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Alright, rather than rehash an old thread..I figured I'd start a new one.
400G-.040" overbore
Erson TQ50H (228/235 @.050)
Factory Distributor-recurved for combination
I'm fighting once again with timing. The car starts as if the ignition timing is too advanced. I tried backing it off a tad, and it still wants to start occasionally as if it's advanced, but now the plugs are reading rich. In chasing that (and vacuum) I had an epiphany..
The consensus had become that while the cam was NOT degreed, per the shop it went to-it ran too well to be that far off. With that being said, A. The shop owner was friends with the guy who assembled the engine (and admitted he didn't degree it) and B. It still acts like something isn't right. One thing that drives me bonkers is the fact that the balancer does not line up with the timing tab (off approx 8°) despite being brand new.
Would it be possible that the balancer mark is off because the cam is not installed properly? If so, being the "new zero" is approx 8° BTDC and the engine feels lazy and makes terrible vacuum..would that mean it's installed retarded?
I've never struggled this bad to get a car to run at least at 90%.
How was TDC found to then determine the balancer is 8° off? Was the piston perfectly at TDC.
When it was picked up from the assembly shop, we were told it had a new zero. over the winter when I was fixing the 180° out situation, I also found TDC and noticed the mark lined up with the "new zero"
I found my previous camshaft was 8 degrees retarded. The engine ran fine with a very smooth idle and strong vacuum, it just didn’t have much low RPM power. Around 3500 RPM it started pulling hard, but was meh below that, power wise.
I don’t know how far off cam timing would have to be to cause idle issues.
Last edited by Fun71; August 31st, 2023 at 07:47 PM.
small dowel in the #1 spark plug hole. Once verified I was on compression stroke, I went back and forth a few times to verify top.
That is not accurate enough. You can easily be off 10 degrees that way. You need to put an actual TDC stop in the plug hole that will solidly stop the piston a few degrees before TDC. Then you do the following:
Turn the engine in one direction until it hits the stop.
Put a mark on the damper lined up with the TDC pointer.
Turn the engine all the way around in the other direction until it hits the stop again.
Put another mark on the damper lined up with the TDC pointer.
Half way between the two marks is your true TDC.
That is not accurate enough. You can easily be off 10 degrees that way. You need to put an actual TDC stop in the plug hole that will solidly stop the piston a few degrees before TDC. Then you do the following:
Turn the engine in one direction until it hits the stop.
Put a mark on the damper lined up with the TDC pointer.
Turn the engine all the way around in the other direction until it hits the stop again.
Put another mark on the damper lined up with the TDC pointer.
Half way between the two marks is your true TDC.
Interesting. I didn't think anything about it as it lined up with where the assembly shop stated the "new zero" was. While I'm assuming they verified this with the heads off during assembly, at this point I don't know what to believe out of there anymore.
Where I also have a hard time is the fact that the balancer is a new, factory replacement. I figured there may be slight variation at most due to the block having been decked, but it still doesn't explain the cam not being degreed and therefore the car running lackluster.
[QUOTE=brotherGood;1520904 it still doesn't explain the cam not being degreed and therefore the car running lackluster.[/QUOTE]
I have to be honest with you . . . . . I have been doing this since 1987 and have probably "degreed" a hundred or more cams but I can only remember one in all that time that was actually off from the cam card specs and had to be moved. I just did an Erson hydraulic roller yesterday in a small block Chevy I am building and it was within a degree.
So realistically I would not be blaming the cam timing.
Dont know how well you can see it in the car but I have a Scat Oldsmobile damper here and it looks like the keyway is at about 16-17 degrees Before TDC. That might be a way to check the damper. Unfortunately Dorman does not have the best reputation for parts
One thing you could try as a quick check is just advance the timing 10 degrees and see what happens. If it makes a huge improvement you are probably on the right track. It is a vacuum advance distributor ?
Also do you happen to have the actual cam card ? If so post the part number and serial number if there is one.
One thing you could try as a quick check is just advance the timing 10 degrees and see what happens. If it makes a huge improvement you are probably on the right track. It is a vacuum advance distributor ?
Also do you happen to have the actual cam card ? If so post the part number and serial number if there is one.
Yeah, vacuum advance distributor (original, just rebuilt & recurved by Ken @ Everyday Performance to the combination). It does run better with more timing, but it's also hard to start..and kicks back as if it's too far advanced. In backing it back off, it has helped a little, however now I'm back to losing vacuum (which when I've got 8", I don't have much to lose)
Here's the cam sheet:
I could change balancers, but I don't see that fixing any issue other than the "new zero" at most. I'm using a dial back light, so I'm taking the guesswork out of where the mark actually is on the balancer as I advance.
