internal backfire?

[nonstuck]

O.K., my doggy 'ol 84 Bronc with the 2.8 has been tuned recently
(plugs, wires, coil, cap and rotor) by me. Was timed mid summer.
Also did the sea foam treatment, vac line, carb, and in the tank.
After driving road miles @ 55 m.p.h. and I shut it off there sounds
like an internal muffled backfire, a muffled "pop".... got me wondering
what the ? Any thoughts ?
Thanks guys.
nonstuck

 

[Capt Jay]

Let all that stuff run through it before you make any assumptions. Seafoam won't make your 2.8 less doggy, it's just the nature of the beast. If it continues, I'd check the timing again. My old 2.8 ran great for years. Remember that there aren't self adjusting lifters in those need to be addressed every now and again. You shouldn't baby the engine, it will get used to it and then start to expect it. (j/k)

 

[nonstuck]

Thanks Cap.
No, I didn't expect the sea-foam to work a miracle, I know the
2.8 is inherently doggy, and my 31's don't help that factor.
Probably should have checked the valve adjustment when
I did the gaskets last year...
Thanks for responding so quick.
nonstuck

 

[kimcrwbr1]

duraspark it if you plan on running it for a while and you dont have to pass emissions get rid of the emissions put in valve guide seals and put a metering block on the carb will bring it to life if it has good compression.

 

[nonstuck]

Good advice Kim. Have been wanting to duraspark it, guess
it'll have to wait 'til spring tho. Damn snow continues to fall
here........

 

[kimcrwbr1]

Yea I did mine but was having vacuum issues so got it apart now waiting for gaskets and am gonna put the 180 thermostat on the water going out too instead of going in the bottom. pretty sure when I put the engine in I did not torque the intake manifold correctly. I always had to run the idle air screws real rich. just the duraspark brought it to life the tech library has all the info. The metering block on the carb works pretty good too and all but two of the valve guide seals were non existant plugs burn real clean. Did you check your timing 10 DBTDC with the spout pulled and should advance well past 30 at high speed.

 

[nonstuck]

no, haven't checked it, but will, am anxious to get it sparked
and see what that does.

 

[bonedoc]

Hey Kim, the metering block on your carb...can you elaborate? I have almost all my parts, still waiting on the distributor. Went with the Holley 350CFM 2 barrel

 

[adsm08]

Any why does durasparking effect emissions? I'd think a better spark system would improve emissions.

 

[kimcrwbr1]

the holly dont need a block bone just hook your advance up to the ported vacuum if your carb has one. the port on the carb that has no vacuum at an idle

 

[kimcrwbr1]

most any older engine the emissions dont work very good anyway alot of guys keep the air pump and cat after they duraspark yea the spark is alot better but the advance gives you the performance. With the air pump and the cat you get better backpressure to keep the valves cooler. These engines last a long time stock depending on the engine do it a favor and put in valve guide seals im sure my cat is not working very good if at all and will put a new one in as soon as I finish the engine