396 Timing - Chevelle Tech
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post #1 of 15 (permalink) Old Jul 24th, 08, 12:34 PM Thread Starter
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Kevan
 
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396 Timing

I was wondering if anyone could help me. I just purchased a 1967 chevelle SS 396 that has a 1971 396/402 that has just been rebuilt. It only has 1/2 hour of run time on it for breaking in the new cam. It is bored .60 over, standard pistons with 454 heads on it that are also redone with roller rockers. I am trying to get it to run well, but I am not sure where the timing should be at on this motor. It does have a Edlebrock performer kit in it with a slightly over stock cam, aluminum intake, and carb. I am also not sure if the carb is set right, so any advice on how to set this edlebrock carb would be great.

I tried to time it last night, but I did not notice any change with the vaccum advance plugged in or not. Not sure what that means either.

Any help here would be greatly appreciated.

Thanks for your time.

Kevan
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post #2 of 15 (permalink) Old Jul 24th, 08, 1:01 PM
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George
 
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Re: 396 Timing

What have you been doing since Aug 2005 Kevan?
Lurking, not posting?

Any idea of the compression for this beast?

Actually, the Performer cam at 218/228 deg dur @ .050is quite a bit more stout than the weenie stock hyd cam or the not-so-spectacular HP hyd cam 214/218

Before SWHEATON chimes in....I'll steal his thunder!
Disconnect the vacuum to the distributor, plug the carb. Check your base timing with idle set to 800 rpm. Factory spec is usually somewhere around 4-8* before top dead center.
Way low. You will probably want 36* total timing, all advance in by 3000 rpm. Your exact combo may like 12 initial plus 24 mech adv or 18 initial and 18 mechanical. Your combo sounds rather mild. You may need a shop to 'recurve' your distributor if you have a stock unit. Most aftermarket units have some tuning features.
Search "IGNITION 101" or any of Scott numerous posts on getting your timing set-up.
I learned most of this the hard way before Team Chevelle.....

I have had an Elelbrock Thunder AVS 800 several years. Best advice is to read the tuning instructions a few times....each carb comes with a set plus online
http://www.edelbrock.com/automotive_...ers_manual.pdf
too much stuff for me to type, easier if you read and understand before digging in there.
Sadly, most users do not get friendly with their Eddy carbs...

There is ported and non-ported/direct vacuum. See this in the instruction manual.
Ported vacuum does not draw at idle so your timing does not change (much) unplugging the distributor compared to if the vacuum was hooked to direct vacuum.

My Eddy became clogged so the 3310 Holley went back on my car. The 3310 died the other day, so the repaired Eddy went back on. Later today, I'm gonna test my Eddy 800 vs a 4780 800DP Holley around town....

George Kettler
o SOLD 8/2016 my beloved 1970 Elky 496.
o 68 Vette 427/M-20/3.36 23 year owner
http://public.fotki.com/kettbo/gearhead/
o 68 Camaro Vert 327 project, painted, assembly stage http://www.camaros.net/forums/showth...183654&page=55
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post #3 of 15 (permalink) Old Jul 24th, 08, 1:33 PM Thread Starter
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Kevan
 
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Re: 396 Timing

George,

Thanks so much for the post and the great infomation. It has been busy since 2005, but I now have this car and a 1970 SS 396 true SS builder car less motor and tranny. I am sure I will posting a lot from this point going forward.

Kevan
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post #4 of 15 (permalink) Old Jul 24th, 08, 1:35 PM Thread Starter
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Kevan
 
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Re: 396 Timing

Oh ya, on the compression, it is lower due to the 454 heads that have a larger chamber on them. I will check the compression tonight and post then. Thanks for the help.

Kevan
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post #5 of 15 (permalink) Old Jul 24th, 08, 1:53 PM
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George
 
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Re: 396 Timing

The 71 402 had small dome pistons and the 820 heads they came with made 9:1 (nominal).
All 71 heads had open chamber hence lower compression
Get me your head casting number also
What distributor? Stock points? HEI? MSD?

George Kettler
o SOLD 8/2016 my beloved 1970 Elky 496.
o 68 Vette 427/M-20/3.36 23 year owner
http://public.fotki.com/kettbo/gearhead/
o 68 Camaro Vert 327 project, painted, assembly stage http://www.camaros.net/forums/showth...183654&page=55
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post #6 of 15 (permalink) Old Jul 24th, 08, 3:05 PM
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Smile Re: 396 Timing

fotr a mild perf cam in a 396 you need approx 18 deg base timing set with idle low like 600-650 rpm to keep mech adv from partially activating when setting base timing,along with the vac adv unhooked/plugged.

Then rev motor to 3krpm with 18 base timking to see if the total is at 36-38 ,if yes and total doesnt go over 38 over 3k rpm your good to go.

But if total is over 38 at 3k rpk or highe rpm then you need to have the mech adv in the dist recurved for 18 deg in by 2800rpm ,then 18 base + 18mech = 36 total .

You need a vac adv hooked to full vac all the time too for street use.

Dont forget to reattach the vac adv to full vacuum all the time and reset idle speed & mixture too post any timing adj.

Scott

SCOTT
1969 CHEVELLE SS396,ORIGINAL #'S MATCH,GOT IN 1978,(In 2001 rblt/bored original 396 .030 to 402)/M20/12BOLT/3:31'S
2002 MAXIMA (DAILY DRIVER/1 owner,GOT 3/2013 w-44k miles)
2009 HD ELECTRAGLIDE CLASSIC ULTRA (GOT 11/14 W-9,700 miles)
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post #7 of 15 (permalink) Old Jul 24th, 08, 5:21 PM Thread Starter
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Kevan
 
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Re: 396 Timing

Jegs HEI distributor. I just timed it to what you recommended. So far, So good. Thanks for the help

Kevan
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post #8 of 15 (permalink) Old Jul 24th, 08, 8:33 PM
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Smile Re: 396 Timing

Opps,sorry George,didnt see you already had it covered untill now after i had already posted.

