Whats the best way to set TDC with the heads off? I have a dial indicator that I can set on the piston.....Im trying to get the TDC mark on my pointer correct...so then I can see if my cam is set correctly with the lift mark at TDC.

Should I set TDC on number 1 piston...with dots at 12? when I installed the timing gears I lined up the dots at 12 and 6 but I understand that is for firing number 6 piston..so I can just roll it over 1 complete turn and that will put the dots at 12 and 6 wihich is suppose to be firing number 1..correct?


but I need to get TDC mark right on my pointer so I can continue with the buildup

thanks

 

You start off with the number 1 piston at the top.

To find top dead center with the head off And I'm guessing you don't have

a degree wheel...so

anything I would tell you would be a guess at best, with that said.

Put the timing cover with a few bolts finger tight then place the Dampner on

the crank so you can use the timing marks and see if it lines up with 0 deg

if not, line it up. Take the dampner and cover off and put the gears on DOT

to DOT (cam at 6:00 and crank at 12:00) there easer to line up that way.

This is the number 6 position.

Roll the engine over 1 turn and this would be the number 1 position .

Hope this helps........

 

THis is what Im doing...

I put the dots on the gears at 6 and 12..I know that is TDC on #6...I then setup the dial indicator on the #1 piston and ZERO it out cause both pistons are at the top. I then roll the motor over just to see if it goes past the ZERO mark and if it does I move it how ever much and ZERO the indicator out again..I do that a few times just to make sure that it never goes past my ZERO mark...if it does I just ZERO out again. I then move the adjustable timing pointer so that it is over the TDC mark on the balancer....I have it set so that if I am at 6 and 12 #6 or 6 and 6 #1 the timing pointer is always on the TDC mark on the balancer.

would that be TRUE TDC?

 

Doesn't matter if the camshaft dots are 12 and 12 or 6 and 12. To my knowledge, 12 and 12 is #1 TDC. When installing the camshaft, it's just easier to line up when you have them at 6 and 12.

Using the timing pointer isn't accurate because you need to know where TDC is to set the pointer.

Because of piston dwell (the amount of degrees of rotation while the piston is at TDC), you're not going to know the exact TDC without a degree wheel and some sort of piston stop.

Get a degree wheel and understand how to use it. Fabricate a simple stop. A piece of steel that's not going to easily bend with a bolt through one end. Bolt the steel onto the deck through one of the head bolt holes. The bolt extends into the cylinder and prevents the piston from coming up to the top. It doesn't have to be down very far. Rotate the engine until the piston touches the bolt. Read the degree wheel. Rotate the engine in the opposite direction until the piston touches the bolt again. Read the degree wheel. Half the distance between the 2 readings is TDC. Remove the piston stop and rotate the engine until that distance is on the degree wheel pointer.

Now the engine is exactly at TDC. Doesn't matter if it's #1 or #6 (assuming a V8). Check your timing marks to see if they line up. Even factory pointers can be off a lot.

 

so your saying the way Im doing it ..will not be TRUE TDC? I dont have a piston stop or degree wheel....and dont want to have to buy one.

 

Using a dial indicator to find DTC.
Important:
Dial probe must be in the exact radial center of the piston.
Piston travel should always be read when piston is moving upward, you should push down on the piston when taking actual readings to compensate for play.

1. Bring the piston up until you don't see any movment. Set up the dial indicator to read zero with the dial probe completely extended touching the center of the piston, now move the indictor down to read 1/2 rotation of the dial.
2. Back the piston down (counterclockwise) until the dial probe isn't in contact with the piston.
3. Move the piston back up (clockwise) note the pointer reading any where you like past zero (I use .050".)
4. Continue rotating the piston in the same direction until the dial is again at zero, now back up (counterclockwise) to your choosen reading and make another mark on the balancer. The Balancer TDC groove should be exactly halfway between the two marks you made.
5. Rotate the crank clockwise until the dial reads 1/2 the reading you choose in my case .025".)

This is your true TDC, and the balancer TDC groove should be aligned with the timing tab's zero mark.

 

MAN!..setting TDC is BS....I dont understand what your talking about....

