Front cylinders not firing when cold

[Belsinor]

I have a 400 based 512 stroker I just finished installing and the front cylinders (1, 2, 3 and 4) won't fire until the engine is warm. I've changed the ignition box with a spare I have aswell as the coil. Tested spark on all cylinders and I'm running out of ideas and looking for help.

Currently have a holley street avenger on an edelbrock rpm intake. Roller cam with unknown specs.

 

[Curiousyellow71]

Just suggestions, odd problems are the frustrating ones! Try taking both the nonfiring plug and wire and switch it out w one that's working. See if the problem moves. Look over distributer cap and rotor for issues. Maybe double check the lifter preload or valve lash. Compression check always a good idea. I would also check for vacuum leaks on the front 4.

 

[padam]

How do you know they aren’t firing?

 

[PurpleBeeper]

Yes, how do you know they’re not firing? What is your spark plug gap?

 

[Belsinor]

How do you know they aren’t firing?

Infrared camera, engine struggles and the front 4 exhaust ports are cold.

 

[Belsinor]

Yes, how do you know they’re not firing? What is your spark plug gap?

Gapped to .04

 

[padam]

Compression test?

 

[pnora]

Hydraulic or solid lifters? What rockers and how are they set? Cap off all the vacuum ports to eliminate a vacuum leak. Cold and hot compression tests might show something as well as a leak down test on the dead holes. Also do a close check on the gap of all 8 reluctor points.

 

[4speed68rt]

Carb too rich.

 

[RemCharger]

Carb too rich.

Choke? On a roller cam stroker?

 

[BeepBeepRR]

Cap and rotor damaged? Bad cores in the wires? Bad plugs? Distributor shaft warped?

 

[kiwigtx]

I have a 400 based 512 stroker I just finished installing and the front cylinders (1, 2, 3 and 4) won't fire until the engine is warm. I've changed the ignition box with a spare I have aswell as the coil. Tested spark on all cylinders and I'm running out of ideas and looking for help.

Currently have a holley street avenger on an edelbrock rpm intake. Roller cam with unknown specs.

View attachment 1695024

Check the inside of the distributor cap for condensation. There should also be a small ventilation hole in the cap.

I notice there is no wiring to or from the ballast resistor....are you sure all the wiring is correct as it needs to be for firing the engine?

 

[Geoff 2]

Spark plug heat range too cold. Should be a '5' in NGKs or '12' if Champion. I would leave the Champions at the store....

 

[Belsinor]

Check the inside of the distributor cap for condensation. There should also be a small ventilation hole in the cap.

I notice there is no wiring to or from the ballast resistor....are you sure all the wiring is correct as it needs to be for firing the engine?

Checked the cap, no condensation even tried another cap no luck. I bypassed the resistor during troubleshooting, engine behaves this way with or without it.

 

[Belsinor]

Choke? On a roller cam stroker?

It does have a choke, tried max and min settings no luck.

 

[Belsinor]

Carb too rich.

Tried adjusting the idle on the front 4, no change at half a turn in either direction. Took apart the carb and checked the idle circut for the front nothing wrong I could see.

 

[Belsinor]

Hydraulic or solid lifters? What rockers and how are they set? Cap off all the vacuum ports to eliminate a vacuum leak. Cold and hot compression tests might show something as well as a leak down test on the dead holes. Also do a close check on the gap of all 8 reluctor points.

I believe they are hydraulic, or so I was told. Rockers are 440 source rollers, tried running with all vacuum port capped no change.

 

[PurpleBeeper]

Gapped to .04

Are you running a stock ignition coil? The stock gap is .035” and a stock coil might not fire at all at .040” (ask me how I know)

 

[pnora]

I believe they are hydraulic, or so I was told. Rockers are 440 source rollers, tried running with all vacuum port capped no change.

So you do not know if you have solid or hydraulic? Have you done a compression or leak down test? You ask for help but chose what questions to answer. I just do not get it.

 

[eldubb440]

valve lash too tight?