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Message: <blockquote data-quote="swampratt" data-source="post: 3101603" data-attributes="member: 15054">for a mild build with a mildish cam that will still make 400+ HP in a 350 you can use stock size lifters and cam.Larger diameter cam will take much more spring pressure.But then there are machine costs. But there are small diameter cams that will take a lot of pressures alsoYou are not building a 700+ HP small block so no worries.I have heard many say they had issues in the upper elevations.I never had any issues at all  I  went up pikes peak in my 84 ford van and no issues. It was not stock.302 +.030 for 306 inches.. decked block Keith black flat top pistons, ported and surfaced small valve 302 heads and ported ex manifolds and ported 2 barrel iron intake with spacers.. running motorcraft 2 barrel carb.3" exhaust single outlet.Timing curve was quick 16 initial and 35 total all in by 2000 rpm. 260H comp magnum cam flat tappet hydraulic.maybe the old school timing curves hurt those going to higher elevations.My van ran perfect up there.My AFR at idle was 18:1 part throttle cruise was 15.1 :1. Full throttle AFR was 13.5.That was down here in Oklahoma.Maybe the ported heads and earlier closing intake valve helped.Our 82 mustang inline 6 with 1 barrel carb was happy everywhere also.Yes The exhaust was not stock and it also had a quick timing curve.No vacuum advance on either of them. But i do like a lot of initial timing and want it to come in quick. Needs to all be in by cruise RPM or MPG will suffer.My van only had 170psi cranking pressure the 82 200" inline 6 had 200 psi cranking pressure.You need to go leaner the higher up you go and most cars are not running on the lean side to begin with at lower elevations.Even reading plugs you will be surprised how much jet you can add to one and still have white plugs.I took 8 thousandths out front and rear from my buddies 750 which he thought was on the money.. this was at the track in Noble .. he came to me and said that is as fast as it would go the tune is perfect no more left in it.That is when i said open the hood and i took the big jets out and stuck different ones in .008 smaller in primary and secondary and said go make another pass.He went 4 tenths quicker!!His plugs were white to begin with and were still the same after the jet change.I jet down until i get a lean surge during slow throttle application.I then jet up until that surge/bucking just goes away. then add .001-.002" more primary jet to be on the safe side.. this will put you in the 14.5 AFR range.Full throttle power is then messed with  shift recovery from first to second. if it noses over on the shift you are lean.Add some rear jet.Yes you have idle and high speed air bleeds but most of the time I do not need to even mess with that.</blockquote>

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