 

The easiest way is doing it with the degree wheel and a pisont stop. It's not very complicated. Just read stephens instructions.You can get both from summit racing for a total of less than 25 dollars. It'll probably be a little over 30 with handling. If you are still confused, just look up degreeing camshaft on yahoo or google. You have to be willing to spend a few bucks on the right tools to get this stuff right. Otherwise your just like every other jonny jackass with a tool box full of wrenches just wingin it.

 

It's really easy.

Both Stephen's and rgarcia's methods are flavors of finding the points on either side of TDC where the piston is the same distance down from the top, using a dial indicator; and once you know that, then TDC is exactly in the middle between them.

It's a little quicker and easier with a piston stop, but the dial indicator method that both guys described works perfect. All you're trying to do is to get out of the situation that exists right close to TDC, where a large motion of the crank results in only a small moition of the piston (thereby making it very difficult to find the exact "top" point), and get into a range where a very small motion of the crank results in a very large motion of the piston (so it's easier and more precise to observe).

The piston stop method is more direct. You put the stop in, so the pitson can't go all the way up; rotate the crank in one direction until it hits, and mark the balancer; rotate it the other way until it hits, and mark the crank there; then TDC is exactly halfway between.

 

OK..I have done the piston stop method and heres whats confusing me...

I got me a flat peice of steel from work and drilled holes on each end so I can bolt it where the head bolts would be on the block. In between the head bolts I have a hole drill so I can put a bolt thru and have it go in the cylinder..
So...I roll the crank (clockwise) til it hits the bolt...I mark my balancer (which just for example would be on *60)...I then roll the crank (counterclockwise) until it goes down and back up again and hits the bolt. I mark the balancer (which for example would be *300) total oppisite ends of my balancer. If I split that...I am no where NEAR the TDC mark on my balancer.

Shouldnt it be at least in the area? or am I making a completely different TDC mark...that is no where close to the original....like inches away from it>

When I get home tonight I will take pictures of what I come up with and post so you guys can see what im talking about

 

If you have an aftermarket balancer it is quite possible that it doesn't read correctly. If you use the method you say you used, then it is correct. No questions about it. The exact point halfway between IS tdc. I would recommend buying marking tape that goes on the balancer that you can get from summit. Put the balancer dead on your determined tdc and put the zero mark of the tape on it.

 

I just cant see an aftermarket balancer being that far of...its an ATI for SBC...surely they are close...when I first put it on...and I had my dots at dot to dot...my timing pointer was right on the TDC mark on the blancer


I will buy a freakin degree wheel....where can I get one? I looked on summit? but that is just the wheel...what about the pointer thing? you just dont buy a wheel and mount it on the balancer...how am I suppose to read it?
I made my piston stop....

 

Then your balancer is WRONG.

That's why you're going through this exercise in the first place: because balancers are WRONG, more often than not.

In your case, the reason the balancer is WRONG, is probably not because it's "defective" or anything of the kind; rather, it's because it's expecting the stationary side of the system to be in one place, but the one you're using (stock?) is somewhere else.

This is why I tell people who think they're going to "set their timing" with some light and magically solve some unrelated problem, and get bizarre results ("my car runs like crap", "my headers glow red", "I can't even turn my distributor that far", "car runs great but I can't see the mark at all, how can this be?", etc. etc. etc.), to throw the damn light away and set it to where the car runs right and then leave it alone until the end of time, or at least until it gets disturbed again.

Now.... you've found TDC, perfectly, absolutely, and accurately, with no possibility of error. Right? Now mark your balancer to match your timing pointer. Or, buy an "adjustable" timing tab, and "adjust" it to match your balancer. Then, maybe if you're lucky, your new mark will stay correct long enough to be useful for something (what that would be, I can't imagine, but let's assume it might be useful for SOMETHING) after you get your engine running. Keeping in mind, that if this is not a BONE STOCK engine, built EXACTLY like it came from the factory, then the factory timing "spec" WILL NOT be ideal for it. Guaranteed. All that you'll accomplish by "setting" it to some number, is giving yourself a place to go back to if you disturb it; and of course, for your ECM to "offset" the timing from, if it's a computer-controlled setup.

You don't need a degree wheel; you need a little can of white or otherwise contrasting color touch-up paint, to paint a little stripe on your balancer, or a suitable timing poiner. A degree wheel won't do anything for you.

