Rotate the distributer 180 degrees = 30% increase ?

[Former member Yoder213]

70 k20 with 292 bored to a 318.

When I bought the truck it ran AWESOME. PO had it tuned up nice. when my alternator went out I went to a friends shop to have it looked at by someone who's job it is to know what's right or wrong. They replaced the alternator, and noticed my distributor cap was rotated 180 degrees.
When I mentioned this to the PO (girlfriend's dad), He said that you can do that and its a 30% increase of performance.

I searched the site and web and wasn't able to find anything, anyone else hear or know of this? (He is a fabricator and electrician and has his own business,).

Since rotating it back to stock position its never ran the same....

[kikkegek]

sounds like a bad april 1st joke!

cars I have seen with 180 degree false distributor only ran idle and cold not accelerate without backfires

[imjeff]

Other than plug wire routing, it makes NO difference where the rotor indexes #1. The base should sit with the vacuum pot to the passenger side for vacuum hose routing and adjustability, but technically could go anywhere it will fit. There is absolutely no difference in performance between how the factory installed it and "180 out". It all boils down to the rotor's relationship to the towers. You can drop the distributor in however it falls, roll to #1 on compression, pick the tower that the rotor is pointing to and make it #1, regardless of whether it points left, right, forward or backward.

[BADAZ chevy guy]

Put the dist in 180 deg out and rotated the cap instead of pulling it out and turning it the right way around.

[imjeff]

Originally Posted by Yoder213

70 k20 with 292 bored to a 318.

When I bought the truck it ran AWESOME.

Forgot to mention, it ran AWESOME...most mechanics won't try to "fix" awesome. Beware of those who would fix the unbroken!

[Former member Yoder213]

Darn I forgot if it was the cap or the distributor, 80% sure it was the cap that was 180 out

[GASoline71]

Originally Posted by BADAZ chevy guy

Put the dist in 180 deg out and rotated the cap instead of pulling it out and turning it the right way around.

Yup... no performance gain at all. Just laziness to install the distributor right.

Gary

[Former member Yoder213]

and CHEVY GUY, is that what the PO did or? is that to get the increase or fix what the PO did?
I apologize for not understanding very clearly.

[BADAZ chevy guy]

it sounds like he put the dist in, in the wrong position and just turned the cap to fix the problem rather then pull the dist back out and reinstall it in the right position.

[imjeff]

Ok. This always degrades into a "right way" debate that is pointless. Your motor will run best at the timing it runs best at, regardless of which cap tower supplies the #1 plug. You cannot rotate the cap because it is indexed. If you want your plug wires routed exactly like they were at the factory and consider that "right", knock yourself out. I tend to do that myself. I won't call someone "lazy"just because they didn't ape the factory, unless I want to argue about ridiculous and trivial matters. Bottom line, as I said, other than plug wire routing it makes no difference. Think about how your truck ran "wrong" compared to how it runs "right". It's the timing!

[GASoline71]

I have bought 3 pre-1979 trucks in the last 30 years with SBC's in them... ALL of them had the wires on the distributor 180 degrees out because the PO was... lazy. To each his own I guess.

Gary

[Former member Yoder213]

That's the issue, I've had it in a shop for 4 hours trying to figure the best timing using this site as a reference for the ball park and got it pretty close, it runs GOOD now,
I wonder if I'm just getting used to the engine and I've had cooling off period


Thanks everyone

[brad_man_72]

I turned the distributor on my boat so the brand nameplate faced foreward/the back of the engine. Timed it and it runs exactly like it did before...... is that because my engine is facing the back of the boat or is something wrong with the motion of my ocean?

[crazy longhorn]

It brings back memories Back in the day, one of my buds dropped an old points dizzy ,180 off & his bro laughed..."bet you wont have that running in the next 5 minutes". He said "watch me", & cut the square peg off the rotor, turned it 180, & fired that pig up! Too damn funny, But it does not matter where #1 wire starts....as long as you are TDC compression stroke, & you have enough room to move the dist to time it properly? CrazyL

['68OrangeSunshine]

Originally Posted by Yoder213

70 k20 with 292 bored to a 318.
....

318 Cubic Inches on an HD/TD block? Really? Did the PO tell you the engine displacement?
While mathematically possible, an overbore of .185" would yield a 320 CI block out of the L-25 series 292 L6, but it would have serious water jacket issues. Cylinder diameters greater than 4.00" are possible in non-street engines with filled water passages in the block and head-only cooling. The cylinder walls would have to be sleeved for this oversize.
Santucci's displacement chart stops at .125'' -over = 311 CI. He recommends cylinder wall sonic checking for anything .080" overbore.
The practical limit for endurance racing is .060''-over [3.935"] @ 301 CI, he says.

[storm9c1]

If you take a good running engine, pull out the distributor, leave the cap and wires alone, turn the rotor 180 degrees and stab it back in, the engine will not run or will run very badly (backfires, pops, etc). This could be fixed by redoing the plug wires 180 degrees, or breaking the tab on cap and rotating it 180 degrees, or yanking and stabbing the distributor again with the correct clocking. As mentioned, TDC at the compression stroke is key.

A common mistake is TDC at the exhaust stroke. As long as the cylinder fires at the compression stroke, it doesn't matter which way the distributor is turned or clocked. And there is no performance gain to be had by messing with this (except by way of timing advance).