TDC or 4 TDC?

[Randall Barringer]

My tag near the firewall says TDC. My Chilton's manual says 4 BTDC. I haven't checked my real service manual yet.

thoughts?

1968 Scout 800 2wd, 3 spd
196 engine with pertronix and a Michael Mayben carb rebuild

thanks,

[76 xlc]

I'd advance it 'til it detonates, then back it off two degrees.

[Dave Nuenke]

Depending on your altitude I run my motors at 10-15 deg BTDC. Where I live it's about 3,000 ft. and I usually shoot for 12 deg BTDC.

Dave

[Doc Stewart]

The IH SV8s are truck engines, designed for heavy loads and constant effort. Under those conditions, TDC or slightly advanced - as far as 4* BTDC - However, in the Scouts, Light Line pickups and Travelalls, the engines almost never work that hard so you can advance the timing more.

There is no hard and fast rule for advancing timing. " Advance until it pings and back off a bit" is a useful rule. Temperature, elevation, condition of your electronics all contribute. Some engines at higher elevations will tolerate 12* BTDC.

Be sure the engine is not pinging under full throttle!
Set timing with the distributor vacuum hose off and plugged.

[76 xlc]

Hey Doc,

I believe the OP had a four banger, but since it's half a SV, I figure the same rules apply.

Waddya think?

[Randall Barringer]

Well, I've been from TDC to about 10 to the left of TDC when looking down at the scale. Would this make it 10* after TDC or 10* BTDC? I know this is simple stuff, but I just haven't had such a problem timing an engine before. I want to make sure I'm doing this correctly.

Right now it idles and starts fine, but sounds real bogged down and runs like trash when there is a load on it.

This all started when I went for a ride and it started acting weird. I got home and discovered that the distributor was loose. This is a new-to-me scout so I'm still learning about it.

When I time it I am removing and plugging the hose from the dist. Idle is around 425 or so.

any help appreciated

[Robert Kenney]

34* total all in peak, but that is tough to measure without a dial back timing light. You will be safe on todays fuel at 8-10 BTDC the way you have things blocked off at 425 rpm.

[Randall Barringer]

So BTDC means to the left of the zero when looking down at the scale? Or to the right when looking down?

I know it's a very basic question, but I need to get this thing fixed.
If it's to the right of the zero, then why does the scale only go to 5*?

thanks,

Randy

[Jay Tabor]

the 'before' side of crank scale goes up to 25*, after is only 5*.
advancing it- the engine speed will increase.
look at it and rev engine while shining timing light, which way do the marks go? thats the advance.
right left up down is all relevant to the way your facing.

[IH64Scout]

good point doc, i set the scouts around 12. when i got my pickup i threw it to 10, first good load i realized it was a bad idea, dropped it to 5 and i'm good now!

-Jon