ok, simple questions here. new cam and lifters. install the cam, set the lash and that`s it? i mean tighten the push rods, 1/2 turn? i hear this stuff about "pump up"? can you install right out of the box? thanks.
ok, simple questions here. new cam and lifters. install the cam, set the lash and that`s it? i mean tighten the push rods, 1/2 turn? i hear this stuff about "pump up"? can you install right out of the box? thanks.
On a typical flat tappet cam, the rocker arm is adjusted when the lifter is on the bottom (heal) of the cam lobe. It's a common practice on with new lifters to soak them overnight in a bath of motor oil completely submerged. A liberal coating of cam lube should be smeared on the bottom of the lifter as well.
When the lifter is on the bottom of the cam lobe (lots of ways to establish this... an internet search will give you these options), the rocker arm is tightened down to first "0" lash. I roll the pushrod to just the point of resistance as the nut is tightened. When you are sure it's 0 lash, then give the nut about 1/2 to 3/4 turn more.
Last edited by 55mike; 02-12-2021 at 05:50 PM.
56-210, 283, 200-4R, Power steering, Power Brakes
thank you, gentlemen! a couple more questions to follow, as i put this together.
Rick,
I don't want to get into a long discussion on this, but If not for thermal expansions how would you explain why there's a difference between the hot AND cold lash specifications on a solid cam? (AND adjusting the lash on a HOT/running engine is a very messy job!)
My comment on this to RD was based on his exhaust valve setting of 0.026 versus the spec of 0.030. Every solid cam I've used over the last 50 years has had different lash settings, and yes those differences are based on the engine/cam design and the specific application of the engine! My own experience with solid cams began with a Lunati cam which matched the '67 Z28 specs in a bored HTC/CSC 302 in a record running '67 Camaro, and continued with 'stock' '68 Z28 (302), stock '69 Z28 (302+0.030) and a '70 350 LT1 engine (two of them), so all of those were Chevy engines from the '67-70 timeframe. As far as any other brand solid lifter engines, I know nothing and don't pretend to. Currently the only solid lifter engine I own is in the '69 Z28 (and I might be changing this to a 'roller cam' design in the future). I installed a 350/350 hydraulic cam in the last LT1 I rebuilt (because IMO it's a pain having to adjust lifters in a street engine).
Last edited by BamaNomad; 02-22-2021 at 06:25 AM.
I don't think you'll find any cold lash specs. What you do is set the initial lash with an educated guess and then when warmed up, check and set again. There is a difference but it's not spec'd and cold lash is not an accurate predictor of hot lash.explain why there's a difference between the hot AND cold lash specifications on a solid cam?
There's an easy answer for that. Don't adjust lash on a solid lifter cam while the engine is running. For that matter there's normally no need to adjust hydraulic lifters with the engine running either.adjusting the lash on a HOT/running engine is a very messy job!
I has been rears since I ran the valves on my 67 Camaro SS 350 it has a Duntov 30/30, it even went 1500 miles of Power Tour in 17.
If it’s a hydraulic flat tappet make sure you use a high zinc break in oil and keep the rpm’s up for about 20 minutes or so.
Last edited by ykf7b0; 02-20-2021 at 03:10 PM.
Jesus is my pilot!
I don't think Dave has clarified whether he's installing a hydraulic or a 'solid' lifter camshaft, but the suggestions of using a high zinc break in oil and keeping the rpms up for 20 min is a good one regardless. I usually run 2500-3000 rpm for close to 30 minutes. The rpm has to be kept high enough that the engine runs 'smoothly.. ie. doesn't try to slow down on it's own.Originally Posted by ykf7b0
The comments about 'pump up' and adjusting for zero lash and then 1/2 turn are a mixture of suggestions and a little misleading. If you're talking about 'hydraulic lifters' and 'zero lash' (you have to be talking about when the inner spring is uncompressed. Then the 1/3 or 1/4 or 1/2 turn extra is 'into the spring' which is also the same as being 'into the hydraulic pressure' while running and the oil pressure will keep the lifter seated on the cam lobe.
For solid lifters you must maintain 'clearance' (not zero lash!)... the exact clearance a solid lifter requires is a function of the cam/lifter/engine specs, and temperature (hot or cold).
Follow your cam instructions for this, and if you have a detailed question(s), then tell us WHICH cam, which engine, and what your question is...
Didn't it come with any instructions?
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