Engine Timing

[Locutus]

This is my engine combo
block: 14010207 ...350...80-85...2 or 4
heads: 3782461....64-66...327......Camel hump,no accessory holes,194/150 Valves,160/62cc port volumes,62cc chamber.
Carb: Brand New Edlebrock 1406 600 CFM
Cam: Crane Energizer Part # 100072 Grind # 284 H12 ( I don't know what info you might need about the cam) It is slightly agressive and is supposed to have a fair idle.
Exhaust: Headers Dual Exhaust 2.5 inch pipe


I have a stock HEI distributor, and my problem is I can't seem to get it timed right. The only place it will seem to idle is well past the degree marks on the timing chain cover. It would be like 20-30 degrees advanced. If I try to put it down to like 4-8 degrees it dies. I recently put on a new edlebrock because the Holley 750 double pumper was way to much carb. Before I replaced the carb it would frequently back fire thru the carb, no matter where I had the timing at. I can't seem find a happy medium. This is one of the few things holding me back from driving my truck on a daily basis. Now here are the only things I can think of, The firing order is off, the cam is indexed way to much or the distributor is off a few teeth. I did not install the cam or the distributor. Any ideas on what might be my problem.

Mike

[crazy longhorn]

Thats a pretty healthy cam, & they tend to have low vacumn issues. I would pick up a crane adjustable advance kit, & try to set it up @ about 14 degrees initial, use the springs to get the mechanicl curve "all in" @ 2800-3000 rpms. Then limit the vac advance to about 10 -12 degrees, & hook it to full man vac At the carb. this will give about 24 to 26 degrees at idle, & pick up the eng vacumn, to smooth it out,& help with throttle responce. If it wants more, you could try advancing the initial to 16 degrees......just check to be sure it doesnt spark rattle under a load. Good luck,crazyL

[70c10]

crazy, how do you know which is full man vac?

[73stepside]

full manifold vacuum is the driver side port on an edelbrock/carter carb. manifold vacuum is below the primary throttle blades and ported/timed is above the primary throttle. ported should be close to the top of the carb on qjet. can't remember how holley's are setup.

[crazy longhorn]

The Holleys have ported vac off the side of the metering block. To check on any carb......ported vac is not present @ idle, but shows as you pick up the throttle,& it drops when you put the truck under a load. Manifold vac is present @ idle, & drops when you put the truck under a load. A vacumn guage will tell the story.....d@mn nice tuning tool too ! crazyL

[Locutus]

Crazy you lost me, does that advance kit have instructions on doing all those steps. Right now my main goal is to just get it running, I am sure I won't be getting peak performance but will I need to do all that just to get it to idle and drive it around.

[Class of 69]

Do they still make timing tapes to go on the harmonic balancer?? I used them to time engines beyond the timing plate, but that was years ago...might be a quick cheap solution for him to see where this is going.

[crazy longhorn]

Yes, the Crane kit has pretty good instructions. You cam will like a lot more timing than a stocker, & many of the larger cams will run in the range of 14- 16 degreees initial(set with a lite). The mechanical advance will be in the range of 20degrees on most HEI distributors.......20 + 14 initail is 34 total, & thats what you will be running @ full throttle. The vac advance helps with milage & throttle responce during cruise, but drops out under full throttle(will also help with the idle & vacumn with a large cam). The stockers have too tight a mechanical curve(not in fast enough), & way too much vac advance for perf useage. Stock vac can may pull as much as 20-22 degrees advance, but for perf, you will be running a looser mechanical curve, & neeed to limit the vac advance to 8-12 degrees to keep from spark rattle under a heavy load. If you use the limiter to the max position on the crane kit, you should have about 12 degrees vac timing. You can also adjust how fast the can "backs off" with an allen wrench provided with the kit. a timing tape on the balancer is also a must to set /check/ total timing. They will all tune a little different, so the figures i gave are not carved in stone, but would be where I would start. Good luck,crazyL

[tom hand]

I have run into this many times. Possible causes are, the balancer and the timing tab you have are different years, the outer ring on the balancer has slipped. Ethier way just forget the timing light, adjust the timing till it runs O.K. the take it out and do a few full trottle blasts. Keep advanceing the timing a little at a time till the engine "pings" then retard it till it just stops. You have just set the best timing for the fuel you have in the tank.

[Locutus]

TTT

[crazy longhorn]

Tom brings up a good point on possibly a slipped balancer ring, or timing tab that doesnt match with the balancer. I think if you look at the timing tag for the cam tho, you will find that it has a lot of overlap & will really like quite a bit more initial timing than a stocker will. To get the most out of your combo, you should recurve the dist. I have no problems with timing by ear, as the lite only tells you where you are set......but cant tell you the best setting(you have to listen for that). As i said before, the mechanical curve is too tight from the factory, & the vacumn advance puts out way to much timing for perf useage, & is hooked to the wrong spot! high perf cams like a full manifold source for the vac can....ported spark was for emmissions. crazyL

[Locutus]

Crazy is this the kit you are talking about?

http://store.summitracing.com/partdetail.asp?part=6808

[crazy longhorn]

Yes sir, thats the one

[Locutus]

No one here carries the Crane version. One store has the Morosso version. Is this just as good? I kinda want to work on my truck tomorrow (if it doesn't rain) so if I do that I can't order from summit it takes to long to get here.


Mike