Alright need help with timing/carb/vac adv - Team Camaro Tech
Engine General Engine Discussion.

 
LinkBack Thread Tools Display Modes
post #1 of 8 (permalink) Old Jul 21st, 14, 04:33 PM Thread Starter
Senior Tech
 
Join Date: Jul 2013
Location: Salem, OR
Posts: 121
Alright need help with timing/carb/vac adv

So I'm trying to get my engine running properly. Its a chevy 350 stock iron block and heads. Its in my 67.

I have an older Holley double pumper 4777-2 Just got rebuilt

Cam specs are DUR @.050 223 ADV DUR 290

Im trying to get my timing and carb adjusted properly. I put a vacuum gauge on my carb and read 11 but was not very steady it would jump around at times. I hunted for a vacuum leak but found none.

i read the timing 101 and got some clarity but really don't know how to start. What do I need to do to find what timing should be set at.

I'm thinking my vacuum advance might not be up for the job but i really don't know. I need some help how to get the basics started.

Thanks !

Justin
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Leblanc is offline  
Sponsored Links
Advertisement
 
post #2 of 8 (permalink) Old Jul 21st, 14, 05:20 PM
Senior Tech
Anne
 
Join Date: Jan 2013
Location: Eddyville KY
Posts: 1,470
Re: Alright need help with timing/carb/vac adv

Check your timing at idle with the vacuum advance hose connected. I bet your timing is going up and down a few degrees.

With 11" of vacuum at idle, your stock vacuum advance will not be fully deployed (it will be "dithering in and out").

Is your distributor a stock "points type" small body ?
If so, try this vacuum can :http://www.autozone.com/autozone/par...artNumber=true

It will be fully advanced at 8" of vacuum and your timing should be stable.

After that you can set your initial + mechanical to 36*. That's a whole other topic. You will probably have to restrict the mechanical and add some initial.

14-16 initial and 20-22 mechanical is a good starting point.

Government's first duty is to protect the people, not run their lives.
Ronald Reagan
Lawrence454 is offline  
post #3 of 8 (permalink) Old Jul 21st, 14, 05:38 PM
Senior Tech
Al
 
Join Date: Nov 2002
Location: Vancouver, USA
Posts: 10,511
Re: Alright need help with timing/carb/vac adv

w/o getting into setting up advance curve - which can be a bit complicated, esp for a novice - I'd set the thing for total timing and see how she runs.

You'll need either a degreed balancer or a timing tape made for the diameter of your balancer.

The old original iron GM heads from the era seem to like ~36* total. So....with your degreed balancer or correctly installed timing tape, disconnect the vac advance hose from the dist and plug the hose with a golf tee or something. Set the park brake, trans in neutral or park, connect your timing light to the #1 plug wire, driver's side front, and start the motor.

Point the light at the timing pointer, paying attention only to "0" if the pointer is also degreed - operating the throttle by hand - bring the RPMs up to 3000 - 3500 and see where the timing is. If you need more to get to 36, rotate the dist CCW. If you're past 36, rotate it CW. Once happy, clamp it down and recheck. Take the RPMs a bit higher to make sure it isn't still advancing. Once you have it set for 36 total and not still advancing, let the motor idle @ about 800 and see where the timing is now. Probably somewhere between 10-16 advanced. Unless you need to mess with the advance curve, this is where you set timing from now on, at idle with VA disconnected and plugged.

It's a bit intimidating setting total timing the first time with your head in there and the motor screaming. Just be sure and keep your fingers and the timing light clear of the fan. Don't wear loose clothing that could get caught in a belt.

I'd expect that cam to have a little more that 11 @ idle, but it also depends on what the idle speed was when checking it. More idle speed = more vacuum. The lumpier the cam as well as the cheaper the vac gauge is can cause an unsteady needle on the vac gauge at idle.

Good luck - we're all counting on you.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
BPOS is offline  
 
post #4 of 8 (permalink) Old Jul 21st, 14, 07:18 PM Thread Starter
Senior Tech
 
Join Date: Jul 2013
Location: Salem, OR
Posts: 121
Re: Alright need help with timing/carb/vac adv

Quote:
Originally Posted by Lawrence454 View Post
Check your timing at idle with the vacuum advance hose connected. I bet your timing is going up and down a few degrees.

With 11" of vacuum at idle, your stock vacuum advance will not be fully deployed (it will be "dithering in and out").

Is your distributor a stock "points type" small body ?
If so, try this vacuum can :http://www.autozone.com/autozone/par...artNumber=true

It will be fully advanced at 8" of vacuum and your timing should be stable.

After that you can set your initial + mechanical to 36*. That's a whole other topic. You will probably have to restrict the mechanical and add some initial.

14-16 initial and 20-22 mechanical is a good starting point.
My dist is an HEI dist, unknown brand.Would that advance can still be a good idea?

Justin
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Leblanc is offline  
post #5 of 8 (permalink) Old Jul 21st, 14, 07:19 PM Thread Starter
Senior Tech
 
Join Date: Jul 2013
Location: Salem, OR
Posts: 121
Re: Alright need help with timing/carb/vac adv

Quote:
Originally Posted by BPOS View Post
w/o getting into setting up advance curve - which can be a bit complicated, esp for a novice - I'd set the thing for total timing and see how she runs.

You'll need either a degreed balancer or a timing tape made for the diameter of your balancer.

The old original iron GM heads from the era seem to like ~36* total. So....with your degreed balancer or correctly installed timing tape, disconnect the vac advance hose from the dist and plug the hose with a golf tee or something. Set the park brake, trans in neutral or park, connect your timing light to the #1 plug wire, driver's side front, and start the motor.

