Low engine vacuum

[etriebe]

Hello just got my boost gauge hooked up to my new engine and have noticed my vac is only 4-6" and fluctuates very fast. Also noticed my headers are starting to turn red idling. I think I have my cam sensor in a little off. I have a ta balancer with a tdc mark and a mark for 25 after. How Do I check my cam sensor? I do have a tr6 ignition, which has cam phasing mode and base timing mode. In base timing mode it sets to ten degrees, I hook the timing light up and it is ten degrees but move forward my cam sensor a lot and the mark never leaves 10 degrees.

 

[pacecarta]

cam sensor doesnt change timing , it can change injector firing timing and can cause a firing of a diferent coil if too far off but not spark timing ..only the ecm (based in ign module output from the crank sensor) or the pyshical position of the reluctor wheel on the balancer can change timing
because the ecm uses the ign module you can change timing with a piggyback unit like the translator plus
cam set is done with a voltmeter or cam sensor tool (from caspers) with the engine at 25after top dead center #1 onthe compression stroke
details here http://vortexbuicks-etc.com/cam_sensor.htm

as to your low vac
where do you have the boost line tied into the engine
check that line for leaks
unless the motor is assembled wrong (timing set not on dot , pushrods too long , bent valves etc ) check for vac leaks and check your iac position ,could be the throttle blade is open too far

 

[RmvBfrFlght]

Hello just got my boost gauge hooked up to my new engine and have noticed my vac is only 4-6" and fluctuates very fast. Also noticed my headers are starting to turn red idling.

Being a new engine I'd be looking at mechanical issues. Such as the cam timing (not the cam sensor), lifter preload and so on. Was the balancer checked for a proper TDC timing mark? Was the shutter wheel checked for proper location relative to TDC?

Note that the cam sensor signal only sets up the injector firing sequence. The injectors are fired relative to the ICM reference pulses from the shutter wheel (crank sensor).

RemoveBeforeFlight

 

[etriebe]

I think I'll check the valve adjust tonight I guess

 

[etriebe]

Well got the valve covers off and brought it up to tdc 1 and my push rods were at 0 lash, didn't have time to adjust. Could loose adjusted valves cause low fluctuating vacuum? Both headers glowing red, ordered a new tt chip for my combo, hopefully getting that and the valves adjusted properly will fix that

 

[Pronto]

What rockers are in there?

 

[etriebe]

T and d 1.65

 

[Pronto]

Sounds to me more like a big ass vacuum leak like the manifold causing to be lean.

 

[TurboTdr3.8]

Well got the valve covers off and brought it up to tdc 1 and my push rods were at 0 lash, didn't have time to adjust. Could loose adjusted valves cause low fluctuating vacuum? Both headers glowing red, ordered a new tt chip for my combo, hopefully getting that and the valves adjusted properly will fix that

Nope on the 0 lash causing that , look some where else , sounds like a huge vacuum leak and it putting fuel to compensate or valve timing is way off

 

[Toby_Goodmk]

huge vacuum leak, ill put money on it.

 

[etriebe]

Smoked the intake, no leaks, just out the air filter after about 3 minutes. Flopped a set of stock rockers on there and valvetrain was noisier but had 10-15" fluctuating, now that suck too though, what's the easiest way to check cam timing?

 

[etriebe]

How about a compression test?

 

[etriebe]

Does this help at all, my no 1 piston was tdc when taken

 

[pacecarta]

were the pushrods measured for your combo ????

 

[etriebe]

when I bought the cam lifters and pushrods all came from weber, they say 8.050.

 

[pacecarta]

so the answer is ..no

 

[etriebe]

no is correct. it says with weber lifters and iron heads to get 8.050 length rods, so thats what I got. i just watched a few videos on valvetrain geometry, very interesting. now if i knew where my cam card went???

 

[etriebe]

way to long booooo

 

[Chuck Leeper]

http://www.turbobuick.com/forums/threads/extra-wires-from-maf-translator.430286/ ??

 

[Pronto]

Well, you'll need a measuring pushrod to determine what size you really need.