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Discussion Starter · #1 · (Edited)
this is bits of several posts on differant sites but it will give you a good start!.......Frank_T posted some of it.. most of the guys probably won,t admit it but theres not a single guy thats ever built several engines that has not screwed up something some how so don,t feel bad just learn from your mistakes
Id bet more than 1/2 the guys did not carefully check all the clearances durring their first cam swap, Id bet more than 1/2 the guys did not carefully check and degree in their first cam,3/4 of the guys never checked quench, thrust bearing clearance or lifter bore angles on their first engine build and Id bet 7/8ths of the guys did not pull all the oil gallery plugs and clean out all the oil passages with a rifle bore brush on their last bearing swap, theres something about human nature that makes us only learn the hard way ,not from OTHER PEOPLES mistakes so don,t feel like your the only guy to ever make a mistake, just LEARN FROM YOUR MISTAKES,TAKE NOTES, and BUY AND READ THESE BOOKS

REPEAT!!! buy these FIVE books, it will be the best money you ever spent, read them, and you will be miles ahead of the average guy.

JOHN LINGENFELTER on modifying small-block chevy engines

how to build & modify CHEVROLET small-block V-8 CAMSHAFTS & VALVTRAINS BY DAVID VIZARD


if your bending pushrods.... check these things first
valves/pushrods bend from clearance problems 90% of the time
cam indexed/installed wrong
rocker to rocker stud
rocker to valve retainer
pushrod to cylinder head slot
valve retainer to valve guide
spring bind height
valve to piston
lifter to lifter bore
valves stuck in valve guides
bent valve stems
pushrod to pushrod guide plate
rocker lock nut to internal rocker clearance
rocker to valve cover
intake manifold bolts too long binding pushrods
just to name the more obvious

I try for 0.100 on the intake and 0.100 on the exhaust as absolute minimums but am far happier with 0.120 thousands (just under 1/8") or greater on both!
Ill always trade increased clearance to gain reliablity for a slight loss in compression,keep in mind that if you get to tight on those clearances you will be locked into that cam timing and dropping it back (RETARDING the cam) for greater high rpm power or (advancing the cam) for more low rpm torque becomes next to impossiable in some cases while you tune the engine combo!
I have found that minimum clearance is normally close to 10* BTDC on exhaust or 10* ATDC on intake, you can adjust cam timing slightly to gain max clearance with very little change in performance.

here read this, degreeing in your own cam after buying the tools listed below is a great idea because

(1) youll learn a great deal about your engine doing it!

(2)even with the cost of the tool kit depreciated over only a single engine build-up, it will still cost less than most shops charge to do it for you CORRECTLY and over several engine builds its a total no-brainer that your way ahead cost wise

(3) you can get the purchase price of the tools back over very little time charging a minimal fee to check/install cams CORRECTLY

(4) youll prevent lots of major problems by checking and finding manufacturing errors and assembly screw-ups and a single manufacturing mistake not caught in time before starting your engine can easily cost you a whole engine

(5) the dial indicator and base can be used to check other engine clearances

(6) the kit comes with a video tape instructions, all the tools, degree wheel, dial indicator ETC.

previous post

tool kit

on the crank gear
0 - Indicates standard cam timing
A - Advances the cam timing 4°
R or a square - Retards the cam timing 4°

One of the easiest and quickest methods thats a bunch
more accurate than the clay-method , would be to use

Acid-core solder (usually .120" thick )
Resin-core solder (usually .090" thick )

With the solder-method , you don't actually need a degree wheel
..just the harmonic balancer timing marks and a 6" dial caliper

Turn the engine over till you are coming up to TDC-Overlap
with both the exhaust valve on its way to closing, and
the intake valve beginning to open

Turn the engine till you are about 1/2 inch from TDC ,
then rollout and straighten a piece of acid-core solder about
6 to 8 inches long ....then with headers off , look thru
#1 Cylinder's exhaust port with a penlite...take the solder
and place it thru the spark plug hole , placing solder
across the Exhaust valve piston notch...then hold solder at that
angle while someone slowly turns engine over to TDC-Overlap
and then past TDC until you "feel" you can pull out solder .

as you turn the engine over at TDC the exhaust valve will
touch or squeeze the solder to the valve-to-piston clearance you keep turning engine past TDC-Overlap,
the solder will be released

remove the solder and look for indentation ...measure with
dial-caliper ..and this is the valve-to-piston clearance !
No clay mess , no clay spring-back , very much accurate than clay-method

Cut a new piece of solder ...and just repeat for intake side !

the best method would be to use a 1.000" dial indicator and
magnetic stand ....bolt a 1/8 thick small plate to valve cover
bolt hole then stick the indicator in place on the steel plate .
(sometimes a SBC fuel-pump cover works great)

attach a degree wheel and pointer and find true TDC ,
then turn engine over till 10 degrees BEFORE TDC-Overlap
to measure Exhaust clearance . (8 -to- 12 deg closest points)

at 10 deg BTDC the 1.000" dial indicator's point on
the flat part of the spring retainer , zero the indicator,
and with the set-screw backed out of the adjuster nut, take
a wrench and turn the adjuster nut till you force the valve to
bottom out against the piston's exhaust notch how much
the dial indicator traveled ...thats your Exhaust clearance

back-off Exhaust adjuster nut back to ZERO point on dial indicator

now, repeat the same proceedure on the Intake side ...but this
time turn engine past TDC-Overlap to 10 degrees AFTER TDC
then check Intake clearance .

Note : You should always check valve-to-piston clearance with
a fully assembled valvetrain with the real springs in place
and every rocker lashed ...and ONLY turning the engine over in
the direction of rotation (ClockWise).

using light checker type springs will make you flycut pistons
approx. .030" more than necessary other words, what ever
valve-to-piston clearance you check with lite-springs, when the
engine is fully assembled with the real springs, it will have
approx. .030" more clearance !

using lite-checker springs will be a "SAFER" way to check and will
be a good method to use for a beginner engine builder !!!

I still use the strips of modeling clay about 1" square and .2" (two tenths thick) but one thing everyone forgot to mention so far is that you need to spray the piston and valve and clay strips with WD-40 to ensure the clay does not stick to any parts, otherwise the clay will tend to stick to the valve and piston allowing them to push the clay between them durring the compression of its surface by the valve (exactly what its there for) and PULL ON THE SURFACE of the clay as the valve moves away durring seperation (because the clay tends to stick ever so slightly as the parts pull away from each other if you don,t)which tends to give a false slightly greater than correct clearance measurement
most people tend to tell me Im wrong about that untill they try it both ways yeah the differance is usually minor but five to 10 thousands differance is not rare if the parts are clean and dry versus sprayed with an oil mist
The clay method is probably the best as mentioned, when the engine is apart. If your engine is together, ie. just a cam change, the solder method saves having to pull the cyl heads off of the engine..
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