318 knock under hard acceleration

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

Mattman389

Junior Member
Joined
Apr 30, 2016
Posts
5
Reaction score
0
Ram Year
1980
Engine
318
Hello all I just recently got a 1980 dodge pick up I know it's not technically a ram but I figured you guys could help me out anyway. So here's what's going on its got a "built" 318 in it with the 4 speed OD here's the details I know. The guy I got it from said it has a cam and is bored 30 over its got a quadrajet 4 barrel carb and a 340/360 intake I don't know what the heads are yet I'm going to pull the valve covers and check asap but haven't yet.
So here's the problem it runs and drives good has good power no smoke or anything like that but under hard load knocks pretty loud I can't tell if it's engine or drive train sounds like it's coming more from the floor than the engine. But it sounds exactly like a rod knock just only does it under heavy load. So what do you guys think it could be? something in the drive train ( trans or maybe driveshaft related) or should I start with the engine and hope it's not a rod
 
OP
OP
M

Mattman389

Junior Member
Joined
Apr 30, 2016
Posts
5
Reaction score
0
Ram Year
1980
Engine
318
I've only had the truck 5 days but I filled it up with 93 the day I got it. I don't have a timing light yet to check timing. Is their a way to check it with out that?
 

crazzywolfie

Senior Member
Joined
Apr 6, 2013
Posts
16,422
Reaction score
3,183
Location
under the truck
Ram Year
81 93
Engine
5.2
There is no way to know exact timing without a timing light but you can try playing with the timing to see if it makes a difference.
 
OP
OP
M

Mattman389

Junior Member
Joined
Apr 30, 2016
Posts
5
Reaction score
0
Ram Year
1980
Engine
318
Ill try that tonight and let you know how it goes thanks
 
OP
OP
M

Mattman389

Junior Member
Joined
Apr 30, 2016
Posts
5
Reaction score
0
Ram Year
1980
Engine
318
So I've finally had some time to look at the old girl and found the the vacuum line for the distributor advance is unhooked and blocked off. So now I'm just trying to figure out where it is supposed to be hooked up. Hopefully that will solve my issue does anyone know off hand were it should go. It's a Quadrajet 4 barrel. Can I just stick it on one of the blocked off ports on the carb or is their one in particular it needs to be on?
 

crazzywolfie

Senior Member
Joined
Apr 6, 2013
Posts
16,422
Reaction score
3,183
Location
under the truck
Ram Year
81 93
Engine
5.2
i am pretty sure the vacuum advance port is one of the small ones on the front of the carb. there is a special port that it needs to be plugged into
 

Gaboy02

Junior Member
Joined
Jun 11, 2015
Posts
16
Reaction score
2
Ram Year
2002
Engine
5.9l
Could the knocking be the driveshaft hitting the floor pan or something else? Under heavy load the frame could be twisting just a little but enough to cause the drive shaft to pop something
 

Rustycowl69

Senior Member
Joined
Oct 24, 2015
Posts
857
Reaction score
171
Ram Year
2001 ram 3500
Engine
V10
Are you sure it's a Rochester QuadraJet? I believe, factory for that Era were Carter ThermoQuads. If it is a Carter TQ, you're in luck, they are awesome carbs. But it is unusual for a 4bbl 318. The vacuum advance hose plugs into the front of a TQ, at the ported vacuum port, if I remember correctly it is on the passenger side. The vacuum advance can be adjusted with an Allen wrench reaching in thru the nipple on the vacuum advance cannister.
 
OP
OP
M

Mattman389

Junior Member
Joined
Apr 30, 2016
Posts
5
Reaction score
0
Ram Year
1980
Engine
318
Ya I'm sure it's a quadrajet I ran the part number on it and the intake manifold. So I looked at a few vacuum diagrams and it looked like most of the quadrajet carbs go into the side. It was the only one the hose would reach. So I stuck it on their and took it for a spin. It ran better, than I put a fresh set of plugs in it that came with the truck and it got a little better again. Than I just decided to give it a good service and see what happens. Changed the oil the air filter fuel filter distributer cap and botton didn't change the wires because the parts store didn't have any. After all that it has almost completely gone away. And I suspect that the plug wires and some better 98 octane fuel will take care of the little ping that is left. It has a lot more power now and starts a little easier
 

Jimmy68

Senior Member
Joined
Aug 30, 2015
Posts
1,419
Reaction score
645
Location
Lethbridge Alberta Canada
Ram Year
2001
Engine
5.2L Magnum
IMO, don't swap out the great Q-jet for a POS Thermobog.
Once you get your advance working hopefully it's all good. Check to see if the advance is not seized in the distributor.
 

Rustycowl69

Senior Member
Joined
Oct 24, 2015
Posts
857
Reaction score
171
Ram Year
2001 ram 3500
Engine
V10
IMO, don't swap out the great Q-jet for a POS Thermobog.
Once you get your advance working hopefully it's all good. Check to see if the advance is not seized in the distributor.

No offense, cause I don't know you from Adam, but I have rebuilt at least a 100 TQ's and I think they are great carbs. The QJ's are OK. but no where near as elegant, and sophisticated as the TQ. I am guessing, you had one that somebody had messed up. The TQ has like 4 external links. I once bought one at a swap meet, where someone had every single link in the wrong spot and had bent the rat-**** out of every one trying to make them fit. It's no wonder they were selling it.
 

Jimmy68

Senior Member
Joined
Aug 30, 2015
Posts
1,419
Reaction score
645
Location
Lethbridge Alberta Canada
Ram Year
2001
Engine
5.2L Magnum
No offense, cause I don't know you from Adam, but I have rebuilt at least a 100 TQ's and I think they are great carbs. The QJ's are OK. but no where near as elegant, and sophisticated as the TQ. I am guessing, you had one that somebody had messed up. The TQ has like 4 external links. I once bought one at a swap meet, where someone had every single link in the wrong spot and had bent the rat-**** out of every one trying to make them fit. It's no wonder they were selling it.

My dad loves those TQ's too.
I had one. On my mud truck/ bush buggy. Finicky sumbitch.

The Q-jet is unreal easy to rebuild and set up and bouncing hard through a muddy trail it never gave up.

Big draw is NOTHING sounds as good to me as those big vacuum secondaries wide open.
 

Attachments

  • 24050240001_large.jpg
    24050240001_large.jpg
    44 KB · Views: 13
Top