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Timing Question

6

69redvette

Guest
When you check / set total advance, do you still disconnect the vacuum advance hose and plug it?

I have a Summit 355ci / 400hp motor in my '69. I'm not sure where to set timing. On one of the spec sheets I have with the motor it says that at cam break in when the motor is running at 2,000 - 2,5000 rpm, set the total advance to 34 degrees. I assume that's ATDC, right?

I don't know where to set the timing at idle...( 1,000 rpm ) I searched thru older posts but it's still unclear to me. :confused
 

Jack

Well-known member
Joined
Dec 27, 2000
Messages
1,825
Location
Florence, SC (Timmonsville SC)
Corvette
71 War Bonnet Yellow VERT 71 BH Blue CPE (SOLD)
If cam is NEW ... don't idle at all or try to set idle until after break in per instructions ... if NEW you must go to 2-2.5K rpm immediately.

Depending on the springs' tension in the mechanical advance portion of dist ... full mech advance will probably be fully in (fully-advanced) by somewhere between 2K-3K ... can't make closer estimate cuz I dunno which springs/which dist you have.

Yes you disconnect the vac can & plug-off the motor side & bring the motor up to about 2.5-3K rpm ... set the timing to 34 degrees Before Top Dead Center ... NOT After. Do you have a method to see where 34 BTDC is??? ... such as an adjustable timing light ... or does your damper have that range of timing marks on it?

Once you have completed cam break in ... idle is probably about 700-900 ... depends on your cam?

Somebody else chime in here too if we're missing something ... this is a break-in!

JACK:gap
 
6

69redvette

Guest
Thanks for the reply Jack. I should have mentioned that this is not a new motor. It's been broken in for about 3, 000 miles now. The only mention of any timing setting on the paperwork is in the break in section.

OK... so it's 34 degrees Before TDC. Glad you straightened me out on that, Thanks. Is setting the total advance good enough? Like I said, I don't have any spec for idle. Any ideas on what that could be?

Components of motor are:
Trick Flow Twisted Wedge alumium heads 64cc
9.8:1 compression
Comp Cams solid lifter 500/500 lift
Edlebrock Victor Jr. intake
Holley 750cfm double pump
also has Fluid damper with full scle so setting timing at 34 degrees Before TDC is no problem

Joe
 

Jack

Well-known member
Joined
Dec 27, 2000
Messages
1,825
Location
Florence, SC (Timmonsville SC)
Corvette
71 War Bonnet Yellow VERT 71 BH Blue CPE (SOLD)
Hey Joe (great Hendrix tune):
Cool ... so already broke in ... still dunno which springs in dist ... if ya have a spec shhet on yer dist setup ... maybe it shows the curve ... & where full mech adv is fully in (might be 2.4K 2.6K, 2.8K ???) ...short of a spec sheet ... twist it to 3K & set it at 34 BTDC with the vac can disconnected & motor plugged. Seems you gotta nice heavy-hitter under yer hood! G'luck!
JACK:gap
 
6

69redvette

Guest
Thanks, yeh it's a screamer. I forgot to mention the most important part. It has MSD Billet dist. with medium springs. Hendrix is great to listen to in a '69. :beer

OK, I'll set to 34 degrees BTDC at 3K.

Thanks!
 

Jack

Well-known member
Joined
Dec 27, 2000
Messages
1,825
Location
Florence, SC (Timmonsville SC)
Corvette
71 War Bonnet Yellow VERT 71 BH Blue CPE (SOLD)
Joe:
according to my MSD info ... medium springs are blue. With blue springs, Full mechanical advance could be in as early as 2.5K or as late as 3.7K ... depending on which color mechanical stop bushing is installed. With blue springs ... and black bushing (all in at 2.5) ... blue bushing (all in at 2.8) ... silver bushing (all in at 3.4) ... red bushing (all in at 3.7).
JACK:gap
 
6

69redvette

Guest
OK Jack, I'll stick my head in there tomorrow and see which stops I have and double check the spring color and give it a whirl. Thanks again.

After that... I'm gettin ready to head out to Englishtown for the Nationals on Saturday. C'MON AND BRING ON THE PRO STOCKS, FUNNY CARS AND DRAGSTERS. GOD I LOVE THAT STUFF. :BOW THERE'S NOTHING LIKE THE SMELL OF NITRO METHANE IN THE MORNING. I think I stole that from a movie.

Have a good weekend!

Joe
 
6

69vettester

Guest
this is a link to how I set up the probillet for my 69 small block.
Maybe it will clear up any confusion.
http://weavermill.com/dist/dist.htm

my setup has always run great, havent touched it in 20k miles.
Good luck,
Tom
 

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