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Old 09-04-2009, 09:22 AM
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Sbc Timing help.

I was swapping cams in my 350 and i lined the gears dot to dot and put the timing cover back on, how can i be sure that i am not 180 out (haven't put the distributor in yet, and how can i make the engine fire at first crank.

All help preciated.

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Old 09-04-2009, 09:38 AM
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Quote:
Originally Posted by monzter
I was swapping cams in my 350 and i lined the gears dot to dot and put the timing cover back on, how can i be sure that i am not 180 out (haven't put the distributor in yet, and how can i make the engine fire at first crank. All help preciated.
Remove #1 spark plug. Put a wrench on the crank bolt and turn the motor clockwise while your buddy holds his thumb over the plug hole. When he begins to feel compression on his thumb, you should be watching the harmonic damper. Continue turning the crank and bring the TDC mark on the inertia ring of the damper up to the "0" mark on the timing tab on the timing cover. This will put #1 at TDC on the firing position. Drop the distributor in, with the rotor pointing at the 5:30 O'Clock position as you stand at the front of the motor. Run the #1 plug wire from the cap at this 5:30 position on the cap, then going around the cap clockwide, plug in the remainder of the plug wires in the firing order 1-8-4-3-6-5-7-2. Make sure the battery is fully charged and the carb bowls are full of fuel and you have hot to the coil.

You might want to review this list of things I compiled to insure a good installation for flat tappet cams....

DISCLAIMER: THE FOLLOWING INFORMATION WAS GLEANED FROM MANY DIFFERENT SOURCES. SOME OF IT MAKES SENSE TO ME AND SOME OF IT DOESN'T. USE WHAT YOU THINK IS REAL AND THROW OUT THE REST OF IT. I HAVE NOT USED ALL OF THE SUGGESTIONS LISTED HERE. THROUGH THE YEARS, I HAVE ACCOMPLISHED MANY SUCCESSFUL FLAT TAPPET CAMSHAFT BREAK-INS, BUT I HAVE ALSO ROACHED A FEW. USE THIS LIST AS A GUIDELINE SO THAT YOU REMEMBER TO CHECK ALL THESE THINGS WHEN INSTALLING A NEW FLAT TAPPET CAMSHAFT. DO NOT TAKE EVERYTHING POSTED HERE AS GOSPEL. IF THE MANUFACTURER OF THE CAMSHAFT YOU'RE USING RECOMMENDS PROCEDURES THAT DIFFER FROM WHAT IS SHOWN HERE, USE THE MANUFACTURER'S RECOMMENDATIONS TO THE LETTER AND DISREGARD THIS INFORMATION.

Mistakes that may "frag" a flat-tappet camshaft and lifters.

1. Failure to remove all rust-preventative from cam and lifters with solvent once you get them home. (This advice does not include removing coatings applied at the factory such as phosphates. It is only suggesting to remove rust-preventative grease that may or may not have been applied to the cam/lifters to prevent rust in storage. This grease will not have the extreme pressure characteristics that Molybdenum Disulphide has and should be removed so that MD can be applied properly. MD is the black, tar-like extreme-pressure grease that is recommended by some camshaft manufacturers to be applied to the lifter crowns/cam lobes for initial camshaft break-in).

2. Failure to wash the cam and lifters with hot soapy water to remove the remainder of rust-preventative not removed with solvent. CAUTION; WASH ONLY THE CROWN OF THE LIFTERS. (THE VERY BOTTOM OF THE LIFTER WHERE IT CONTACTS THE CAMSHAFT LOBE). DO NOT ALLOW WATER TO GET INTO THE INTERIOR OF THE LIFTER BODY. BE VERY CAREFUL HERE IF THE LIFTER HAS AN OILING HOLE THAT HAS BEEN EDM'D INTO THE CROWN TO PROVIDE OIL FROM THE INTERIOR OF THE LIFTER BODY TO THE CAMSHAFT LOBE. Dry the cam and lifter crowns thoroughly with hot air from a hot air gun or hair dryer to remove all traces of moisture before applying Molybdenum Disulfide.
WARNING: DO NOT USE ANY ABRASIVE MATERIALS SUCH AS SCOTCHBRITE PADS OR SANDPAPER OF ANY KIND TO ACCOMPLISH THESE SOLVENT AND SOAP CLEANING OPERATIONS. USE ONLY SOFT, CLEAN RAGS. THE WHOLE INTENT OF CLEANING THE CAMSHAFT IS SO THAT WE CAN REMOVE RUST-PREVENTATIVE OILS AND GREASES THAT MIGHT HINDER GETTING DOWN TO THE BASE METAL IN ORDER TO PERFORM OPERATION #3 SHOWN HERE.

3. Failure to properly massage an extreme pressure lubricant such as Molybdenum Disulfide into the pores of the metal on all lobes and lifter faces. Moly will actually bond with the metal and give maximum protection to the lifter crown/lobe.

