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85 E9 AMBAC Pump question


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Sorry for a stupid question,but here goes-Do any of the AMBAC pumps on the V-8s have hand primers on them? If not what is the large (7/8?)bolt/plug in the rear center of the pump that sticks almost straight up? It is in the housing which both filter hoses connect to. Thanks for any help

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I had one I put on my 84, I have seem them I just don't know if they were original. I'm actually planning on putting one on my 85 I just haven't got there yet.

"Any Society that would give up a little LIBERTY to gain a little SECURITY will Deserve Neither and LOSE BOTH" -Benjamin Franklin

"If your gonna be STUPID, you gotta be TOUGH"

"You cant always get what you want, but if you try sometimes you get what you need"

:SMOKIE-LFT: My spare E9 in the archives is an 84 with AMBAC pump and it had a hand primer on it, but the 82 in my dads with AMBAC pump does not and my 92 Robert Bosch inline pump has no primer. It was a bitch getting that thing primed by myself after it was stored for 5 years.

Thanks for the quick replies.Bad Dog- does what I'm describing sound like what you have on your 84?I'm trying to get this pup goin after a few years. Seems to be a solo mission...all my helpers disappeared when it didnt fire up in 5 minutes(typical) :-/ . I hate using any more ether than I have to. You wouldnt happen to have a picture of the top of that pump would ya? Thanx much- Geo

Edited by GEOD998

perhaps I should ask,on the AMBAC pumps with the hand primer,what did you have to do to "release" the plunger for hand use? To describe my setup again, at the rear of the center "galley" of the injector pump, I have what I think would have to be a transfer pump.Lines from both the primary and secondary fuel filter go in horizonally: one on each side, in the top of that, there is a vertical 7/8 bolt/plunger (maybe) tilted toward the front of the truck, a 1/4 bolt seems to pass thru the large "bolt" horizonally (perhaps a keeper?). Bottom line-I dont want to mess with anything on that pump if I'm not sure what it is. Thanks again for any insight into this. BTW what do you mean by "in the archives?"

I think the plunger handle just tighten and loosens by twisting and locks in when all the way down mine is too tight to twist by hand and I didn't try pliers on it to tonight. My archives is just what I refer to my stash of parts out in the shop.

Yep turn it counter clockwise to loosen and pump, press in and turn clockwise to lock. You should be able to get that primer pump at and diesel pump shop.

"Any Society that would give up a little LIBERTY to gain a little SECURITY will Deserve Neither and LOSE BOTH" -Benjamin Franklin

"If your gonna be STUPID, you gotta be TOUGH"

"You cant always get what you want, but if you try sometimes you get what you need"

And after you get it running, cut the lock wire and remove the 6 bolts on the rectangular housing at the back of the pump and remove the cover. Inside right up top is a threaded rod with two nuts. Loosen the nut towards the front of the engine and then tighten the other nut to move the fuel rack stop forward. Then look at the lever behind the stop, half way down there is an Allen screw used as a fulcrum, loosen that screw a few rounds. There now you have just turned up your full load rack stop and your mid range fuel delivery. Get ready for the smoke! Oh and remove the puff limiter, its not really doing anything and its gonna try to stop that fuel rack from moving to our new adjustment till you have boost.

"Any Society that would give up a little LIBERTY to gain a little SECURITY will Deserve Neither and LOSE BOTH" -Benjamin Franklin

"If your gonna be STUPID, you gotta be TOUGH"

"You cant always get what you want, but if you try sometimes you get what you need"

Looks like this......

post-5240-0-03487900-1365562219_thumb.jp

"Any Society that would give up a little LIBERTY to gain a little SECURITY will Deserve Neither and LOSE BOTH" -Benjamin Franklin

"If your gonna be STUPID, you gotta be TOUGH"

"You cant always get what you want, but if you try sometimes you get what you need"

BAD DOG-it seems my truck has everything in the pic except the plunger. . You've been a tremendous help. 84 superdog- I'm wondering if a 6 cyl mack plunger would work? I,d just be happy if I get it running...then maybe I'll get fancy-lol. If you have a primer on that,could you zoom out on that pic a little bit ? thanks a million

Yep thats it, make sure you use a new o-ring if it leaks you'll have to use it.

"Any Society that would give up a little LIBERTY to gain a little SECURITY will Deserve Neither and LOSE BOTH" -Benjamin Franklin

"If your gonna be STUPID, you gotta be TOUGH"

"You cant always get what you want, but if you try sometimes you get what you need"

anyone have any recommendations for a diesel pump shop? particularly one that would know what I'm talking about (because I think we've already determined that I surely dont :blush: ). I kinda doubt that there's one within driving distance to me, so if I gotta pay for shipping anyway ,I'd prefer to go with someone that doesnt get hostile when I ask for a part that isnt original to the truck/pump-you know, someone who really knows their stuff outside of the catalog. It's been a few years since I did any hardcore "re-engineering" ,but I used to get really tired of sayin "whatta ya mean I can't do that!?!" :huh:

Antrim diesel in pa they know ambac pumps well, they're on the internet. I dont have a primer on this E9 I'm still spending money on other things and the pump may change so I'm waiting for right now.

"Any Society that would give up a little LIBERTY to gain a little SECURITY will Deserve Neither and LOSE BOTH" -Benjamin Franklin

"If your gonna be STUPID, you gotta be TOUGH"

"You cant always get what you want, but if you try sometimes you get what you need"

I think the plunger handle just tighten and loosens by twisting and locks in when all the way down mine is too tight to twist by hand and I didn't try pliers on it to tonight. My archives is just what I refer to my stash of parts out in the shop.

On mine it doesn't seem to lock by twisting, there is a U shape piece that swivels up over the top of the plunger, the U piece has a threaded bit that tightens onto the plunger to hold it in.

You can see the U piece in pics 1 and 3, it looks like the threaded bit is missing.

Let me know if you need a pic, but I won't see the truck in daylight for a few days...

Hopefully you get what I am meaning.

  • 6 years later...
On 2/20/2020 at 8:08 AM, Random said:

Hello how do you time these pumps?

There are two different ways, high pressure & low pressure. There is a procedure in the Mack Overhaul Manual for a drip (low pressure) test on the AMBAC pump. This is in the old 865 V8 manual. Basically remove #1 cyl. injector line, take out fuel delivery valve & spring from holder, reinstall holder, fab. an old fuel line into a small glass of water. Block off fuel inlet and & return on the pump. There should be a 1/8" plug into the fuel galley to plumb an air line into, regulate air to no more than 15psi. Put throttle lever to full. Bar engine over and when air bubbles in the glass of water stop this indicated port closure. Look at your crankshaft timing mark, it should be within 1 degree of what the tag says on your valve cover. if not take loose timing gear on pump and adjust to get it right, as in the manual. Reassemble pump and inj. line, prime pump and try running engine. This whole procedure should take no more than a few hours doing it the first time.

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