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Car has stock 241s, a btr stage 3 cam and MLS gaskets. I pulled the heads to swap on some 243s. And every piston has a light valve mark. I ran the engine like this for 5k miles. And never heard any weird noises, it also seemed to run fine. I also performed a compression test and had very good numbers. What would’ve caused this? I can see light marks on the valves but they don’t look damaged. Am I okay to run the engine with the pistons like this?
Not enough piston to valve clearance Is the obvious answer, over rev floating the valve, too long pushrods, any cam over .600 lift is a must to check clearances. And should be done on any build to be safe.
Not enough piston to valve clearance Is the obvious answer, over rev floating the valve, too long pushrods, any cam over .600 lift is a must to check clearances. And should be done on any build to be safe.
it’s never been revved past 6500, has BTR dual springs. will double check but I’m pretty sure my pushrods length is right( 7.4). Currently working on pulling the front cover, to check timing. I’m wondering if I misread the crank sprocket that came with my adjustable timing set.
What head gasket have you been running? With the Cometic options available it should be possible to get just enough clearance with inconsequential change to compression.
What head gasket have you been running? With the Cometic options available it should be possible to get just enough clearance with inconsequential change to compression.
GM MLS head gaskets. I thought about that, I just wasn’t sure if that was a good idea. Seems like a band-aid fix to something that isn’t right. What do you think?
GM MLS head gaskets. I thought about that, I just wasn’t sure if that was a good idea. Seems like a band-aid fix to something that isn’t right. What do you think?
Yes, that would be a band-aid. Why are you pulling the timing cover? I get the impression you did not use a push-rod checker and properly sized the pushrods.
Yes, that would be a band-aid. Why are you pulling the timing cover? I get the impression you did not use a push-rod checker and properly sized the pushrods.
I did not. I bought an adjustable pushrod and was planning on checking it before I pull the cover. Wouldn’t the pushrods have to be significantly longer than they should be for this to happen?
alright, I will check that, hopefully that’s my issue. Should have done that initially when I was putting it together
well I’m a little confused now. Got my adjustable pushrod. And I’m measuring 7.3”! They are currently 7.4. If this was actually the difference, wouldn’t that hang the valves open to the point that the car wouldn’t start? I’m just really confused and could use some guidance.
I don't think they make a 7.3 pushrod so 7.4 would/should work. What is the next size shorter than a 7.4 pushrod?
Valve timing would be my next guess. I would also call BTR and see what their recommendation and thoughts are.
I don't think they make a 7.3 pushrod so 7.4 would/should work. What is the next size shorter than a 7.4 pushrod?
Valve timing would be my next guess. I would also call BTR and see what their recommendation and thoughts are.
with the cam on the base circle. With my 7.4 pushrods it was still compressing my springs ALOT. So it seemed like they were way too long. I have not given BTR a call yet. It seems like 7.325 is the correct size after I add my preload
As far as I know the pushrod length won't change the lift of the cam. The wrong pushrod length is going to hang a valve open or make the rocker arm run across the top of the valve incorrectly causing stress on the guide. I would consider thicker head gaskets but you really should check piston to valve clearance with the new heads. Not too hard to do with clay and a solid lifter. You will probably also want to degree your cam while you are in there.
As far as I know the pushrod length won't change the lift of the cam. The wrong pushrod length is going to hang a valve open or make the rocker arm run across the top of the valve incorrectly causing stress on the guide. I would consider thicker head gaskets but you really should check piston to valve clearance with the new heads. Not too hard to do with clay and a solid lifter. You will probably also want to degree your cam while you are in there.
is there any negative side effects to running thicker head gaskets?( other than lowering compression)
Yes. You still have not solved the problem. If you do not troubleshoot, how do you even know if a thicker head gasket will work?
Checked my PTV clearance with the new heads clay. Used a light checked spring. There was absolutely no clearance at all( obviously that’s why the were hitting) im very suprised I didn’t have a single bent valve. I am going to be fly cutting the pistons, because at some point I will be installing a bigger cam in the car.
PTV contact cammed ls1