4. Failure to use an extreme pressure lubricant additive to the engine oil for camshaft break-in.

5. Failure to use the proper valve springs for cam break-in. You can't use the 300 lb over-the-nose springs that you'll eventually use in the motor and expect the cam to live at break-in. Assemble the heads with stock or weak single springs to break in the cam, then use one of the many tools available to change the springs with the heads on the motor. Alternately, assemble the heads with the springs you will run and use reduced-ratio break-in rockers, then change out the rockers after break-in. These rockers are available from Crower in different ratios for different motors. A popular ratio for a small block Chevy would be a 1.3:1 rocker. In other words, let's say the lift at the cam is 0.350" and the theoretical lift at the valve with 1.5:1 rockers is 0.525". Using the 1.3:1 rockers would result in lift at the valve of only 0.455", thus reducing stress at the camshaft/lifter interface during the crucial break-in period.

6. Failure to check for valve spring coil bind at max lift.

7. Failure to check for retainer to valve guide/seal clearance.

8. Failure to check for binding at the rocker/stud interface.

9. Failure to check for piston/valve clearance..... 0.080" on the intake and 0.100" on the exhaust is considered by many to be the minimum clearance acceptable. You will probably find the closest near-miss at the exhaust valve on overlap, when the piston is chasing the exhaust valve back onto its seat.

10. Failure to run the motor at high rpms (2500 or higher, alternating 1000 rpm's up and/or down to allow the crank to throw oil in different places at different revs) for the first 40-45 minutes of its life. NO IDLING. NO IDLING. NO IDLING. The motor should not be run at less than 2500 rpm's for a minimum of 40 minutes. If a problem develops, shut the motor down and fix it, then resume break-in. The main source of camshaft lubrication is oil thrown off the crankshaft at speed, drainback from the oil rings and oil vapors circulating in the crankcase. At idle, the crank isn't spinning fast enough to provide sufficient oil splash to the camshaft/lifters for proper break-in protection.

11. Failure to clearance lifters in their bores so that they spin freely. Lifter clearance should be 0.0012" to 0.002", with 0.0015" (one and one/half thousandths) considered close to ideal. Too loose is as bad as too tight.

12. Failure to initially adjust the valves properly. Using the "spin the pushrod until it feels tight" method will normally result in valves too tight. Jiggle the pushrod up and down with your thumb/forefinger until all play is removed, then turn the rocker nut 1/2 to 3/4 turn to set the preload.

13. Failure to inspect the distributor drive gear for wear. Too much wear can allow the cam to walk in its cam bore and contact an adjacent lifter.

14. Failure to have everything ready for the motor to fire on the first few turns. Fully charged battery, good starter, known-good carburetor with full fuel bowl, source of fuel to the carburetor to allow minimum 40 minutes of uninterrupted running. Ignition timing set. NO GRINDING ON THE STARTER. NO GRINDING ON THE STARTER. NO GRINDING ON THE STARTER.

15. Failure to prime the oiling system prior to firing the motor. Prime until you get oil out of the top of each and every pushrod. Observe the oil pressure gauge to be sure pressure is registering. Priming will aid lubing the valvetrain at initial startup. It's the last area of the motor to get lubed on dry start.

16. Failure to use new lifters on a used cam. Used lifters should only be used on the very same cam, in the very same block and in the very same positions they were removed from. Chances that the lifter bores will be machined on the very same angles on a different block as the block the lifters came out of are about equal to you hitting the lottery.

Now, this last bit of advice comes from Racer Brown, world-renowned camshaft manufacturer/engineer who ground the hot cams for Chrysler Corporation during the horsepower wars of the 60's.
"Overfill the crankcase by at least 4 or 5 quarts of oil so that the oil level comes to within an inch of the top of the oil pan. Install a set of fairly hot spark plugs with a gap of 0.050" to 0.060" to prevent oil-fouling of the plugs, which is otherwise inevitable under no-load conditions with all the extra oil aboard. During this operation, we want near-maximum oil flow, together with a maximum of oil vapors and liquid oil thrashing about in the crankcase so that the cam lobe and lifter interface lubrication is considerably better than marginal."

This advice from the Racer is too scary for me, but I included it so that you know someone, somewhere has done it.

Just a note to make you aware of the loading between the camshaft lobe and lifter crown. That pencil-point of contact, if carried out to a square inch, would be somewhere between 250,000 and 300,000 POUNDS PER SQUARE INCH.
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Old 09-04-2009, 11:35 AM
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Quote:
Originally Posted by monzter
I was swapping cams in my 350 and i lined the gears dot to dot and put the timing cover back on, how can i be sure that i am not 180 out (haven't put the distributor in yet, and how can i make the engine fire at first crank.

All help preciated.
If you installed the timing gears and chain with the timing dots at 12 and 6 oclock "dot to dot" and have not turned the crankshaft since this ...you are at TDC fireing on #6 cylinder.
You can:

#1 install the distributor with the rotor pointing to #6 on the cap.

or # 2 First rotate the crank 1 complete revolution to TDC and then install the distributor with the rotor pointing at #1 on the cap.
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Old 09-05-2009, 04:46 AM
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Ok thanks for the help, I got her runnin at first crank (no problem)
But here's another thing, when i was brakeing the camshaft in the headers started to glow red (probably to retarded timing) so i advanced the timing a little, and then the idle speed went up to around 3000 rpm's so i tried to ease up on the idle screw (holley 600) but it didn't do a thing, and when i start the engine the idle speed imediatly goes to 2500 rpm, and wont go any lower !!! what is my problem ?

