Magnum motor with Mechanical fuel pump ?

-
wes beem

wes beem

Well-Known Member
Joined
Apr 16, 2017
Messages
952
Reaction score
582
Location
ohio
Howdy, planning on hitting up my local junkyard for a 318 or 360 magnum motor to put in my 71 duster. I want to run mechanical fuel pump setup with a 4 bbl carb ext.

My question is, what all do i need to make that happen? I know i need a LA style timing cover, but is that all?
 
A camshaft with an eccentric to drive the fuel pump.
Might be easier to run an electric pump.
 
its deff easier, but those damn electric pumps are loud as hell and always seem to burn up. I went through two of them in a year on my 70 dart and i went through 6 of them in a year on my 67 impala.
 
Hughes Engines has an adapter to bolt to the front of the camshaft to run the eccentric.
 
So in theory all i need is that Hughest Snout extender and a LA timing cover and that's it? Easy!
 
wes beem said:
Howdy, planning on hitting up my local junkyard for a 318 or 360 magnum motor to put in my 71 duster. I want to run mechanical fuel pump setup with a 4 bbl carb ext.

My question is, what all do i need to make that happen? I know i need a LA style timing cover, but is that all?
Click to expand...

If you want to run the factory 5.9 roller cam or another magnum cam, Hughes engines sells a bolt on cam eccentric snout. For certain you will have to use the old LA style timing cover, and I think the LA style accessories and pullies as well. Not 100% on that last part.
 
The stock magnum water pump(serpentine) turns the opposite of the LA with pulleys.
Not really an easy change.
I have used the same 12 volt pump for 5 years with no issues.
Good luck either way you go.
 
Good plan. Magnums are good engines. Basically, you want the entire front off of your LA. Timing cover, water pump, pulleys, alternator, power steering pump. All my pulleys lined right up.

Magnums are externally balanced, so you'll need a weighted harmonic balancer and you'll need the Magnum flywheel. Oh, and a neutral balanced torque converter.

I've been running an electric fuel pump for years but over the winter, I'm going mechanical. I bought an eccentric from a FABO member, just need to buy the Hughes adapter and a new mechanical pump.
 
Thanks guys, i did a magnum swap in a 70 dart 5 years ago, then spent 5 years douching up and running LS Swapchevys...so i forgot most of this stuff.

We ran electric pumps last time tho so the mechanical thing is totally new to me. Sounds like ill be running the exact same setup i had before except the hughes extension and eccentric.
 
Has anyone here actually used the Hughes extender? I had to get my hydraulic roller for my 273 ground on a Magnum blank because that was all that Bullet had at the time. I'm having a helluva time finding a woodruff key to fit the cam keyway and also work with the extender. I called Hughes today and talked to Dave, and he said they had never had the first complaint about the extender, so maybe I'm missing something. I saw a You Tube video where one failed, that I wondered if it belonged to @gdonovan ?
 
JDMopar said:
Has anyone here actually used the Hughes extender? I had to get my hydraulic roller for my 273 ground on a Magnum blank because that was all that Bullet had at the time. I'm having a helluva time finding a woodruff key to fit the cam keyway and also work with the extender. I called Hughes today and talked to Dave, and he said they had never had the first complaint about the extender, so maybe I'm missing something. I saw a You Tube video where one failed, that I wondered if it belonged to @gdonovan ?
Click to expand...

I know Gary had a failure. I've been running one for several years, even swapped it to a different cam last winter. No issues for me (so far). No idea where the woodruff key came from, do they ship one in the kit and that's the one that won't work?

Only issue I have had was that the pump arm would rub on the links of the timing chain. I believe it is an issue because a roller cam can move forward in the block a little while a FT cam is constantly pushed back into the block. I tweaked the arm where it rubbed and it stopped being an issue. Wasn't much of a rub.
 
I just bought a LA roller cam for my swap, and a harmonic balancer with no pulleys for a mag.
Used everything else LA, timing cover, fuel pump eccentric, water pump, oil pan, pulleys, and all the LA accessories, like alternator, and ps pump.

PcLfWI.jpg
 
I have one of these adapters on my Magnum 360.
My brother has had one in use for ten years or more now on his Magnum 360 with a lot of street miles and run time and no failures.

The key is basically only for initial alignment of the cam gear. Stock keys and adapter keys usually fail because somebody did not tighten the bolt properly or used a lower quality replacement bolt.

The fit of the stock style key into aftermarket camshafts is occasionally way too tight also. Consider the key the cheapest part to modify. File it until it can be tapped into the camshaft without excessive force, then file the other side to just snuggly fit the camshaft sprocket itself.

