Change the #2 and #7 plugs, get new ones. Replace the gasket that is missing the piece. Start the car up and see how it runs. Check to see if you burnt any of the spark plug wires as well, if they were laying on the exhaust or too close. Replace if any are burnt.

Mark

any news?

start with the basics. check compression of all cylinders. needs to be within 10% from lowest to highest. please post the results.

Thanks to everyone for the help so far. Shoveling snow has been keeping me from the garage so I don't have much news to report. I decided to pull the intake so I could get a good look at the cam and rule out a leaking intake gasket. The cam looked fine to me and all the pushrods are in the lifters and none seem bent. Based on what I read above, my next step should be a compression test. Before I put everything back together, can I run the test? I read that the engine needs to be warm to get the best results, but thought I should see what the group thought.

Thanks,

Matt

warm is ideal and gives you the highest readings but a cold test will for sure suffice here as we are seeking a cyl that is not doing it's job (for one reason or another)so we can rule out the long block so the variations and of much less concern the total will tell us if your long block is healthy. EDIT be sure to block the choke and the throttle all the way wide open

Do I have to do the test with the intake and carb back on?

Do it as is & lets see what you got. Pull the plugs and if a helper is using the key to crank it take off the pentastar ECU connector. Let er rip & post some #'s.

Just ran the compression test. Here are the numbers:

#1 - 150
#2 - 140
#3 - 165
#4 - 170
#5 - 150
#6 - 160
#7 - 150
#8 - 150

Could this be a head gasket leak between #2 and #4? The numbers all seem good to me, but the variance between these cylinders has me thinking. Thoughts?

Thanks,

Matt

what intake? if its a edelbrock w/ a spreadbore pattern [performer/sp2p??]ect ect,do you have the gold plate under the carb? this prevents a vacuum leak in the 2ndary area of the intake to carb area.might be a chance?

It has an Edelbrock Performer RPM with squarebore.

check for a broken valve spring.

You have a major timing issue. Rotate engine to TDC compression stroke and check to see if #1 is being pointed at under the dist cap. My vote is a broken oil pump gear or something let go in the dist, timing chain.

if timing chain breaks, no compresion and no start. if oil pump gear or dist breaks, no start.

I thought I'd replied; since #7 and #2 are right next to ea other in the firing order I'd look for bad wires, bad dist cap (carbon track between them?) etc.

Thanks for the continued help. I checked the cap and wires and they are fine. Any other thoughts based on the compression numbers I posted above?

nobody mention ing coil Ihave msd coil #8253 on my 340 backfired one day stalled got it restared ran poorly started to smoke from tailpipes changed msd box didnt work changed coil was back to normal when it backfired blowed out Intake gsks. your Comp readings are fine I did same ckd .comp readings were 35psi off please try know good coil

Is this a new re-build with a new cam lifters etc.? Or has the engine been in the car and run just fine last year etc.? If the engine has been in the car and ran fine last year, what changes were made from when it ran just fine until now? Did you change ignition setups? Did you change the distributor? Did you add gas to the tank? It could be bad gas. I would pull the carb off and empty all the gas out of it and use dry air and blow the carb out as best as you can. I am with Andy F that some debri is probably caught in the carb. Especially if the car runs at higher RPM's with no problem. The debri is probably clogging up the transition circuit from off-idle.