Slant Six Forum :: Timing out of whack

At this point I agree that you should have the camshaft installation verified. The camshaft centerline needs to be verified to be in the correct orientation to the crankshaft. You should be getting much more vacuum than that at 12 BTDC. You seem to be doing everything right but you are not getting the right results. That suggests the problem lies deeper in the motor.

Moving the vacuum pod "down" retards the timing (makes it fire closer to or even after TDC). Moving the vacuum pod "up" advances the timing (makes it fire more before TDC).

At this point I agree that you should have the camshaft installation verified. The camshaft centerline needs to be verified to be in the correct orientation to the crankshaft. You should be getting much more vacuum than that at 12 BTDC. You seem to be doing everything right but you are not getting the right results. That suggests the problem lies deeper in the motor.

Quote:

I watched the video and suspected as much as well, the fact that it needs a lot of advance to be happy and that at TDC it only throws in 11" shows that the cam is probably retarded a tooth or so leaving the valves open at the wrong time...Time for a degree wheel and piston stop along with a look at the cam card to see where the events are at...If it is really retarded, hopefully it is something that can be remedied by advancing the cam 2 teeth to get it a little past straight up. I can say from experience that I degreed a cam in late one night ( I was tired, but wanted to get "one more thing done", and should have waited until the morning) and didn't check it the next morning and buttoned everything up and installed it in the duster...vacuum was about 13" at 1000 rpm idle, and power was sluggish...vacuum and power got better at 2000-3000 rpm...
That weekend I pulled the timing cover and rechecked it, and found I had installed the cam 13 degrees retarded ...I corrected it by advancing a couple teeth and using a bushing to put me at 3.5 degrees advanced and buttoned it up, and took it on a test drive...all the power and vacuum and everything went back in the goal posts (it was real fun to drive, instead of being 'sluggy').

If your machinist assembled it and he said it was fine, then checked it and it was fine, his damper has slipped and needs to be recalibrated or replaced.

At least you are very close and we know why. And I learned my lesson, and after setting it, I rotate the engine through the "cycle" a few times on the intake side just to be sure the events line up, and then check the exhaust side just to see if the cam grinder was spot on his grind....

-D.Idiot

What do you mean by cam card, I have heard this term before.

I have been reading and saving some of your old posts, I think you have said something similar to this in the past...........advancing the cam 2 teeth to get it a little past straight up..............why not straight up, you have lead me to believe that the set-up is happier not in spec as per the manual if you get my meaning.

What if I have a cam with no data available ? Can I use the degree wheel to figure it out or am I stuck ?

Yes, you will have to "map" the intake and exhaust lobes to see where it lands and then you might be able to ID the mystery cam from there...sometimes the manufacturer will stamp some ID marks on the front or back of the cam and you might be able to look it up from there.

-D.Idiot

Can you recommend any more good reading that starts at the basics and guides me thru more of what I need to know?

that he installed whatever stock cam was called for in a 1986 slant engine.
I am going to assume that the cam is pretty weak, dummied down for a lean burn set-up engine and emissions standards that had to be met at the time.

I would like to change the cam while I am in there, I would like a cam that will give me optimum results for my specific vehicle. How would I go about choosing the correct cam?

I want the gear drive cause I like the sound of a blower, plain and simple, I love that whine.

I would like to change the cam while I am in there, I would like a cam that will give me optimum results for my specific vehicle. How would I go about choosing the correct cam?

Author:	1930 [ Sat Jan 25, 2014 3:58 pm ]
Post subject:	Timing out of whack
As many of you know I have been having issues with timing on my truck, quick overview. 1986 225 hydraulic engine. Basically a stock re-build with the exception of 40 over on the cylinders, shaved the head a bit to bump compression. I have it running and it runs very well where it is right now but I am only getting 11 inches of vacuum at idle. I decided to start all over again with the timing, found TDC on the dampner, ( yes I know it too be TDC ) I then lined up my dist rotor just before the # 1 spark plug port on the dist itself. Would not start, I had to move the dist housing up toward the engine to get it too fire. The most vacuum I could get out of it with all my playing around moving the dist whilst running was 16 inches on the gauge but that was a stretch. Here is a video of what I m up against and hopefully it will show you guys clues to tell me what the heck is going on. At this point I am guessing ( as has been mentioned ) that my cam is out of whack. The vacuum gauge is hooked up to read manifold pressure below the throttle plates. At this point the engine has about 5 hours on it and Ive driven it maybe 25 miles so I am sure not completely broken in yet. http://www.youtube.com/watch?v=FevRsU8H ... e=youtu.be

Author:	Reed [ Sat Jan 25, 2014 6:34 pm ]
Post subject:
Moving the vacuum pod "down" retards the timing (makes it fire closer to or even after TDC). Moving the vacuum pod "up" advances the timing (makes it fire more before TDC). At this point I agree that you should have the camshaft installation verified. The camshaft centerline needs to be verified to be in the correct orientation to the crankshaft. You should be getting much more vacuum than that at 12 BTDC. You seem to be doing everything right but you are not getting the right results. That suggests the problem lies deeper in the motor.

