Team Camaro Tech banner

1 - 11 of 11 Posts

·
Registered
Joined
·
44 Posts
Discussion Starter #1
Specs:
5.7L V8 350...95-00...383 Stroker
4 Bolt Main
Vortec Gen. 1 crate motor and "ZZ4" One piece rear seal
Lunati Hyd. roller cam (478 intake/470 exhaust, 227/234 @0.50)
3.750 Eagle Crank
5.7 - 5140 I beam floated rod
KB forged dish pistons
plasma moly rings
Clevite 77 bearings
Melling True Roller timing set
Melling hydraulic roller lifters
Melling h/v oil pump, pickup and shaft
Scorpian 1.5 rockers
Comp Cam push rods
Edelbrock E-Tec 178cc Alum. heads
Edelbrock RPM Air gap manifold
Holley Street Avenger 670 vacuum secondaries w/ electric choke
Holley fuel pump
Mallory HEI Distributor #29212
Mallory 6A HiFire ignition system

Question:
I installed the Hyfire 6A and it starts a harder than usual. Understand this is so the box can energize. However, sometimes, it will idle roughly for a good while then just die. It will not idle in any gear - dies right when it is put into gear. I can heel-toe it into gear and it will take off and run but I have to keep my foot on the gas to keep it moving or it will die. Is it the ignition box at all? Are my wires crossed? The light blinks 3 times when I put the key in (a sign from Mallory that it's hooked up right). It seemed to run fine before I installed the Hyfire 6A? My transmission guy seems to think it's the carburetor b/c it dies (seems to lose fuel). However, I have an Edelbrock 600 that I've hooked up and it does the same thing. Could it be a bad ground??

All in all, it won't idle in gear. Help and Thanks!
 

·
Registered
Joined
·
5,277 Posts
I'd get a vacuum gauge and see what your idle vacuum is. Timing and carb idle mixture will impact idle vacuum quite a bit. The idle mixture should be adjusted for highest idle vacuum. BTW: Your 670 carb should be a good match for that motor.

You don't say wheather or not you have vacuum advance (I'm not familiar with the Mallory 29212), but vacuum advance will help a lot.
 

·
Registered
Joined
·
44 Posts
Discussion Starter #3
It's an HEI vacuum advance distributor. Don't have a vacuum guage but I bet I could get one. Just in checking other possibilties today, I noticed my fuel pump is quite grimy and looks like it's been leaking so I've pulled it off and in the process of rebuilding it now. I also relocated the ground from the distibutor to the engine block.

If I hook up a vacuum guage, what should I be looking for - total novice in that area.

Thanks for the help so far.
 

·
Registered
Joined
·
5,277 Posts
First off, if you're going to buy a vacuum gauge, don't over look the hand pump type. They should be about the same price as a vacuum gauge and will serve double duty allowing you to use them for things like checking AC damper servos, EGR valves, vacuum advance canisters etc.

Idle vacuum varies depending on the cam. I see you posted your cam specs, but not being a cam guru, I'm not sure what to make of it. A stock motor will have an idle vacuum of about 17" while a cammed motor will have idle vacuum from 10" down to 8". It varies greatly.

What you want to see is steady vacuum with no significant flutter in the needle. Things like vacuum leaks, improperly adjusted or burned valves can cause the vacuum to read low and / or flutter.

When setting your idle mixture, you're looking for an increase in vacuum (small change ~ 1 or 2 "Hg) as you find the optimum mixture. If you search you'll find some good descriptions of the procedure.

Vacuum advance should cause the idle vacuum to increase also. If you get a hand vacuum pump, you can even apply it directly to the vacuum advance canister to characterize the amount of advance at various vacuum levels.

Long story short, idle vacuum is a good health check that will help you rule out a number of problems affecting idle and off-idle performance. Although you may have another issue like a leaky carb, too much fuel pressure, blown power valve, or other things causing the motor to load up. But I think you'll find the idle vacuum reading valuable feedback as you troubleshoot.
 

·
Super Moderator
Joined
·
32,527 Posts
You might even try to run the engine on the HEI unit itself and view the results, after you've done Dave's suggestions.
 

·
Registered
Joined
·
44 Posts
Discussion Starter #6
@Everett#2390 - I've definitely thought of that and I might go that route if I don't figure something else out.

@Dnult - Thanks alot for all your great info. Picked up a cheap vacuum gage yesterday and I hope to hook it up tonight.

FYI - I found this cool little widget that shows you ALL the scenarios related to reading a vac gauge - http://www.secondchancegarage.com/public/186.cfm

I'll let you fellas know what I find
 

·
Registered
Joined
·
8,349 Posts
I'm going to say that if you installed the new box and but did not adjust the timing at all then that may be it. You can probably advance your initial a little to get past the hard starting.

Take the cap off your HEI and see if it has eight triangles cast into it on the distributor body and rotor assembly body that point towards each other. If so, you can set your initial timing easily.

Rotate your engine around clockwise so that the rotor is coming up on #1 and your timing mark on the distributor is at 12 degrees advanced (before top dead center). If you're not sure exactly how to read that, then get the timing mark on the balancer at exactly 0 and rotor pointing where #1 post of distributor should be (about 5 o'clock), then rotate the motor counter-clockwise so that the mark is at the 12 BTDC mark on the timing tab. Then loosen the distributor clamp. Rotate the distributor body so that the triangle points are lined up dead on with one another. You may have to take the rotor off to see the triangles easily (if you have them). Lock it back down and see what that does with your initial at 12.
 

·
Registered
Joined
·
44 Posts
Discussion Starter #8
Ok. Talked to the guys at Mallory and they said I should be wiring the box differently. After disassembling the distributor, they instructed me to remove the 4-pin magnetic pick up module in the distributor base. Then I used the supplied wires in the kit directly to the magnetic pick up prongs.

He informed me that the box and the magnetic pick up module were competing and actually told me the problems I was having before I told him. Made me feel better but now the engine will not start at all. :mad:

The engine tries to start but it seems to be misfiring. Checked the wiring and the plug wires and all is ok. Grounded out the coil wire to test for spark and got none.

Anyone have experience with this? Thanks again.
 

·
Super Moderator
Joined
·
32,527 Posts
You might have the spark occuring at the wrong time, use a timing light and observe the timing marks on the scale and harmoinic balancer and rotate dist body as needed.

Yes, module should be removed from dist and MSD box does the spark thing for the coil. To test the coil, wire as normal, 12 volts to + terminal, a wire to - terminal, and coil wire to tower. Hold coil high tension wire away from ground about 1/4 inch, ground - wire on coil and pull away from ground. Once current flow stops, as wire is pulled away from ground, spark should occur from coil.
 

·
Registered
Joined
·
44 Posts
Discussion Starter #10
Thanks Fellas for all the help. I think I've fixed my previous issues. I rewired and removed the module. I wired my own magnetic pick up straight to the 6A box (purple and green wires). I know have an engine that runs in gear and I have been able to set the timing. However, now, when I take it for a test run, it will die intermittently - almost like I've turned the key off.

Anyone seen this before? It runs great, no misses or misfires, just quits unexpectedly.

Thanks again!
 

·
Super Moderator
Joined
·
32,527 Posts
Either the box or another component is getting hot or a wire connection is getting hot and limiting currrent flow when hot.
 
1 - 11 of 11 Posts
Top