NEW INSTALL, CAM & LIFTERS

[Dave the Wave]

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.

[55mike]

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.

[56Mark]

http://www.route66hotrodhigh.com/Lifters.html

[Dave the Wave]

thank you, gentlemen! a couple more questions to follow, as i put this together.

[ykf7b0]

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.

[55 Rescue Dog]

Didn't it come with any instructions?

[Dave the Wave]

i like info like from you guys who have done it, that`s all. thanx

[55 Rescue Dog]

If you had a more specific question I'm sure someone could help, but otherwise to try and explain the whole correct procedure for installing a cam would take forever. There are endless sites and videos on how it's done would be the best place to start.

[BamaNomad]

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.

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.

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...

[55 Rescue Dog]

I've have always been trying to figure out what clearance to run in my original 1970 spec LT-1 11:1 crate engine with a solid lifter cam. I have been just setting them cold at .024 on the intake, and .026 on the exhaust. It seems fine, but even though it is difficult I want to do it on a hot engine sometime. I also started using the use the EOIC method when setting valve lash, and it works on any 4 cycle engine. Doing one cylinder at a time you just rotate the engine until the exhaust valve just starts to open, and then set the lash on the intake valve. Then you rotate until the intake valve just starts to close, and adjust the exhaust valve. Simplest method I've ever tried.

[BamaNomad]

RD: I found this spec for the '70 LT1 camshaft.. including lash specs. Your 0.026 on the exhaust may not allow sufficient expansion for a hot engine??

OEM part #3972178 is the original LT-1 setup. 242/254 @ .050 with 316/336 advertised, with a 116L/S. Lift @ valve .459" x .485". Lash settings of .024"-intake and .030"-exhaust.

[Rick_L]

BamaNomad, lash specs on solid lifter cams are for a fully warmed up engine. So it's not about expansion, it's about matching the lash to the camshaft design.

It's up to you to figure out how much to "fudge" the cold lash. Usually it's .002-.003" but it varies with the engine and camshaft. Aluminum vs. iron heads are also a factor.

[BamaNomad]

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).

[Rick_L]

explain why there's a difference between the hot AND cold lash specifications on a solid cam?

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.


adjusting the lash on a HOT/running engine is a very messy job!

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.

[markm]

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.

[55 Rescue Dog]

RD: I found this spec for the '70 LT1 camshaft.. including lash specs. Your 0.026 on the exhaust may not allow sufficient expansion for a hot engine??

OEM part #3972178 is the original LT-1 setup. 242/254 @ .050 with 316/336 advertised, with a 116L/S. Lift @ valve .459" x .485". Lash settings of .024"-intake and .030"-exhaust.
Yeah I'm a little tight on the exhaust side, but it seemed noisy at .030 setting cold. But the engine runs great, and trying to get them all set at near operating temp would be too hard and I like to have the plugs out. I would like to just put a hydraulic cam in it and forget it, but holy crap this engine pulls hard and I haven't even ran it to 6500rpm that it would easily go to. It is such a great engine that Chevy sold as a long block 50 years ago, and the angle plug turbo iron heads came separate. The one I bought for $1000 in 1989 had never been run. It currently has 700 miles on it, and is one the best SBC you could by from GM back then.11798

[Rick_L]

A 30-30 Duntov cam is noisy, I thought many liked that. Just like they like the random misses at idle. And I agree with markm, you don't have to adjust the valves often. It's just not necessary.

[shoeboxpaul]

I have always used 1/4 turn after zero lash with new lifters and have never had an issue.