Best regards.
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Old 09-05-2009, 05:35 AM
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I'll bet you are using very light tension advance springs. This tends to cause the timing to jump around at low rpm.
Allowing the idle to flair up and down.
With vacuum advance disconnected and using a timing light, set the timing to 34-36deg while reving the engine high enough to observe the mechanical advance maxing out. 3500-4000rpm.

When you do this what is the resulting timing at idle? 700-900rpm.
Then slow the engine idle way down.
What is the idle timing at what ever rpm is the slowest you can run the engine at? 500-600rpm (base static timing) Is it the same or different?
What camshaft is in this motor?
Auto trans? converter stall speed?
You probabily need to modify the distributor advance curve.

Last edited by F-BIRD'88; 09-05-2009 at 05:44 AM.
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Old 09-05-2009, 05:46 AM
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I am currently brakeing the camshaft in, that's why i want to lower the idle speed to about 2000 rpm, so i can brake the cam in at 2000-3000 rpm, safely and so that the headers are not glowing red after 2 minutes.

It was ok before i teared the engine apart, it just ran 600-700 rpm idle speed.
The camshaft is 272 Crane Powermax.
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Old 09-05-2009, 06:00 AM
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Do not guess at the timing or try to set it by ear.
Your "ear" ain;t that good.

get a timing light.( a advance type is required unles you have a balancer timing tape to slow full advance.)...Get a buddy to help you. While reving the engine at 3000-4500rpm set the timing to 34deg with vacuum advance disconnected.
Shut the car off.

Tighten down the distributor. without upseting the timing setting.
Reconect the vacuum advance (To ported vacuum) restart the car and continue to run in the cam. 3000-4500rpm up and down
Do not allow the engine to idle.
UNless you have a massive vacuum leak the headers will not glow once the timing is set correctly. Break in the cam at more than 2000rpm and vary the rpm up and down.
Do not allow the engine to idle. for the first 45minutes.
Make sure the rad and cooling system is full of water/coolant and lots of airflow thru the rad. Get an extra house/shop/ box fan in front of the car if nessessary.
The cam should not need more than minor timing curve adjustment but do not use light/low tension distributor advance springs.

is this a new timing cover/timing tab/balancer?

Last edited by F-BIRD'88; 09-05-2009 at 06:07 AM.
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Old 09-05-2009, 06:05 AM
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No the ballancer and timing cover is original gm unit.
Is it ok to rev the engine to 4000 rpm when brakeing the cam in (to set the timing)

And do you have a clue why the engine goes immediatly to 2500 rpm and just stayes there ?

Best regards.
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Old 09-05-2009, 06:11 AM
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rev it as high as you wish up and down but not below 2000rpm.(keep it under 6000rpm). More rpm = more oil flow and splash on the cam. Do not let the motor over heat. Do not run the motor with retarded timing. Make sure the cooling system is full.

The timing is not set and the engine is flairing on the vacuum advance curve and mechanical advance curve. set the timing correctly with a timing light.
possible vacuum leak look for a open vac port on the carb base or manifold or p/brakes.
Connect the PCV correctly.
Timing should be 12 to 16 base at idle (+/-700rpm) and 34-36 at max mechanical advance 3000-3400rpm
Vacuum advance should be a maximum of around 12 to 15deg at max on the hyway.

Last edited by F-BIRD'88; 09-05-2009 at 06:16 AM.
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Old 09-08-2009, 05:57 PM
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Ok, I've found out that i forgot to close vacuum port on the carburetor base plate and thats probably why the engine just rev'd to 2500 rpm's and stayed there.

So i have original timing tab on the timing cover and stock harmonic balancer, which way is the best to see that the engine is at 36 when i'am timing the engine in ? do i just have to aprox it out or what ?

Best regards.
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Old 09-09-2009, 05:44 AM
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Quote:
Originally Posted by monzter
Ok,
So i have original timing tab on the timing cover and stock harmonic balancer, which way is the best to see that the engine is at 36 when i'am timing the engine in ? do i just have to aprox it out or what ?

Best regards.
That does not mean the timing tab accuratly indicates true TDC at all.
Verify True TDC using a piston stop. When you verify true TDC and find that it is off a bit, re-mark or move the timing tab TDC point.
Then, mark the balancer for 36 BTDC.

I have found many OEM stock balancers/ timing tabs to be off a bit.
If its really off mark either you have the wrong mismatched timing cover/balancer pair or the balancer outer ring is slipped. (Replace)

36 is exactly 1/10th around the circumference of the balancer.

Or get a Mr. Gasket balancer timing tape. Or get a advance type timing light.
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Old 09-09-2009, 06:23 AM
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ok, so when my 36* marker lines up with the zero marker on the timing tab, that means i'am good to go right ?
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