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73-87 Chevy _ GMC Trucks => 73-87 Chevy & GMC Trucks => Topic started by: SUX2BU99 on May 13, 2006, 01:18:00 pm
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Do all HEIs, including stock, have an adjustment inside the vacuum advance canister? I'm talking where you take the hose off the nipple and then insert an allen wrench inside the nipple to adjust timing. Am I correct about this? I'd like to get some more oomph out of my truck and maybe this could be it. What way should I turn it? Do I need a really long wrench? I have a set of wrenches but they don't appear long enough to touch anything inside.
Thanks!
85 SWB FS mild 350 2wd TH350
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No
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Grrr. I hate EZboard. No that's not how it works. I think you are thinking of the vacuum modulator on the trans. If you want more oomph, try a tune up and advancing the timing curve a little bit.
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Many aftermarket vacuum advance canisters have that feature, stock ones dont
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I've never heard of an adjusting vacuum advance either. Wow, didn't know they existed. I don't see why you would need it. Just make sure your vacuum line is healthy with good suction. As mentioned earlier, you can bump up your timing a little (advance slightly) for a stronger advance..makes sense, huh.
SgtDel
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Stock doesn't have it eh? Alrighty. I have turned the distributor counter-clockwise to get some better response out of it. I don't have a timing light so I basically turned it until performance dropped off, then backed it off a bit.
Are the Haynes books useful for these kinds of adjustments? My 350 isn't stock, but has a stock HEI and has an Edelbrock carb. It doesn't downshift like I want it to either. If the RPM's are anywhere past 2000, it won't downshift at WOT. Kinda sucks. And when its warm, it will shift way early at like 3700 RPM too 
The motor doesn't really make any power past 4500 and I think starts to valve float at like 5000 but I would like to nail it and not have to manually shift it just to take it to 4500.
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which trans do you have?
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You have a th350 in an 85, if it is the same as my 79, you can adjust the kickdown cable at the throttle cable bracket on the intake. Pull up on the plastic tab, move the cable slightly and push it back down.
If your shift points aren't right, adjust your modulator at your th350.
SgtDel
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Thanks guys. I'll print this out and add it to my 'to do' list
