i'm a little ticked off right now about this. i have a 383 that i did a top end rebuild on. heads rebuilt, new cam, lifters, valve springs, timing chain, oil pump. put it all back together and had it running for about 2 weeks. all of a sudden, i developed a fuel delivery problem, no fuel coming out of the pump. so i put on a new fuel pump and it didn't even work for a day. i take off the pump and remove the fuel pump push rod, it won't come out. can't get anything in there to get it out, so i take apart the the front of the motor and get the timing chain cover off. i get the rod out and the end is worn about a 1/4" (just measured with digital caliper 2.910", should be 3.220") and the end of the rod is concaved. so i take the rest of the engine apart and get the cam out. the lobe for the fuel pump push rod definitely looks worn. i get my old cam, the cam i originally replaced, set the 2 next to each other, make sure the timing chain dowels are both facing in the same direction, and measure both. no matter what direction i turn both cams, the measurements on the caliper are the same.

so what would cause the fuel pump push rod to wear like that? does it spin in the bore like the lifters and for some reason it wasn't spinning? is it only suppose to go in the block one way and i had it in backwards? the fuel pump that was in the car, when i first put it back together, was in the car for 10 years with the old cam, and never had a problem. i'm kind of at a loss with this. the lobes on the cam and the bottom of the lifters all look great, no abnormal wear there. the fuel pump is a stock over the counter replacement, no HP pump.

the new cam (.420/.442), lifters, timing chain and valve springs are Edelbrock stuff. this isn't a HP application either. it's in my '70 Newport, 383 2bbl. and i wanna keep it that way too. it seems to be difficult to find stock replacement cam and lifters for a B/RB engine. I know i'm replacing the cam and lifters, i don't want to get it back together and have the same thing happen with a new fuel pump push rod. Howards cams has a .420/.420 lift cam i'd like to try with new lifters and the fuel pump push rod. but i'm not sure if that will fix the problem. any input would be appreciated.

thanks, Greg

It is a wear item and it can happen. It's not that uncommon. Usually after they sit for a while and don't get good start up lube. Can be poor metalllurgical quality as well.

Did you lubricate the pump drive lobe and end of the pushrod with the new cam install?

poor metallurgy and or not enough zinc in the oil. Hughes' ones are likely good ones and 440source sells good used ones & those OE ones were reportedly pretty much bulletproof

that's the fuel pump push rod that was in the engine since it was new in 1970. the car sat from the mid 80's until i got it in 2002. drove it from then till i rebuilt the top end. it made 6 trips from NJ to the Nationals over the years that i had it. when i rebuilt it, I DEFINITELY know that the rod didn't look like that. i scrutinize and check everything when i put something back together. as for oil and additive, I use Hughes high pressure additive in all my flat tappet cars, and rotella 15w-40. everything gets a liberal coat of assembly lube when i put an engine together. and i used the cam lube from Edelbrock as they recommended.

sorry guys, that kind of rules out oil and additives. I would have never put that fuel pump push rod in dry.

if that was the case, why just the fuel pump push rod and not the rest of the cam and lifters?

A few questions:

When you changed the cam, was there any noticeable wear on the fuel pump pushrod?
Any wear when you changed the fuel pump?
What type of fuel pump is the new one?
Is it easy move the pump lever by hand?

To my knowledge the fuel pump pushrod doesn´t rotate and I am surprised to read about fuel pumps with claimed open spring pressures on 200 lb considering the small area the pushrod has on the camshaft.

They're a known wear item and people have been having problems with them since the '70s, or maybe even earlier, and there was plenty of zinc in the oil in those days. I believe they have some hardening on the ends but it must have been a rudimentary process because even new ones back in the day would suddenly start wearing. They usually would wear out on family vacations, at least that's what most of the stories include.

So, you didn't do anything wrong and I believe it's more a "luck of the draw" kind of thing, unless there was something wrong with the fuel pump that wouldn't allow the pump lever to move when the rod kicked it over. The cam/pushrod/lever arrangement doesn't push the fuel out of the pump, the spring in the pump does that. The idea was that the pushrod kicks the lever when it can, probably not on every revolution of the camshaft, and the lever operates the diaphragm that draws fuel into the pump. The spring pushes the fuel into the carb. As the fuel leaves the pump, the diaphragm moves and the lever moves back, so the pushrod can kick it open again.

In your case, suppose the hardened layer on the end of the pushrod was almost gone, and during the last bit of driving it wore off, leaving the softer steel to fend for itself.

I am not a restorer and what you have described is the reason I like electric fuel pumps so much. They either work or they don't, and I have yet to have a Carter P4070 pump fail. They are at the back of the car so they pressurize the fuel line, mostly eliminating the possibility of vapor lock. You can turn them off whenever you want to if you provide a switch or a switching mechanism. They cost less than $100, or at least they did when I was buying them.

R.

Q: When you changed the cam, was there any noticeable wear on the fuel pump pushrod? A: no, i had one on the shelf and the one from the car, both looked identical with no indication of wear.


Q: Any wear when you changed the fuel pump? A: wear on what, the pump or the rod? if your talking about the fuel pump lever, than no.


Q: What type of fuel pump is the new one? A: basic stock replacement over the counter pump that you buy at any advance auto/autozone/o'reilly parts store. the wear happened before i replaced the pump.


Q: Is it easy move the pump lever by hand? A: as easy as any other pump i've tried. the levers weren't seized or bound up.

that's easy, poor metallurgy in the pushrod & acceptable/adequate metallurgy in the cam/lifters, however yes if it was a "zinc" issue it could (& would) affect both (& possibly other items)

We have descended into the murky waters of guesswork. Let's stop beating this deceased equine carcass.

As I said earlier, it happened a lot in the days when zinc (and phosphorus) were plentiful. Doesn't sound like anything more than bad luck. That's the old car game, sometimes you eat the bear .........

R.

Tried to get another clichéd phrase in there but couldn't think of one!

Mopar supposedly had put a bad batch of the push rods out years ago so when you get a new one I would look elsewhere.

oh well, thanks guys.


i guess it's gonna be a do over. new cam and lifters and push rod. gonna triple check everything and cross my fingers.

why change the cam/lifters?

I think he believes it's the cam's fault

If the camshaft fuel pump lobe looks and measures ok,I'd reuse the cam and lifters that were in the motor.Just use a quality pump pushrod and you should be good to go. John.

From the original post...

There was a member that had some NOS ones for like 18 bucks shipped.Got one for my 440.I do have a few from my blocks that are from the 60s and still close to stock.The last new one aftermarket was worn in like 5K miles.
Rocky

I read all this and I wonder why we work so hard to keep the mechanical pump. It doesn't make sense to me.

The OP also said he'd measured the fuel pump cam and it wasn't different than the stock cam. I agree why not use the same cam (even if it is the Edelbrock Performer version of a cam that is definitely a chevy lobe, 50 years old design). It's broken in. The price of a new cam and lifters would definitely cover the cost of an electric pump, and then no more worries about fuel pump pushrods!

R.

hey,

the lobe for the fuel pump push rod has this metal grinding on metal look to it. it's not smooth and shiny like the lifter lobes. knowing my luck, if i put it back together with the Edelbrock cam, i'd wind up having the same thing happen had have to take it apart again.

i'm a little overwhelmed with repairs right now. out of 5 classic cars, i have only one that is reliable. i need to get cars fixed right and back on the road. at this point i can't afford to take chances, but i can afford to spend the money to fix it right.

i don't want to go with the electric fuel pump cause that isn't what this car is. i want it 99% completely stock running exactly how it did in 1970. people have been using stock mechanical fuel pumps for years with no problems , so why should i change now.