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  #46 (permalink)  
Old 09-06-2012, 04:49 PM
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Originally Posted by thinwhiteduke View Post
So those figures must have the static setting factored in. I'd still make sure that the limiter bush is fitted.

Duke
There wasn't a bushing on the mech. adv. limiter on this distributor, it's a rebuilt unit I bought 2 yrs ago, the speed shop thinks it was setup this way, but the vac adv unit I bought and recurve kit both have a bushing to install. The recurve kit has the brass one, that's the one I pressed on, Didn't hammer on the shaft.
I used dieelectric grease to grease the mech. adv. and weights, Is this OK to do?

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  #47 (permalink)  
Old 09-06-2012, 10:01 PM
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As far as I know, and I'm not an expert, the mech adv doesn't have a bush as a standard feature. It's just something that is put on afterwards in an effort to reduce/limit the mech adv when modifying, so that your able to dial in more static/initial timing without exceeding total advance requirements once the mechanical advance comes into play. Dieelectric grease would prob be ok but not absolutely nessessary in this situation as there should be no charge or current at that part of the mechanism. Make sure that your static and mechanical advance doesn't total more than 36deg.

Duke
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  #48 (permalink)  
Old 09-07-2012, 05:29 AM
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Now that makes a lot of sense to me , Thanks Duke
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Old 09-07-2012, 06:18 AM
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So what is being said to me by you and F-bird, I need to advance the timing to 12-16deg, no vac adv.
then connect it to a timed port on the carb.?
If yes, this is why my Carter AFB 9635SA doesn't run good, both the ports are timed, the only full vacuum is the 3/8" opening in the front and I don't use it.
Then play with the timing from that point work with it on the advance and weights. til I get a pinging or knock.
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  #50 (permalink)  
Old 09-07-2012, 06:50 AM
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Originally Posted by raguza123 View Post
It has been suggested to recheck my valve lash, by a friend and by Comp Cams. They both believe my low vacuum reading is from improperly adjusted valves.
I adjusted them Putting the engine at TDC #1 and doing 8 valves and then put at TDC on #6 and doing the remaining 8 valves. It did run better after the adjustment. You might be wondering why I need to readjust the valves, I replaced the lifters only, now I realize it was not a nessesary.
It's recommended to do one Valve at a time by Comp Cams: At #1 when th exhaust begins to open stop and adjust the intake valve. Turning the push rod tightne the rocker nut til I feel resistance then stop and go 1/2 turn or 180deg then tighten down and then when the intake valve starts to closestop and adjust the exhaust valve the same as the intake.
The engine is a Pontiac 326 with poly locks.
The 2nd method is to go to TDC of #1 adjust valves the same as above but instead of 1/2 turn after zero lash go only 1/4 turn, do both valves on #1 then go 90deg on the crank and do the next in the firing order.
I'm not sure which one I should use, what does anyone here recommend?
A couple links:

Valve train points to check
Pontiac firing order. It's easy to get #5 and #7 mixed up!
Ignition advance. This page was originally written on the GM HEI but much of the info holds true regardless of the brand of distributor. Be sure the weights and cam for the mechanical advance are installed correctly- because the Pontiac distributor spins opposite of a Chevy, it's easy to get the orientation of the weights wrong.
Adjusting hydraulic lifter preload

Are you using the stock Pontiac bottleneck studs with polylocs, or were the stock studs replaced?

Are the rockers stock 1.5 ratio? Stock length pushrods?

I don't recall reading where the sputter came in. Does it do it at an idle, or when accelerating from idle, or where?

Are you using a PCV system? Have you disconnected all the unnecessary vacuum accessories and plugged the ports to be sure there's no vacuum leaks from an accessory?

You'll want to check the vacuum advance for correct operation and also be sure the mechanical advance is working smoothly and not hanging up.
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Old 09-07-2012, 06:59 AM
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I don't know if the engine builder replaced them, but if I read his build sheet he did not replaced them.
Stock rockers 1.5 ratio and stock lenth rods.
The sputter started when I would accelerate, then I heard it at idle, thought it was the carb? rebuilt carb2 times tried 3 or 4 carbs all do the same.
Yes I am using my PCV and I checked with all the vac hoses off.
I am actually replacing the weights and vac adv units today.
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Old 09-07-2012, 07:11 AM
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Quote:
Originally Posted by raguza123 View Post
I don't know if the engine builder replaced them, but if I read his build sheet he did not replaced them.
Stock rockers 1.5 ratio and stock lenth rods.
The sputter started when I would accelerate, then I heard it at idle, thought it was the carb? rebuilt carb2 times tried 3 or 4 carbs all do the same.
Yes I am using my PCV and I checked with all the vac hoses off.
I am actually replacing the weights and vac adv units today.
If you can, put a vacuum gauge on it to see if the needle of the gauge has a random or rhythmical bounce to it.

How much run time is on the engine now? Sometimes it can take some break in time for the valves and seats to become mated and until then you can have some leakage through them.

Has a compression test been done?
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Old 09-07-2012, 07:57 AM
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I put a vac gauge on it, it idles at 12" steady, when I remove my bake booster and the advance and trans modulator, it goes to 13" steady.
When I accelerate it has no lag or bog, the needle drops to 2" then up to 18", if I hold it at 1500rpm's she go back to 12 or 13" and bounce a little between the two of them.
It's has about 18000 miles on it since it's total overhaul, I just realized I'm running a modified from stock specs at stock specs. since it was rebuilt.
It starts good and revs good, but I have a sputter at idle out the exhaust.
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Old 09-07-2012, 12:17 PM
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Originally Posted by cobalt327 View Post
If you can, put a vacuum gauge on it to see if the needle of the gauge has a random or rhythmical bounce to it.

How much run time is on the engine now? Sometimes it can take some break in time for the valves and seats to become mated and until then you can have some leakage through them.

Has a compression test been done?
I think we can stop now, I opened her up and found cam lobes worn down, my #1 is good but my #2 is worn and there are several more, so we can rest assured the rest of the valve train is bad, I ordered a new Cam and lifters, and I'll check the timing chain out too, they usually have that in stock.
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Old 09-07-2012, 12:29 PM
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If you have worn cam lobes that metal went somewhere, so you had better check rod and main bearings while you're at it.

Bill
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  #56 (permalink)  
Old 09-07-2012, 12:52 PM
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your talking pulling the whole engine out, it's still in the car.
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Old 09-07-2012, 03:52 PM
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Quote:
Originally Posted by raguza123 View Post
your talking pulling the whole engine out, it's still in the car.
Wiped lobes, sorry to hear that. I thought once a cam survived the break-in and ya kept the zinc up, it was all good. I got about 500miles on mine now, I hope it don't go south. Like I said before, I'm no expert but I wonder HOW bad the bearings would be. Surely the filter system account for something.

Good luc.

Duke
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  #58 (permalink)  
Old 09-07-2012, 04:08 PM
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I'm a fanatic about oil and changing it, I had about 18000 on this cam, I think it was never right from the start.
I hope my filter stopped all the metal.
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Old 09-07-2012, 05:19 PM
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Don't take my word for it that everything's gonna be alright, I was just wondering if everybody that has a cam go bad, completely pulls their engine down.
Maybe some pro's with more experience could chime in..

Duke
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Old 09-07-2012, 06:00 PM
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Ya know I remember when I broke it in, it got real hot during it. That is the engine break in, I made the mistake 2 yrs back of hearing a ticking sound so I decided to replace the lifters only, that was the final nail in the coffin for the cam. Lesson here is replace both together.
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