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Old 01-15-2010, 01:02 PM   #1
Michael Mayben
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Join Date: Jan 2007
Member Number: 10
Location: Leaburg, Orygone
Age: 72
Posts: 7,156
Default IH SV Engine Distributor Stab

The question regarding "how do I stab a distributor in my 266/304/345/395 engine?" comes up over and over in our "ignition tech" sub-forum, so I'm putting up a stickee here that addresses this issue.

This is a cut and paste of text from a few other threads so it's not "new" information but hopefully this will put it all in one place for easy access!

First off, a brief description of why we must use cylinder #8 for our "reference" cylinder when placing the crankshaft hub/harmonic balancer in a static position:

"why does the hash Mark on the crank hub/balancer reference cylinder #8???? Simple...the I-4/sv motor balance scenario originally used a "crank hub", not a "harmonic balancer". What we call a "mutton chop" hub or a "cutaway" hub.

Due to the crank throw indexing and the way the engines were balanced, there is nothing but air on the hub when #1 cylinder is at tdc on the compression stroke! No place to stamp a timing Mark!

The "harmonic balancer" system was phased in on some 345 engines over time, and also used exclusively on the 392 version. But look at the harmonic balancer...it still has the "mutton chop" segment behind the vulcanized hub.

If ya go to this link:

the ultimate IH fourbanger

and look at post #37, you will see a pic of a "crank hub", that one is matched to one dedicated 152 rotating assembly, the balance drillings are evident. That exact same "raw" hub was used for 196,266, 304, and "some" 345 apps over the years...but...each one was drilled for it's mating engine assembly. Ya don't mix and match these parts or swap 'em around without expecting engine balance to go to hell. The hub in that pic is actually going onto a 196 crankshaft as part of a stroker engine build. Once all the parts are gathered and the block is bored to the pistons we're gonna use, then the entire rotating assembly will be balanced along with the clutch and flywheel set that's going behind it.

Yeah...ihc could have designed a totally different "system" for the crank hub/balancer...but why reinvent the wheel for an engine where by the mid-1970's the entire focus was on making 'em meet emissions and reducing manufacturing costs across the board. IH mechanics had been used to working from #8 tdc since day one, who gave a shit about that, if you were "trained" ya just knew this stuff!

#8 cylinder is at top dead center on the compression stroke when both of the rocker arms for that cylinder allow the valves to be seated, you should be able to feel a small amount of "slack" in both rockers simultaneously when in that position"

Once you have established the correct crankshaft/camshaft position for sticking the distributor in the hole, then use this procedure to stab it:

"align the timing Mark on the crank balancer to tdc on the compression stroke for number eight (8) cylinder. As you come to tdc, stop rotating just before the timing Mark aligns, do not go past the Mark and then come back to it! Important!

Make certain that the oilite bronze bushing is in correct position in the block just above the oil pump drive, it must be there otherwise that distributor will not last more than 10 minutes once the engine cranks.

Then align the distributor rotor with #8 plug wire terminal on the cap and rotate the distributor about 1/8th of a turn counter-clockwise and then drop into position while ya wiggle the rotor to allow the gears to mesh, the oil pump drive tang will go into it's slot first and then the drive gear will slide into mesh with the cam gear. The rotor tip should now be pointing at the #8 cap terminal. It won't be perfect alignment until ya rotate the distributor a tad.

Next just snug the distributor holdown in place to allow the distributor to be rotated by hand so you can set the timing.

Next up, re-wire the distributor cap starting with #1 cap terminal which is the terminal just to the right of #8. The firing order again is...1, 8, 4, 3, 6, 5, 7, 2. So follow that pattern around the cap, plugging each wire into it's appropriate cap terminal and then to the spark plug for that cylinder. The distributor on this gear-drive camshaft/crankshaft drive system rotates in a clockwise direction when viewed from the top."

For adjusting the distributor timing for any engine when a timing light is not available, try this procedure:

Are yawl ready??? If not here's some training ya might need to prepare:


Last edited by Michael Mayben; 01-15-2010 at 01:44 PM..
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