whats up with my timing?? anybody got ideas?

[dwhitley167]

i gotta 67 with a 402 that doesnt wanna stay timed up. ill set the timing and it will drive fine for a little while, untill i get on it then it starts poppin and just gets worse within a few days. any ideas?

[cdowns]

do you have a cheap chrome aftermarket dizzy hold down clamp??

[dwhitley167]

yeaa i was thinkin that my clamp was jacked or maybe my threads were worn.... but im hopin its just the clamp. but i wont be home for another month to actually check it. and i was also thinkin that maybe it had somethin to do with the timing chain/gears, or vaccum issues somewhere. i know just about enough to get myself in trouble tho. lol

[Ilike 72"s]

Mechanical advance is probably worn or missing a spring.Allot of times it gets dirty or sticky und hangs up, causing the timing to be way off.

[67vetteal]

I'd suggest you buy an HEI aftermarket on ebay. They work great and will improve power and fuel economy. (Greater Spark). Al W.

[johnechi]

Yep, either you have a holddown clamp that is either cheap aftermarket, the bolt is stripped and won't tighten, or the vacuum advance unit is shot, contact plate is jammed, or the advance weight springs have lost their temper and the advance weights don't swing out when they should. Hopefully its the clamp or a bad dizzy.

I just had a worn out dizzy in my case. Replaced it with a Mallory vacuum advance, magnetic pickup type. (pn# 4248201) Works great out of the box (stock 80s 350 4 bolt main), the vacuum advance unit is adjustable and it comes with a advance spring kit and directions if you need to fine tune it to your engine.

[chas350]

Make sure the distributor hold down bolt is not to long and bottoming out just before its tight enough to hold.

[Myself]

Sounds kind of like a cam starting to lose lobes to me.

[dwhitley167]

thanks for the info guys. i think i love this place already!!

[GASoline71]

Also... the rubber between the outer ring and hub on stock harmonic dampners can rot, and the outer ring will spin. Making the engine to appear to be out of time, when it's not. Then when you "adjust" it... your're making it worse.

Bring the engine up to TDC, and if the timing mark is nowhere near the timing tab... your ring is prolly slipping on the hub.

Gary

[kwmech]

Bad set of points?

[Sinister]

If your able to retime it to where it's good, my vote is the hold down clamp or threads in the intake. I'd get a hold down clamp that uses a stud instead of a bolt.

[johnechi]

Originally Posted by GASoline71

Also... the rubber between the outer ring and hub on stock harmonic dampners can rot, and the outer ring will spin. Making the engine to appear to be out of time, when it's not. Then when you "adjust" it... your're making it worse.

Bring the engine up to TDC, and if the timing mark is nowhere near the timing tab... your ring is prolly slipping on the hub.

Gary

Dude! I completely forgot about that! Yep, that has happenned as well. Mark the whole balancer from the center on outward.

[dwhitley167]

hey thanks for the info guys. also wonderin how much force it takes to actually move the distributor..... i tried to twist it with my hand to see if the clamp was crap or not. and def didnt move at all. and im not really a weak guy. also thought bout just getin the hei msd distro to see if that will fix the prob or not...... any ideas?

[cplkillian]

If you go HEI i recommend on ebay Skip White, i was turned on to these guys and am very impressed with the product and the customer service and pretty inexpensive

[Myself]

It's a big block Chevy, I'm still leaning towards cam failure. But, you need to pull the valve covers and have a look before any more damage is done. It could just be a broken rocker arm or bent pushrod. If all rocker arms and pushrods are ok then unhook power to the distributor and have somebody turn it over while you watch. Look for any rocker arms that aren't moving as much as the rest.

[dwhitley167]

thanks for the posts guys, i was up at a shop to order a msd pro billet distributor the other day and was talkin to them about it. and they had said that they had one do the same exact thing and said that the spline in the top half of the distributor was all chewed up, and i was planning on going with the msd anyways. so im just waiting on parts, and hhopefully thats it.

[Huck]

I think if the cam lobe's were warn, you would have the problem warm or cold. Using a timing light to check warm and cold at idle would tell you a lot---any deviation would be obvious and you could trace it back. If you have a vacuum sensative leak--that would throw you the same kind of symptoms so I think I would hook up a vacuum gauge and see what's happening at idle--cold and then warm. Then check with timing light will show advance as you rev it. Vac gauge would show if valves are kaka too. Find a local board member with some tools and some knowledge and you might save yourself a lot of time and money.
Huck

[George Kraus]

I'm happy your going to the HEI, I got the Jegs Red Cap and it works great. I found out that the wire suppy to the old coil was a resister wire that doesn't put out a full 12 volts so the old coil would not burn out, after replacing this wire with a 14 ga. from the out let on the fire wall a very noticable change occured, smoother acceleration and better power. You will also need to remove the wire down to the selanoid (outside stud) since it will no longer needed.

[Tkmadone]

Could the gear on the distributor be worn enough to be jumping teeth?

[George Kraus]

I have never seen a dist. gear worn down that much, however it is possible and I think a quick look would be obvious to you, there are some after market dist. with incompadible gears to your application but this is also pretty rare. Go get another clamp and check your threads to make sure they are not stripped. Again, an HEI distributer is far better than the ole point dist. and a good one will only run about $130-$160 from Jegs or Summit Racing (don't forget the new plug wires and Plugs to match) I will never go back.

[crakarjax]

Originally Posted by cplkillian

If you go HEI i recommend on ebay Skip White, i was turned on to these guys and am very impressed with the product and the customer service and pretty inexpensive

+1, just bought a FULL HEI with cap, rotor, coil, adjustable vaccum advance, everything. $50.49 shipped to my door the day after purchase! It is made in China, but looks to be fairly high quality. 65kV btw, and LIFETIME warranty! LEt's see MSD match that!

[dwhitley167]

i got all my parts today from summit, but had to take care of the wifey's water pump. so no time to play today, but im gonna borrow a timing gun from a buddy tomrrow and see if i can get the girl runnin right. i dont know if he's gotta vac gauge so i can see what im workin with. i also picked up a holley 770 street avenger instead of the 670 that i had been runnin, and plannin on replacin some old vac lines. so i guess ill find out tomrrow what the deal is with it. ill def keep u guys posted on it.

[dwhitley167]

FOUND IT!!! I pulled the valve covers off last weekend and the rockers were way out of adjustment and saw that the nbr 1 cyl. had a thinner pushrod and was rattling around in the guide. and not to mention the nbr 2 and 6 intake lifters wasnt pushin any oil. so i guess im getin new lifters, and might as well get a cam. anyone got suggestions on a cam for the 402. ill just drive it here and there and want to notice the idle, but prob not to the track very much.