Thread: 383 Stroker low vacuum and sluggish

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Originally Posted by Devon32

I really appreciate your time and help, but I might have to either take it somewhere or just work on it over time. Thank you so much!

WHOA!, don’t give up yet, you’ve made great progress. This is an unknown motor that the previous owner may not be telling you the truth about, so CONGRATULATE yourself, you’ve already found a lot about it. Lets move forward, relax, take your time and enjoy the journey. You’re not offending or putting any of us out, lets getter done.

Originally Posted by Devon32

I have the gauge hooked up to the right manifold port one.

Perfect.

Originally Posted by Devon32

With throttle stop backed all the way out, adjusting the carb still has no effect. I can shut both mixture screws and it’ll still run, but makes some squeaking noise. With idle screw backed out and timing advanced to keep rpm around 700, vacuum was at around 5. Bring it to about 1000 rpm and it’s at 10 inches vacuum.

OK, this tells us you have a sizable vacuum leak (still running with mixture screws shut and whistle noise gives it away).
Not all carb cleaners raise the rpm, some cause it to lower, lets try it again as follows;
Seal all the vacuum ports (front and back) on your carburetor and spray a mist of water around everything, the water mist usually lowers the rpm and is quite noticable.
Start at idle and mist everything, then raise the rpm to around 1500 and mist again.
With the oils signs on your plug’s housing, you may not have a good enough valve cover seal to use the dip stick vacuum gauge trick for underside of intake leaks, try tightening your covers and checking again.
With the carburetor ports sealed only your intake manifold and carburetor base gaskets are left as a leak source, so this should show up quick.
Your plugs show signs of some oil consumption on a couple plugs, this could be the cylinders that were not firing and why I keep plugs in order.

Originally Posted by Devon32

Also, looks like I don’t have a choke at all.

You can add the choke back later to help cold starts, but it’s not the issue right now.

Originally Posted by Devon32

Starting to think I just have a lot of problems. I checked the balancer and for slippage and it was good. I’ll find TDC this weekend but even if the marks are incorrect, that won’t help because I’ve tried finding the best vacuum with a wide range of timing adjustments and can’t seem to get over 10ish.

If you have a vacuum leak, usually you’re not going to get the timing to raise the vacuum enough to make a difference on the vacuum gauge, especially with a larger leak.
And beware, setting timing to the highest will usually be too much timing for the motor. Usually this method requires backing back off a little after highest vacuum is achieved.

The pictures of your motor show the tab at a higher placement than usually is used, there are some motor balancer combinations that use it, but it warrants checking to be sure. True TDC never lies.

I’m not a big fan of opening plug gaps up, but as Glen noted with your possible oil consumption, opening the plug gap usually helps to run the plug a little hotter and burn the oil off.

Hang in there, you’ll get this, we’re rooting for you, there are a lot of great people here helping and we all enjoy helping each other.

Low vacume but even compression figures----------oily sparp plugs-ummmmmmmm????? Valve stem seals and/or guide condition on the intake valves---------

Originally Posted by jerry clayton

Low vacume but even compression figures----------oily sparp plugs-ummmmmmmm????? Valve stem seals and/or guide condition on the intake valves---------

Strong possibility Jerry, and it should show with a crankcase vacuum test.

36sedan,

Alright just did the vacuum test on the oil dipstick again. Valve covers were tightened down and breathers were plugged. I plugged all ports in the carburetor and no vacuum. Actually saw maybe half a pound of pressure. Steady .5psi all the way to 2k rpm.

I just tried spraying water on all the gaskets and hoses and got no change. I’m going to order a new carburetor gasket anyways since they’re relatively cheap. Leak down test kit should be here this weekend and I’ll also find TDC then as well. I really appreciate everyone’s help on this.