Yeah, vacuum advance distributor (original, just rebuilt & recurved by Ken @ Everyday Performance to the combination). It does run better with more timing, but it's also hard to start..and kicks back as if it's too far advanced. In backing it back off, it has helped a little, however now I'm back to losing vacuum (which when I've got 8", I don't have much to lose)
Here's the cam sheet:
I could change balancers, but I don't see that fixing any issue other than the "new zero" at most. I'm using a dial back light, so I'm taking the guesswork out of where the mark actually is on the balancer as I advance.
Thats part of your problem. Beyond the obvious Ken is clueless.
The fact that they didn’t actually degree the cam will always be your grey area. But that has nothing to do with ignition timing. If you say you’ve verified the balancer, one way or another, then your focus should be to continue to look elsewhere.
Thats part of your problem. Beyond the obvious Ken is clueless.
The fact that they didn’t actually degree the cam will always be your grey area. But that has nothing to do with ignition timing. If you say you’ve verified the balancer, one way or another, then your quest is to continue to look elsewhere.
So even though the cam wasn't degreed, that wouldn't have anything to do with the fact I've got so much ignition timing to get throttle response & mild vacuum?
I almost called you, but figured Ive worn out the free advise on this..haha
It does run better with more timing, but it's also hard to start..and kicks back as if it's too far advanced.
Is the vacuum advance working ? Is is connected to direct manifold vacuum ? How much does the advance change when you connect it to vacuum ?
Originally Posted by brotherGood
I could change balancers, but I don't see that fixing any issue other than the "new zero" at most. I'm using a dial back light, so I'm taking the guesswork out of where the mark actually is on the balancer as I advance.
i dont think you need to replace the damper but you do need to determine the correct TDC mark which I dont think you can do without using a TDC stop.
Also just for grins . . . do you have a friend who will loan you a non dial back timing light to try ? I have no confidence in them at all after finding a couple of them reading very wrong.
Is the vacuum advance working ? Is is connected to direct manifold vacuum ? How much does the advance change when you connect it to vacuum ? I'm assuming, though I'm not entirely sure how to check it. Vacuum is hooked to full Vacuum source (I've gone back and forth hoping that'd be the key).
i dont think you need to replace the damper but you do need to determine the correct TDC mark which I dont think you can do without using a TDC stop.
Also just for grins . . . do you have a friend who will loan you a non dial back timing light to try ? I have no confidence in them at all after finding a couple of them reading very wrong.
I'll have to see if Pops has my old (non-dial back) timing light in that case. That was all I had until I got a dial back (which now I have 2 as I needed a more accurate tach readout)
There's not really anything to reread. Just put a timing light on it with the vacuum advance hooked up at idle. Note the number. Then remove the line and plug the port in the carb/manifold (or use a clamp to close the line). Recheck the timing at idle. Note the number. If they aren't different, it isn't working. If they are, the difference is how much vacuum advance you have.
Thats part of your problem. Beyond the obvious Ken is clueless.
The fact that they didn’t actually degree the cam will always be your grey area. But that has nothing to do with ignition timing. If you say you’ve verified the balancer, one way or another, then your focus should be to continue to look elsewhere.
Well according to some there isn't a need for degree wheels. You buy a cam, put it the engine, line up the marks and you're good to go.
There's not really anything to reread. Just put a timing light on it with the vacuum advance hooked up at idle. Note the number. Then remove the line and plug the port in the carb/manifold (or use a clamp to close the line). Recheck the timing at idle. Note the number. If they aren't different, it isn't working. If they are, the difference is how much vacuum advance you have.
Thats probably where I got confused..as per the distributor card, nothing comes in until 1000 RPM, though with being hooked to full manifold vacuum I'm not sure how it wouldn't.
Unless the card was meaning mechanical didn't come in until 1000 RPM, which incidentally I noticed looking at pictures the other day that I believe it has 2 heavier springs.
So even though the cam wasn't degreed, that wouldn't have anything to do with the fact I've got so much ignition timing to get throttle response & mild vacuum?
I almost called you, but figured Ive worn out the free advise on this..haha
No problem.
Yes, if the cam is retarded more IGNITION timing could be beneficial. But I thought you said you’ve verified the ignition timing and still have low vacuum?
If so, then you really need to quit beating a dead horse, sorry. Get back into the engine and verify Cam timing one way or another. Otherwise you’re just wasting your time and energy chasing your tail.
No problem.
