Well, since my last post I have had my carburetor gone thru and flow tested. I had an internal leak which turned out to be the accell pump housing, my fault. I put the power valve backfire protection into the baseplate. Changed the oil because of the leak. I used a piston stop and found TDC. Exactly where it is supposed to be. I set the balancer at 8* btdc because my expensive blueprinted 480 distributor has 28* centrifugal for a total of 36* at 2800 rpm. Well, it backfires thru the carb when I start it and when it is warm and dies it backfires thru the carb trying to keep it running. So I get the timing light on it and set it at 40* total to get it to run. No backfires and it runs very well. Now it turns out that the initial is at 2* atdc with 40* total. It sounds like the distributor is out of whack, right? With my 15* vacuum it does idle fairly well. It may have been my distributor all along. I never thought to check on my own. I thought I didn't need to.:(

Maybe the stop that limits the travel is gone?

sounds like it time to pick up a recurve kit, and a timing tape if you don't have a degreed balancer, and tame that "expensive" distributor.

Before you do, tho, play some more and see how much advance it really likes. Bet it likes a bunch!

Gary;
Ditto Jim's comments. Come to think of it Gary Jerry re-built your distributor right? I'd bet it's dead on curve wise. maybe the advance limiter came off doubt it though, usually brass. Need to find where it likes advance without pinging. Did you tackle the carb rebuild?

Todd

The carburetor is as good as it will get. What I am saying is that when I timed the engine after reinstalling the carb, the spark plugs and finding TDC something does not add up. I set the initial at 8* BTDC and turned the distributor to get a spark. Should be close, right. No, it backfires when I start it and runs poorly. After I can keep it running I use the backdial timing light and set the total to 40* This should be 28* centrifugal and 12* initial. Now it is running well. Then I check the initial with the vacuum disconnected and idling below 1000 rpm it reads 2* ATDC. Somehow the total is not adding up. Either the distributor is comming in took quickly or my 8 month old barely used timing light is faulty. Any other things it could be?

The brass stop is on the distributor. I will need to find a Sun machine to check the distributor. I never thought that could be a problem

I rechecked everything this morning. The idling total advance at 950-1150 rpm with no vaccum is 22* by the timing lite. I do know that if I set the initial at 8* with the spark plug method it backfires. SOMETHING IS WAY WRONG. BUT IT RUNS GREAT. NO PINGING. Excellent throttle response and no bogging at take off. I did put a little lube on the distributor weights.

Did balancer ring slip? Set motor to run and starts best. Then start checking stuff from there . Sounds like you checked everything else. Borrow another timing lite and check your dial back.

Balancer has not slipped. I did a TDC check with a piston stop. TDC is where it is supposed to be. I will Try another timing lite. Runs darn good right now. I actually went to work today as an excuse to drive it.

It bugs me that I set the initial at 8* and snap the spark plug for start-up. That turns out to be backfire city.:confused:

Gary I to have a 302 that likes the timing way up. I gave up on the timing light and just set it where it likes it. Mine was just rebuilt so I'm still taking it easy but it pings abit at 7,000 but just in 3rd & 4th ? I to think it might be the dist. giving me problems. Bob

Gary I to have a 302 that likes the timing way up. I gave up on the timing light and just set it where it likes it. Mine was just rebuilt so I'm still taking it easy but it pings abit at 7,000 but just in 3rd & 4th ? I to think it might be the dist. giving me problems. Bob

You can actually hear pinging at 7000 rpm? :eek:

Ping or Ding at 7K,,, Hope you are watching oil psi and temp also.

Gary;
Sounds like something is amiss. I'd suggest mapping the curve from idle to
3000 rpm. Mine liked 10-11 degress BTDC at idle no ping. I found the best way to determine ping is lug the motor a little (upshift) to see if it ocurrs. Curve to start at 1300 all in by 2700-2800 off idle curve causes irratic transition so I'd definately map the curve. Write the timing events down at each rpm transition level. Sorry if I seem pretentious but I fiddled with mine for six months till I figured it out and it liked the medium springs in the Mallory curve kits that all speed shops sell. The weaker springs silver I think brought the curve in to quickly cause an off-idle transition. What vac can are you running and what does it develop at idle? Probably not the can but I'd test it with a miti-vac.
Todd

Gary,
I know you said you found TDC and it's right, but I'll throw this in here anyway. Finding tdc (http://www.camaros.net/forums/showthread.php?t=73977) If that's the procedure you followed, or something similar, then good to go there.