"Dot-to-dot" doesn't matter. The relationship of the balancer to the crankshaft is not affected by the relationship of the cam to the crank.

Enjoy!!!

 

One small question for you wishy. When you figured out the center point. Did you put it on the correct side. What I'm saying is if you have a wheel that reads from 0 to 359 and you come up with 300 and 60 if you put it in the middle of the 2 numbers on the wrong side you would (please someone correct me if I'm wrong) be closer to bdc. Here's what it would look like on a degree wheel.



as you can see from the drawing, tdc would be exactly at 0 degrees. however if you did it backwards, you end up with the exact opposite. On your balancer it would be on the complete opposite side. That's just using your numbers from your earlier example. This is why you really need a degree wheel.

 

ok!!!...I figured it out. I did the piston stop method. and halfway between both my marks is the TDC mark on my balancer....NOW!..my question is, what do I do next? Move the balancer where? where do I put the balancer so I can adjust my timing tab so it's in lined with the TDC mark on my balancer?

Roll it over so both dots are where they are suppose to be? and then move the tab to line uup with the mark?

guys!! thanks for working with me!

 

when I started I just left my pointer where it was....so how do I know where to put it..I know it lines up with the tdc mark but where do I put the blancer so I can move the tab if it need to be moved.

 

Excellent picture representing the explanation. Even I've gotten confused doing calculations before.

The reason you find TDC with a degree wheel is because of the timing pointer. There's very little chance of the mark on the balancer moving unless you have a very old balancer that's had the rubber spun. The balancer goes over a key in the crank. Where the mark on the balancer is doesn't really matter however the timing indicator on the cover needs to know where TDC is to accurately set the timing. Years ago I had a factory pointer and was wondering why the car was going faster when I kept advancing the timing to 45*. I used a degree wheel to find TDC and found out my timing mark was out 8* so what I originally thought was 38* was really 30* and advancing it to 45* was really 37* roughly where I originally though the timing was set at.

Once you know where TDC is and the crank is positioned at TDC you adjust the pointer to point at the mark on the balancer. That's why you buy adjustable timing pointers.

Using a dial gauge on top of the piston isn't 100% accurate. As mentioned above, you need to have it over the wrist pin to eliminate any piston rock but it's still very hard to find the exact TDC because of dwell. When the piston reaches TDC it will stay at TDC for a few degrees of crank rotation (dwell). If you could determine the amount of degrees that the piston is at TDC and divide that number in half you could find TDC but that would mean using a degree wheel again. Dwell isn't very much but it can put your timing mark out a few degrees.

 

Not sure what your getting at wishy. If it's reading tdc when you actually are at tdc, then the pointer is correct and doesn't need moving. From what your showing on the pictures I would say, your already set, but you can't be 100% sure without using a wheel. I would say your close enough for a street beast, but if you plan on going with big compression or nitrous I would recommend you do it with a wheel. I'm also not sure what you mean by where do you put the balancer. Unless you have a multiple keyway balancer that makes no sense to me.

By the way, do you have that thing zero decked. I know it's just a picture but it almost looks like that piston is moving out of the bore.

 

The pictures indicate that the piston stopped at 29° before and after the ATI TDC mark and the arrow indicates the mid point, then you've verified that the ATI Balancer TDC mark is correctly aligned with the #1 cylinder centerline and that the pointer is where it should be (good because you're currently at the limit of counterclockwise pointer adjustment.)

Removing the piston stop and rotating the crankshaft clockwise until the ATI TDC mark is aligned with the pointer should put the piston at the the top of the stroke, now if the gear dots are at 6 and 12, or 12 and 12 O'clock then all is good, if not then you need to realign the gears preferably at 6 and 12.

Had the mid point had been located say at 355° after the ATI TDC mark, then once you rotated it to that mid point then the pointer could be moved clockwise to realigned it with the ATI TDC mark anything outside of the pointer adjustment range would require moving the pointer base, or painting a new TDC mark on the ATI balancer, or returning it as defective.

The point (no pun intended) I make is that the TDC mark on the balancer should be with in range of where you can mount the pointer that is easily visible to access with a timing light so that cam and crank timing can be verified, after that you can set the timing by sight, or sound.

