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Topic Review (Newest First)
06-04-2012 06:09 PM
reyes134 It's almost there. After fixing timing chain gears, I gassed motor to 3000rpm's and timed to 30 btcd with it disconnected. Ran good, idles around 1500rpm's so checked timing w/ vac adv connected, it was 14btdc. If I d/c vac adv it stalls out quick. It's weird...the idle speed screw is almost turned all the way out yet I can't get it to idle around 1000...if I turn it out more it then jumps to idle at 2000. I give it some gas and it idles high, then SLOWLY begins to die over 20 secs. I tried adjusting fuel/air mixture screws but no help. Faulty vac adv? Gas running lean? What do you guys think?
06-03-2012 10:59 AM
reyes134 hey thanks for all your help...I'll post the results once I get it all put back together. If anyone out there has trouble idling and backfiring @ idle after new cam/timing gear...check the cam/crank gear dots please. My bad...I heated the crank gear and overlooked that since I was in a hurry preventing a burning hand. I guess that 4 degree difference between the circle, triangle, and rectangle markings on the crank gear make a huge difference.
06-03-2012 09:59 AM
spinn reyes you are back on track now? The symbols for zero adv/retard are lined up?

Find TDC compression and install distributor to no1. Its been over a year honestly can not recall if the crank was turned 180 to install distributor. It was not even important. only that the dots for 0 remained aligned. Both valves were shut and the distributor was pointing to no1 pin on the cap.
06-03-2012 08:41 AM
reyes134 hey guys...thanks for your help. I did indeed set the crank gear in the advanced position without noticing. I am fixing it now but I noticed the standard mark is pretty close to the advanced/retarded marks...meaning they all have about 2 and 1/2 teeths between mark and keyway. Hopefully this will be the difference though, right?. Also, can someone verify that on Edelbrock timing set 7800 you install dot-dot (cam 6oclock and crank 12 oclock) and then rotate crank 360 (cam 12oclock and crank 12oclock) before putting in dizzy? My friend says that's only for factory and to put it in dizzy for Edelbrock w/ dot-dot but that makes no sense to me. Thanks!
06-02-2012 10:51 PM
cobalt327
Quote:
Originally Posted by spinn
If that is the case. There are 3 symbols and they correspond directly to the matching symbol on the edge of the cams gear. Do you think you made this mistake?

Usually a O, A and R.
O/A/R ...triangle/ dot/ square...something like that.

edit-Except if you advance/ retard the timing. Then you would choose the center mark and retime to the corresponding other symbol on the cam gear.

They also make styles that are NOT marked inside and outside. Just on the outside of the cam gear, that has a coresponding symbol on the crank to follow.
Sounds like the crank gear was installed advanced. Or something, look at post #13.

Might have been nice to have added that info to THIS thread, but oh well. I'm done anyway.
06-01-2012 07:49 PM
spinn If that is the case. There are 3 symbols and they correspond directly to the matching symbol on the edge of the cams gear. Do you think you made this mistake?

Usually a O, A and R.
O/A/R ...triangle/ dot/ square...something like that.

edit-Except if you advance/ retard the timing. Then you would choose the center mark and retime to the corresponding other symbol on the cam gear.

They also make styles that are NOT marked inside and outside. Just on the outside of the cam gear, that has a coresponding symbol on the crank to follow.
06-01-2012 07:24 PM
eloc431962
Quote:
Originally Posted by cobalt327
Does the crank gear have multiple keyways for advancing and retarding the cam? If so, attention has to be paid to which keyway is used along w/the one correct dot that sets the alignment.
X2 this could very well be the problem.


Cole
06-01-2012 07:14 PM
cobalt327 Does the crank gear have multiple keyways for advancing and retarding the cam? If so, attention has to be paid to which keyway is used along w/the one correct dot that sets the alignment.
06-01-2012 05:28 PM
spinn That camn sounds in phase. Move on to something else. What is the carb situation?
06-01-2012 02:07 PM
eloc431962 Have you sprayed around checking for a vacuum leak. either that or the carb is out of wack has anyone been adjusting on it ?

Cole
06-01-2012 01:57 PM
reyes134 So i pulled off the timing cover and here's the deal. dot-to-dot lines up at crank (12oclock) and cam (6oclock)...this is tdc @ exhaust.
rotate crank till air pushes my finger thru spark plug#1 so tdc @ compression...crank gear and cam gear both at 12 oclock w/ dist rotor pointing to #1 spark plug which is #1 cylinder that starts firing order. Harmonic balancer was pointing to tdc.
This all seems correct...can you verify this? I gotta be missing something...why wont it idle at low rpm's?
05-30-2012 09:36 PM
cobalt327
Quote:
Originally Posted by reyes134
I readjusted valves...only did 1/4 turns this time. Still same thing. I am thinking about pulling off timing cover to verify dots/tdc...guess that's my only option now.
If you believe there's any chance the dot-to-dot alignment (aka "cam phasing") is off, that's a good move- providing the firing order is correct and you are timing the engine off of cylinder #1 (or #6) and not another cylinder. Double check everything before pulling it back apart.
05-30-2012 07:31 PM
reyes134
Quote:
Originally Posted by JeffB
Try backing off the valve adjustment 1/2 turn and see if it changes anything.
I readjusted valves...only did 1/4 turns this time. Still same thing. I am thinking about pulling off timing cover to verify dots/tdc...guess that's my only option now.
05-30-2012 09:38 AM
cobalt327
Quote:
Originally Posted by reyes134
does anyone know what the symptoms are for the cam being off one tooth?
For now, forget about the total timing. JUST for now.

Set the initial timing (with vacuum advance disconnected) to 14 degrees BTDC. Hook the vacuum advance back up to full time (aka "manifold" vacuum). Readjust the idle speed to around 800 rpm or so, or to where you like it. BTW, the vacuum advance can may be giving too much advance- you only need about 10-12 degrees from it, an adjustable can may be the ticket- but for now, run what you have.

Reset the idle mixture screws to give the highest idle speed, and readjust idle speed if needed.

Now, see how the idle and off idle response is. No need to worry about the total timing being too high- you're not going to be driving it yet. Don't run the engine under load until you have seen the total advance is 34-36 degrees or less w/the initial set to 14 degrees.

To get the right timing curve, the distributor may need modifying. But if the engine refuses to run right w/these settings, the cam may be out of phase.

You can check the cam phasing by using a dial indicator and a timing tape on the damper, but before doing that, see what you get by doing the above.
05-30-2012 01:34 AM
JeffB Try backing off the valve adjustment 1/2 turn and see if it changes anything.
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