Guys
I have a really strange problem on my hands. It just started. First some backround info. the truck has a 390 and the driver side manifold has a leak. Cant replace the gasket bec the headbolts are rusted in there so I have been driving it like this for years. Only recently, a strange thing has happened. sometime it does it idling or after a hard run through the gears. There is a regular pop through the exhaust pipe. It doesnt do it under power; I only hear it cruising or idling. Its like a pop pop pop pop pop pop pop sound. It only does it on the side that has the manifold leak too. This actually has me worried because it just started and I dont want to have to do major engine repair. If it means anything also, the truck is using some oil as well; id say a quart in 500 miles? I do believe it is coming from the heads but im not sure. The last time I did a compression test, I found one cylinder with 30 lbs. I didnt think the guage was right so I just left it alone since the truck runs and started fine...until this popping! That test by the way, was done when I put all new valve guide seals in (roughly 4 months ago)
Any ideas?
regards
Ben

 

I had a leak on the passenger side it made that annoying poping.
My first truck w/390 had a leak in the donut but it back fired
hard abunch causing a couple burnt valves. I don't think the
pops are bad for it just annoying, but booms are'nt good at
all especially being so close to the valves. I soaked the bolts
twice a day with WD-40 for a whole week which really helps.

 

There are a number of things that could cause what you are describing so lets start really simple. All FE engines have the number 7 and 8 cylinders firing together. This can cause crossfiring if your spark plug wires are old or cheap quality. To remedy this get better wires or get a cap from a later model TFI distributor and the stand that goes underneath it. You will also need the TFI rotor of course. This will put a greater distance between the two wires. The leak itself could be casuing the popping.

 

 

Well
I checked my wires as suggested and I even replaced a point set.....starts fine then the popping starts. I had a few people come up to me and ask what was making that awful sound! So tomorrow, Im gonna rip into it and pop off the heads. I called autozone and they have a set of 360 heads ( 1 year warranty) for 190.00. This seems kind of cheap to me! Has anyone had experience with their heads? Im hoping to find a burnt valve but who knows at this point. A compression test would be prudent but with the amount of noise this thing is making, I think I need to pull it!
regards
Ben

 

[updated:LAST EDITED ON 06-Jan-03 AT 07:05 PM (EST)]Might be a little cheap. I'd make sure they have hard valve seats. I picked up a set of heads (that needed to be cleaned up) for 50 bucks from a local junkyard. They'd have needed new exhaust seats and a good dip to get the rust off though. Right now I'm just holding them in reserve for my truck in case I have a big problem with my desert performance heads.

John

 

I'ld would guess the leaky manifold has caused an over heated problem some how. Thus causing a burnt valve. thusly cuasing the loader popping. It will probably run forever that way. With it progressively getting worse over time.

I you are going to replace the heads with the Auto Zone ones, be sure to check for hardened seats, make sure the valves are seated, and check for any kind of a crack in the heads. I would go as far as using a magnifing glass to look for cracks if it were me.

Good luck on the truck.


Scotty

 

Hey scotty
these heads are supposedly 'reconditioned' units. When I get them, how would I know if they have hardened seats? After all, they will be fully assembled! The good thing about them are, they have a 1 yr warranty.
Now, Ill make ya laugh. I called several auto houses here in jersey looking for reconditioned heads. At least 2 places told me (no lie) that this engine (in their words) is A DINOSAUR and that IF they were lucky to hunt one down, it would cost me $400.00 per head. I mean, I dont know if they thought that I was stupid, but I could go to the local U-pull it and grab a set myself for $75.00 and slap em on. However, my time, then machine work ect, its better to just go on a exchange basis with the locals. Once again it amazes me how ignornat folks here are of these old diamonds! Where I live, I guess if you dont have a Lexxus or BMW, the locals dont wanna be bothered. Seems like 5 yrs is too old to warrant looking up or ordering parts! sorry about the long post and thanks for letting me vent! I think IM gonna go with the autozone units today. FYI---they want FULL payment BEFORE they order them too! thats $400 up front--I never heard of anything like that before but I need the heads so Im kind of in a pinch! I told the guy that I didnt have a $$$$ tree in my backyrd but he just laughed at me! Ill post back when I get them!
regards
Ben

 

Before I'd pay over 800 for a set of reconditioned heads, I'd save up and buy the Edelbrock aluminium units. Jegs has them for $614.99 each.
William in Atlanta

 

His autozone ones are 190 a piece, not 400 a piece. If I'm reading right. And that's a far cry cheaper than the 1200 dollar edelbrock heads.

Personally, I'd rather have the old iron. It doesn't have a tendency to warp.

John