Author:	DusterIdiot [ Sat Jan 25, 2014 7:32 pm ]
Post subject:	x2 Ted is on his game!
Quote: At this point I agree that you should have the camshaft installation verified. The camshaft centerline needs to be verified to be in the correct orientation to the crankshaft. You should be getting much more vacuum than that at 12 BTDC. You seem to be doing everything right but you are not getting the right results. That suggests the problem lies deeper in the motor. I watched the video and suspected as much as well, the fact that it needs a lot of advance to be happy and that at TDC it only throws in 11" shows that the cam is probably retarded a tooth or so leaving the valves open at the wrong time...Time for a degree wheel and piston stop along with a look at the cam card to see where the events are at...If it is really retarded, hopefully it is something that can be remedied by advancing the cam 2 teeth to get it a little past straight up. I can say from experience that I degreed a cam in late one night ( I was tired, but wanted to get "one more thing done", and should have waited until the morning) and didn't check it the next morning and buttoned everything up and installed it in the duster...vacuum was about 13" at 1000 rpm idle, and power was sluggish...vacuum and power got better at 2000-3000 rpm... That weekend I pulled the timing cover and rechecked it, and found I had installed the cam 13 degrees retarded ...I corrected it by advancing a couple teeth and using a bushing to put me at 3.5 degrees advanced and buttoned it up, and took it on a test drive...all the power and vacuum and everything went back in the goal posts (it was real fun to drive, instead of being 'sluggy'). If your machinist assembled it and he said it was fine, then checked it and it was fine, his damper has slipped and needs to be recalibrated or replaced. At least you are very close and we know why. And I learned my lesson, and after setting it, I rotate the engine through the "cycle" a few times on the intake side just to be sure the events line up, and then check the exhaust side just to see if the cam grinder was spot on his grind.... -D.Idiot

Author:	1930 [ Sun Jan 26, 2014 4:05 am ]
Post subject:
Quote: Moving the vacuum pod "down" retards the timing (makes it fire closer to or even after TDC). Moving the vacuum pod "up" advances the timing (makes it fire more before TDC). At this point I agree that you should have the camshaft installation verified. The camshaft centerline needs to be verified to be in the correct orientation to the crankshaft. You should be getting much more vacuum than that at 12 BTDC. You seem to be doing everything right but you are not getting the right results. That suggests the problem lies deeper in the motor. Quote: Moving the vacuum pod "down" retards the timing (makes it fire closer to or even after TDC). Moving the vacuum pod "up" advances the timing (makes it fire more before TDC). ............... Sometimes it takes me a while to get things and this was one of them, this came to me while laying in bed last night trying to put some of this together. Thanks

