vacume leak

[bohn333]

my truck won\'t idle in gear anymore, i changed intake gaskets and carb gaskets, went through all vacume lines and tried the WD40 trick, but i can\'t hold it in gear and spay the engine at the same time, so doing it in park is kinda pointless. Anybody have any suggestions???

[ZZ4Blazer]

You don\'t have an Ebrake?

[bohn333]

nope

[s15laynrubba]

Jack the rear end up in the air and use a couple of jack stands to support the rear end up.I use heavy duty military style jackstands that have a claw.I know a couple people will balk at it , but have done it this way a long time without problems.I also leave the jack under the rearend to support it also, but i allow it to sit on the stands.

[bohn333]

just tried that..spayed everywhere around the intake and carb and still can\'t find anything.

[s15laynrubba]

Hey bohn, I use a unlit propane torch to look for vacuum leaks.You might want to try that and stick the nozzle into the valve cover.I know it sounds crazy, but you may have a leak in the intake gasket that may be contributing to the vacuum loss.I found a thread about this over at chevytalk, if i can find it , i will post the link....Jay

[s15laynrubba]

You also might want to try to see if the vacuum loss is coming from the tranny modulator valve.Unhook the vacuum line and plug it up to see if it helps.You could have a blown mod valve.Just a thought...Jay

[Diablo]

if you have a shiftkit, whut do you do about the transmission modulator? do you just put a rubber plug on it or whut? If its not plugged does it affect shifting? and if so.. how? good or bad? plugged does it let it shift harder?

[bohn333]

some different levels of shift kits tell you to remove the modulator, but with my B&M kit it says i need it, if i remove it or plug it off i won\'t let the tranny shift till like 4000rpm.



i think my distributor is junk, the timing mark is really erratic and plugs look like crap, i unhooked the vacume advance and it idled good, even in gear. Its either that or the carbs junk, i\'m gonna pick up a proform HEI tomorrow and see if that helps. I\'ve always been meaning to get one, this is an excuse i guess..lol.

[tracker]

what is your base timing set at? and your total timing? if you have too much it will idle fine but will die just as if you didnt have enough.

[s15laynrubba]

i unhooked the vacume advance and it idled good, even in gear

Usually if you disconnect the vacuum advance and it runs good or better, it signifies a rich condition.I was also gonna ask if you checked the vacuum advance for the vacuum leak(bad diaphram) but you ruled that out.It sounds more like a carb than the distributor.What do the plugs look like?

[bohn333]

plugs are black i just changed them yesterday, i wanted a new distributor anyways..if thats not it then it has to be in the carb

[speeder]

It sounds like the rotor button is not exactly on the pole at the spark event. Make sure that the timing mark is on TDC on the balancer, when you pull off the distributor cap. If the middle of the button and the pole on the cap are not aligned, then you need to adjust that. That should solve the probs. How is the idle in park? Can you adust the timing then at all? What kind of cam you got? ALso make sure that you have the vacuum advance connected to prted vacuum, not manifold vacuum.

[s10rodder]

I had the same problem happen twice. First time I never screwed the rotor on tight enough to the dist. and the springs and weights flew out and fell down inside the dist.



I had a mechanic look at it and he fixed the dist and put on a new drive gear becuase it had gotten all chewed up by the cam gear. A month or two later I started having tthe same problem again. Pulled the dist out and found the jackass put a bronze drive gear on when I\'m not using a roller cam. Pull your dist. out and check the gear for wear. You might just need a new gear. If you still want a new dist. I got a GM HEI with a full MSD upgrade (coil, module, rotor, cap) for sale. Only prob. is it\'s the one with the chewed up bronze gear. You can replace it with cast iron gear for about $25 if you want it. I just said screw it and got a brand new MSD pro billet with external blaster 2 coil. I say screw those huge HEI caps.

[bohn333]

i put a brand new HEI in it, wanted a proform one but the one i got is made by Mallory..called a Big End Distributor. Its got the polished shaft and H.O. coil and all the good crap. Put it in and it did the same thing, all it was, was a vacuum leak at my fuel pressure regulator..it was causing the pressure to spike at various RPM\'s. Oh well..nothing like spending $150 for a distributor i didn\'t need..lol. But hey it runs great again..atleast this way if i keep the truck and do the motor i want this winter, i have a good distributor now... http://www.s10v8.com/images/smilies/icon_biggrin.gif