Longer pushrods, or can I use lash caps?

Scott, I know you said the stem length is the same (intake / exhaust ), but if you put a straight edge across the valve stems installed in the head is the installed hieght the same?

 

VERY good question...just went out and measured and they are the same. So problem is on the cam end, not the valve/rocker end...still pointing at the cam profile.

Thanks for the suggestion to help eliminate variables.

The degree wheel was mailed on Saturday, I should have it by Tuesday.

 

I have ran MANY dual pattern cams with none of the problems you are having...The only way that the cam could cause the problem you`ve described would be if the base circles of the intake and exhaust lobes were ground differently. I have never heard of a cam being made that way and I can`t see any reason for it to be done.



Just a quick question scooper... You are SURE that you are checking the lash on BOTH lobes with the cam on it`s base circle right?

 

It is not uncommon to have different length push rods on custom ground dual pattern cams.That said if all else checks out,get 8 pushrods the correct length and fire that bad boy up!!Definitely degree that cam beforehand.It could have been ground improperly causing all the problems rick had with it and now its your turn.You should check the figures on each lobe(I know,time consuming PITA)but necessary with a suspect cam.Good luck.

 

I agree with you Mavman. Not only is it a PITA and time consuming, it will be good practice for me to do it. I am new to degreeing, and this is the kit that comes with the instruction video and all needed parts. So after I do it eight times or so, I may find that I did something wrong the first time or two and can catch any errors I might make.

I am going to go out and measure the lifter height and see if it is different on the base lobe. THAT should help clear things up some more.

 

HAS To be base circle grind

I measured from the machined flat spot below the dog bone to the top of the lifter and got these numbers. Even rotated 4* (Comp cams state most grinds are made 4* advanced at TDC) even though it shouldn't make a difference, and of course it didn't...

You can even see that the exhaust sits a little lower compared to the top of the dogbone...

Looks like base circle is different between the intake and exhaust lobes, by .060...hmmm, that number sounds familiar (see post #1...).

Thanks for the help guys...:Handshake

 

I have never seen a dual pattern cam require different length pushrods for the intake and exhaust on a SBF. Aything is possible, I suppose.

 

Me either

I was just thinking that something is way out of whack for his combo and the dual pattern cam was causing it to be noticed on the exhaust side???


Seth

 

hmm, that doesn't sound good, tell rick you want a refund

 

This could be a small base circle cam designed for a non roller block. I would try to find out exactly what i had before going much further. I don't know if a retro roller cam would cause any problems, but being the one that had the cam had problems, I would investigate, or not use the cam. A new roller cam is not that expensive, A motor failure is.

 

I was thinking that it had to be the base circle being smaller on the exhaust side, but I thought I'd sit back and let everybody else take a crack at it first.....

 

Rick said this was a one-off custom grind cam from Comp, so there is no telling what it was.

I am now more interested in finding out if he used the stock pushrods on this cam, and his motor failed because his mechanic didn't catch this problem. Seems like .060 play in the valvetrain can lead to NO good...

 

I would call Comp an talk to tech line, if you get a wisecrack, hang up an call again. I never heard of it but it's possible. Backside of cam should have their # an will help them ID it!

 

Scott, standard length (hardened) pushrods were used with this combo using the stock heads (1990 5.0), Windosr Jr. heads and the AFR 185's. I used aftermarket rockers (all 1.6). There were no "valve train related" problems - ever.

I adjusted the valves myself several times and had no problems like what you are describing.

You've already answered the 1st question I had about the valves being inline or not.

I'm stumped.

Having said that, which lifters did you use, the truck lifters (that I scored at that shop for you) or the ones I gave you (that I thought were bad but weren't)?

 

Rick,at this point, I am using your cam, lifters, and my 1.7 roller rockers. And with this setup, i have .060 slop in my exhaust. I was just wondering if this is what caused your motor to fail?