72 360 first start question

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Mophile said:
Ok so here's my latest test. I tried Rapid Robert's rockover test and everything seems to be correct.
Click to expand...
If I may ask: When you did this test, did you check the intake and exhaust valve retainers on #1 (or #6) with some sort of measuring device like a dial caliper or scale to see that they were open equal amounts, within about 1/64"? If not, then you could be off; you can't do that check just by eyeball and expect good results. If indeed it was done with precision, where was the timing mark on the damper relative to the timing scale on the cover? (You should have taken a reading to the degree.)

Sorry to be so direct; I do want to help. But the point of his check was a shortcut to check cam timing, but if not done carefully, it will not give valid results. Do you have access to a dial caliper or dial indicator? Valve timing can be readily checked with the engine together with a dial indicator. If none, then the timing cover can be taken off as suggested.

As Mopar Tim says, cam timing and ignition timing are different. You can't fix cam timing at the distributor.

But there also seem to be a lot of very basic unanswered questions in this thread..... like vacuum readings, fuel pressure, actual timing, etc. I would suggest you go back and reread such question and answer them. It's impossible to troubleshoot long distance without actual measurements; the questions are being asked for a reason.
 
So when I did the test on #1 I did not use a dial caliper. I eyeballed/ felt it with my fingers while I moved it back and forth. I didn't realize that it needed to be down to the 64th". Sorry if i haven't been clear on any responses. I don't have a dial indicator either but I'll pick one up. My vacuum test was to spray carb cleaner everywhere with a potential for a leak and look to see if it got sucked in as well as pull all the vacuum plugs one at a time on the carb and plug them with a finger and then let go and see if it worsens. Ghetto I know but that's how we always did it. Anyway I switched the carb out with the 500cfm eddy from my 68 340 dart and the running drastically improved! I still can't get it to idle under 25 degrees advanced but it will run like that all day now. This makes me think that it is a vacuum issue. If it was cam timing changing the carb wouldn't have done anything right? So it'll run at 25-35 degrees advanced with the rpm's kept pretty high but steady (haven't hooked up a tach yet). If i lower the throttle screw or retard the timing past that it'll die. Any thoughts. I do have a vacuum gauge that i guess i need to learn how to use.
thanks
 
also I have no way to test fuel pressure other than visually and it's definitely getting gas out of the stock mechanical fuel pump. I definitely don't want to take the timing cover back off if I can avoid it. I'm going to buy a dial indicator tomorrow and see if I can get some more accurate measurements.
 
Priorly you set the slit at 15BTDC and lined up the magnet with the tooth. Was it still in that setting when you swapped carbs? If not then I would set it back to that & holler what happens. If yes then we might put a light on it now & see if we can get a reading (a dialback would be handy here). What is the lowest RPM you can get it to idle at now?
 
You can't make any conclusion that having the cam timing off would not show an engine change with a change in carb.

Fuel pressure gauges are cheap. A lot cheaper than a dial indicator. (A dial caliper will work and is a lot cheaper than a dial indicator.... see if you can borrow one.) You need get/borrow a timing light too.

Connect that vacuum gauge up to the manifold under the carb and see what you have.

What cam do you have? (I ask this as it relates to what you may expect on the timing check.)
 
A smaller CFM carb will increase vacuum which MIGHT make engine run better, but its not the issue, I dont think. :burnout:MT
 
"Priorly you set the slit at 15BTDC and lined up the magnet with the tooth. Was it still in that setting when you swapped carbs? If not then I would set it back to that & holler what happens. If yes then we might put a light on it now & see if we can get a reading (a dialback would be handy here). What is the lowest RPM you can get it to idle at now?"

ok so just to be clear: when you say the slit, you mean the timing mark on the dampener right? and when you say BTDC you mean "before TDC" right? If so my factory mark didn't line up with TDC on my engine. so I made a new mark that is at TDC on the #1 cylinder and that is what i have been using as my timing mark. Also my timing cover only gives me 5 degrees before and after marks so in order for me to move it back 15 degress, i maeusred that distance on the timing cover and multiplied it by three and marked it on the cover then spun the crank counter clockwise until my new dampner timing mark lined up at my new cover 15deg. mark. I then pulled the dist. and reset the oil gear pointing back at #1 and reinstalled the dist. rotor now pointing at #1 I ran it with the new carb at both this setting and back at TDC. It seems to run better at TDC but will run at the 15 BTDC setting but roughly. I don't have a tach hooked up so I can't tell you actual rpm's but I'm guessing I'm in the 2000-2200 range. I put a timing light on it and I'm at 25-35 degrees advanced when it's running best. It's revved quite a bit above a normal idle and sounds good at that rpm, but when i lower the throttle or retard timing it dies.
 
