First fire problem

by JF74chevelle Thu Sep 14, 2017 9:32 pm

I got my new motor all in and buttoned up and tried to fire it to break in the cam but it wouldn't light off. I know it's getting fuel. It backfired once through the mufflers and once through the carb. I think I may have it 180* out on the exhaust stroke Instead of #1 on the compression stroke.

by Joe73 Thu Sep 14, 2017 9:47 pm

Take #1 plug out, put your finger over the plug hole and have someone bump the starter. When compression tries to blow your finger off the hole your on compression stroke. Pop the dizzy cap off and make sure the rotor is pointing to the #1 plug wire terminal.

by JF74chevelle Thu Sep 14, 2017 10:15 pm

Okay thanks joe. I'll be checking this tomorrow morning and get back to you

by bracketchev1221 Fri Sep 15, 2017 6:47 am

Otherwise, take the driver side valve cover off, watch the INTAKE rocker. Double check and make sure you are watching the right one. Its easy to get them mixed up especially on your first try. Spin the engine with a breaker bar if you can until you see the intake go down and then come back up. Now you are creeping up on TDC for #1. Watch the balancer and continue to rotate it until you are about 10 degrees before TDC. On a stock type timing tab, this should be close to the top edge of the tab. Now take note of where the rotor is pointing. This is where #1 on the distributor cap should be. It can point anywhere, but common idea is to set the distributor so that it is pointing towards the driver side front corner of the car. Once that is where you want it, put the cap on. Draw a line on the distributor body where the #1 terminal is on the cap. Now you can take the cap off and set the line to line up with the rotor terminal. Put the cap back on, get the firing order right, and this should get you close enough to fire the engine. Advanced is always better than retarded for initial start. Once you get it running, try to set it at 15-20 degrees at idle and let it run.

by JF74chevelle Fri Sep 15, 2017 3:50 pm

The timing isn't 180* out and I have spark and fuel. What gives

by Joe73 Fri Sep 15, 2017 4:12 pm

Confused. Did you check if your 180 out? You will still have spark even if your 180 out.

by REVINKEVIN / Mr. 600+HP Fri Sep 15, 2017 4:13 pm

Check to make sure you have fire. Pull one plug and leave it connected to the plug wire and have someone turn the engine over to see if it has spark. Check to see if the distributor has the power wire connected corrected. Check the plug wires again against the firing order. Check your carb for open vacuum ports. What carb do you have? Holley has a big port in the rear that people sometimes forget about.

by JF74chevelle Fri Sep 15, 2017 4:20 pm

Joe73 wrote:Confused. Did you check if your 180 out? You will still have spark even if your 180 out.

Yes I checked if it is 180 out but it wasn't. And I checked the park at the plug and it has spark. Also got one of those spake plugs checkers. If you've used one whatvis the bulb supposed to look like. Mine was orange and wasn't very bright

by JF74chevelle Fri Sep 15, 2017 4:20 pm

REVINKEVIN wrote:Check to make sure you have fire. Pull one plug and leave it connected to the plug wire and have someone turn the engine over to see if it has spark. Check to see if the distributor has the power wire connected corrected. Check the plug wires again against the firing order. Check your carb for open vacuum ports. What carb do you have? Holley has a big port in the rear that people sometimes forget about.

I have and edelbrock 600cfm

by Hawk03 Fri Sep 15, 2017 4:40 pm

When I was trying to fire my engine for the first time it would turn over and try to start but wouldn't run. It was exactly what RevKev said, the back vacuum port was not plugged. Mine was a new edelbrock carb. Once we plugged that, it fired and ran with no issues.

by JF74chevelle Fri Sep 15, 2017 4:54 pm

Thanks guys, I'm so stressed now. I was praying for this thing to fire and I didnt change anything from the old motor than ran well

by REVINKEVIN / Mr. 600+HP Fri Sep 15, 2017 5:11 pm

Where are you located? What brand/type distributor do you have? Check your ground wires. Both at the battery and at the engine block. If your valve lash is to tight it might have some valves hanging open slightly.

by JF74chevelle Fri Sep 15, 2017 5:13 pm

I checked the grounds and both places. I'm in SoCal. And it's an HEI not sure on the brand exactly.

Other things I should mention. The carb squirts fuel. The plugs are completely dry, they don't even smell.

by JF74chevelle Fri Sep 15, 2017 5:28 pm

REVINKEVIN wrote:Where are you located? What brand/type distributor do you have? Check your ground wires. Both at the battery and at the engine block. If your valve lash is to tight it might have some valves hanging open slightly.

