^^^^^^^^^ Sounds like your using 1967 stock specs 6-8 deg, Like he said & maybe more initial, Give the motor what it likes start off with a vacuum gauge, (initial ) and there's no set rule that only 38 total each motor is different, & depends on how serious you are on your tuning you need to make your own bushings in 1 deg increments , the 4 Colors , most time get you close , You will probably have the distributor out at least 4 times changing bushings, not including spring, which does not require removal the distributor. And if you had a Mallory you need this little black key
In light of this new information....first I would ask did you rev the engine higher, say 4000 rpm, to confirm the timing didn't keep gaining due to extremely stiff springs? The MSD distributors typically come stock with the heaviest springs (slow curve) on them. If it did, then .... This is the next move, crank in some more initial timing, maybe clear up to 18°. Low compression and low engine speeds means low air velocity into the engine, so you end up with a low density mix in the cylinder that you have to lead more when introducing the spark in order to get the peak push on the piston to happen at the right range of degrees after TDC. Put the spark in there earlier, you're not getting enough push on the piston at the right time to be efficient. If you didn't confirm you were at the end of the mechanical advance curve, then you need to proceed more cautiously to prevent running into higher rpm detonation due to the advance increasing at high rpm. Ultimately, you want to end up with a short curve on top of a lot of initial advance for the low compression engine.
In summary, 1. With vacuum gauge hooked up, vacuum advance hose removed and plugged, advanced timing to a point where the vacuum gauge shows happy. 2. Adjust idle mixture screws to get the most happy reading on the vacuum gauge. 3. Rev the engine up past 3000 RPM until advancing stops in an attempt to determine where the mechanical advance ends. 4. Swap out springs to make step 3 better suit actual driving conditions Does that sound like a good plan for this afternoon?
What would be the maximum mechanical advance? You would advise? What RPM would you want that to be at? I don't ever plan on cranking it over 5000
I set my distributor up with 18 degrees initial, 18 degrees of centrifugal all in at 2600 rpm. It required bushings on the post to limit the mechanical. Mine runs very happily with this combo. I have timing tape on my balancer as I wasn't sure I trusted my dial back timing light. I also found my Pertronix seemed to scatter the timing at higher rpm (by about 12 degrees!) so I went back to points and the readings are now solid as a rock.
There's your problem right there! You need to degree it. What does "straight up" even mean? Doesn't that mean you installed it without the cams 4* advance ground into it? I'm sure you mean dot to dot. In any case, how do you know dot to dot is where it's meant to be run? How do you know it was ground correctly if you're not degreeing it? How do you know it's not a Friday afternoon or apprentice ground cam if you havnt checked it with a degree wheel? Cams should be degreed in, the dots only give a reference, they're irrelevant other than that. Get back to basics, get it in the right spot before playing with things.
Nah, I'm good. I'm sure it'll run fine dot to dot, not trying to set a record ET or anything, just want to cruise. My dad put together many good running engines without degreeing the cam. Good idea, sure, but not wholly necessary.
Maximum is probably going to be in the 36-38° area, with initial in the 15-20° range. You'll have to experiment with how early you can get it all in, you want as early as it will take and not give you detonation, most likely somewhere between 2300 and 3000 rpm.
Man, I can't see how you guys are getting over 12 degrees initial. If I do that, the vacuum drops considerably (over 8 degrees) and the engine gets hot, fast. The MSD distributor pro-billet vacuum advance distributor maxes out at 36 degrees in it's factory configuration. With the factory weights, bushings and springs, I get the full 35 degrees at 3800-4000. Here's where I landed after trying many combinations over the weekend: The engine likes 8 degrees initial (vac advance plugged) - this is a median between not heating-up while idling and good power in low and mid-range. I get around 18 vacuum with that setup. fires right up when you first bump the throttle, even hot. IF I set initial at 12, it's much more snappy off the line (big burnouts), but runs hot (hasn't over heated, but was pingy and seemed headed for a boil-over)...vacuum is at around 14. I tried fattening the idle mixture to get the temp down but that didn't effect much. Also was getting hard to hot start with 12 degrees initial. I am going to try and change the accelerator pump "curve" by playing with the linkage positions - also may put a larger squirter in it (have a pack of those on my bench) and see if that helps off-the-line response.
@SDS ...I re-read the thread...when you put your timing tab on, did you confirm piston TDC in relation to your timing tab and balancer mark?
It hasn't been mentioned and actually really doesn't matter at this point but the bolt-on timing tabs were matched to a balancer/damper that had the keyway offset from the crank key about eight degrees compared to the early ones being inline.
^^^^^ By using a timing tape on the balancer and using a piston stop on #1 cylinder, you can find any error for TDC and reset the adjustable timing tab. Trust but verify. I installed a Cloyes timing set on my 327 and had to return it because the key ways weren't correct. They sent me a replacement. I also used an earlier timing cover with the tab spot welded in place and it didn't work with the Fluidamper balancer that I wanted to use. I used a degree wheel to sort out everything AND remark TDC on the damper.
Make sure pump accelerating pump shot is sufficient. Edelbrocks are problematic in that space. 36-38 deg timing all in, as 462 heads are not efficient. I missed the intake dual plane?
I agree on checking TDC. Using your piston stop in plug #1 hole: 1. Turn crank bolt in one direction until it stops. Put a 4 inch long piece of masking tape on the damper, with the center of the tape length at the zero mark. Make a mark on the masking tape at the zero mark on the tab. 2. Rotate crank bolt the other direction until it stops. Make a second mark on the masking tape at the zero mark on your tab. 3. Remove piston stop. Move crank until zero mark on tab is half way between the two marks on the masking tape. 4. Remove the masking tape and mark on the damper at the zero mark on the timing tab. Now check your initial timing, with vacuum plugged.