 

sorry it took me so long to get back.....but thirdgen was messed up and I couldnt get on..but anyways,

I did the piston stop method with a bolt running thru the middle of the piston stop to keep the piston from coming all the way to the top....so when you look the picture with the tape on it...thats with the piston hittin the bolt...so I removed the bolt and rolled it to line up with the pointer and my dots are lined up 6 and 12...so I should be good to go...


and yeah the block is suppose to be ZERO decked...thats why I couldnt just use a flat piston stop cause it would come to the top and just kiss the stop and go back down....

 

Good job.
Let us know when you get it running - RJ

 

all that and come to find out that my cam timing is off by about 2*...thats why I needed to find TDC ...so I could check the (lift at TDC)...and its suppose to be .0587 on intake but Im coming up with .0450 and I want it exact so I had to order a hex-adjust timing set (and the ***** was $120.)cause I cant use the one thats on there cause I cant adjust that small...it only goes in 4* increments. the hex adjust can be done in fractions of a degree. So now I sit and wait til Friday when it comes in.

Hey? what would being the 2* off do? will it not run correctly?

 

It shouldn't give you any problems at all. Is it advanced or retarded? Most cams are installed advanced. I have my cam set 5 degrees advanced. What are your cam specs?

 

I've always been a strong proponent of the postive stop method of finding TDC. The reason is piston dwell time at TDC.

Using a dial indicator you'll find that the crank will turn a degree or two in each duration at TDC but the piston (hence the dial indicator) will not move. So the question then becomes "Which reading is absolute TDC?

A positive stop bolted across the #1 hole will account for and eliminate that variable.

Just my thoughts.

Jake

 

The right way to find TDC with a dial indicator is similar to using a piston stop. Mark the balancer at two points before and after TDC at the same distance down the hole as shown by the indicator, then divide the interval between the two points in half.

 

Anytime something like this is posted on a forum, either on this Forum or others, there will nearly always be someone who posts a conflicting view. Some folks just aren't amenable to change.

If you try this dial indicator method, you'll soon see just how difficult it can be. Trying to get the dial indiactor to stop at the EXACT same reading will definitely test your patience and persistence.

Now let's not belabor this point, but it's MUCH easier to use the positive stop method than any other method.

Most of us are searching for the easiest, most accurate way to do - whatever.

The reader has to use his grey matter to decide which road he wishes to walk. It's not my intent to change anyone's mind - do what you want. I only want to give input that I've learned from over 40 years of screwing on these suckas; years of trying to keep my cars in competition.

So if you believe that using a dial indicator is the BEST way, HEY, go for it. Write me back on your experience.

Jake

 

Where did I say that using a dial indicator is the best method?

 

I used the word "BEST" in my final sentence, asking those who believe it is the BEST method to write me their experience after using it.

It wasn't meant to be directed to you, but only to those who are wrestling with the decision and trying to decide which procedure to use.

Perhaps I should have phrased it differently so as to prevent any confusion and, for that, I apologize. I mean no harm and am only trying to help; that's the cut of my jib.

Jake

 

FAULBALL67> heres my cam specs ...Im thinking its retarded by 2*

Cubic Inch and Engine Type 383 CID Small Block Chevrolet
Camshaft Type Hydraulic Roller
Firing Order STD SBC
Cam Bearing STD SBC
Lobe Separation 113.5
Overlap at .050” 2.2 Degrees

Camshaft Measurement Intake Exhaust
Duration at .006” 281.5 286.5
Duration at .020” 255.5 260.9
Duration at .050” 226.0 232.1
Duration at .200” 145.4 151.7
Lobe Lift .34961” .35323”
Rocker Ratio 1.52 1.52
Gross Lift .531” .537”
Lash HOT HYD HYD
Designed Lobe Centerline 110.9 ATDC 116.0 BTDC
Open at .050” 2.1 BTDC 52.1 BBDC
Close at .050” 43.9 ABDC 0.1 ATDC
Lift at Top Dead Center .0587” @ 110.9 In. Cente .0591” @ 116.0 Ex. Center

Spring Recommendation Hopefully the AFR springs work. If not, contact me for a spring kit.
Cranking Compression 189 PSI
Vacuum At Idle 15.7 Inches
Idle RPM 850 RPM
Peak Torque RPM 4400 RPM
Peak Horsepower RPM 5500 RPM
Torque Convertor Stall 4000 RPM to 4500 RPM (Flash In High Gear At 5-10 mph)
Starting Shift Point RPM 6300 RPM
Starting RPM To Cross 6600 RPM
NORES: Visit my site and read about how to install the camshaft by the “Lift at TDC”.