Also I replaced the cap, rotor, module, and coil. Still nothing. It cranks and cranks and cranks but no fire. The plugs are completely dry

by REVINKEVIN / Mr. 600+HP Fri Sep 15, 2017 6:18 pm

We are about 1,300 miles apart so I can't come help. Let's start at the top. I see everything that you have done so let's make sure we are getting spark to the plug. So:
1) Pull the plug and make sure you have spark when the engine is turned over. Hold the plug by the wire boot next to the header but not touching to see if there is spark. If so,
2) Pull the carb and make sure fuel is getting into engine. You said you had fuel squirting in. See if you have fuel residue in the intake. Also make sure your vacuum ports are plugged or used. Plugged ports must have plugs that are not cracked or worn. If so, and nothing has been left in the intake ports of the heads to keep things from falling in during the rebuild check
3) Pull plug and have friend crank engine over. Put finger over plug hole. Do you get a fuel residue on your finger? Do you feel compression?

If you have fuel to the combustion chamber and good spark with no vacuum leaks then about the only thing left is the timing. Do you set the cam up retarded, advanced, or straight up?

by JF74chevelle Fri Sep 15, 2017 6:31 pm

I set the cam straight up. And I know it is not off by checking the valves and both valves are closed when #1 is TDC 0 to 0 on compression.

by REVINKEVIN / Mr. 600+HP Fri Sep 15, 2017 6:33 pm

Sending you a PM with my phone number.

by bracketchev1221 Fri Sep 15, 2017 7:19 pm

Since it broke the rotor, check the button under the coil for being burnt. Pull the coil out of the cap and there is a carbon button with a spring. If it's busted or burnt it won't transfer voltage to the rotor.

by JF74chevelle Fri Sep 15, 2017 7:31 pm

bracketchev1221 wrote:Since it broke the rotor, check the button under the coil for being burnt. Pull the coil out of the cap and there is a carbon button with a spring. If it's busted or burnt it won't transfer voltage to the rotor.

What does it look like if it's burnt?

by JF74chevelle Fri Sep 15, 2017 10:08 pm

Also, the timing light isn't flashing at all. Doesn't that indicate a lack of spark?

by bigredlaguna Fri Sep 15, 2017 10:27 pm

I'm not sure about the spark tester you are using. Having trouble finding an image that matches your description of it. But if you think the spark is weak, then go over the distributor again.

The button needs to be under the rubber washer or else it will not make contact with the rotor which could cause the weak spark.

Take the rotor off and look at the bottom side. It is possible for the spark to burn through the middle and ground out to the shaft or carbon track to the screws if they are metal.

The module is sensitive to low voltage, double check the supply voltage and just as importantly, make sure there is a ground strap connecting the engine to the body. This one item will create myriad electrical gremlins if not connected and is the reason I suspect multiple failures of ignition modules on my car. You may want to invest in a spare module, and make sure you get the white heat transfer compound. I believe the clear stuff is not as effective.

You can take the module to an auto parts store and have it tested.

by JF74chevelle Mon Sep 18, 2017 1:48 am

So I have come to think that the cam is out of phase. Can the camshaft be installed so incorrectly that the motor can crank and crank but not fire?

Right now when I am at TDC #1 on compression, #6 TDC exhauststroke has its exhaust valve open and the intake closed. Same for the other way around. 6 at TDC compression and 1 atTDC exhaust , the exhaust valve is open

Is there something wrong with that?

by bracketchev1221 Mon Sep 18, 2017 8:06 am

Cam is hard to install wrong. If anything I would go with the rockers not being adjusted right.

by JF74chevelle Mon Sep 18, 2017 11:59 pm

Do you guys think my 74' came with HEI? I

by bigredlaguna Tue Sep 19, 2017 12:13 am

If your car was built with a points distributor from the factory, and the factory harness is intact, the positive wire for the coil will be black with some writing on it showing a resistance rating.

If is was built for HEI from the factory, it will have a pink wire. (It may fade to white, but you should be able to find some part of it still colored.)

If it was modified from an original points wire, it could be any color but it won't have any script on it. Make sure there isn't just a short section replaced- the entire length from the bulkhead plug was a resistance wire if built for points. Also make sure the gauge is large enough to carry the load without resistance.

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