here's the comp cam that I'm running I got the valve train idea from a mopar muscle article which compared cam/lifter'pushrod set ups. This one sounded right for me a little more than stock with a good deep sound but a street set up. It's in a 67 A100 van I didn't want it to be a rocket. S i just hook up the vac gauge to any intake vac port while its rinning and that's my total vaccum amount? It's the comp cam magnum 270H

Grind Number: 270H
Lifter Type:
Engine Family:
Description:
Cam Family:
Specifications Intake Exhaust
RPM Range: Valve Lash:
Valve Timing: Duration:
Lobe Separation: Duration @ .050" Lift:
Intake Centerline: Valve Lift:
Lobe Lift:
Valve Timing @ 0.006 Lift:
Exhaust
Closes 21
ATDC
Opens 69
BBDC 106
Intake
29 Opens
BTDC
61 Closes




http://www.compperformancegroupstor...&Product_Code=20-214-4&Category_Code=LACAMHFM
 
Correct, the slit is the slit in the dampener and BTDC is before TDC. Yes when the piston is at true TDC the slit needs to be at zero (TDC) on the tab & a slipped dampener or a mismarked dampener is somewhat rare. Just wanted to get that out of the way for clarification. 15 BTDC is a VG ballpark initial timing setting & turning the slit to that is a very close correct initial timing setting then getting the magnet dead even with the tooth and the rotor at that point should be pointing fairly close to the cap terminal. 0.0632683" is (1) degree around the dampener circumference so 15 deg would be .949" if you have some calipers and or a mike or even get close with a tape measure & cut a strip of white paper & use it as a ruler to mark 15. EDIT I reread your post & you found true piston TDC with the stop or the dial indicator and at that point the slit ain't at zero on the timing tab? If not how off was it for curiousity. We gotta get that straightened out first
 
glad that i'm understanding you correctly just wnated to make sure. the dampener will only go on one way and when I installed it and then checked for true TDC it was way off. I'd say about 90 - 100 degrees. I'll check and give you a more accurate number when i get home. The way I've always found TDC is to find the highest #1 piston point on the compression stroke and mark it on the dampner then reverse the engine until it come back to the top and mark it and then true TDC is halfway between those points.
 
with the piston as high as it will go (roughly at TDC) then back the crank up ~2" or so CCW then install the piston stop with the bolt down an inch or so then go back CW till the piston contacts the bolt (gently but firmly) & mark the dampener at the zero on the tab then go back CCW the other way all the way around till it contacts again & make another mark then remove the piston stop & turn the crank till a point halfway between the two marks is at zero on the tab & that is true TDC (piston at TDC and the slit hopefully right at the zero mark on the tab (which'd be halfway in between your two marks). are we on the same page?
 
BTW, for that cam it has 4 degrees ground-in advance, and is a symmetrical cam. So, at equal lift at intake and exhaust, the damper zero mark (slit) should line up at 4 degrees BTDC.

Is your damper one without any imbalance with with imbalance? It is pretty obvious and should be the imbalanced one, with a large area of weight removed or added.. The damper being so far off is certainly of concern, and making your own marks may work but just adds to the inaccuracy if not done with a lot of precision.
 
copy that, we are on the same page. That's is how i found TDC. My 2 marks were about 10 degrees apart my true TDC mark is about 10 degrees before the factory mark. I was incorrect before about the slit being so far off. I just realized that my dampner has 4 slits with their zero degree mark being the first. I was thinking that the next mark after zero was their slit but was just confused. anyway, true TDC is about 10 degrees before the factory slit that they marked zero. When the #1 piston is at the highest point on it's compression stroke my new mark lines up with the zero mark on the timing cover perfectly. you can see mark just above theirs between the two blue dots.
 

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So at this point you need to do the rockover test. I have never had to do this test.
 
ok I'm gonna try and do the rockover test one more time. I'm not 100% sure that I did it correctly. It's a little confusing that if I'm testing #1 I'm actually looking at #6 and vice versa but I think I got my head around it now. keep you posted.
 
well that's what threw me. He said if you checking #1 take off the pass. side valve cover and if #6 the dr. side. #1 cylinder is on the driver side so... I thought he meant bring #6 to TDC and look at #1 valves or bring #1 to TDC and look at #6 valves. Your way seems to make more sense. RR??
 
And yes that's actually my exact dampner right there. I believe I'm using the thinner of the two bannana shaped weights as per the instructions.
 
"BTW, for that cam it has 4 degrees ground-in advance, and is a symmetrical cam. So, at equal lift at intake and exhaust, the damper zero mark (slit) should line up at 4 degrees BTDC."

so if I'm at 10 deg. BTDC with my actual TDC mak and this cam should line up at 4 deg BTDC does that mean that my cam is actually sitting with 6 deg. initial advance?
 
#1 is confirming true TDC (that when the slit is on zero that the piston is actually at true piston/deck TDC). The slit was 10 deg off from actual/true TDC? #2 is confirming correct crank to cam phasing which includes lining up the dots which I'm sure they got right and that the cam has no error in how the lobes were ground on the stick at the cam factory (which is rare) and that the tchain/gears are marked correct (errors are seen somewhat regularly) and step 2 is confirmed to the nth degree by degreeing the cam & rockover gives us a reasonably close idea of where phasing is. With the slit on TDC on the tab either #1 or #6 cyl is on TDC compression. To tell which one you are on, if the rotor is on #1 then #1 is on compression (its firing so has to be on compression) and you go to its companion cyl which is #6 & check the rockers on it for rockover. vice versa. I'm still bothered by the slit being 10 deg off for #1 as that is somewhat rare but your procedure sounds OK unless we missed something
 
Mophile said:
Ok so here's my latest test. I tried Rapid Robert's rockover test and everything seems to be correct. ?
Click to expand...

YOU CAN NOT GO BY THAT!!!!!!!!!!!!!!!!!!!!!!!

That used to be known as "split overlap" and does not apply and has not applied on engines for DECADES due to cam designs
 
Mophile said:
When the #1 piston is at the highest point on it's compression stroke my new mark lines up with the zero mark on the timing cover perfectly..
Click to expand...

YOU DO NOT check TDC by trying to put the piston at the top.

HOW exactly did you "determine" true TDC?
 
Mophile said:
"BTW, for that cam it has 4 degrees ground-in advance, and is a symmetrical cam. So, at equal lift at intake and exhaust, the damper zero mark (slit) should line up at 4 degrees BTDC."

so if I'm at 10 deg. BTDC with my actual TDC mak and this cam should line up at 4 deg BTDC does that mean that my cam is actually sitting with 6 deg. initial advance?
Click to expand...
(1) We'll assume that your newly marked slit is TDC. (2) find exact rockover on either #1 or #6's rockers depending on which ones' companion cyl is on compression. (3) see if the slit is 4 deg BTDC & if not then how far away is it (4) no matter what degree it shows up as in #3, if it is reasonably close (good enough to run) then turn the slit to 15 BTDC & (5) install dist & line up the magnet/confirm rotor is pointing to #1 plug wire (or #6 if #6 is on compression)
 
Here is what you do.

1... Use a piston stop to CONFIRM TDC if you have not.

2...Look at your cam specs. Intake opens 29 BTDC. you can easily mark the dampener out that far, ................and it should be anyway, and CHECK that cam event

Exhaust closes at 21 ATDC. You can easily measure and mark that off on your balancer and check THAT event.

Be aware, when doing this, of hydraulic lifter collapse!!

3....Install the distributor. DO NOT set the marks at TDC, rather set them where you want initial timing, perhaps 15 BTDC. With the rotor "approaching" the no1 plug tower going CW, set the reluctor in the center of the pickup coil.

4....Put the cap and wires together, hook up your timing light, and set the timing 15 or more ON THE STARTER.

5...Then....put a little fuel down the carb and fire the engine.
 
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