Lucas CAV rotary injection pump math

fitterski · Sep 25, 2017

Did some research about part #'s, I'm thinking a Head & Rotor Assembly as a possible expense (on spec just like the TxPump parts were). I've asked Sparex but sofat they haven't matched theengine No. with anything they have. Also managed to lose most of the test-run videos but recovered the essentials from backups.

http://trixtar.org/3/tinkerings/12valve208hp

I've got so much time into this pump I might just make a utube video

thepumpguysc · Sep 26, 2017

Your wasting your time & money replacing the H&R..
The H&R is deemed replaceable if, A> its worn beyond meeting starting specifications on the test stand.. does the engine start?? YES? H&R is good..
& B> if the H&R is seized.. we know its not seized because you can rotate it in your hand AND the engine starts..
The P# for the H&R is Delphi P#> 7180-727L
It costs $574.32 list price from the factory.. MY PRICE is OVER 300.00 & I'm a dealer!!! So if your paying 150.00 from Sparex.. it aint new.. maybe aftermarket new, but not FACTORY NEW..
There is a "note" when I looked the pump up.. it states, Cummins speced the engine at.. a 4 HOUR ENGINE LIFE at full load.!!!

fitterski · Sep 26, 2017

thepumpguysc said:
Your wasting your time & money replacing the H&R..
The H&R is deemed replaceable if, A> its worn beyond meeting starting specifications on the test stand.. does the engine start?? YES? H&R is good..
& B> if the H&R is seized.. we know its not seized because you can rotate it in your hand AND the engine starts..
The P# for the H&R is Delphi P#> 7180-727L
It costs $574.32 list price from the factory.. MY PRICE is OVER 300.00 & I'm a dealer!!! So if your paying 150.00 from Sparex.. it aint new.. maybe aftermarket new, but not FACTORY NEW..
There is a "note" when I looked the pump up.. it states, Cummins speced the engine at.. a 4 HOUR ENGINE LIFE at full load.!!!

The $150 price was for some Lucas-CAV pump Head & Rotor Assy's on e-bay, Sparex has not quoted yet. I did see a 3063F523 elsewhere on the net for less than $800 but no way to take it any further (probably a typo).

I was "thinking" of replacing the Head & Rotor seeing that I found no other significant problems in the injector to explain the unacceptably stumbling test runs. Also I figured that until I discover otherwise, the pistons & rollers might be part of that sub-assembly so since I'm not equipped to measure the total pump roller travel as shown in the manual, replacing the whole sub-unit seemed like a path to explore. Remember, I have an unacceptable running signature while the setup is stock Cummins for which I have NO explanation but for which I have to find FIX. Mechanics swap sub-units out all the time, they pull one that's suspect & charge the customer, if it doesn't fix they pull another and so on. The only other area I can think of looking into is pistons and rollers especially if those are not part of a Head & Rotor sub. I've measured them several times and got very precisely 5.96mm on ALL rollers and 6.97mm on ALL pistons so there again are again signs of a hardly used pump consistent with just 1290 hours.

You could be right that I'm barking up the wrong tree, you've said that before and it too is as valuable as all the other info you have given, I appreciate it. I am a little surprised about the 4 hours not being anywhere on the net

Reviewing everything at my disposal and short of deciding to rebuild the engine right away I'm going to put the pump together and abandon the stock timing to only 5 degrees of static advance (using gear letter G) in favor of the common 10 degrees of static advance (using gear letter D). I've already improved on its original running condition A LOT. Then I'll make test runs with that setup only and get a lot more opinion. The current engine on my snow blower is a Deutz 4-holer and it runs very smoothly up to around 1900 rpm but then begins to 'sound weird' up to 2500 rpm to a person more used to the sound of gas engines. This high-end sound is what seems much more pronounced with the Cummins added the stumbling. The short of the long is that I'll leave it at that if all the opinion I get says "it's normal, don't sweat it". In all other cases I'm going to strip the engine and really go for a blue-printing exercise, maybe reverting the setup to a more common automotive or tractor configuration including a VE pump, appropriate injectors and possibly cam (I would NOT want to build an engine good for only 4 hours, and as I said the bottom end seems just like new).

thepumpguysc · Sep 27, 2017

The rollers & shoes come seperatly from the head.. as do the check plates..
all you get is a head & rotor & pumping plungers.. & its still up to you to set the fuel output..

fitterski · Sep 27, 2017

thepumpguysc said:
The rollers & shoes come seperatly from the head.. as do the check plates..
all you get is a head & rotor & pumping plungers.. & its still up to you to set the fuel output..

The new (special order) pump would cost me $4,356.19 cdn + $650 tax, total $5,006, this is insane! Even if the Head & Rotor Assy did include the pump/piston section I wouldn't pay the prices you mentioned earlier. Fortunately all pistons measured identical as did all rollers so I think they're really like new.

So far the interventions that did make a difference were the valve lash and the bottom spring in the inlet fitting. I really SHOULD have done the other test run also at that last stage with 10 degres of advance (gear letter D) ..but I was too tired.

Right now I'm waiting for a seal kit and putting it back together (3-4 days). The next run will decide the next steps. My son says "Dad, there's NOTHING wrong with either the engine or the pump", but to that I counter with 'then do expalin why it's bogging/lugging like a dying donkey?'

fitterski · Oct 2, 2017

Stripped & built the pump, nothing major found although the lack of familiarity, documentation and test-bench resources may well have hidden some! The youtube is uploading and should come up later tonight with a search for

'Partial strip & build of lucas CAV injection pump'

Bottom line is that compared to the as-received state the engine runs better although still very FAR from acceptable with stock timing. With another 5 degrees of advance (using the pump gear-letter D) the engine runs almost normal. I'm happy with this result for the time being. The last 2 test runs (top of page) are @

http://trixtar.org/3/tinkerings/12valve208hp/index.html

One interesting detail is that during the second run the engine starved for fuel. The stuttering and missing during this time were VERY similar to the symptoms plaguing the engine all this time.

dodge man · Oct 7, 2017

I don’t know if you covered this, but are the injectors o.k.?

fitterski · Oct 7, 2017

dodge man said:
I don’t know if you covered this, but are the injectors o.k.?

First thing i did was have them professionally checked for misting and pattern, they were just leaking like sick cows so I had them rebuilt. Result: nothing observable. What I do not have is the setup to test pump high pressure output. What if it's low or peaks only briefly? Could that be a possibility, could it be at 1300 hours? Like I said before, my diesel knowhow is one big zero

What i have found about the 4-hour life is that these engines were required do demonstrate continuous full power until fuel-tank exhaustion at 4 hours.