Next on the list is "Throw away that darned dialback timing light", or at least lock it on zero, and borrow a non dialback to do a comparsion and verify it is indicating right. It is lying to you. There is NOT an 11:1 solid cam motor ON THIS EARTH EVER that would idle happily at 2 degrees!

You "correct Z/28" guys will just hafta shoot me, but get a degreed balancer, or at least a timing tape, so you can read the whole advance curve with a non-dialback light. Then start over.

Untill then, set the timing where it's happy, drive it when you can, and enjoy. Just keep outa the secondary's and below 4000 rpm and avoid any audible pinging until you can accurately determine your total timing.

Jim
I'd never shoot you! Maybe a spank'n I digress
anyways almost forgot my favorite non-original 302 part..... timing tape
I'd be lost without it!

Todd

I suspect that the timing light is wrong or the engine is idling on the curve. I plan to get both checked. I want to know everything. I will report back. Thanks guys.

Well, I found one problem today. It turns out my distributor has 10* @ 1200 rpm and 30* @ 2200 rpm. It was checked on a Sun machine while I stood there. Also the VC1810 vacuum can adds 20* @ 11". It will be recurved to 0 @1200 rpm and 28* @ 2800 rpm.

I would think that the 10* at 1200 was a problem trying to get it to idle down from 1200 rpm, back when I was chasing a vacuum leak.The timing was changing faster than the idle speed was.

Next I will use another timing lite once the distributor is back in place.

Progress :thumbsup:

Gary;
NAPA/Echlin #VC-1810, should fully deployed at 8" vacuum so you'll have a stable idle. Need to check it if not repalce it your engine will only give you 7-9 in hg at idle. Your initial timing is at 8* with the vacuum advance disconnected, when you connect it, advance will jump up to 23* (and idle speed will increase); just set idle speed back down to around 900 rpm with the idle speed screw and re-adjust the idle mixture screws for highest steady vacuum with a vacuum gauge connected to full manifold vacuum. This is how I went back and forth on mine but remember to map the curve. I had mine transitioning at idle with the black ones thus moving advance. after that in with silver second lightest springs Advance starting @ 1150-1200 RPM and all in @ 2400 RPM. After trying 8 going to 9 degrees advance to see when it starts pinging I found 13-14 to be too high based on CA fuel 91 octane

Todd

I had the distributor curved correctly. It starts at about 1250 rpm and is 30* @3000 rpm, 28* at 2800 rpm. The slot is too long for a bushing to stop at 28*. I have it 6* btdc at idle for 36* total at 3000 rpm. I still need to investigate a new vacuum can and see if I can get down to 15*. I have 26* at idle. Idle speed is 950 to 1000 rpm. I will play with it to see how much initial I can run. I think that because the vacuum can does not come in fully until 11" hg that I am getting some dithering making the idle not quite as stable as it should be at 900 rpm.

Gary;
Ordered mine right online through NAPA shipped right to the house. If it's not fully in at idle it's probably not consitent. I'd repalce sounds like its coming along.
How does it run? you didn't say how you liked 6* I didn't understand what you mean on the bushing it has one right?

Todd

As tuned it runs strong. I have said it before, I really do not understand the complaints about lack of torque and driveability in town with a 302. I am running AC45 plugs with no fouling issues. Th idle needs to be a little more stable and now I understand that the vacuum can is bad.

The bushing to stop the centrifugal advance is round. The width of the slot limits the diameter of bushing used. The slot is a little too long for the maximum diameter bushing that can be used. The bushing does not hit the end of the slot until 30*. The cam in the distributor would need to be filled to stop at 28*. I do not want to molest it.

Gary;
Almost forgot the advance kit I ordered through Jegs had a couple bushings with it both press fit and brass. Maybe if you get a kit it might have a few different diameter bushings. I understand what you mean with the slot vs bushing o.d. not the same size also the radius of the end of the slot is a weird diameter. so the bushing never contacts the full periphary of the slot to stop in either direction. This might sound a little un-orthodox too but playing with the weights gave me some ideas on the center post cam and mechanical stop. You'll notice when together the cam on the drive shaft is at full stop with the weights on. The cam slot doesn't stop the return or zero point the weights and the drive shaft cam do. So why did the weights from 67/68 to 69 change? if you modify a set of 67/68 weights (die grinder) they seem to perform better than the 69 weights plus they ride the weight plate more during travel and bind less.
Worked for me.

Todd