1) I got a 8RT oil dipstick in a 8BA motor. Are they compatable?
2) I get a back fire every once in a while when, at 45 to 50 mp, as I begin to decelerate and usually going down a grade. Not a big deal but,...What can cause this type of backfire.
3) I got a real cootiebob of an exhaust rig on this panel truck. Crossover pipe is crap. It's an all around, " get it thru DMV " rig. I get a fair amount of exhaust smell in the cab as well, but I also have not put on the door rubber yet . Joblot has a decent priced package but I think I ought to replace manafold gaskets while I am at it. Actually, I may just gather up the parts and take it to a muffler shop and let then install it but,.. I would like to go in informed. Any common problems to look for when replacing exhaust manifold gaskets and pipes?

Thanks
John

 

The 8RT is the truck version and the oil pan is different than the 8BA which is the car version. The truck is a rear sump and the dipstick is just to the rear of the middle exhaust port. The car is a mid sump and the dipstick is just forward of the middle exhaust port. So not sure which pan you have as that will depend on which dipstick you need.
Sounds like the butterfly in the carb is closing too fast causing air starvation and backfire. might try turning up the idle speed to open the butterfly a tad more.

 

Not entirely true about the car pans vs. truck; I run a rear sump car pan (Merc). Put in 5 qts and see if it reads Full. A lot of parts that aren't different between models are stamped 8BA (or 0BA, 1BA, etc). But the parts catalog says you should have a 8RT-6750-B with a truck pan. I'll have to check mine, I have no idea if my dipstick is car or truck, but it reads right.

Exhaust manifold gaskets at the block are a total b**** to put on!!! Pay someone to do it, just make sure they don't strip out any holes.

If there are leaks in the exhaust system, they can draw in air on coasting and cause a backfire if you are running a bit rich.

 

After doing the truck restoration thing, I had to laugh at Ross' suggestion for the oil dip stick....becuase I did the same thing with my 390. I bought a "stock" chrome dipstick that must have been marked for a VW or something. So when I changed the oil the next time I filled it up one quart short and marked the oil level with a scribe, then filled it up and marked it again. Works fine.

I'm wondering if on the flathead you might be sucking in a little cool air in that exhaust leak to help with the backfire - just guessing.

Also, you really don't want to fool with fumes in the cab. Smelling the fumes is a good thing because it forces you to roll down the window for fresh air. But you really want to worry about carbon monoxide. It'll kill you real fast and it's odorless. If you feel sleepy, look at your fingernails - they will turn bluish with CO poisoning.

So maybe it's time to get the old panel up to the "muffler king," get the crossover and exhaust pipes done, along with the manifold gaskets.

 

I got the truck pan and the dip is just rear of the middle port.It read OK last oil change.
Would shooting the manifold bolts a couple times, for a couple days, with a PB Blaster type juice, before taking it to a muffler shop, help to prevent them from stripping out any holes?
Thanks
John

 

Probably not, I was referring to putting them back in. The deal is, there are 6 bolts to put thru 3 gaskets. Nothing on earth will hold the gaskets in position on the block or the manifold while you jockey it to get it all lined up. If I had to do the job over, I would put temporary studs on the block and put the gaskets on them, put the manifold onto the studs, then one by one replace the studs with the real bolts. (Remember, the front ones are bigger than the rear!). It will still be no fun.
BTW, the port gaskets are exactly the same as the manifold outlet flange gaskets, so you need a total of 8.

Going back in with bolts, however you do it, be sure to put antiseize on the bolts.

This is thankfully a job that rarely needs doing!

 

Nice tip Ross. I heard the "stud" idea before for lining up the oil pan/ gasket. Sound like a third hand would come in handy.

 

Studs are available at napa and use brass nuts instead of steel. I doubt PB blaster will work to loosen any of the bolts but the ones going into the engine will probably come out ok it is the two on the flange that most likely will break off. Using heat on the nuts or cutting the nuts off may save the studs.

 

oss , I thought I was the only one that still beleived in Anti - seeze compound . I swear by that product too ! It has saved me so many broken offbrake bleeder screws and small pieces on trucks , I can;t even remember now as im nearly 60 . Ed Shaver

 

I had some off time today so I took a good look at the manifolds. The passanger side has a crack just front of the middle port that looks to go all the way around the manofold. Also looks like the PO had some issues with the flange studs on both sides. There looks like a bolt in place of a stud in one side and a doubled up nut on a stud on the other side .The manifold flange gaskets are really toasted too. Looks like another one to add to the list. I guess I need to get some parts together.