I'm new to having a motor with an aggressive cam and have a couple of things happening with my freshly rebuilt motor that I can't figure out.
1) To get the car to idle on it's own I have to advance it pretty far. When I put the timing light on it, I have to set the timing so far advanced that the indicator on the harmonic balancer is pointing to a position about a half inch to the left of the timing cover. I'm thinking maybe the cam was put in a tooth off? Here's a twist though, I have a 68 timing cover on the 73 motor and I don't know if the covers are so different that the timing would show that far off.
2) This maybe related to issue number one but, when the car is stone cold, it will turn over fast and start right up. After about a minute or so, if I shut it off and turn it over to start it again, it turns over slow. The temp gauge shows less than a 100 degrees so I know it's not too hot. The starter might be getting hot though since it's right next to the headers, but could it heat up that fast?
Here is some specific points about the motor: 1) 73 455 bored .10 over, 6X rebuilt heads, Weiend intake, rebuilt Holly 650, headers, compression - aprox 9.5., mechanical advance dist. 2) Run time so far is about 30 minutes 3) The cam is aggressive (I don't have the specs, but it has a good lop during idle) 4) Oil pressure is good (about 60 psi.) 5) It runs great during acceleration and if I hold it at 2500-3000 RPM its a little more rough running than a standard cam.
Did you bring the #1 piston to TDC on the compression stroke before installing the distributor? Did the mark on the balancer line up with 0 degrees on the timing tab? Did the rotor point toward a distributor cap tower, and does the wire on that tower connect to #1 cylinder? When installing the distributor, did you account for the helix of the distributor gears and start out with the rotor pointing about 3/4 inch clockwise of where you wanted to end up?
These four questions are to determine whether you are actually "advancing it pretty far". It may just be that the distributor is a tooth off.
Is the starter stock or mini, used or rebuilt, and how about the solenoid?
The starter issue is generally heat + timing. Sort out the timing first, then recheck the starter. Yes, headers can heat up a marginal starter very quickly. You may want to consider a heat shield.
Vikki
1969 Goldenrod Yellow / black 400 convertible numbers matching
1. check for vaccume leaks. 2. This is a old school timing trick to help. or at least give you a point of where the timing should be. disconnect the vaccume advance then set the idle as low as possible. next advance the engine slowly till the motor runs freely or in othere words the idle picks up and the engine is running irradically. then stop and start retarding it till the engine idle starts to slow and seems to have a normal lope idle thats the point where the timing is close to what your engine needs. set the carb at 1 1/2 turns then set the idle. increase as necessary 1/4 a turn till you feel it runs good.
It doesn't matter if the distributor was a tooth off. It will not effect timing at all. The only crucial thing when dropping a distributor in would be getting the plug wires in the right place on the cap after you dropped it in, #1 in the right place and the wires in their proper order. It sounds like you have that correct or it wouldn't run the way you describe it. If the cam/timing chain was a tooth off the engine wouldn't run. What could be going on with the timing mark being off; Sometimes an old harmonic balancer will 'slip'. The outer part will break loose and turn a little and your timing mark will be off. Try setting it up by ear like Mark described. What distributor do you have?
"68 tmg cvr on a 73 motor". Neans you have a 69 & up balancer? I can check this afternoon to see if there's that much diff between tmg marks on a 68 & 73.
I'm with Fbody69, need to find tdc on #1 cyl. Then have the rotor coming up just before #1 terminal in cap with tmg mark about 12 degrees before 0 on balancer. Doesnt matter where #1 is on distributor cap as long as you make that your starting point for the rest of the wires.
You may have to locate actual TDC for No 1 cylinder on your balancer...and re-mark the balancer. I just had to do this on my new rebuild. The marks were 13 degrees off.
I'm a hobbyist. Not a professional. Don't be hatin'!
Thanks guys. It's been a while since I first set it up, so I'll re-check everything you mentioned this weekend.
Vikki - I did go through the steps you mentioned, and remember something about the timing mark not aligning with the zero at TDC. I'll re-check all the steps though. The heat shield might be a good idea for that starter. Or maybe I'll look into a high torque mini starter.
ho4spdtogo - 1) Vacuum leaks - I only have one vacuum line and that's for the power brakes. It appears to be fine. 2) Yes that's definitely a good way to get it going. That's basically the process I tried to get it running this time. Once I got it running the best I could, I threw the timing light on it to make a note for future use. It's then that I noticed the timing mark was pretty far off.
FBody69 - Thanks for letting me know that it wouldn't run if the cam was a tooth off. I'm learning as I go. I've heard of the balancer shifting and that could be the case here. When I re-check the timing at TDC, that might answer the question. The type of distributor is a Mallory dual point, converted to single Pertronix pick up, mechanical advance. By the way, there's no slack in the assembly so I don't think I’m getting issues from that.
Ponchshop - Thanks for checking the differences. Yes one less thing to think about. I'll re-check the position of the rotor.
Quenton - That's correct.
Bronze Bird - Yes, it may be that the balancer is off. If so I'll re-stripe it.
Thanks again all. I'll let you all know what I see this weekend.
But Jim is wrong, it will run if the cam is a tooth off. Through inattention and lack of experience I managed to swap cams on an engine way back, got the timing out by a tooth and it ran quite well, other than a general lack of power. I've seen a few other examples of this since.
The procedure for checking cam timing is quite a bit different. Verify TDC and correct alignment of the timing marks on your engine first before worrying about this.
But Jim is wrong, it will run if the cam is a tooth off. Through inattention and lack of experience I managed to swap cams on an engine way back, got the timing out by a tooth and it ran quite well, other than a general lack of power. I've seen a few other examples of this since.
The procedure for checking cam timing is quite a bit different. Verify TDC and correct alignment of the timing marks on your engine first before worrying about this.
Live and learn. I've only seen terrible running engines with the timing gears mis-aligned.
It also depends on the cam specs. A stock cam can run reasonably well as long as nothing hits (valves and pistons). The problem gets a lot worse when the timing chain is worn enough to skip and the distributor timing ends up about 15-20 degrees less than normal at the same time. I've replaced the chains on a couple of Dodges that had skipped twice before not being able to run - luckily!
The variable timing controls on newer cars have quite a wide range of movement, in some cases enough to mimic skipping a tooth.
It also depends on the cam specs. A stock cam can run reasonably well as long as nothing hits (valves and pistons). The problem gets a lot worse when the timing chain is worn enough to skip and the distributor timing ends up about 15-20 degrees less than normal at the same time.
I had that happen on a 350 Chevy powered '77 Ventura. I was on my way back from Florida, and heard the engine lose power in Tennessee. I stopped for gas in Kentucky, and could barely get it started again. So I kept it running the rest of the way home. It would not start after that, until it was repaired.
Vikki
1969 Goldenrod Yellow / black 400 convertible numbers matching
Boy Vikki you got lucky there when it started one more time to get you home.
This engine is completely rebuilt so the chain is nice and tight. The cam is definitely not stock. I can't find the receipts and can't remember the cam I bought, but I remember the builder telling me it will have a choppy idle like a race car, which is does.
Okay here's an update. I brought it to top dead center and the timing mark on the balancer stood at about an inch in front of the timing cover. My assumption is that the balancer slipped. It the same balancer that came with the engine, so I don't know it's history.
To set the timing, I just marked the spot where TDC is now and then advanced the timing about 9-12 degrees from there. The engine seems to run well.
I still have the starting problem though. It turns over quickly when it's cold, but after running it a while it turns over very slowly and starts. If I start and stop the engine a about 4-5 times the battery gets drained to about 60% and starter won't even turn . The engine is at a good operating temp (about 170), so it's not overheating. I have a feeling it has to do with the timing or the starter is heating up since it's so close to the headers, but ran out of time to troubleshoot.
Starter's heating up. It's very common with older starters and solenoids, with headers and stock starters and solenoids, and on cars missing heat shields.
Most of the time replacing the solenoid with a new heavy duty solenoid will fix it, but mine did what yours is doing and I replaced both the starter and solenoid. It works perfectly now.
Vikki
1969 Goldenrod Yellow / black 400 convertible numbers matching
Interesting. It's a new high output GM type starter and solenoid from Napa. I have an old one that worked fine when I pulled it out years ago. I could toss it in to see if the napa starter is defective.
That brings a couple of questions to mind:
Is the solenoid the part that heats up and won't work or is it the starter windings? The reason I ask is that the solenoid does kick in, but the starter won't turn the engine fast enough.
Which heat shield is a good one? I'd like to get one in any case.
I forget, is it that when the timing is too far advanced or retarded that it will have the same symptoms? I'm trying to think ahead a little if the starter improves things but doesn’t eliminate it.
A solenoid is a relay, if it's bad or marginal it won't pull in the main circuit. Sometimes you can hear if the solenoid clicks, if it clicks but doesn't turn it's the starter motor.
If the timing is too far advanced it will make it worse. You can take the starter in for a load test at many auto parts stores. Or swap the old one in.
Also check all the cables...battery to engine ground, battery to starter positive especially, and that the starter bolts are tight.
I just use the stamped factory heat shield, but there are modern insulating jackets that probably work better.
Vikki
1969 Goldenrod Yellow / black 400 convertible numbers matching
Another check would be to get the engine up to temp, shut it off and disconnect the + lead to the coil (insulate it somehow to keep it from shorting) and see if the starter still has trouble cranking the engine over. If the problem goes away, you likely have too much initial timing.
Thanks. I had a second to turn it over today. I turned the key on without giving it any gas to see if the starter would turn freely. It turned over quickly. Then I gave it some gas and the engine definitely fought the starter. I had the timing advanced too far. I backed off the timing and it seemed much better. That's all I could do today.
When I get more time, I'll get it warm and try it again. If it has the same issue, I'll pull the starter and have it tested, check the cables, etc.
I will also take a look at the insulating jackets.
I brought it to top dead center and the timing mark on the balancer stood at about an inch in front of the timing cover. My assumption is that the balancer slipped. It the same balancer that came with the engine, so I don't know it's history.
Vikki
1969 Goldenrod Yellow / black 400 convertible numbers matching
I brought it up to TDC by putting my finger over the spark plug hole of the number 1 cylinder and had someone bump the starter until the air pushed my finger out. I looked inside the cylinder and the piston was at what seemed liked it's highest point closest to the spark plug hole.
The 9-12 degrees was estimated since I don’t have a timing mark to go by. Since 12 degrees is about a half an inch in front of TDC on the timing cover, than I used that same distance in front the current tdc location to determine the amount of advance.
So given all the estimation, I could have been off enough to be beyond 12 degrees. To be safe, I'm going to back the advance off to just before TDC and see what happens both when it’s cold and after running it a while.
If I still see an issue, I'm going to switch the starter out with a known good one and go from there.
What’s the recommended amount of advance if you have an aggressive cam? Or is it different per cam?
Eventually, I'll replace the balancer too to eliminate the confusion.
Next time, grab a spare pushrod and insert it into the spark plug hole while someone turns the engine back and forth at TDC with a breaking bar and a socket on the crank bolt. Even by feel you should be able to get quite close but a dial gauge on a magnetic stand will allow you get very close and also you can do this by yourself. Even though your chain is new you'll likely feel the slop as you go back and forth locating TDC. If you have trouble feeling it, take the cap off your distributor and watch the rotor. More than about 5 degrees movement at the crank without the rotor moving means the timing chain is pretty loose even if it is new. I've seen this and replaced new ones before.
This shouldn't take more than half an hour and is well worth doing.
Thanks I'll have to try that. I would be curious to see if the timing chain is loose.
Unfortunately I lost spark to most of the cylinders today, so the engine just barely sputters when I turn the key. I'm chasing that down right now. When I get that figured out, I'll continue with this.
Have you verified this with a timing light on each of the wires?
A jumped timing chain, a bad rotor (or cap/rotor if rotor strikes the cap), points/dwell, bad coil, loose coil wires, or broken/missing distributor gear drive pin are common suspects.