Yes, if the cam is retarded more IGNITION timing could be beneficial. But I thought you said you’ve verified the ignition timing and still have low vacuum?
If so, then you really need to quit beating a dead horse, sorry. Get back into the engine and verify Cam timing one way or another. Otherwise you’re just wasting your time and energy chasing your tail.
That's where I'm at..98% sure the cam timing being off is the fault, just trying to continue to learn until I can find someone who can fix it (and be able to afford it.. lol)
Thats probably where I got confused..as per the distributor card, nothing comes in until 1000 RPM, though with being hooked to full manifold vacuum I'm not sure how it wouldn't.
Unless the card was meaning mechanical didn't come in until 1000 RPM, which incidentally I noticed looking at pictures the other day that I believe it has 2 heavier springs.
Your distributor card is talking about mechanical advance. Vacuum advance happens when vacuum is applied.
Absolutely. I had a friend who had a 65 442 that wouldn't pull the hat off his head,a pure dog. Told him to check the cam timing and guess what? One of my engine guys years ago bought a Cloyes double roller chain set and it was mismarked from the factory. He took it back to the supply house and they checked the rest of the stock and the same was true of all of them. Don't even get me started when we bought a set of ARP rod bolts that had bolts that wasn't threaded. Just because it's new doesn't mean jack.
Absolutely. I had a friend who had a 65 442 that wouldn't pull the hat off his head,a pure dog. Told him to check the cam timing and guess what? One of my engine guys years ago bought a Cloyes double roller chain set and it was mismarked from the factory. He took it back to the supply house and they checked the rest of the stock and the same was true of all of them. Don't even get me started when we bought a set of ARP rod bolts that had bolts that wasn't threaded. Just because it's new doesn't mean jack.
And away we go…lol.. I hear ya loud and clear..So Mark, you have put in hundreds of cams, out of 100 how many were off enough that you had to re-key them? Just curious?
You were told about the piston stop method long long time ago to find true TDC…like a couple years ago when you first mentioned it had a new TDC
You were also told to do a compression test..which also took like two years to do. When you did finally do it…it gave a clear indication that something wasn’t right. All were low and there was way to much variation for it being a fresh build.
the TDC being off is only going to mess with your head because it’s only giving you a false spark timing. It’s got nothing to do with the cam not being degree’d
if the cam is in retarded, which I think it is because of your low compression numbers, then you would need more spark advance for it to run better
if you still refuse to find the true TDC by the piston stop method so you can get a correct spark timing on the tab…then you have to do some guess work and road testing.
keep advancing the timing until the acceleration drops off, then go back to previous best acceleration.
that’s all you can do ..unless you want to dig into the engine again
And away we go…lol.. I hear ya loud and clear..So Mark, you have put in hundreds of cams, out of 100 how many were off enough that you had to re-key them? Just curious?
Didn't have to rekey any but I’ve had more than one that were way off, ie, retarding the cam 11* to get the 4* advance I was looking for. Why do you ask? I never said anything about having to rekey any of them.
I know who you are now.
Last edited by cutlassefi; September 2nd, 2023 at 02:25 PM.
I'll start with this one, it should pretty well sum things up...
Originally Posted by CANADIANOLDS
You were told about the piston stop method long long time ago to find true TDC…like a couple years ago when you first mentioned it had a new TDC I've only had the engine back just over a year, and didn't even think about the need to find TDC until probably January/February when I was relocating the distributor. With that being said, the method used has been done countless times by countless people on countless engines. While yes, the proper tool is always best..it's not a failed system.
You were also told to do a compression test..which also took like two years to do. When you did finally do it…it gave a clear indication that something wasn’t right. All were low and there was way to much variation for it being a fresh build. Correct, I was told to do a compression test. Most of the hesitancy was due to the fact that is WAS a brand new engine, so I had no reason to doubt. Though as time has progressed, I'm doubting everything. Once I finally conceded to doing a test, I needed to find my tester as it went MIA as well as find the time to do the test. Unlike most, the car is not my top priority..which is why I spend so much of what free time I have researching (whether it be free time at work, free time during functions away from home, or even free time in which I can't go out and fire the car up). At that point yes, it was discussed that the numbers were low and there was too much variation for a FRESH build.
the TDC being off is only going to mess with your head because it’s only giving you a false spark timing. It’s got nothing to do with the cam not being degree’d
Correct, especially with the dial back light..I just reference the "new zero". It's still hard to remember though in the moment since I've never dealt with this before. Especially when I've done more researching the problem/solution than actually going out and working on it.