Once everything fits properly, use a drop of red loctite on the threads of the camshaft during final installation.
 
wes beem said:
its deff easier, but those damn electric pumps are loud as hell and always seem to burn up. I went through two of them in a year on my 70 dart and i went through 6 of them in a year on my 67 impala.
Click to expand...
Might be a case of they dont make them like they used to. Were they re buildable?
Was it the gas? I was thinking the fuel for some, a friend kept having needle seat failures in his holley and went to fi tech. Lives near the mountains.
I have a holley red pump I used for 4 yrs straight 'daily driver' , it did have a little buzz sound being it was mounted to the frame via thin rubber gasket they give you.. but I bet a well thought bracket with rubber isolator grommets would cure that.
 
DionR said:
I know Gary had a failure. I've been running one for several years, even swapped it to a different cam last winter. No issues for me (so far). No idea where the woodruff key came from, do they ship one in the kit and that's the one that won't work?

Only issue I have had was that the pump arm would rub on the links of the timing chain. I believe it is an issue because a roller cam can move forward in the block a little while a FT cam is constantly pushed back into the block. I tweaked the arm where it rubbed and it stopped being an issue. Wasn't much of a rub.
Click to expand...

I've had this scenario with a 340. I was thinking the chain set was the culprit. JP performance billet. I put a tensioner on it and that stopped. I noticed it had some slop with little mileage..chain slack was my final conclusion...but could have been the arm on the pump too.
 
MOPAROFFICIAL said:
I've had this scenario with a 340. I was thinking the chain set was the culprit. JP performance billet. I put a tensioner on it and that stopped. I noticed it had some slop with little mileage..chain slack was my final conclusion...but could have been the arm on the pump too.
Click to expand...

Mine had some witness marks and went away after I banged on it with a hammer. The cam moving around is purely my speculation though. For all I know, the slop in the bolt holes of the pump were enough to make it clear. That pump arm was hard and I'm not certain I bent it at all. The noise stopped so I didn't care. :D
 
I didn't get a new woodruff key with the cam. I bought a hardware kit for the bolts and oil dripper for the chain, that also had 2 keys in it. The one for an LA cam is a mile too long and the other one a half mile. The only woodruff keys I have found are also too long and maybe a little too tall to get the cam gear on. I can fix that easy enough, but the fit of the small, stepped key that came with the extender is what is worrying me. When you assemble it as shown in the diagram that came with it, the key doesn't go but halfway into the fuel pump eccentric. I bought some bar stock of the correct size to make a new one that goes all the way in, but it may fit better when I get the cam gear on after monkeying with the key for that. Glad to hear that some of you have had a good experience with the extender. It's probably fine and I'm just too nit-picky in my old age. I kind of miss the days when I was young and dumb and would just throw stuff together without checking anything, and it would run like a gut shot cat and last forever....lol.
 
BDF48D61-E885-4CE8-9287-31FB4D05E140.jpeg
C94F9467-C194-4746-BD5F-3CFEE2AB0E6C.jpeg
5F4DC42A-F50A-481C-BC30-A965CFC37113.jpeg


I’m using the Hughes extender. Seems to be working fine for me.

If I had to do it over I’d look for a cheap donor vehicle so I got all the accessories and try to find a fuel pump to put in the tank.
 
Last edited:
JDMopar said:
I didn't get a new woodruff key with the cam. I bought a hardware kit for the bolts and oil dripper for the chain, that also had 2 keys in it. The one for an LA cam is a mile too long and the other one a half mile. The only woodruff keys I have found are also too long and maybe a little too tall to get the cam gear on. I can fix that easy enough, but the fit of the small, stepped key that came with the extender is what is worrying me. When you assemble it as shown in the diagram that came with it, the key doesn't go buy halfway into the fuel pump eccentric. I bought some bar stock of the correct size to make a new one that goes all the way in, but it may fit better when I get the cam gear on after monkeying with the key for that. Glad to hear that some of you have had a good experience with the extender. It's probably fine and I'm just too nit-picky in my old age. I kind of miss the days when I was young and dumb and would just throw stuff together without checking anything, and it would run like a gut shot cat and last forever....lol.
Click to expand...

I remember thinking the woodruff key I had when I put it back together this last time seemed really short. But I figured it lasted several years with the same setup so I put it back together the way the instructions said. Hopefully it lasts for a couple years this time, too.
 
You must log in or register to reply here.
-

Back
Top