Check for consistent power to the coil with a test lamp on coil +. It should light and hold steady while cranking. If not, check for a loose ignition wire to coil +.
Test for point operation with either timing light on the coil to distributor spark wire or with a test lamp from coil - to ground. Either way you should get a rapidly, evenly flashing light. If not, check to see if your distributor is bolted down tight, or it may have lost its initial timing. Check cap and rotor, points, coil to distributor primary wire, distributor drive gear pin (if this is bad, rotor will turn by hand with the distributor installed). Also check the advance springs and weights, make sure none are broken or stuck.
Vikki
1969 Goldenrod Yellow / black 400 convertible numbers matching
Okay, I took a second look and here's what I found:
I originally used a test light to check for spark on the first few cyclinders. None of them showed spark. I changed to the timing light as suggested and found spark on all eight cylinders. So I do have spark.
I checked the distributor and rotor and thier good and tight. The ditributor postion is in the same place it was the last time it ran good. The weights are still together and are moveable. The cap and rotor don't show any burn marks or significant wear. Also, the wires are new. I also had a new coil and threw it in just in case the spark was present, but not strong. No improvement.
I'm thinking about the timing chain. Although this build only has about 45 minutes of run time on it, so it seems unlikley that it woiuld slip, but it sounds like TOcan has run into that issue.
You have ignition. You have cranking. Are you positive you have fuel? If you have fuel, it comes down to timing. Disconnect the vacuum advance, plug the hose on the vacuum side, and hook up your timing light. Check against your timing mark and see if it shows the same as before.
One that is not too uncommon is the fuel pump eccentric. If the bolt comes loose in the fuel pump eccentric, on the nose of the cam, the fuel pump will no longer pump. If the bolt comes out too far the timing gear will come off too. So check your fuel pump output; you can disconnect the fuel line from the carb and install a piece of fuel line routed safely away from the fan and ignition sources. Place the hose in a weighted container and have a helper crank the engine. If you get steady pulses of fuel in the jar, then your eccentric should be okay.
You can also often get a sense of what's going on inside the cylinders if you pull a few plugs. Are they wet and oily, wet and gassy, dry and looking new, dry and speckled, smashed electrodes, cracked porcelain?
Vikki
1969 Goldenrod Yellow / black 400 convertible numbers matching
Just to clarify, the new timing chains that were loose didn't skip and weren't likely to skip for quite a while, I just didn't want to leave it loose. Check yours and let us know what you find when you get the chance.
If you are going to pull the plugs, do the fuel pump test when the plugs are out. Less strain on your starter and battery, and might clear things out if you somehow got a shot of gas in the engine. Remember to disconnect the power wire to the coil unless you also want to check for spark at the same time. If you're going to do that, hook up one spark plug to the coil wire and watch that while cranking (safety first though!). The sparks should be blueish white.
Okay I found out the no start problem. I could see the carb was spraying good in the carb, so I went back to the electrical side of things and went through each component. I found that the wires connecting to the distributor side of the coil were loose. I tightened them up and it started right up.
I brought the timing in better and adjusted the carb since it was dry fouling the plugs and causing black smoke in the exhaust.
The car runs great now and starts perfectly.
So going back to my original problem. The starter works fine until the engine gets up to normal operating temp. Then it will barely turn the engine. If I wait a few hours to let it cool down below 100 degrees, it will turn over quickly and start normally.
So, next weekend I'm going to replace the new starter with an old one that worked fine before the engine was rebuilt and re-test. I had different headers on the old engine, so it will be interesting to see if the issue is truly with the starter or that I need a strong heat shield.
I finally had a chnace to get back to this. I changed the starter and had the same issues. As a matter of fact, the starter I just put in had worse symptoms since it wasn't a higher torgue stater.
Just to refresh your memeory, the freshly rebuilt street/strip engine turns over fine and runs well when it's cold, but when it reaches operating temp, it turns too slow to start.
BTW, I checked the charging system and it's producing 14.5 volts during idle, so I think it's okay and the battery seems to accept and hold the charge fine.
