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Rebuild for a performance oriented 6.5

Burning oil said:
Thats definitely not like the pics that were going around. Looks like you said, a light contact. Only on the one piston though?
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It was on all 8 to varying degrees. This one was the one that showed up best in a picture.
 
Really that's very odd that the intakes are doing that . The exhaust I can see as they usually chase the piston and can cause problems . I think it was Little Boy who noticed that type of markings on some of his pistons but can't seem to remember what became of the solution . Maybe heavier valve springs ? Do you remember what numbers you had with the clay ?
 
EWC said:
Really that's very odd that the intakes are doing that . The exhaust I can see as they usually chase the piston and can cause problems . I think it was Little Boy who noticed that type of markings on some of his pistons but can't seem to remember what became of the solution . Maybe heavier valve springs ? Do you remember what numbers you had with the clay ?
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Yeah I think it's odd too, I still can't reason why it happened. I had 4/64 (.063) clearance on the intake and 7/64 (.109) clearance on the exhaust.
 
Weak springs & boost the valves can & do float "common problem!" Not sure if N/A valve springs are different than on boosted applications....
 
In college we got to watch video of a race car engine valvetrain while running a hot lap. The problem wasn't valve float, it's valve bounce. The valves would literally bounce off of the valve seats multiple times when they would close. They would actually never stay fully close before they were being opened again. You could see when they would be opened by what appeared to be spaghetti noodles (the pushrods would bend and wobble) and then you could see the valve bouncing multiple times before the spaghetti noodle would open the valve again. It was pretty amazing to watch and even more amazing to think that these things can hold together for more than 30 seconds.

Now, those are engines running over 2x the rpms we are running, but they are also running a lot higher spring pressures than we are too. So I wouldn't put it past, especially a seasoned or worn valve spring, to allow the valves to bounce off of the seat enough for it to "kiss" the piston. No doubt it is possible to do that while running a regrind with steeper lobes, 1.6 rockers that create even more dramatic lifts and drops of the valves and already tight clearances.


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3500_6.5 said:
In college we got to watch video of a race car engine valvetrain while running a hot lap. The problem wasn't valve float, it's valve bounce. The valves would literally bounce off of the valve seats multiple times when they would close. They would actually never stay fully close before they were being opened again. You could see when they would be opened by what appeared to be spaghetti noodles (the pushrods would bend and wobble) and then you could see the valve bouncing multiple times before the spaghetti noodle would open the valve again. It was pretty amazing to watch and even more amazing to think that these things can hold together for more than 30 seconds.

Now, those are engines running over 2x the rpms we are running, but they are also running a lot higher spring pressures than we are too. So I wouldn't put it past, especially a seasoned or worn valve spring, to allow the valves to bounce off of the seat enough for it to "kiss" the piston. No doubt it is possible to do that while running a regrind with steeper lobes, 1.6 rockers that create even more dramatic lifts and drops of the valves and already tight clearances.


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So what you're saying is: the pistons were actually helping the valves close. Dang it, I shouldn't have changed anything!! :D;)

Was that video from a Spintron? How did they get the video footage? That would be cool to watch.
 
Yeah, I love those type of videos. That's when you really understand why things are the way they are.

Part of a rebuild should always be testing or just replacing the valve springs. When I was playing hot rod, cam options didn't exist. Different cams mandate different springs usually. Do the cam suppliers offer you a set of matching springs or give you specs to fit within?

Sending parts like springs and pushrods to be cryogenics makes a difference. Idk I recommend it for a stock build, but pushing lots of ponies I do.
 
Will L. said:
Yeah, I love those type of videos. That's when you really understand why things are the way they are.

Part of a rebuild should always be testing or just replacing the valve springs. When I was playing hot rod, cam options didn't exist. Different cams mandate different springs usually. Do the cam suppliers offer you a set of matching springs or give you specs to fit within?

Sending parts like springs and pushrods to be cryogenics makes a difference. Idk I recommend it for a stock build, but pushing lots of ponies I do.
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I asked Delta about valve springs and they told me the stock springs would work fine with their cam.