 

with that cam there is a built in advance of approx. 1.25 degrees (if I remember my cam math correctly) that would explain why some one might install it retarded 2 degrees.

My desktop dyno (not always THE most reliable but usually pretty close) with the cam installed with a lobe center angle of 113.4 and an intake centerline of 112.9 degrees (cam 2 degrees retarded) I get a max torque of 457@4000rpm and a max HP of 422@5500rpm. With the cam installed with a lobe center angle of 113.4 and the intake centerline at 110.9 I get a max torque of 456@4400rpm but the max HP is 411@5000rpm. With retarding the cam that 2 degrees you get a more top end but lose just a slight bit of torque in the low end. Maybe 2-5 ft lbs max. All cam specs were directly input using these numbers your numbers.

This was done without knowing any other engine specs. I just slapped the numbers in for a set of basic world sportsman 2 heads, 10.5:1 compression ratio, small tube headers with performance mufflers, a single plane intake manifold, a 750cfm carb, and a basic 350 block. If you give me all your specs I could give you a pretty good idea of what to expect.

 

damn thats all!...I was hoping for at least in the area of 500 fwhp & fwtq..

So what you would say I do? Im trying to get my "lift at TDC intake" correct...Im coming up with .0450 and it should be .0587

So I already ordered me a adjustable timing set so I can get the L@TDC correct.

The guy I got the cam from says I should be at about 400 tq at the wheels at 4000rpm's..he says that cam will put me well into the 11's

did you figure that up using AFR heads? 383 ci. 6" rods, hooker 1.75 full headers, borla exhaust, HSR intake, 30lbs injectors, underdrive pullies,

what else you need to know?

 

I have the specs for afr 180's and 190's on file. The dyno program doesn't take into account pulleys/rod length/injector rate. The program assumes detonation free fuel use. Honestly I would leave it retarded or even retard the cam another degree or 2 to get better top end, especially if you are using a big stall converter.

I still need to know your
cylinder head volume in cc's
valve relief volume in cc's
compressed thickness of the head gaskets
the cfm rating of the hsr intake (holley stealth ram?)

Is the hsr intake considered a tuned port style system?

Assuming 10.5 and, afr 190's, and assuming 1000 cfm for the hsr intake, and moving you to large tube headers (1.75 or bigger), and 2 degrees retarded, I got torque of 520@4000RPM and HP 472@5500rpm. Very respectable numbers.

I also have a drag strip simulator. It can directly import the engine specs from the dyno program. You then choose car weight, drag coefficient, transmission, stall speed (if using an automatic), rear end gear ratio, tire size, tire type (street, mild race, slicks), and track conditions. It can choose your shift points for you, or you can input your own shift points, launch rpm, and redline.

 

THose lift numbers are with 1.52 rockers..Im thinking about changing to 1.6's How much will that change the data?

AFR 195's 65cc 2.050 intake 1.060 exhaust
flow numbers are according to AFR

.200 137cfm 110cfm
.300 194cfm 158cfm
.400 240cfm 190cfm
.500 270cfm 207cfm
.550 280cfm 211cfm
.600 286cfm 215cfm

flat top pistons with a 7cc VR

Zero decked block....
Head gasket compressed? I have no idea but its a .041 felpro 1003

The flow rating of the holley stealthram is suppose to be around 280cfm and its considered a tunnel ram intake

3400lbs car with driver 3.42 gears.Im going with a bigger stall..I now have a 2800 but Im getting a 3400 stall...26 in tall drag radials.



anyway you can post the HP/TQ chart so I can see it?

hey, thanks for taking the time to do this for me

if you need to know anything else let me know.,

 

I think the results arent going to fall into the realistic range if you simulate it as a tunnel ram instead of a TPI. It'll be closer, although probably low, as a TPI.

