Seth Mathis

Hello all, a Ford guy here hehe. I just did a tune-up on my truck recently and she hasn't ran quite right after the tune-up.

The motor is a 80's 350 block 4 bolt main, RV cam, headers, edelbrock intake/650 carb, 192 fueler heads I believe, 4 speed transmission, HEI distributer. The motor was dyno'd at 411hp 404 torque back in its day after being built, I wasn't the one who built, i've just had the motor and been whoring it out with all my vehicles. She's now sitting in my 78 GMC 2wd longbed. I've never given this motor a tune-up since i have had it, it was kinda of a weekend warrior. I didn't write the firing order down from what it was, I was just gonna go off the manual. It's an HEI dist, yes I did go off the HEI firing order and not the points firing order if there is any difference. The truck didn't even start, but you could hear alot of detination so I know the firing order is off severely. But I've gone over it over and over. Today i did get the truck to run and I even drove it to work and back, but I can still hear it popping in the motor in the lower RPM's.

I'm stuck here... only thing I can think of, is it maybe has a stroker crank that changes the firing order by a couple plugs. Any input is great!

kevinkpk

Set the rotor pointer to the plug that goes to #1 cylinder. With the piston at or about top dead center of #1 that will be the (facing the front of the engine) first on your right. That side is the odd numbers 1, 3, 5, 7. Left side is even 2, 4, 6, 8. Follow the timing order clockwise (I believe since it is chevy) plug wires on the cap matching the firing order cast on the intake, 1-8-5-3 or whatever it is. You should be able to start then set intial vacuum timming with a timming light.

Seth Mathis

Thank you sir. I've been doing a little research on it, found a few different things. I'm having a hard time finding which is the actual #1 plug on the dist cap. Some say its at 5:30 and some say its at 6:30. I've got lots of time to tinker with it tomorrow or today (I'm up late lol). Guess I'll just start with putting the crank at TDC and see where it points me. I doubt it's a stroker crank from a 383, but who knows. I also know the motor has been bored .30 over but don;t know if that changes a thing. I can tell you everything there is to know about a 302 or 351 with the dist in THE FRONT haha. But thanks for the advice! appreciate it bud.

regedit024

hey seth, you probably already figured this out, but im pretty sure i know exactly what your problem is because i made some same mistake when i came over from ford. basically its just what kevin said about the cylinder numbering, fords number their cylinders 1, 2, 3, 4 down one side and 5, 6, 7, 8 down the other while gm goes 1, 3, 5, 7 and 2, 4, 6, 8.. an easy mistake for a ford guy working on a chevy, as far as 5:30 vs 6:30 it really shouldnt matter either position should be close enough to get it to crank and still leave room to adjust it to the correct position. just use the firing order from the book which i THINK is 1, 8, 4, 2, 5, 3, 7, 6

MrMarty51

Sometimes humidity or lack of it can cause problems if there are any open connectors.
Different temps can also cause a broken wire to make or break contact.A poor transistor in say the ignition system may work just fine when the engine is cold but as soon as it warms up said transistor can break down.
Could be the battery is getting weak and will start just fine on a warm day but when the temps drops to about 32f it zaps quite a bit of cold cranking amps from the battery.
A little history/make/model of vehicle could help too.
I know the wipers on my 93 GMC will work just fine when it is warm but when the temps cool down they fail,I think that is a broken wire in the steering column,That problematic spot where the wires makes the corner then they are always flexing right there when the turnsignals are used.

jwruss

The correct firing order for HEI V/8 is 1,8,4,3,6,5,7,2.