Point the light at the timing pointer, paying attention only to "0" if the pointer is also degreed - operating the throttle by hand - bring the RPMs up to 3000 - 3500 and see where the timing is. If you need more to get to 36, rotate the dist CCW. If you're past 36, rotate it CW. Once happy, clamp it down and recheck. Take the RPMs a bit higher to make sure it isn't still advancing. Once you have it set for 36 total and not still advancing, let the motor idle @ about 800 and see where the timing is now. Probably somewhere between 10-16 advanced. Unless you need to mess with the advance curve, this is where you set timing from now on, at idle with VA disconnected and plugged.

It's a bit intimidating setting total timing the first time with your head in there and the motor screaming. Just be sure and keep your fingers and the timing light clear of the fan. Don't wear loose clothing that could get caught in a belt.

I'd expect that cam to have a little more that 11 @ idle, but it also depends on what the idle speed was when checking it. More idle speed = more vacuum. The lumpier the cam as well as the cheaper the vac gauge is can cause an unsteady needle on the vac gauge at idle.

Good luck - we're all counting on you.
Thank you! I appreciate the help with a starting point!

Justin
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Leblanc is offline  
post #6 of 8 (permalink) Old Jul 21st, 14, 07:22 PM
Moderator
John
 
Vega$69's Avatar
 
Join Date: Sep 2010
Location: Vegas NV/Wesley Chapel FL
Posts: 12,728
Garage
Re: Alright need help with timing/carb/vac adv

Quote:
Originally Posted by BPOS View Post
w/o getting into setting up advance curve - which can be a bit complicated, esp for a novice - I'd set the thing for total timing and see how she runs.

You'll need either a degreed balancer or a timing tape made for the diameter of your balancer.

The old original iron GM heads from the era seem to like ~36* total. So....with your degreed balancer or correctly installed timing tape, disconnect the vac advance hose from the dist and plug the hose with a golf tee or something. Set the park brake, trans in neutral or park, connect your timing light to the #1 plug wire, driver's side front, and start the motor.

Point the light at the timing pointer, paying attention only to "0" if the pointer is also degreed - operating the throttle by hand - bring the RPMs up to 3000 - 3500 and see where the timing is. If you need more to get to 36, rotate the dist CCW. If you're past 36, rotate it CW. Once happy, clamp it down and recheck. Take the RPMs a bit higher to make sure it isn't still advancing. Once you have it set for 36 total and not still advancing, let the motor idle @ about 800 and see where the timing is now. Probably somewhere between 10-16 advanced. Unless you need to mess with the advance curve, this is where you set timing from now on, at idle with VA disconnected and plugged.

It's a bit intimidating setting total timing the first time with your head in there and the motor screaming. Just be sure and keep your fingers and the timing light clear of the fan. Don't wear loose clothing that could get caught in a belt.

I'd expect that cam to have a little more that 11 @ idle, but it also depends on what the idle speed was when checking it. More idle speed = more vacuum. The lumpier the cam as well as the cheaper the vac gauge is can cause an unsteady needle on the vac gauge at idle.

Good luck - we're all counting on you.
Great advice.

Might want to have someone in the driver seat do the gas pedal so under the hood you can concentrate on the timing light and dizzy

2017 Corvette ZO6 with ZO7 Option
66 Chevelle Protour LS3/525(SOLD AT Mecum 2018)
69 SS396 Cortez Silver(SOLD)
69 Z28(Sold)
69 Pro Tour - LS3/T56
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
(SOLD)
69 Pro Tour - LS7/T56 (SOLD)
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

69 Z28/RS Tribute355/5 Speed (SOLD)
69 RS Clone 427/TH400 (SOLD)
67 RSZZ502/5 Speed (SOLD)
69 Camaro 406 SBC/TH400 (SOLD)
Vega$69 is offline  
post #7 of 8 (permalink) Old Jul 23rd, 14, 12:54 PM
Senior Tech
Anne
 
Join Date: Jan 2013
Location: Eddyville KY
Posts: 1,470
Re: Alright need help with timing/carb/vac adv

Quote:
Originally Posted by Leblanc View Post
My dist is an HEI dist, unknown brand.Would that advance can still be a good idea?
The DV-1810 can is for a points type distributor.

Here is one that should work for an HEI :
http://www.autozone.com/autozone/par...artNumber=true

And here is a document covering the different cans available :
http://www.lbfun.com/warehouse/tech_...ance_Specs.pdf

Government's first duty is to protect the people, not run their lives.
Ronald Reagan
Lawrence454 is offline  
post #8 of 8 (permalink) Old Jul 24th, 14, 02:31 PM Thread Starter
Senior Tech
 
Join Date: Jul 2013
Location: Salem, OR
Posts: 121
Re: Alright need help with timing/carb/vac adv

UPDATE

Well I got the total timing to 36 and at idle it hits about 13 BTDC. Adjusted by carb and rerouted by vacuum line to the full manifold pressure port on my carb.

Holy crap it runs so damn good now, its reading about 16 on the van gauge, and just purrs at idle. It use to be very choppy at idle and sounded kind of splatty, if that makes sense. I assumed it was my cam. Now its very smooth and much quieter. Almost too quiet, lol. But it idles and runs very smooth, it use to randomly hesitate and pop, now not at all. Thanks for all the help! The amount of knowledge and experience on this forum make trouble shooting so less painful

Justin
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Leblanc is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Team Camaro Tech forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address.
NOTE we receive a lot of registrations with bad email addresses. IF you do not receive your confirmation email you will not be able to post. contact support and we will try and help.
Be sure you enter a valid email address and check your spam folder as well.



Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome