Rapid Robert
Well-Known Member
a strip of paper 1.329" will give you 21 deg and a strip 1.835" will give you 29 deg. #1 first confirm the new slit is exact TDC
72 360 first start question
- Thread starter Mophile
- Start date
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nm9stheham
Well-Known Member
Hey Del. I asked the OP for the cam ID and looked up the cam and it is a symmetrical intake-to-exhaust design. If you check out the open/close points, it works out to show a 4 degree advance. The whole point of this check is a quick check of cam timing to see if it is close to where it should be (4 degrees advance), or is 15 or 30 degrees off, indicating that a sprocket is off. It is not meant in this case to be a method to actually set cam timing exactly.
Rapid Robert
Well-Known Member
NM9STHEHAM, thanks for the support/backup! OP your gettin alot of love on this one & its gonna be interesting to see what it ends up being. We are getting closer
thanks ofr all the responses everyone. I won;t be abl to work on the car again until fri. afternoon. It's killin me. Anyway just wanted to say thanks to everybody for all the help. This is my first time using one of these forums and it's great. Everybody has so much knowledge and might know something you don't know and vice versa. Very cool. I hope to return the favor someday.
cheers!
cheers!
Rapid Robert
Well-Known Member
Oh, we're more wound up (on this one) than you are. Maybe!
So, I decided to go back to square one. Originally I had found TDC by finding the highest point of the #1 on the compression stroke. and then reversing it until it was the highest pint again. I did not use a piston stop to do this. I used a screwdriver in the piston hole and thought that i had found the two highest points which re vealed the TDC to be 10 deg. after TDC. So this morning I made a piston stop and did it all again and realized that my factory timing mark was actually correct. Crazy how far off the screwdriver technique could actually be. So that's good news , actual TDC lines up with the factory dampner mark. Unfortunately, I set the initial timing to 12 degrees BTDC and it acted exactly the same as it had before. I set it to 15 BTDC and same thing. I set it to zero and same thing. One thing I noticed is that no matter the initial timing setting. I fire it up and it revs pretty hard before settling down. I still can't get it to idle below 35 deg. advance with the throttle pretty signifigantly advanced. It will run there all day and sounds good, but if i lower the throttle or retard timing it still dies. I'm starting to lean towards vaccum leak or throwing a match in it. any thoughts?
Aint it funny how things work out when you actually use the advice you're given?
What's screw exactly? Be specific.
Rapid Robert
Well-Known Member
Progress! Now we can either do rockover or degree the cam then yes all that is left is that pesky vac leak possibility unless there is an off the wall possibility that we have overlooked (as a potential) . With you haveing a symetrical cam I would do rockover.
There has been lots of "thoughts", somehow you skim over them without answering.
I mentioned vac leak 3 pages ago.
I also asked what carb are you running 2 pages ago.
sorry if i skipped your response. vac. leak was suggested by lots of guys as well as myself. I originally was runnig a holley 650 vac.secondary that ran fine before this build but then after my issues i tried my eddie 500 of my 68 dart and it actually ran a lot better but did not correct the issue of only runnning at high rpm.
I was wondering Eddie, is the plug in the back of it? I'm guessing so since it was on another car, but.....
Well, when i had the TDC incorrect (10 deg. After TDC) it ran screwy in that. I could get it to run but only with lots of throttle and advance. When I was using that as my starting point I set the initial timing very way from !5 deg. after TDC to 15 deg. BTDC and it would basically run the same. If the throttle's pegged it'll run ad sounds good but if i reterad it or idle down it dies... Now that I've found the coorrect TDC nothing has changed. I set the initial timing (15 deg. BTDC and ATDC) according to the new (factory zero mark) and it's same ****. Also when I fire it at any settingthe throttle revs then after a few minutes mellows which makes me think vaccuum leak.
As long as you have something hooked to it, you're OK. I have seen some put the carb on, open hole and wondered why it didn't run right.
nm9stheham
Well-Known Member
You can measure from spring height (top of retainer) to any fixed point down around the spring seat. The point is to find the height on both intake and also exhaust springs when they are un-compressed (no cam lift), and then find the point where they are both compressed the exact same amount at the same point in crankshaft rotation. From looking at the cam specs, the valve lift is probably going to be somewhere in the .040"-.060" lift range on each valve when they are equal.
One thing to be aware of is that you have hydraulic lifters. If one of them has leaked down when you try this test, then it will throw the test off. Push down as hard as you can on each rocker at the pushrod end for cylinder #1 (which I suggest you test) when the lift is zero, and see if there is any movement. If not, you are probably good. Running the engine for 20-30 seconds to pump up the lifters just before you do the test may help prevent this.
The only way to know for sure if either lifter has not leaked down is to pull the intake and look at pistons within the tops the lifters. If you have to do that, you might as well just measure the equal lift point at the lifter body.
BTW, glad you found the correct point for TDC.
Ok, so i did the rockover test with a digital caliper and the #1 springs are exactly the same height within 125/inch at the fully open position as well as the fully compressed position. So it looks like my timing marks must be lined up correctly. That's good news. The bad news is It's still doing the same thing. I set the dist. at 15 BTDC and lined up the gear/rotor facing #1 and exactly the same thing. It'll run with the dist. to far advanced and the throttle pegged. If i try to bring it down to idle it dies. I also tried moving the oil drive gear a tooth each way at this setting and it wouldn't run. I'm going to do vac./fuel pressure test tommorrow. I think I'm getting closer but...
Rapid Robert
Well-Known Member
On rockover you want the heights to be the same and for both of em to be moving, in other words if you move the dampener back & forth a bit BOTH rockers are moving then split the difference (in the middle) & get em both at the same height. We ARE gettin closer!
yep, i was able to get them both dead even. When they're at the most open TDC position and i move the dampner it takes a several degrees for them to begin to move again. The other valves start to open/close before #1 starts again. But that seems like it's the normal rotation of the valve train??
Rapid Robert
Well-Known Member
On rockover one will be going up and the other will be going down & even a hint of movement of the dampener either way will move both of em (go CW on the dampener & one will rise and the other will fall (& vice versa, going CCW the one that rised up will now be falling and the one that was falling will now be rising) & you just rock back & forth a hair till the height is the same as one is going up and the other is going down. even height/constant movement
ok crap well constant movement is not happening in my case. when #1 reaches TDC they both seem to stall for a few cranks of the dampner until they start to move again. Does this suggest a collapsed lifter or that perhaps my timing marks are off? they are dead even when both uncompressed. ??
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