73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: JJSZABO on March 06, 2008, 08:21:40 pm
-
I am ready to startup my new 350 crate motor. It has been many years since I did this, so I want to go over some procedures to see if I am on track.
I started by putting an old distributor shaft (cut from old distributor) into the distributor hole and primed the motor with oil using an electric drill.
I put #1 cyl at TDC and dropped in the HEI distributor. I had to rotate the oil pump shaft so I can align the rotor to point forward. The 0 degree timing mark on the dampner tape is aligned with 0 degree on my timing pointer.
I connected all the plug wires up.
Now, once the motor starts, I bring the motor up to 2000 rpms. When do I set initial timing - now? And if I remember correctly, If I check total timing (~36 degree) at 3000 rpms - that would be the initial timing + mechanical advance. Is this correct?
So, if I add initial timing (12 degrees) + mechanical advance (20 degree built into distributor with counter weights) + vacuum advance (14 degree for non-EGR motor) I should have a TOTAL advance of 46 degrees.
Does this sound correct?
-
First make sure you are on TDC compression not exhaust! Then arrange it like you described.
When you initially start it do not immediately rev it to 2000RPM, inspect for leaks, make sure you have a good spill free funnel on the neck of the radiator and that the cooling system has room to expand. Now bring the idle speed up to around 2200 RPM and set your total advance to 36°BTDC for a good safe baseline. Once the engine reaches operating temp vary the RPM and adjust to a good idle speed. Now shut it down, cap the radiator, double check your fluids and go drive it. Accelerate to wide open throttle from a stop several times. Come back and change your oil and dial in your timing more precisely.
-
Do I have the timing parameters correct?
-
No, your total advance will depend on many factors:
Altitude, temperature, compression ratio, fuel etc....
Your best bet is 36° total advance and then do the trial method to see what's best suited for your engine. Any idea what your compression ratio is?
-
No :-\ the crate motor is an ATK DC08 bare bones stock motor - 8._:1 I am guessing.
So, I set total advance to 36 degree at 3200 rpms. Is this with the vacuum advance connected? I guess once I get total timing set, I test drive it to listen for spark knock and adjust from there?
-
Jeff, I have good results with initial start up by putting the timing mark on 8-10* btc & put the distributor in with the rotor centered on the cap on number one. This way there's a little less guessing on where your at when you crank it for the first time. Lorne
-
Thanks Lorne, I read that also - I think that is what is confusing me.
-
Total timing means with the vacuum advance hooked up. It's best to check your total advance since you will be running it at high RPM for the first time. That's why dialing it in around 36° is a good idea since you won't be at idle speed so base timing isn't your concern at this point.
-
Ok - I understand it now. I am confusing total timing with total advance.
My distributor has an adjustable advance and I was trying to think when I would start adjusting it. But I should have my vacuum advance disconnected when I first fire it up since all I am interested in is my centrifugal advance (total timing). I should get my centrifigal advance set before I adjust for vacuum advance? That is what I am reading in Crane adjustable vacuum advance kit instructions and my MSD timing tape sheet.
The two sources I referenced state that:
Total advance = the total of initial advance, centrifigual advance, and vacuum advance added together. This would be subjuect to many factors. So this could equal a total advance of 45 to 51.
Total timing = total of the initial plus the centrifugal advance added together. This should be 36 degrees.
Since I will be Accelerating to wide open throttle from a stop several times I will not need vacuum advance, so I should plug the vacuum line for now.
-
Vile, I was suggesting what I do for the initial turn of the key & then adjust as you stated. I have found it to be closer than guessing about where the rotor is (not being at 3 or 16 btc,ect) It just gives a line on here to go by when the rotor is dead center of there, understand? Jeff, You got a handle on it now, you don't have to be concerned with the vacuum on initial start-up. Do as Vile said, just get it going quickly, check for leaks & get it up a little over 2000. Good Luck, Lorne
-
Thanks Lorne.
I've read in two different startup procedures where the only difference was in how the distributor was set. One said to set everything to TDC on #1 cyl then drop in distributor and the other source said to initially set the timing to 12 degree BTDC and drop the distributor in. Which is correct - BOTH. This is what was causing me confusion. This and total timing vs total advance.
Being an engineer - I have to over analyze EVERYTHING.
-
Jeff, Both will work, just 12* off before you start it. No, this is not total vs.total advance. Total timing would be what the engine sees with the initial,centrifugal,vacuum added together. Total advance would be minus the base timing or say the amount it gains from the base setting. What you described is just two ways of setting the base timing for initial start-up. The engine is going to want 8-12* initial, so I just find it easier to get the balancer on, say 10* & drop the distributor in with the rotor on a line drawn on the base in the center of # 1. Either way will work, however if you set it on TDC, your likely going to need to start moving the distributor around (about 10*) as your trying to get it to light off. I feel it's one less thing to do while your on the initial start-up, just have a timing light ready to check the it once your up to 2000 rpm. Hope this helps, Lorne
-
Yes it does Lorne - thanks. I am debating now if I should remove dist. and rotate to 12 degrees BTDC. I'll mull it over.
One other question - with a stock HEI and coil (35,000 volts) the data sheet supplied with my crate motor says to set the spark gap to .040". But I have a distributor and coil that can supply 50,000 volts - can I open the gap on my plugs to say .045-.050 for a smidge more HP or will this just cause me trouble? I wont be doing this at initial startup - just "down the road" kind of thinking.
Again, thanks for the help.
-
Jeff, You most likely won't have to pull the distributor back out unless the vac. can hits or you really were off when you put it in. Set the balancer on 10* BTDC With the timing mark (you did verify it is true TDC, didn't you? Draw a line on the distributor base, centered under the # 1 electrode (center of the lump of plastic-cap) Pop the cap off & rotate the distributor base until your drawn line is centered with the rotor & tighten it down. As far as plug gaps, You'll have to check it out & see, may show a SMALL gain in power & mileage. Your good to go, Lorne
-
OK thanks, I'll try that.
Quick question, when I installed the transmission (th400), I put 2 quarts of fluid in the convertor - how much more fluid do I put in the transmission before first start?
-
dry fill is 11 quarts including the converter
-
Great - Thanks Vile ;D
If the weather cooperates - startup on Sunday ;D
-
JJSZABO,
Are you going to video it? Post it if you do. GOOD LUCK!
-
yea take a video
-
Yes, I plan on it - stay tuned.
I didn't start it this weekend - weather did not cooperate. I am looking at this weekend.