Anyway,to me there is no thunder to be had in any of this stuff,all i get are dirty looks from the wife because of the time i spend trying to help other fellow t/cr's sort out some of thier chevelle problems & thats about it along with an occasion thanks from a t/c member.

I guess i keep doing it becasue i am into these cars/engines & i like to help out others in this same hobby that may not have as much experience yet but are willing to ask questions/learn/and then follow our instructions to eventually/hopefully fix the problem.

Scott

SCOTT
1969 CHEVELLE SS396,ORIGINAL #'S MATCH,GOT IN 1978,(In 2001 rblt/bored original 396 .030 to 402)/M20/12BOLT/3:31'S
2002 MAXIMA (DAILY DRIVER/1 owner,GOT 3/2013 w-44k miles)
2009 HD ELECTRAGLIDE CLASSIC ULTRA (GOT 11/14 W-9,700 miles)
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post #9 of 15 (permalink) Old Jul 24th, 08, 9:02 PM
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Jim
 
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Re: 396 Timing

Quote:
Originally Posted by SWHEATON View Post
Opps,sorry George,didnt see you already had it covered untill now after i had already posted.

Anyway,to me there is no thunder to be had in any of this stuff,all i get are dirty looks from the wife because of the time i spend trying to help other fellow t/cr's sort out some of thier chevelle problems & thats about it along with an occasion thanks from a t/c member.

I guess i keep doing it becasue i am into these cars/engines & i like to help out others in this same hobby that may not have as much experience yet but are willing to ask questions/learn/and then follow our instructions to eventually/hopefully fix the problem.

Scott
Scott,

You have helped me directly and indirectly....I appreciate it!

jim
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post #10 of 15 (permalink) Old Jul 24th, 08, 10:57 PM
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Smile Re: 396 Timing

Jim,thanks,

scott

SCOTT
1969 CHEVELLE SS396,ORIGINAL #'S MATCH,GOT IN 1978,(In 2001 rblt/bored original 396 .030 to 402)/M20/12BOLT/3:31'S
2002 MAXIMA (DAILY DRIVER/1 owner,GOT 3/2013 w-44k miles)
2009 HD ELECTRAGLIDE CLASSIC ULTRA (GOT 11/14 W-9,700 miles)
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post #11 of 15 (permalink) Old Jul 24th, 08, 11:26 PM Thread Starter
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Kevan
 
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Re: 396 Timing

Well, The car seems to run a lot better after this. I will do some reading on the carb to see if that is set properly. There does seem to be quite a bit of Black residue in the tailpipes, but it is definately running much better. I did not get to the compression test, maybe tomorrow night.

Thanks to Scott and George for their help and advice. I really appreciate it. Have a great night.

Kevan
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post #12 of 15 (permalink) Old Jul 25th, 08, 2:10 AM
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George
 
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Re: 396 Timing

Some of that black residue will go away with your new timing setup.
The engine will run better and cleaner....

Also adjust your idle mixture.
Warm-up the engine.
set the idle to 700 or there about...
adjust one idle mixture screw for the highest idle speed. then adjust the other one.
reset the base idle speed down, possibly lower than before. Adjust both screws again.
Reset the base idle
now, turn each screw in 1/16 turn IN...this greatly reduces emissions.
Reset base idle
After that, have fun!

George Kettler
o SOLD 8/2016 my beloved 1970 Elky 496.
o 68 Vette 427/M-20/3.36 23 year owner
http://public.fotki.com/kettbo/gearhead/
o 68 Camaro Vert 327 project, painted, assembly stage http://www.camaros.net/forums/showth...183654&page=55
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post #13 of 15 (permalink) Old Jul 25th, 08, 3:47 AM
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John
 
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Re: 396 Timing

Quote:
Originally Posted by SWHEATON View Post
I guess i keep doing it becasue i am into these cars/engines & i like to help out others in this same hobby that may not have as much experience yet but are willing to ask questions/learn/and then follow our instructions to eventually/hopefully fix the problem.

Scott
Scott, I owe my successful cam break-in to your sticky in Engines or Performance. I sure as heck would have rounded that thing off if I had just winged it.

Thanks to you, and others, for taking the time to answer the questions...often the same ones, with good, clear information...and patience.

I know there's a whole lot of us on this board who appreciate it.

Thanks.
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post #14 of 15 (permalink) Old Jul 25th, 08, 9:36 AM Thread Starter
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Kevan
 
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Re: 396 Timing

George, Again, thanks for the help. I will do this procedure tonight and let you know how it works.

Someday, hopefully I will not need to ask these type of questions due to the help you and others like you have provided and maybe offer some help to someone in need!!

Have a great weekend.

Kevan
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post #15 of 15 (permalink) Old Jul 25th, 08, 9:56 AM
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Smile Re: 396 Timing

John,thanks,GLAD TO HEAR YOUR FLAT TAPPET CAM SURVIVED ITS BREAKIN AND AFTER THAT TOO.

Scott

SCOTT
1969 CHEVELLE SS396,ORIGINAL #'S MATCH,GOT IN 1978,(In 2001 rblt/bored original 396 .030 to 402)/M20/12BOLT/3:31'S
2002 MAXIMA (DAILY DRIVER/1 owner,GOT 3/2013 w-44k miles)
2009 HD ELECTRAGLIDE CLASSIC ULTRA (GOT 11/14 W-9,700 miles)
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