if the cam is in retarded, which I think it is because of your low compression numbers, then you would need more spark advance for it to run better
That's where I'm at..which was why I started this thread to begin with-to confirm my train of thought.
if you still refuse to find the true TDC by the piston stop method so you can get a correct spark timing on the tab…then you have to do some guess work and road testing.
keep advancing the timing until the acceleration drops off, then go back to previous best acceleration.
that’s all you can do ..unless you want to dig into the engine again
I am beyond nervous adding more than 20 degrees of initial timing into it. I've heard too many horror stories over the years of pistons being destroyed by detonation/too much timing. Knowing the pistons in there are obsolete, the last thing I want to do is risk it. I have come to the conclusion that I need to dig into it. When it came back from the most recent shop and the guy said it was fine, knowing what he wrenched on all the time made me feel a bit better about what he was saying. Though, the more I drive it since then, the more I'm left wondering why it is so lethargic. My truck is snappier, my 318 small block was snappier, heck my lawnmower is snappier at times. I get it..a BB (especially a 400G) isn't going to have that instant "holy smokes" feel to it..but it should at least have some sort of torque. Then there's the whole issue of vacuum & drivability (not just the lack of torque feel)
I'll probably go ahead and order a new timing set with a 9 keyway gear, as the assembler blamed the 3 key way as to why he didn't degree it (though he had no issues buying other items to put it together). Then I'll try to find someone who is willing to degree it in the car. I'll be honest, if it were out of the car, I'd take the time and learn how to do it myself (again, I research too much) but I'm not yanking it again. We realized after it was too late that the engine hoist I had was not big enough, and how we managed to get it in there without tearing anything up (other than the AC condenser) is still a mystery. I've gone past the point of being upset that a 10k engine is a dud..and I'm to the point now where I just need to have it done right, at the very least so that I don't have to worry about it.
Didn't have to rekey any but I’ve had more than one that were way off, ie, retarding the cam 11* to get the 4* advance I was looking for. Why do you ask? I never said anything about having to rekey any of them.
I know who you are now.
Well of course you know who I am.. I live not far from you and have talked to you several times..I never alluded to you having to rekey anything. It was simply a question about how often you identify cams ground incorrectly when using the wheel. As Bill states in this post he has found one cam in hundreds using a degree wheel far enough off to make any real difference.. Mikeand I have had many discussions on this and yes, if your drag racing, trying to get every inch of hp out of your engine its surely a must..same thing with fully blueprinting during your rebuild..My opinion only as I am not an engine builder. All I can say is the factory never used a degree wheel when assembly was going on in the production line..Again, not saying it shouldn’t be done but the same can be said of folks doing a rebuild for their classic car and not blueprinting the engine during the build..
I'll probably go ahead and order a new timing set with a 9 keyway gear, as the assembler blamed the 3 key way as to why he didn't degree it (though he had no issues buying other items to put it together). Then I'll try to find someone who is willing to degree it in the car. I'll be honest, if it were out of the car, I'd take the time and learn how to do it myself (again, I research too much) but I'm not yanking it again. We realized after it was too late that the engine hoist I had was not big enough, and how we managed to get it in there without tearing anything up (other than the AC condenser) is still a mystery. I've gone past the point of being upset that a 10k engine is a dud..and I'm to the point now where I just need to have it done right, at the very least so that I don't have to worry about it.
Before you waste any more money, buy a tdc stop and find true tdc on your damper. At that point any decent engine guy with a dial indicator would be able to pull the drivers side valve cover and tell you within 10 minutes if the cam is "degreed" correctly.
Thats my last comment. If you need somebody near you who can do this for you post your exact location and I will find somebody for you.
If you need somebody near you who can do this for you post your exact location and I will find somebody for you.
I'll start here..located between Dayton & Columbus OH
I have called multiple shops around me. The first challenge is finding anyone who is willing to do it at all. Second, the issue is the fact that the engine is still in the car. I don't have many around here who I'd trust enough with it to take the engine out/reinstall-especially since I'm not really set up to be pulling engines with ease anyway (install was a nightmare when it didn't have to be). I even called down to the assembly shop that put the engine together, and they will not work on it while in the car. I get it, it'll be a nightmare just to get to it..but still somewhat irritating that the best thing is to pull it. He did however say he did not see any reason to pull the cam, but then again has maintained that this entire time.
I've got a few people who have degree wheels, and as much as my wallet says to just go that route-I know at the end of the day I need to ensure its right and not put cost ahead of it. I think it's something I could do, but I'd rather find out I did something wrong on a non-numbers matching engine that I didn't already have north of 10k in.
August 31st, 2023, 06:09 PM