Author:	1930 [ Sun Jan 26, 2014 4:16 am ]
Post subject:	Re: x2 Ted is on his game!
Quote: Quote: At this point I agree that you should have the camshaft installation verified. The camshaft centerline needs to be verified to be in the correct orientation to the crankshaft. You should be getting much more vacuum than that at 12 BTDC. You seem to be doing everything right but you are not getting the right results. That suggests the problem lies deeper in the motor. I watched the video and suspected as much as well, the fact that it needs a lot of advance to be happy and that at TDC it only throws in 11" shows that the cam is probably retarded a tooth or so leaving the valves open at the wrong time...Time for a degree wheel and piston stop along with a look at the cam card to see where the events are at...If it is really retarded, hopefully it is something that can be remedied by advancing the cam 2 teeth to get it a little past straight up. I can say from experience that I degreed a cam in late one night ( I was tired, but wanted to get "one more thing done", and should have waited until the morning) and didn't check it the next morning and buttoned everything up and installed it in the duster...vacuum was about 13" at 1000 rpm idle, and power was sluggish...vacuum and power got better at 2000-3000 rpm... That weekend I pulled the timing cover and rechecked it, and found I had installed the cam 13 degrees retarded ...I corrected it by advancing a couple teeth and using a bushing to put me at 3.5 degrees advanced and buttoned it up, and took it on a test drive...all the power and vacuum and everything went back in the goal posts (it was real fun to drive, instead of being 'sluggy'). If your machinist assembled it and he said it was fine, then checked it and it was fine, his damper has slipped and needs to be recalibrated or replaced. At least you are very close and we know why. And I learned my lesson, and after setting it, I rotate the engine through the "cycle" a few times on the intake side just to be sure the events line up, and then check the exhaust side just to see if the cam grinder was spot on his grind.... -D.Idiot What do you mean by cam card, I have heard this term before. I have been reading and saving some of your old posts, I think you have said something similar to this in the past...........advancing the cam 2 teeth to get it a little past straight up..............why not straight up, you have lead me to believe that the set-up is happier not in spec as per the manual if you get my meaning. Quote: power was sluggish.......... Thats what gets me, the truck is not sluggish or not any more sluggish than I would expect the truck to be considering I am still running the old worn out carb. I dont expect the truck to be a rocket but cant help but too think how much more responsive it might be once I get this problem fixed. I have saved a few links that get into the how to of degree the cam but these links showed engines with head removed ect. I am going to be doing the work myself, no more machinest involved, I am hoping to be able to do this without removing the A/C condenser cause I have no way to recover the freon here at the house. Is it possible to do this work with the head in place? If anyone knows of any slant topics showing a how to with engine assembled and as little removed as possible it would be appreciated to see a link. Thanks

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Timing out of whack https://slantsix.org/forum/viewtopic.php?t=54425	Page 1 of 3

Author:	DusterIdiot [ Sun Jan 26, 2014 11:36 am ]
Post subject:	No problem...long winded cam lesson.
Quote: What do you mean by cam card, I have heard this term before. When you get a camshaft, it should come with a card that gives the grind data...If this were a comp cam, it's a yellow post card that has: the blank number (225 blank), the grind (catalog lobe numbers), it will include the duration for exhaust and intake, the lift of the cam, sometimes the lobe separation, and 4 numbers measured off the cam lobe at a stable spot (usually about .020 or .050 rise off the base circle of the lobe)...these 4 numbers will tell you when the intake valve will open, intake valve will close, and similar events on the exhaust side...using the degree wheel these will help determine if the cam is retarded, straight up, or advanced and by how much... That being said...typically melling "stock" replacement cams included in some rebuild kits do not have a card, so you will have to get the data online (some is here on the board), and "map" the locations of .050 lift yourself...(a little more involved but not hard once you get the hang of it). Quote: I have been reading and saving some of your old posts, I think you have said something similar to this in the past...........advancing the cam 2 teeth to get it a little past straight up..............why not straight up, you have lead me to believe that the set-up is happier not in spec as per the manual if you get my meaning. The factory spec is to comply with emissions standards for the year your truck was produced...this may not be conducive to power or mileage in many cases....If this is a new cam or aftermarket cam, they are not per factory, so you will be setting it for best performance...in many cases the factories changed the "dot" to line up on the cam gear to meet those requirements ( my buddy replaced the OEM timing chain on his early 80's Ford Truck quite a few years back...to meet the factory standards ofr his 460, on the timing set had the dots line up so the cam was 12 degrees retarded...he had a spare 460 from a mid-70's T-bird in the garage and it still had it's factory timing set and it was set at 4 degrees retarded) Generally speaking when installing a cam, straight up is OK...but if you phase the cam in relation to the crank (advance or retard) it will have the following effects in general: Retarding the cam (opening the valve a little later), produces more top end horsepower, shifts the useable torque band to a higher rpm, is somewhat better for emissions (reduces NOx)...if you really go this route you get an Oval track special...the engine will love to run at 3000-6000 rpm and makes the best work in that range... On the other side, if you advance the cam in relation to the crank (get the valves to open a few degrees sooner), produces a little less top end horsepower (3000-6000 rpm), shifts the torque band to a lower rpm ( best torque at idle to 2500 in most cases)... for a street driven vehicle, daily driver, or vehicle where the power to weight ratio is low (truck/van), this is a better pick in our case as it provides a little more leverage for the engine on a daily commute, which can translate to better power/response, improved mileage, and the engine being a little more efficient....(better vacuum signal, etc). If you have A/C, this would also be preferred to make up for the drag the compressor will put on the engine when engaged. Some cam manufacturers by popular request have sometimes included a few degrees of advance ground into the cam (the lobes are ground shifted for so many degrees advanced), the cam card will reflect this, and typically there will be an odd note on the card...in some cases they have a centerline notation that shows something like 111+4...which means the cam has a typical centerline of 111 degrees if "straight up", but they have now included 4 more degrees of advance with means the intake lobe is ground to be centered at 107 instead... That being said...there is a point where you can advance the cam "too far"...if this happens, the engine will develop higher cylinder pressures and you will be nagged by pinging a fair amount of the time....The old street rule of just setting that cam up at "4 degrees" advanced has been around a while and is fairly safe for most lower compression applications... (you will notice in some posts the recommendations can be as far as 7 degrees of advance, but on a daily driver with a 1 barrel or 2 barrel carb there isn't much gain in the torque band after 4 degrees of advance...in other words if the "stock" cam is ground with a 108 degree intake centerline, then it is desireable to set it to 104 centerline...but not to exceed 101 centerline...), if you aren't wanting/needing to install a bushing kit, you will be limited to what the cam gear cam offer per tooth: typical silent chain/stock cam gears have something like 7.4 degrees per tooth...so if you install it "as close as possible" with the gear and not use a bushing kit, you can only adjust it +/- 7.4 degrees... (i.e. if it's installed at an intake centerline of 112, and the cam card says straight up is 108...you will only get two choices without an offset bushing: 119 retarded (a little too far the wrong way), or 105 (which is 3 degrees advanced and would work out fine for what you are doing). Since we are just changing the cam position, the head does not need to be removed, but, you will need a thread in piston stop to set the degree wheel, and if your dial indicator is mounted on the valve side of the rocker arm you will need to multiply the cam lobe lift by the rocker ratio (1.5-ish...i.e. if the lift at the top of the lobe is 0.3", the valve will see 0.450" at the top of the lobe). There is a lot to digest, so take some time to read and analyze, but this is a fairly critical step in getting the most out of the engine build. -D.Idiot

