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Old 12-19-2004, 07:06 PM
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305 Timing Problems

Hello All - I have a stock '86 Chevy pickup with a 305 that likes to drink a little oil with it's gas (she has a few miles.) A few months ago I replaced the mag pickup (thanks again to everyone and to this board!) Everything seemed pretty good, thought all I needed to do was tweak the timing - boy, I was wrong. She's pretty stubborn about starting - generally requires alot of cranking and then on a few occasions she has just right out refused. Idle is somewhat decent - a little rough, but when you are driving and get into it, it detonates really, really bad. Any adjustment on the dist. seems to go from bad to worse. Is it possible that when I put the dist. back in that I put it in a notch off? That's what I think may have happened, but would it even run if it was a little off? I'm also wondering if maybe something on the vacuum advance isn't working, is there an easy way to check? I know she's pretty worn out, but I think she should should run smoother. I have noticed oil in the PVC valve, hose and air cleaner - what does that mean? I finally got a timing light, so this week I'm probably going to start over and set it to top dead center and see where I end up. Well that's about all I can think of right now, thanks for reading and for any help and ideas.

Robby
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Old 12-20-2004, 11:44 AM
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anyone?
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Old 12-20-2004, 12:06 PM
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static timing

it does sound like you have the timing out, you've probably read/heard this before but;
take out no 1 plug(take em all out and it is easier to rotate the engine)
rotate engine with wrench/socket until timing mark lines up on bottom pulley/indicator also use a short screwdriver or bit of wire to follow piston up until it is a top dead centre
remove dizzy cap and see how close the rotor is pointing to the number 1 plug lead (if it is totally opposite then you need to rotate another 180degrees)
if it is a fair way off then turn dizzy to line it up, if you cant get enough turn out of the dizzy you could move all the plug leads around one space or lift out the dizzy and line it up.
As for the Vac advance, it wont make a lot of difference to the idle unless you have a vacuum leak which tends to make the idle run higher, the vac advance only really comes into play during acceleration/deceleration. If the static timing is too far advanced then you will get the detonation whether or not you have a vaccuum advance hooked up or not. As for the oil in the pcv and air cleaner it sounds like the engine is probably a bit worn and thus you are getting more blowby than a normal engine, check the pcv valve to make sure it is not gunked up and open all the time, you may find that if you get the timing better this problem will reduce a little; depending on whether you live in a smog state you could swap to a crankcase evacuation system which runs breather hoses from the rocker covers into the exhausts.
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Old 12-30-2004, 11:26 AM
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Thanks for the reply Mr ED... you were right, the timing was off. I think I needed some reassurance because I have never had to backup and set the timing from scratch. Everything worked out perfectly...she starts great and I have not detonation. I'm not sure what I'm going to do about the blow by. The PVC is working but the tube from the other valve cover to the air filter has a bunch of blow-by coming out of it. I really don't want to put any money into because I know a rebuild is just around the corner but I would like to do something to baby it along for a while. Would there be any benefit in stripping all of the smog equipment off - vacuum lines, air pump, cat. converter? Sorry about not being very timely about my reply, I ended up going on a last minute trip. Thanks again and have a Happy New Year.

Robby
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Old 12-30-2004, 01:28 PM
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Leave the smog on. Unless something is wrong with the smog equiptment, they generally do not use up any power.

Your earlier problem sounds like your timing it too far advanced.
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Old 12-30-2004, 08:17 PM
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Take all that smog crap out... not only does it rob HP, it weighs down the frontend. Depending on the engine you can save 10-15hp from a air pump. Or you could leave it all on and just take off the belt so if you ever need emissions crap, all you have to do is put the belt back on. You can save a good 20-50 pounds by removing that crap.

(assuming its a v-belt and not a serp.)
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Old 12-30-2004, 11:01 PM
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Check your emmissions regulations and rules BEFORE removing any smog related items. You may find that your car is no longer street legal, and you wont get your tags when the time comes.
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Old 12-31-2004, 01:30 PM
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I am real tempted to remove all the smog crap, anything to help prolong this girl's life. I live in Texas and I know off several other trucks the same year that does not have any smog equip. but it definitely would be the first thing I check on because I would hate to have to put it all back on. Anyone know of any guides of what exactly needs to stay and what goes? Alot of the vac. lines are old but there is now way I am going to attempt to replace everything with the smog stuff still on. I heard that removing the belt to the air pump would cause my cat. to clog up. I figured that it's old enough that the cat is probably already blown out and wouldn't matter. Any cheap ideas on what I should do about the blow-by? Thanks again for the replies and all the help.
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Old 12-31-2004, 01:39 PM
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Removing the smog crap isn't going to make a difference in the engine life (unless its malfunctioning). Most of the smog takes places after the engine, in the exhaust. Unless you live outside city limits where smog laws dont apply, keep all the smog stuff. The year of your vehicle is not outside of the smog date.

The vacuum lines and smog stuff really isn't all that complicated. Most vehicles have diagrams of where these lines run on a sticker in the engine compartment. Now that you have it timed right, I would advise you to get a new cat, and freshen up the vacuum lines and oxygen sensor(s) as well. You'll notice a MPG increase as well as help the environment a little . Make sure your EGR is functioning as well.
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