cams and they gave my info on a Hydraulic roller with a custom grind. 258/264 duration and 558/558 lift with 110 lobe seperation. This would be more to my 3500 rpm converters liking. Guy at Crane said he only recommends running Hydraulic rollers the street for cars that are street strip cars. If race only then go Mechanical roller? He stated Hydraulics are much more reliable. Any thoughts on this subject? I only shy'd away from mechanical roller because of the adjusting constantly not because of reliability. Mike Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.