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Old 08-31-2017, 07:42 PM   #1
Econman
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Need help setting the timing of a 305

Hi, guys! I just broke in a mildly built 305. Seeking some advice from the 305 experts, please... and please don't criticize my engine choice lol. I had a reason for going that route - the safety of a teen-ager.. ugh!

9.7:1 compression
Rebuilt 305 HO heads
Comp Cams XE256 full cam kit
Edelbrock Performer RPM intake
Edelbrock 1403 carb (500 cfm)
Stock HEI distributor
Stainless shorty headers

I used a stock harmonic balancer with the zero mark painted white but it has no numbers on it. Broke in the cam today - that went fine..

Straight headers right now and it's too loud to get a good feel for the timing.

I presume I need some timing tape... What initial timing should I start with and how much total timing should this engine need?

Thanks for any input!
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Last edited by Econman; 08-31-2017 at 08:31 PM.
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Old 08-31-2017, 08:55 PM   #2
geezer#99
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Re: Need help setting the timing of a 305

You'll need to experiment but here's some good info on figuring it out.
http://www.badasscars.com/index.cfm/...d=76/prd76.htm
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Old 09-01-2017, 12:39 AM   #3
AcampoDave
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Re: Need help setting the timing of a 305

There's no timing tab on the timing chain cover? And btw that 305 seems like it'll be pretty sweet... still be plenty o' motor for a teenager.
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Old 09-01-2017, 12:58 AM   #4
kwmech
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Re: Need help setting the timing of a 305

Is that a 350 cam spec or a 305 cam spec. May be kinda small for the compression
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Old 09-01-2017, 11:19 AM   #5
mattfranklin
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Re: Need help setting the timing of a 305

Quote:
Originally Posted by AcampoDave View Post
There's no timing tab on the timing chain cover? And btw that 305 seems like it'll be pretty sweet... still be plenty o' motor for a teenager.
2x Is it possible that the timing tab on the cover got hit with a thick coat of paint hiding the numbers and lines? If you can't see any markings, there should be v-shaped notches of varying sizes to guide you. Leme see if I can dig up a picture.

Unfortunately you have open headers, so the ear method won't work so well.

EDIT: There is a nice discussion and picture here of what you should be seeing:
http://67-72chevytrucks.com/vboard/s...d.php?t=151464
or maybe this one, depending on the style used in your engine:
https://www.thirdgen.org/forums/tech...et-timing.html
(see post #6)
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Old 09-01-2017, 01:28 PM   #6
61K10
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Re: Need help setting the timing of a 305

My 305 had the timing mark at the 12 o'clock on the stock H/Bal Don't know if all were this way.
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Old 09-01-2017, 02:45 PM   #7
Econman
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Re: Need help setting the timing of a 305

Quote:
Originally Posted by geezer#99 View Post
You'll need to experiment but here's some good info on figuring it out.
http://www.badasscars.com/index.cfm/...d=76/prd76.htm
Thanks for the link..

The engine runs better the more throttle, but it is rough and wants to die pulling out of the hole. It is a stock/rebuilt TH350 with 1,750 stock stall converter.

I haven't adjusted on the carb yet. I need to get the exhaust on it and then I can tell more about it. It rattles my teeth at this stage.
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Old 09-01-2017, 02:46 PM   #8
Econman
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Re: Need help setting the timing of a 305

Quote:
Originally Posted by AcampoDave View Post
There's no timing tab on the timing chain cover? And btw that 305 seems like it'll be pretty sweet... still be plenty o' motor for a teenager.
Yeah, it has a timing tab. I think more than anything I am using an old-school race engine builder that is near retirement and isn't equipped to dial this timing in with a quality gun and is cranky about trying to getting the advance curved properly.

Last edited by Econman; 09-01-2017 at 02:52 PM.
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Old 09-01-2017, 02:47 PM   #9
Econman
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Re: Need help setting the timing of a 305

Quote:
Originally Posted by 61K10 View Post
My 305 had the timing mark at the 12 o'clock on the stock H/Bal Don't know if all were this way.
This one was 12 o'clock also.
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Old 09-01-2017, 02:49 PM   #10
Econman
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Re: Need help setting the timing of a 305

Quote:
Originally Posted by mattfranklin View Post
2x Is it possible that the timing tab on the cover got hit with a thick coat of paint hiding the numbers and lines? If you can't see any markings, there should be v-shaped notches of varying sizes to guide you. Leme see if I can dig up a picture.

Unfortunately you have open headers, so the ear method won't work so well.

EDIT: There is a nice discussion and picture here of what you should be seeing:
http://67-72chevytrucks.com/vboard/s...d.php?t=151464
or maybe this one, depending on the style used in your engine:
https://www.thirdgen.org/forums/tech...et-timing.html
(see post #6)
I appreciate that!

And yes, you're right! These shorty headers open are deafening.. lol
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