Valves set, timing and idle speed right, motor running, vacume guage jumping between 7 and 8. idle mixture screws on my 800 edlebrock are both 11/2 turns out. i turn 1st screw all the way in, no change in vacume, all the way out, no change. Do i have a vacume leak? drove it around the block, ist timeon the road, it stumbles a bit on takeoff.
Cooter

 

When it is running put your hand over the primarys, if it idles up then you have a vaccume leak somewhere.

 

Ok, i tried the hand over the carb, i can kill the engine, i even ran an unlit propane torch around the intake to see if i had any leaks, nothin. I have this spark plug viewer thing im gonna try, lets you see the fire in the combustion chamber then you tune it to the best color. I also read about taping everything but a small tube down the carb up and blowing cigarette smoke in the unrunning engine to find vacume leaks.
Cooter

 

You have the throttle blades open too far at idle, and it's idling on your main circuit.
That also explains the stumble.
Run more timing at idle, and close the throttle blades. Pop off the carb, and try to set the hot idle to about .040" of idle "window" viewable.

 

I am running 12deg initial and 36 deg total by 3000 rpm. Think 8 or 9 in of vacume at idle is the problem? mabey two low for that carb, think i might buy a 750 holley double pumper.

 

What are the specs on your cam?

 

FLAT TAPPET CAM, 485" LIFT, 254 DUR @ 50, 114 LC

 

You should be pulling a lot more vacuum with that cam.

 

timing issue

 

Talked to engine builder, he says take initial back to 8 deg and thinks i have a vacume leak.

 

If this isn't a typo, then you're damn lucky to get 8* of vacuum, and you NEED to be running full timing at idle. Typo?

 

I copied it right off the web site, bought the long block from stroker moters its a 383 450 hp motor.

 

IMHO that's a very large cam, duration wise, not very much lift wise. The 114 LSA will help out the vacuum, but 254° duration @.050" is quite big. I think with a cam that big 10" vacuum would be outstanding.

I'm standing by my original suggestion;
What does the rest of the crew here think? xpndl3, I think you've ran big cams before, (more times than I have...), do you think it'd be wise to jump up the timing? I think jbenge might have some insight on this as well.

 

If the idle mixture screws can be run in all the way adn the engine still idles, the main circuit is delivering idle fuel. That could be from too much throttle angle, a high fuel level, or internal leakage.

I personally know of two peopel with three brand new (old?) Edlebrock AFB clones which are now back in the box in lieu of a different carburetor. I'm not hearing really good things about them. And all these years, I thought that Holley was a steaming pile of dog dung. The Edelbrocks installed by people I know are making the Holleys look like technological marvels, even though we all know better.

 

That's a huge duration for a flat tappet, normally once they're above 240 duration it's all roller or solid tappet/solid roller especially for such small lift, I'd like to see a part number for the cam in question. Either way the carb should be pulled and see how much the transition slots are exposed. If the engine builder is calling for 8 degrees at idle then it sounds like a much milder cam, than the duration he stated.

 

• GM 350 2 BOLT, CNC MACHINED & CLEARANCED BLOCK 4.060" BORE
• NEW 3.750" HIGH NODULAR STROKER CRANKSHAFT
• GM STAGE 1 5.565" I BEAM CONNECTING RODS
• CAST FLAT TOP PISTONS
• 58cc= 10.0-1, 64cc= 9.9-1, 72cc=8.5-1
• SPEED PRO CAST RING SET
• CLEVITE ROD AND MAIN BEARINGS
• BALANCED EXTERNALLY TO 1/2 GRAM
• EXPERT BLUEPRINT ASSEMBLY

• DART IRON EAGLE 64cc HEADS, 2.02/1.60 VALVES 200cc INT. RUNNER
• ARP HEAD BOLTS, FEL PRO GASKETS,MANLEY PUSHRODS
• STAINLESS STEEL ROLLER ROCKER ARMS
• S.A. GEAR DOUBLE ROLLER TIMING SET
• MELLING PERFORMANCE SOLID FLAT TAPPET CAM, 485" LIFT, 254 DUR @ 50, 114 LC

That is the whole build minus the performer rpm intake, 800 edelbrock carb, slp shorty headers, moroso 7 qt oilpan and pump. I was thinkin about it as i was tryin to go to sleep last night and thought i might have forgotton that little vacume line on the brake sensor, got up early and damn it was hooked up. The engine will die now with the screws all the way in so mabey it was timing. I am getting a little closer on the mixture. Took my plugs out and they are black so i am gonna change them and my oil and start over. It sounds awesome just when i snap the throttle it backfires and its putting out some white smoke that smells like unburnt fuel.

 

I was curious if that cam existed or not, so I looked it up, Melling does make it, part number 22410, 254* and .485", solid cam.

I'm shocked you could pull that much vacuum with minimal initial advance, I would think everything would be a lot happier with the advance well in the teens. My tiny little cam in my 305 will idle with almost no advance at all, but it runs very, very nice with 14* of initial.

 

IF that cam is indeed 254 duration and a solid cam, do you hear the clicking of rockers as the motor runs? It sounds like all the valves are ticking loudly. If this is indeed that cam, then you might as well run 25 initial and 32-38 total depending on what the motor likes or just lock out the timing all together and run it that way. A cam with that duration will want a 3800-4400 stall at least and be a total dog under those RPMs. A 4.11 or larger gearset for the rear as well. If you're running a manual that means keeping the motor in that rpm range as well. I see your little info chart shows 3.08s, and that plain won't cut it with this large of a cam, it'll be out of the powerband all the time.

Did you bother to check the transition slot opening like I stated above either yet?

 

Turned out to be a mixture of problems, First i added a spacer plate with new gaskets, took both mixture screws out and blew compresssed air through, reset the valve lash, 1st time ever doing a solid lifter cam set at .30 for intake and exaust, and lastly hooked vacume advance up to ported vacume because it was coming in to early. Seems to be running alot better. Thank you for all your advice.http://s203.photobucket.com/albums/a...t=19a4370a.flv