5.7 vortec timing

[Gbow]

Hi, having some trouble with a carbed vortec. I just had a 5.7 vortec installed in my 85 k10 and when I got home (7 min from shop) I had the truck idling and it died. I thought OK maybe the carb was not adjusted right. I broke out my vac gauge and went to work. At temp the engine would not idle no matter what I did to air fuel or idle screw. Finally found the vac distributor was not hooked up to a vac line. Connected that and it runs but not like I think it should. The mechanic said he timed it and set the carb by going all in and three complete revs out. But the thing that is messing with me is there is no timing tab on the motor. Well there is a tab with no marks about 1" long.

My questions are how do I time this and how do I adjust the carb if it won't idle at temp without the vac distributor line in it?

It is a carbed 350 vortec with a 2" carb spacer quadrajet and hei coil vac advance distributor

 

[chevyk10]

There should be a groove on the balancer. Does the tab have marks on it? Sounds like your base timing is off.


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[Gbow]

Yeah there is a groove on the balancer. I cleaned the tab and do not see any marks.

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[Gbow]

There is a groove on the balancer. I cleaned the tab but could not see any marks. I believe it to be the timing as well.

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[yevgenievich]

You might need to get the motor to top dead center and see where the mark on the balancer is in relation to the tab.

 

[Gbow]

That's what it looks like. I am going to see if I can find a tdc indicator and a timing tape so I can check everything. Hopefully I can get this thing back on the road soon.

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[Gbow]

I started looking online for tdc locators and they all want you to let the top of the piston touch a hardened steel bolt. I don't like the sound of that. So I was thinking could I use a compression tester gauge to find tdc by looking at the highest pressure while turning the crank. Where ever the pressure starts to drop i back off a hair and that should be tdc right?

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[Green79Scottsdale]

Usually compression testers hold the readings, at least the ones I have used did. May not work like you hope.

Do you have an indicator with a long reach that you can stick down the hole? That would be very precise.

 

[Gbow]

I was looking at a cheaper one that screws into the spark plug hole and has a valve to release pressure. Hose looks to be about a foot long.

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[yevgenievich]

I always used a long screwdriver through spark plug hole. Compression will not give exact top position.

 

[Gbow]

Thanks for the advice. I will try the screwdriver. I couldn't find any timing tape locally so i ordered it on Amazon. Msd timing tape had all sizes for GM small block for $8 and I bought a cheap timing light and a paint marker. I think I can get it figured out. I will keep you updated. Thanks again for your input.

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[yevgenievich]

First feel/watch for compression stroke with spark plug out, then use screw driver for final adjustment. You don't want to score the cylinder bore, just feel when top of the piston comes up.

 

[chevyk10]

For a stock engine the line on the balancer should line up with a mark or the point of the pointer on the timing tab or notch. If this was a racing application it would be necessary to be exact. Stock with some wear won't get "perfect"


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[Gbow]

Thanks guys. I did find a mark on the tab and I was able to time it. (I think my neighbors thought i was nuts trying to kneel on my grill to reach and see everything.) I got done and still had trouble tuning the air fuel. I got as close as I could and thought "hey let's take her around the block." About 75 yards later it died but crunk right up. So now I am thinking it is an intake manifold leak. The mechanic used a lot of rtv sealant so I didn't think of it earlier. I guess I have to take off my manifold and clear all that trash off to start again. Any other ideas for possible issues? Thanks again for all your help.

 

[yevgenievich]

Check for vacuum leaks by spraying carb cleaner around leak prone areas and see if you gwt increase in rpm