firechicken_3

iTrader: (4)

ok well, i finally got my new motor all together and in the car, specs are

350ci .040 over
flat tops with 4 eyebrow .003-.004 in the hole, using a .038 gasket puts me a shade over 10-1 if recall correctly
comp xe274 hydraulic flat tappet
vortec heads from scoggin dickey good for .525 lift
edelbrock rpm air gap for vortec
currently 600cfm vac secondary(i think im too small here but i thought i would try it)
car has hedman shorties no cat 3in intermediate and dual out muffler


we are trying to set total timing and aren't able to get it done. when we rais rpm to bring on the mechanical and vaccuum advance the timing light begins to flash erraticly beginning at 18-1900rpm, by the time you get to 2500rpm and up its competely dead aside from an occasional flash, it does this on multiple cylinders on both sides of the motor. the car definately doesnt sound like its completely dropping the cylinder either, although the tone does change in that rpm range, but the cam and intake suggested powerband starts there also

as you can imagine this is making things quite difficult.

we tried a second timing light and it repeated the problem, and both lights have been used on this and other cars at those rpms before

i have tried 2 hei distributors both new, i tried one of them with with a summit ignition box (appears to be a mallory) and no change in issue. this was to rule out ignition module issues

both distributors shared a coil, as i didnt have an extra around and it was 4th of july, but they used their own cap rotor and guts

plug wires are new accel super stocks 8mm, and are routed through a set of rm specialties center bolt looms to champion rs12yc plugs.

after this post i plan to go get a coil to try, and i plan to try and draw my hei power from the battery as a test to rule out supply problems.

i also read an article/post somewhere about compression loss creating a similar issue for someone, so i plan to run the valves to make sure they are where they should be and not pumping up holding valves off seat


what timing am i looking to be at , i have read more initial less advance such as 24-26 and 30-32 all in at 2500.. but i know every motor could be a bit different

right now its 21 at 800rpm, vaccuum advance is disconnected, tho i dont recall why we left it that way, things were getting pretty frustrating

i drove it some and it seems labored in the area where the timing light is acting up, so i believe i there is an issue but dont know what

firechicken_3

iTrader: (4)

well today didnt go as my earlier post planned i never got another coil, or tried powering my dizzy from the battery

also never got to re setting valves as i checked compression on some cylinders and got 175lbs consistently, didnt do all due to not being able to get the fitting /hose in due to headers in the way

put vacuum advance back on full port and seemed to help it some,

drove the car on the highway a bit today and noted that in the 2000-2200rpm range it felt a bit rough, but smoothed out as i went a bit faster like 2400-2500rpm this was done in overdrive...

could this be secondaries fluttering a bit and then coming steadily open? need to check what spring is in the secondaries, but i believe its a heavier one, brown i think? i will try a different spring and see if this moves around,

but if its pulling the secondaries in that soon under just cruising load with a heavy spring that would indicate it wants more carb right?

also idle vacuum was around 11-12in if i recall i need to recheck as i dont remember for certain

hope someone has some thoughts on this, dont be scared i wont hold you responsible too much

firechicken_3

iTrader: (4)

bumpity, any ideas are welcome

Atilla the Fun

GM claims 64cc, but vortecs are really close to 61cc, you're right around 10.5:1. I'll leave the coil and module issues alone, and get to your advance curve. 21 degrees at idle would be a little low with vacuum advance, but is too much without. So reset your initial to 6 degrees without vacuum, then reconnect the vacuum advance to manifold vacuum, and use a 20-degree vacuum advance for 26 degrees at idle with vacuum. Then for your centrif. advance, set that to add another 22 degrees, all in no sooner than 3000. This will give you a baseline of 28 degrees total, which is fine with 10.5:1 and Vortec heads on pump premium unleaded. Drive that, then you can experiment with advancing the whole distributor another 2 degrees.

firechicken_3

iTrader: (4)

ok so pull the vacuum line shoot for 6 degrees,

put the vacuum back on and dial it to 20 degrees, the distributor has an adjustable vac chamber which is where i will adjust to get my 20 dialed in right?

for centrifugal i need to get a curve kit for weights and springs right? will it also include some means of limiting advance?


i think i get it, although before i can go beyond setting idle timing i need to work out whatever is keeping my timing lights from working at higher revs

Stekman

Correct. 6 base is vac. unplugged, 26 base is vac. hooked up.

You'll need a spring and bushing kit. If you run the MSD spring and stop kit, I think it will be 2 blue springs and the blue stop that yields the mechanical curve Atilla describes. Been a while since I've messed with the advance stuff, though, so don't quote me on that.

firechicken_3

iTrader: (4)

can i use that kit on any hei distributor then?

i bought the summit blueprinted hei dizzy, but its not in the car because during all the changing and swapping it took a flying leap off the top of my toolbox and busted up the lip the cap sits on,

im using a loaner blue printed accel right now, it was also new and sitting here from my step dad, that never made it into one of his projects. im not sure if its going to stay in the car permanently. i need to see what he wants for it and or get the one i bought welded up or swap guts to another housing

Atilla the Fun

MSD offers at least 2 different styles of everything related to an HEI, so there's no telling without calling them, but when I bought my last Accel, it came with weights, springs, adjustable vac. adv., an allen wrench for the vac., and good instructions. And that was with their 59107c. It worked fine to 7000 rpm. GM vacuum advance "cans" have numbers stamped into them, you can see these numbers when you pull the dist. cap and look down from above, if you see an 18, that means it adds 18 degrees to your initial. 20 adds 20, etc. A can marked 20 and setting the initial at 6 with no vac will give you 26 with vac.

firechicken_3

iTrader: (4)

according to summit the msd bushing spring kit only fits their pro billet units, but i already had one ordered locally because it doesnt say that in the msd catalog.. so i will take a look at it

wont really know any think new untill probably sat morning, i went ahead and picked up a 750 vac secondary holley to replace the 600 thats on it. i tried it, since i had it.

but i don't think its enough as its easily pulling the secondary open revving no load which im told should not happen....... i was fore warned of the carb size being an issue so its no surprise