1986 backfiring thru carb

I didn't see a forum for 86's so I hope I am posting in the right place.

I can't find anything anywhere on the truck specifying what the timing should be. It's currently at 0 degrees. Does anyone know what a 360 in a 1500 series should time at and the total suggested timing?

About two years ago someone dumped a lot of money into the motor to rebuild it.

1) It has an MSD ignition coil.
2) It has a Holley Carb, but I don't think it is hooked up right because the kickdown isn't working.
3) About two years ago the distributor was replaced with a new one.
4) The truck sat for 6 months before my boss purchased it.

I've had two people tell me two different things are causing the backfiring.

One says its a bent valve. I doubt this because there's not any extra-curricular engine noises coming from the engine compartment.

The other says its the carb and it needs to be rebuilt. I don't think this is the case either because the carb was rebuilt at the time the engine was rebuilt.

I think its as simple as ignition timing.

Please HELP!

FYI, The truck will not pass emissions. It fails on hydro carbons with brand new catalytic converters on it. It also fails on nitrgoen oxides at 25mph by a couple of points, but passes at idle.

The timing should be anywhere from 5-10 deg. ATDC. I use a vacuum gauge sometimes to time my engines. Hook a vacuum gauge up to a constant vacuum source either on the carb. or on the intake manifold. Anywhere between 15-20 Hg is about where you want it without the engine starting to knock.

You really need to hook that kickdown up or you'll be looking for a new transmission. The kickdown also helps control when the transmission upshifts as well.

Last resort would be to trash the Holley and put an Edelbrock 600 cfm carb. on.

Thanks so much.

I don't own a vacuum timing guage though. Would I simply set the initial timing to about 7 deg ATDC with my timing light (clamps around wire) and start tuning from there?

I am really unfamiliar with older engines. I am a computer geek as well as a car guy and anything with computers is easy for me to figure out. These older motors that rely on physics are a little harder for me to understand.

I like Edelbrock too, and when I get the chance I'd like to make your suggested switch.

This truck has the oddest kickdown setup I've seen and once I get the motor running right it will be my next task to tackle. I'll take a picture of the setup the previous owner put on the truck and post it. I've been told that holley sells little conversion kits to make just about any factory setup work iwth any carb so I had planned on figuring out the stock setup, reverting to that and using the holley conversion kit as they inexpensive to purchase.

Do you know what carb might have come stock on an 86 360? I've seen both holleys and rochesters.

And if I can bother you for just one other quick problem ... how do I test and adjust the electric choke on a holley?

I've got to make this thing pass emissions. And so far its not been fun trying to do so. I had to turn down the air and fuel to levels it would barely run on just to get it to read so I would know where to look for problems.

7 deg. sounds good. Your going to have to do a little trial and error. Start with 7 deg. and see how the engine responds to that. Unplug the vacuum advance first before you set the timing.

On a 4bbl. 360 in '86...it was probably the Rochester or maybe even a Thermoquad. Edelbrock has a kit available as well w/ their carbs. I would suggest going to a junkyard and see what the factory did, or get yourself a factory service manual off of Ebay. They usually have all the necessary diagrams.

Can't answer your last question. Sorry.

My contribution to trouble shoot "Backfiring coming from the carbs": at idle speed indicates a cracked distributor cap (may be seen visually - night time excellent time to inspect or get a long screw-driver and ground sides of distributor cap to ground (sparks will emit - be careful not to ground yourself); wrong firing order or defective distributor. Backfiring coming from carbs while increasing engine speed indicates a broken valve spring and may result a bent valve stem - take a compression test to indicate which cylinder is misfiring and take it from there. Good luck!

hey dodgevanman I was wondering what rochester was. Is it a company that is now out of business or what. I am only 17 but I love mechanics and try to learn as much as possible. Oh and if it is any help I own an 86 dodge ram with a 360 and it has a Quadrajet on it stock.

Rochester was the main supplier of carburetors for GM. Your Quadrajet was made by Rochester. That doesn't mean you have a GM carburetor, it just means that like Holley and Edelbrock make carburetors so does Rochester. Up until 1985 (I think) Chrysler was using carburetors made by Carter...as in the AFB, AVS, and the Thermoquad. Early on Chrysler corp. used carburetors made by Carter, Holley and Stromberg.

Thanks guys!

I have been so busy working I haven't had time to look at it as of late but I'll be trying this stuff this weekend and I'll let you know how it goes.

I know the distributor is new 2 years ago and is a MSD factory replacement unit as is the coil. Considering I now know the timing is at least 5 degrees out, I think just resetting that will go a long ways to fixing this problem, but I plan to compression test the cylinders anyway. The engine was completely rebuilt by a reputable local shop 2 years ago when the distributor and coil were replaced.

You are running too rich or you don't have a good strong spark and/or set your timing exactly to spec before you troubleshoot any further.

Carb can still be in need of a rebuild as just sitting around can cause them to gum up inside and the gaskets and rubber parts to shrink.
If you want to get it through emissions tests then do the following...
Fill the gas tank and run a can of SeaFoam though the fuel system..you can get at NAPA or CarQuest. www.seafoamsales.com
After the Seafoam and gas have been used up. Replace the fuel filter, air filter, spark plugs, check/replace the cap,rotor,wires.... make sure you have the correct degree thermostat installed, and last of all, change the oil and filter...diluted(by fuel) oil will increase emissions real bad. I usually run a can of motor flush through my engine before the oil change. Make sure your PCV valve and EGR valve are working correctly and the choke is opening all the way after engine warmup.
Do all of this a day or two before the emissions test and make sure the truck is fully warmed up right before testing. You should pass easily.

the other day my 72 power wagon w/360 4bbl. from an 85 started missing after checking /changing plugs pick up coil ,cap etc, the problem was a push rod had pushed up thru the rocker arm on the intake valve, after replacing push rod & rocker arm the engine had a constant backfire now because the lobe was wore off the cam on the exhaust side.

I set my 86 318 at 8 degrees BTDC and it runs great. Which MSD are you running and is it installed correctly? Is it and aftermarket coil or stock and is the distributor a factory Dodge piece or is it also aftermarket? What does the inside of the cap look like? Are the terminals corroded?