No, but I did mark the balancer in relation to "0" on the new timing tab, using a piston stop (the old balancer was off a bit anyhow)
Centrifugal timing seems to max out at around 4000, 36 degrees. Setting the initial timing did make it snappier, but also made it run hot and have around 14 on the manifold vacuum signal at idle. At 12 degrees initial, it started to get hard to hot start.
Dual Plane is good for cam. Flat tops, 462s should be 275-300hp depending on head gasket thickness, deck height.
It looks /seems , Your Tab , TDC, TDC mark , cam instal is wrong ,,, Even good chance all are wrong, & are Listed / mentioned.. A True 12 deg is not to much initial timing Hot,,,(sbc ) #s are wrong Some of us Run over 20 hot (& plus) , hard to start , when that happens , remote button , spinning engine then flipping power to coil on , to over come kick back , slow turning .
Have you tried adding more fuel to cool things off now that you've added more timing? It might cool things off and help with the hot start issue. All in at 4000 seems awful high to me, try some lighter springs and shoot for around 36 to 38 degrees @ 2500 all in with vacuum advance disconnected. Timing first, then fuel, adjust one at a time and see how it reacts.
I have tried adding more fuel and over a certain point, that drops the vacuum signal. It's pretty fat right now, but that didn't fix the heat problem with the initial timing at 12. Don't get me wrong here guys, at 8 degree initial, the thing runs well - it's very drive-able and starts right up...I'm just trying to get it to run GREAT
If runs good @ 8 deg according to your timing tab ,,, ok & Good !! Keep a mental note, Its more likely ""Not true 8° "" , ( 8 is very low sbc initial timing)) More like 12-15ish maybe more,, You will not know for sure unless you deg cam , & verify top dead center , & verify a positive TDC pointer & Mark
Okay... Now that you can actually measure timing advance, check timing at idle, 1000, 1500 1800 2000, and 2500. Plot out the advance curve you have. As said, this engine will probably want 12 initial. Start there. Drive and listen for knock. Knock is bad! Try again at 16. Drive it again. If it doesn't knock, you have achieved the 8 degrees more at full advance. If it knocks, you want to limit the timing where it knocks. Do all of this with vacuum disconnected. Get initial and total worked out first. Plot each timing curve with your changes. Once it is happy with initial and mechanical which is total, then refine it with vacuum. If you run manifold vacuum, it will be adding at any point in RPM with light load. You will have to reduce initial. Since you have been plotting timing at each step, you can tell what the engine likes so set it up at this same point with vacuum connected. The drop in vacuum just off idle when opening the throttle can cause a stumble. This can be addressed with carb adjustments. If you run ported vacuum, it will only start to pull in additional timing above 1200-1500 RPM. document how much vacuum advance is changing from initial and mechanical, usually 8-12 degrees. It's very likely that total timing with ported vacuum included will be higher than the typical 36 initial and mechanical advance, often into the low to mid 40 degrees. So long as it doesn't knock or ping, this will help with MPG.
Oops, took so long typing that there was a whole conversation I missed. I will say that using vacuum gauge to set initial timing, this is what I found. Have engine warm and idling pretty well at RPM you plan on, in Park or Neutral. Connect gauge to manifold vacuum. Typical for stock engines is 16-20, with that top being a big, lazy stocker. Mild cams will be 14-18. Hot cams will be as low as 8. Below that you have issues or need to bump idle (or are running a pro stock engine!). Adjust timing to highest vacuum. Then back off timing to reduce vacuum reading 2 inches. 20 to 18, 18 to 16, etc. If you leave it at highest vacuum, it WILL ping. This may require jumping back and forth between idle speed, mixture and timing. It's all a balancing act. as @19Eddy30 says, the numbers everyone is offering are on engines with verified TDC, but if yours is happy at a different number, that's all that matters. Not everyone fits in 30x30 Levi's.
Don't mean to sound "shoulda-woulda" but.....those are really mild specs and the LSA shoulda been 108* for more SNAP when you punch it Jus say'in... Now....advancing the timing has a cooling effect on an engine...not heating issue so something doesn't sound right here. Did you know there are 'some guys' who like to lock their distributor to full advance (wire or tie wraps to hold the weights out all the time) and just use a switch to spin the engine and THEN turn on the ignition! That tells us that light spring(s) that let the weights fling out to full advance at just above idle and are strong enough to pull the weights back to the closed position when the engine is killed...is most nearly ideal in your case. (less than 10:1 CR stock and not very efficient heads.) IF the engine starts to immediately run hotter (like you posted) then sump'in ain't right. It could be the cam is NOT advanced enough to give the performance it's suppose to. One thing for sure....they make front covers for Chevys so you can easily access the crank pulley to adjust an 'adjustable' pulley with different advance keys . I would put in the lightest springs..... rev the engine (wing it)...and turn the distributor so it stops advancing at 36-42 degrees and bolt it down. To heck with what the initial reads! BINGO your total timing is set....leave the vacuum advance plugged Re-adjust your carb curb idle to 500 RPM. Use hi-test gas and go for a test drive. IF it gets hot....you got other issues. 6sally6 Hope this makes sense. It seems like so many guys are too shy about their cam specs and don't want to re-curve their ignition..
Then what's the problem? Why are you here? Surely it cruises fine it's just sluggish off the line right? It's not sluggish at cruise? So, no problem. If he's put many together fine without degreeing them, this one shouldn't be sluggish off the line, right? How do you know this isn't the 1 out of 100 cams a cam company messes up and he got lucky till now? Suppose the cam company mixed up the cam and put it in the wrong box.. If he's so good at putting them together, why can't he solve this issue? My point is, you don't know till you make sure the cam is correct to begin with, then you can relax and look at other things.
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