valve lashing help
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On The Tree
Joined: Feb 2007
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valve lashing help The issue im having is with lash setting. the standard setting is .26 cold on intake and exhaust. so that is where i put them. the question i have is my vacuum is 6 with compression of 125-130. now if i increase the gap to .35 my compression goes to 150-155 and vacuum jumps to 11-12.
i cant figure out why this is happening. everything is stock expect compression. stock is 11 to 1 its been dropped to 9.5 to 1. should i leave it with the .35 or go back to .26 and lose vacuum?
im being told by friends im just damaging the valve train at .35.
i cant figure out why this is happening. everything is stock expect compression. stock is 11 to 1 its been dropped to 9.5 to 1. should i leave it with the .35 or go back to .26 and lose vacuum?
im being told by friends im just damaging the valve train at .35.
TECH Addict
Joined: Dec 2017
Posts: 2,180
Likes: 969
One of the outstanding virtues of solid lifters is, they're a TUNING AID. You can vary the lash over a fairly substantial range, and as long as they're CONSISTENT among cylinders, use it to make fine adjustments to the overall product.
"Stock" covers ALOT of ground. For example, if you have ANY iron components (the block in this case), the change in lash due to the engine reaching operating temperature, is COMPLETELY different from all-aluminum. You don't mention that, so, yeah.
The castings in an all-aluminum motor grow something around .008" - .012" from cold to hot, meaning, you have to set em that much too tight, if you do em cold but the spec is for hot. In an all-iron motor, the lash goes the other way; you typically lose maybe .004" or a bit more.
Still in all, allow me to quote one of the GOATs in a totally unrelated field. The man was an absolute GIANT. Somebody asked him how he could tell if something was good or not, even if it wasn't what he expected; and his answer would have been, if he was building motors,
"If it RUNS good, it IS good".
Words of wisdom to live by.
That said, I suspect your lashing technique is resulting in the ACTUAL lash being tighter than what you think it is. Which is not an inherent problem, as long as you can do whatever you're doing CONSISTENTLY. I think you're setting em with too much drag on the feeler gauge. Butt whatevz. If whatever you do works best if you set em to .035", and you can do EXACTLY that EVERY TIME, then ... you do the math.
You're not hurting the valve train no matter what your friends that haven't ever had solids think.
"Stock" covers ALOT of ground. For example, if you have ANY iron components (the block in this case), the change in lash due to the engine reaching operating temperature, is COMPLETELY different from all-aluminum. You don't mention that, so, yeah.
The castings in an all-aluminum motor grow something around .008" - .012" from cold to hot, meaning, you have to set em that much too tight, if you do em cold but the spec is for hot. In an all-iron motor, the lash goes the other way; you typically lose maybe .004" or a bit more.
Still in all, allow me to quote one of the GOATs in a totally unrelated field. The man was an absolute GIANT. Somebody asked him how he could tell if something was good or not, even if it wasn't what he expected; and his answer would have been, if he was building motors,
"If it RUNS good, it IS good".
Words of wisdom to live by.
That said, I suspect your lashing technique is resulting in the ACTUAL lash being tighter than what you think it is. Which is not an inherent problem, as long as you can do whatever you're doing CONSISTENTLY. I think you're setting em with too much drag on the feeler gauge. Butt whatevz. If whatever you do works best if you set em to .035", and you can do EXACTLY that EVERY TIME, then ... you do the math.
You're not hurting the valve train no matter what your friends that haven't ever had solids think.
EOIC and tighten the rocker arm while spinning the PR until you feel zero lash and then go an additional 1/4-1/2 turn. Another way which can get a little messy is to run the engine and back the rocker arm off until it starts to tick and then tighten the rocker arm until it quiets down.
TECH Addict
Joined: Dec 2017
Posts: 2,180
Likes: 969
He has a solid cam. Adjusting it that way, like a hydraulic, won't work.
OP, the first motor I had with a solid, I had put the same cam into (283 back in the early 70s); the old "30/30" exactly like this one https://www.summitracing.com/parts/cca-12-107-3 I think I bought The copy I had at the Perfect Circle dealer. I sprung for the edge-orifice (high-$$$ at the time) lifters, which turned out to be a very good choice. It ended up in a 69 Chevelle 4-speed. Would literally smoke the tires in 1st gear going down the freeway at 60 mph, then get more rubber when you grabbed 2nd at 70 or so. My late little bro wrecked it eventually around maybe 80 or 81, hit a little old man who pulled out of a parking lot unexpectedly in front of him one day when he was late to work, and d00d stopped across all 3 lanes of the street, when he was at the top of 3rd gear, because d00d was looking for his HAT. The cop who measured the skid marks estimated that he was going 125 mph when he hit the brakes, and about 65 when he hit the side of that late 60s Dodge Polara. MANG I loved that motor...
OP, the first motor I had with a solid, I had put the same cam into (283 back in the early 70s); the old "30/30" exactly like this one https://www.summitracing.com/parts/cca-12-107-3 I think I bought The copy I had at the Perfect Circle dealer. I sprung for the edge-orifice (high-$$$ at the time) lifters, which turned out to be a very good choice. It ended up in a 69 Chevelle 4-speed. Would literally smoke the tires in 1st gear going down the freeway at 60 mph, then get more rubber when you grabbed 2nd at 70 or so. My late little bro wrecked it eventually around maybe 80 or 81, hit a little old man who pulled out of a parking lot unexpectedly in front of him one day when he was late to work, and d00d stopped across all 3 lanes of the street, when he was at the top of 3rd gear, because d00d was looking for his HAT. The cop who measured the skid marks estimated that he was going 125 mph when he hit the brakes, and about 65 when he hit the side of that late 60s Dodge Polara. MANG I loved that motor...
Found a good article on the DZ302. Pretty cool
https://www.chevyhardcore.com/tech-s...lock-camshaft/
https://www.chevyhardcore.com/tech-s...lock-camshaft/
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The issue im having is with lash setting. the standard setting is .26 cold on intake and exhaust. so that is where i put them. the question i have is my vacuum is 6 with compression of 125-130. now if i increase the gap to .35 my compression goes to 150-155 and vacuum jumps to 11-12.
i cant figure out why this is happening. everything is stock expect compression. stock is 11 to 1 its been dropped to 9.5 to 1. should i leave it with the .35 or go back to .26 and lose vacuum?
im being told by friends im just damaging the valve train at .35.
i cant figure out why this is happening. everything is stock expect compression. stock is 11 to 1 its been dropped to 9.5 to 1. should i leave it with the .35 or go back to .26 and lose vacuum?
im being told by friends im just damaging the valve train at .35.
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