Lift doesnt make a whole lot of difference, few HP few TQ.
Whats the cc on the heads? 67?

 

65cc

 

which stealth ram are you going with? The stealth rams I looked at today are all rated 1000cfm. I would assume your using MPFI instead of TBI? Just guessing but thinking your going to be using a holley 91404201 or a 91404211 setup? Also need what kind of tranny your using. If your racing I would recommend not using a 700r4 and get a th350. If you still want an overdrive gear getting a 4L80E.

I'll get the numbers posted as soon as I can. I'm having trouble exporting the graph and table to an image program for posting. I'm going to post 2 sets of numbers. One with mufflers and one without. The difference is pretty impressive. You definately need much higher flowing mufflers at these power ratings. Or you can do like me and chance it without them

 

When my dad and I rebuilt a 350 for my El Camino, we just lined up dot to dot and left it at that. We did the TDC with the engine installed and #1 plug removed, just to get the dizzy in properly, then adjusted until it ran good. 9 years later, it still runs pretty good except for the smoke.

A guy around here that has built a lot of race engines claims it doesn't even matter how the dizzy is installed, as long as you can adjust the timing to make the engine run properly.

 

the stealthram Im using is ...www.stealthram.com thats where I got the cfm's from.
I guess its a MPFI system..it just replaces the TPI.

Yeah Im going to be using the dreaded 700r4...its all I got but it has been built so we'll see..

The Borla exhaust is from what Ive been reading a very high flowing system.

thanks!!!

 

those cfm ratings aren't based on standards used by the program. 1000cfm is the rating based on the overall intake capacity. You gave runner cfm capacity.

 

oh well then I dont know what the CFM rating is for the whole unit. Im also using a 58mm throttle body if that helps in the data input too..

 

Alright. Got the images saved and transfered. Here are my the result.

Dyno 1 with mufflers



Dyno 2 without mufflers



And here's the drag simulator results with assuming 200lbs for the driver

 

WOW!...now those numbers look EXCELLENT!..
and that was with leaving it at -2*? and if I timed the cam at straight up like it suppose to be that would just UP the TQ and lower the top end HP?

Is your program usually correct? or Im sure its probably hitting high numbers.

and that saying I would run in the neighborhood of 11.4 with a 3600lb car? and its actually going to be 3400 so that would mean quicker..I know that the numbers are in a perfect setting but hey!...thats still fast!!!

So I should just leave it at where the cam is at?

let me ask you, if the "lift at TDC" is suppose to be .0587 and Im coming up with .0450 does that mean Im about 2* retarded?


thanks a mil for helping me out and running my numbers for me!

 

The DD2k results would be more realistic if "Small Tube Headers" were used in the model instead.

 

dd2k states in their user manual that headers of 1.75 or larger are considered large tube headers. I will give you that it is the low end of the spectrum, but still within the program. You could take the average of the 2 result and probably get a more accurate representation but, that is more work than I'm willing to do.

Leave the cam retarded. Yes the lift would be slightly different if the cam is retarded. So I would guess the lift numbers are right. I would assume these result to be close to what your going to have, but you can never really know for sure. There are too many veriables. Noted engine builder and designer David Vizard supports the use of this program when building an engine. The numbers I get using my engine specs are really close to the chassis dyno numbers (minus about 15% driveline loss). I like using it to figure out cam and head combos best.

As for the drag strip numbers, if you look at the bottom, it shows that it is based off of average track conditions. It also assumes perfect shift points but that's not as hard to get from an auto tranny. I used 3600 pounds since you said the car would way 3400 pounds. You have to assume some driver weight unless you gave me the weight with driver. I assumed average male weight and tacked on an extra 200 pounds. I would say 11's should be no problem for you.

 

faulball67> one quick question, I have left the cam at 2*retard....but is that going to cause the cam not to perform the way it was designed to and create a bog sluggish feeeling when mashing the gas until it gets in the range due to retarding the cam? or anything down below the 4000 rpm range?..I got the 3400 stall converter.

maybe Im not making sense..sorry

 

Should only drop 2-3 ft lbs of torque below 4000 rpm. Nothing worth worrying about.