I just looked at my build notes and it looks like I reused the springs that came with the Optimizer. Since the engine was an apparent low-mile engine I decided they were still usable. Perhaps that was my fatal flaw, especially since my Intake valve-to-piston clearance was on the tighter end of the scale at .063". Live and learn?
 
n8in8or said:
So what you're saying is: the pistons were actually helping the valves close. Dang it, I shouldn't have changed anything!! :D;)

Was that video from a Spintron? How did they get the video footage? That would be cool to watch.
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This was over ten years ago we're talking, I couldn't tell you where the video came from lol. The school did have its own various race cars, so it's possible it could have been one of their own engines. But they also had a lot of connections in the racing/high performance world, so at this point I really couldn't even point you in the right direction to try and locate a similar video. Hell, I am pretty sure the video was even on vhs. It was definitely wild to see and would be cool for anyone to watch.
 
I've pulled 6.5 springs that were at 300,000 miles and tried to demonstrate with them loss of tension- and got embarrassed when they passed spec. I've seen others from 6.5 with barely over 120,000 fall short. It's really test and see.
If not able to test I would have done what you did and put in the optimizer springs. I think they are the same, but with the 25% higher chromium in the block and heads, maybe they improved springs also? Idk.

I really wish the 6.5 was not an interference engine. 1/4" taller head design would have allowed it and eliminated all cracking of heads and far better flow. If wishes were fishes I'd live in the sea...
 
Burning oil said:
Not quite the running engine, but its funny

Another



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Those are great! I am never going to run an engine past idle now...those really put things in perspective. Also, that last one gives me flashbacks of the Porky's locker room scene! Peephole!
 
That first video is awesome lol. It reminds me of another "test" they would do at school if anyone was willing to try it....

Anyone remember the infomercial with the oil additive that they claimed you could run and then run the engine without oil and the engine would not lock up? Even showed them dumping sand into the valvetrain while it was running with no oil. I don't remember what the additive was called (maybe slick 50 or something??), but there was a teacher that would always ask the students if any of them wanted to try the test on an engine/vehicle they owned. Of course, no one ever took him up on the challenge....except for one person (while I was there anyway). The guy had an old beater car that apparently he was willing to donate to science. The car lasted about ten seconds after the oil was drain before it locked up.... Didn't even have time to do the sand test [emoji19]


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Pushrod length checker came today. Hopefully tomorrow I can start measuring. I was looking at summit to see if I could find pushrods to use and I found their Comp Cam pushrods that come with just the rod and one end. I also found the 3/8" ball tip that I would need for the other end. My only concern/question is: the stock pushrods have the copper colored end for the rocker arm end, will it matter if I use chromoly ends instead?


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Nice coincidence....look what was in the issue of Hot Rod I was reading last night. It also made me think: should you have the 1.6 rockers to check pushrod length? I know you'll be close, and probably realistically close enough, with the 1.5 rockers, but it was a thought....

image.jpeg
 
n8in8or said:
Nice coincidence....look what was in the issue of Hot Rod I was reading last night. It also made me think: should you have the 1.6 rockers to check pushrod length? I know you'll be close, and probably realistically close enough, with the 1.5 rockers, but it was a thought....

View attachment 47998
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Funny you posted that, putting spacers under the rocker arm shaft was something I was considering doing too. Trying to decide what will be the easiest/least expensive without sacrificing quality.

And I was thinking the same thing about checking the 1.6 rockers. Just really sucks that they are on my other engine. I really don't want to tear it down, but I guess I could just swap the stock rocker arms back onto it and run them until the engine gets pulled. I also thought about just ordering another set of 1.6 rockers and then save the other ones for another build. But then if the 1.6 rockers won't work with my cam, the I'll have wasted money on a set of rockers that I can't use.
 
3500_6.5 said:
Funny you posted that, putting spacers under the rocker arm shaft was something I was considering doing too. Trying to decide what will be the easiest/least expensive without sacrificing quality.

And I was thinking the same thing about checking the 1.6 rockers. Just really sucks that they are on my other engine. I really don't want to tear it down, but I guess I could just swap the stock rocker arms back onto it and run them until the engine gets pulled. I also thought about just ordering another set of 1.6 rockers and then save the other ones for another build. But then if the 1.6 rockers won't work with my cam, the I'll have wasted money on a set of rockers that I can't use.
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Hmmm, taking them off the other engine and putting the 1.5s on in their place isn't a terrible idea, but that's a lot of work if you find out you can't use them. It seems like you should be able to validate whether you'll have clearance for them with the 1.5s (or at least have a good enough idea to try them) and then you could do the swap on the other engine. Then dial in the pushrod length and do a final clearance check with the 1.6s in place. Not the easiest thing, but cheaper than buying a whole new set.
 
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