So I'm thinking about bringing the car to normal operating temp and just backing off the timing until it turns over well. I hate to turn the timng down though since it runs well with the timing advanced.
Question - Would the compression be that much differnt once the engine is warm to make the engine turn harder? If so, then I'm wondering if the engine has more compression than I thought and I should pick up a compression tester to fined out what I have.
While running my very cammed 11:1 455, I had similar issues with the starter not turning the motor fast enough to start, even with a high torque starter. To get the motor to spin up to speed, I put a NC / momentary open switch in series with the coil ground lead wire.
Press the switch and turn the key. The starter will run the engine up to cranking speed. When you release the switch button, she should start right up. It's the same basic principal as a cranking retard on an ignition control module.
Place the switch below the dash on the left side of the steering column.
To test if this will work, disconnect the coil ground wire and see if the motor turns over more freely. If so, give this a try.
The compression will be slightly higher but that's not the issue. Too much initial timing is, as you confirmed earlier. Have you ever confirmed TDC? Initial timing? Total timing?
I had the same issue with my 400. Too much initial to start easily when warm, but didn't want to back off the timing because it ran well. I ended up recurving my distributor to allow the engine to start and run (cured my idle surge as well) and retain the proper timing when fully advanced.
First, I would try a a heat shield around the starter.
Then if that didn't improve the hot starts, do this:
First, if you haven't already either get a dial back light, so it's not a guessing game what your timing is, or get the appropriate timing tape for the Pontiac engine. You are wasting your time if you can't properly document your settings and changes.
Then, get an adjustable vacuum advance can. Set your timing for a to the point at which it will restart when hot. Use this as your initial baseline. Now hook up your stock vacuum can to full manifold vacuum instead of ported, while the engine is running. Then note the new idle rpm (yes you should use a tach), and the appropriate timing. Your idle speed will increase, again don't adjust it yet. Next, pull the distibuter and install the vacuum canister per the instructions. Re-install and reset your initial timing without vacuum. Then connect the vacuum again, and adjust until you get close to the stock setup. Then fine tune it by measuring the highest manifold vacuum or highest idle speed (rpm only if you don't have a vacuum gage). Then reset your idle speed down to the desired level. You also need to adjust your idle mixture.
You should also verify your total mechanical timing with the vacuum canister disconnected. Since don't have accurate initial and maximum mechanical advance curves, you are risking engine damage. You can buy a dial-back timing light, or there are digital ones that include a tach if you don't have one of those.
The money you spend on these two pieces of equipment, could save you from thousands in engine damage, lots of time tuning (that you could be using for driving), and allow optimum tune which gives you the best performance and fuel economy.
Do your ground work first and find out where your timing is. Recurving the distributor is done after you know what the initial and full mechanical advance is and what the present curve is. Once you know that, you can fix the problem. Without a baseline you're guessing and can easily do more harm than good.
Start with the basics. That might even fix your problem. If not, the steps needed to do so will be determined by what you find.
Okay, finally got back to this. Got it running good now. There were a few things going on. I went back to the beginning and determined that the harmonic balancer was off, but not much, about a 1/4 inch. So I adjusted my timing with that in mind. The car seemed to run better, but then it just quit. It sounded kind of like the timing chain came off.
I took a look at the distributor and it was in a different position than where I set it and it raised up about 1/4 inch from the block. I found out that bolt that holds the distributor in place had popped out of the threads and the distributor turned enough to make the engine stop. I'm sure the bolt came loose before causing the timing to move a little bit and I just didn’t notice it, confusing my troubleshooting even more. I rethreaded the bolt hole and it stays tight now.
Next, my idle speed was too low and fuel mixture was rich to run right at the proper timing, so I adjusted them both and the motor really came to life.
It was really the combination if many simultaneous issues that lead me down many paths of troubleshooting. This was my first time starting up a new engine, so I learned a lot. Just had to go back to the basics and retest things one at a time until I could eliminate each possibility.
BTW, the starter turned out to be fine and so far, I don't have the need to re-curve the distributor.