Author:	Damraider [ Sun Jan 26, 2014 12:55 pm ]
Post subject:
What if I have a cam with no data available ? Can I use the degree wheel to figure it out or am I stuck ? Thanks, Steve

Author:	DusterIdiot [ Sun Jan 26, 2014 1:01 pm ]
Post subject:	Yep...
Quote: What if I have a cam with no data available ? Can I use the degree wheel to figure it out or am I stuck ? Yes, you will have to "map" the intake and exhaust lobes to see where it lands and then you might be able to ID the mystery cam from there...sometimes the manufacturer will stamp some ID marks on the front or back of the cam and you might be able to look it up from there. -D.Idiot

Author:	1930 [ Sun Jan 26, 2014 1:04 pm ]
Post subject:
That is alot to digest but I will print and re-read a few times to get what I can out of it. Thanks Can you recommend any more good reading that starts at the basics and guides me thru more of what I need to know? I have had these books for quite a few years, at least one of them I just now noticed does go into slant details too my surprise, I will start here. Another questions, I am trying to do what I can to search past posts, I have been on-line now for a couple of hours just sitting here reading old posts made by Dads truck cause I havent found another user with anything similar to what I am trying to do. Dont laugh, I am just going throw this out there......I am going to assume ( that is all I can do at this point cause the guy that did the machine work will no longer be contacted by myself, I am done with dealing with him ) that he installed whatever stock cam was called for in a 1986 slant engine. I am going to assume that the cam is pretty weak, dummied down for a lean burn set-up engine and emissions standards that had to be met at the time. I would like to change the cam while I am in there, I would like a cam that will give me optimum results for my specific vehicle. How would I go about choosing the correct cam? I will assume that my best bet is to contact a cam manufacturer, but I would like to have a general idea of what I might be looking for before doing so cause the manufacturer dosent always have my very best interest in mind. Its a 6000 pound 4 wheel drive truck but I dont think that means it has to be an absolute slug, with the cam that is in there now it is not a slug and I dont expect it too be a speed demon but I would like to get the most I can out of what I have. I would also like to install a gear drive, I am reading past posts and one user ( Joshua Skinner ) said this.......the slant uses the same timing chain and crank sprocket as B/RB engines. You can take that to the bank.............. I have also read him state though that its not just a bolt in deal, havent found anything yet that goes into any detail. I want the gear drive cause I like the sound of a blower, plain and simple, I love that whine. I also have my Super six up-grade that I plan to install and I am wanting to do some ( or have some ) head work done. In the end I would like the truck to have the reliability of a slant but would also like to show others that just cause it is a slant does not mean that it cant be a really neat little engine to use.

