backfire on 440 with a holley, and...

[puddlejumper]

hello everyone, this is my first question and I hope you guys can help.

We just got a 77 Clipper, and love fixing it up...but it backfires really bad from a stop.  I have done the air cleaner, fuel filter, cleaned the carb, checked all electrical...still does it.  I am trying to avoid a rebuild, and otherwise it runs great. 

I have lots of questions, but we will deal with them one at a time...

[clockwork]

As Rodney learned with Katie, it's all about timing my friend!

[puddlejumper]

thanks, I suspected ignition, but a mechanic I know says 'power valve' in the carb?  I did some more research and think its actually a thermo quad carb, there are pics in my manual.

Not wanting to take the carb apart.  I may try some more simple tricks and check vacuum lines first.

Besides timing, any more tips on the thermo quad?

[clockwork]

http://www.rvmechanic.com/current_category.2178/Forum.85476/forum_thread_full.html

The (above) link may help. 

http://www.nothingtodo.org/manual/default.htm

The 2nd links to an user that took the time  to scan his dodge van owner's manual for those of us w/o one.

I also have some docs on the converter ( specifically, upgrading) and a few other systems.

Let me know if you would like any of them.

dave   

[puddlejumper]

yes, thank you!  That first link was exactly the kind of quick fix I was looking for.  I have downloaded the manual, and got two off of ebay for the van mechanicals. 

I have a full can of carb cleaner and will attack the choke linkage tomorrow, and let you know what I find.

Anything that will work without pulling or rebuilding is always first.

One thing though, I see a lot of model numbers for the sportsman front end on our clippers...is it a b300, an mb300, or something else?

And I see from searching that the electrical manual is nonexistent, as is the actual clipper manual...I don't suppose those are online anywhere?

Thanks again

PJ

[tomfridley]

puddlejumper- a b300 is a standard dodge van and an mb300 is a class c motorhome [like your clipper] on a dodge van chassis. the 300 indicates it is a one ton capacity vehicle.
it is a great idea to check all the vacuum lines for cracking or leaks first for your backfire problem. it does not cost a thing to do this, and it is very likely that the vacuum lines can become split after 30 years of neglect in a very hot operating environment under the doghouse engine cover.

[puddlejumper]

absolutely!  Neglect is the word for this clipper... you should have seen the differential grease...yuk!

Were on a mission to get this thing correct...

Mac sold us Irv, in case you were wondering...we put a tranny in it and drove it to Arizona.  And we did stuff like a new roof hatch, roof sealant, interior paint, generator, inverter, solar, new stripes, and tons of other improvements.

[JerryT]

Check the plug wires!
JerryT

[puddlejumper]

ok...finally figured it out, and thanks very very much!

EGF valve gasket, carb assembly, manifold gasket, timing, vacuum... all perfectly fine!  It was the plug wires!!  While putting in new autolites I noticed the inside of one connector was melted and black, then replaced the whole set and it runs like a dream!

Ready for an ac unit and then we hit the road!

Thanks again!!

[JerryT]

PJ, your welcome!
In the day I ran 440's for street racing (sounds wrong now) but we did it out on country roads and had a lot of fun. I ran 1 4bbl, 2 4bbl's and a 6bbl setup and always had trouble keeping the plug wires on and un-burnt. To avoid the problems of the past I have done three things, #1 I use a top quality wire set, Magnecor 8.5mm, these are the choice of racers and heavy duty application users and they stay on!!! IMHO it is worth your time and money to track down a set, 1-248-471-9505 is the factorys #, lifetime guarentee, they will sell you one wire if you wreck one, all custom sets so they fit correctly, I needed a longer coil wire and no problem, just sent the new one back and they sent a longer one. #2 I use DEI's Protect-A-Boot, the Magnecor's will resist the hot manifold but I like to keep them off it, also I feel an exhaust leak could cut into the silcone so why chance it (see pics) #3 I flood the dog house with cooler outside air (see earlier post) with a pair of 3" dryer ducts that you can see in the pics. The extra time and money spent in the driveway before the trip has always paid me back on the road.
JerryT