Author:	1930 [ Sun Jan 26, 2014 1:13 pm ]
Post subject:
I found this post concerning gear drives. http://www.slantsix.org/forum/viewtopic ... 491c794934

Author:	1930 [ Sun Jan 26, 2014 1:15 pm ]
Post subject:
Found this one http://www.youtube.com/watch?v=EeUzSD_Tfmg That sounds tough!! Heres a kit, at that price Id like to hear mor about the B/RB set-up http://www.hemiperformance.com.au/store ... -Drive-Kit

Author:	Damraider [ Sun Jan 26, 2014 1:23 pm ]
Post subject:
Quote: Yes, you will have to "map" the intake and exhaust lobes to see where it lands and then you might be able to ID the mystery cam from there...sometimes the manufacturer will stamp some ID marks on the front or back of the cam and you might be able to look it up from there. -D.Idiot Thanks, I just set it up on my surface plate and checked the lobe lift , it is only .272 . I think I will invest in a bigger cam and then I will have all the info . Steve

Author:	DusterIdiot [ Sun Jan 26, 2014 5:45 pm ]
Post subject:	Some thoughts...
Quote: Can you recommend any more good reading that starts at the basics and guides me thru more of what I need to know? There was a good Hot Rod book on Camshafts that had several good articles on the understanding of the bascis, and some step by step on setting one up, and dyno runs to show what happens when a cam is advanced or retarded (on V-8 platform though, but still pertinent). Quote: that he installed whatever stock cam was called for in a 1986 slant engine. I am going to assume that the cam is pretty weak, dummied down for a lean burn set-up engine and emissions standards that had to be met at the time. I would bet that it is just a generic Melling replacement but only he knows what he used...if it is stockish it will be tame like the engine before the rebuild. Quote: I would like to change the cam while I am in there, I would like a cam that will give me optimum results for my specific vehicle. How would I go about choosing the correct cam? If you change the cam, you will be removing the head as you have a 1975+ engine and the head has to be removed to remove the lifters... Also are you going with a hydraulic cam or a mechanical cam....? This is a big decision as : there aren't as many selections for the hydraulic cam profiles, if the lift is higher you may need new pushrods, and the mech cam will require a change in rockers and pushrods... Selecting the cam will be limited by compression ratio, and the vehicle...since you have a truck you will be looking at no more than 254 or so advertised duration so that you get a fat wide torque band that you can use from idle to highway speeds and more if needed...this will work with a compression ratio that is stockish to 9.2:1, if you have more compression you will get more out of it...also plugging the engine and cam data into a DCR calculator will help determine what will work (keeping the DCR in the 7.5-8.1 range is about right for daily driving). You will notice after fooling around with things that a larger cam will bleed off compression and leave a low compression engine with a lack of performance...(larger cams 268+ duration tend to be a little bit "peaky" allowong best torque at a certain range, more duration means the engine has to turn more rpm to get to it's power band...and need more compression to support it). Quote: I want the gear drive cause I like the sound of a blower, plain and simple, I love that whine. Sadly this is not a good thing for a street slant in your daily driver range...The gear drive is typically used on V-8's to keep the owner from having to replace the timing chain after beating their engine up at the track...that being said the V-8 also can take the loss of power that gear drive will impart (one of my coworkers went to one on his chevy big block...the dyno loss was about 30 horspower difference in the same engine going from the chain to the gear, he made it back up with some timing changes and changing the carburator)...On a slant since the displacement is so little, we don't make large gains from simple items, we have to fight for 1-2 hp or a few ft/lbs of torque here and there unless you build a high compression slant (but then you leave the realm of streetability/mileage at that point naturally aspirated...the make up for this would probably mean going to a turbo to get back the power on a mild build for the gear drive). i use double roller chains in my builds and i have yet to replace one from stretch because I beat the snot out of it at the track or on the street. 2 cents, -D.idiot

Author:	Reed [ Sun Jan 26, 2014 7:05 pm ]
Post subject:
Listen to DI- his is right on the money on everything he has said in this thread (and pretty much elsewhere, too!).

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Author:	Aggressive Ted [ Sun Jan 26, 2014 7:08 pm ]
Post subject:
Quote: I would like to change the cam while I am in there, I would like a cam that will give me optimum results for my specific vehicle. How would I go about choosing the correct cam? The answer to your question is pretty simple for your truck. Doctor Dodge may have built more engine combinations than anybody.....he helped me a lot on mine to get it dialed in since my car is so heavy. Go to the Engine FAQ and read the "Engine Build Matrix" on engine builds and look for mine "Torque Build". That would be a great set up for your truck. I am sorry that the so called engine builder/machinist you went through is clueless. Keep asking questions! and don't give up!