Fuel pump pushrod normally tough to get in?

[Chargerguy74]

I have a new Mancini fuel pump pushrod for my 440, and it seems overly tough to get in. I was expecting it to pretty much slip right in with finger pressure, but it seems rather stiff. Do they normally require being tapped in? I'm worried once I start tapping it's pretty much not coming out until the engine runs.

[A383Wing]

should slide in with only finger pressure.....

[68Charger4me]

It should not be tight at all, usually you have to use some grease on the top end to hold it in place while you insert the pump.  Something is really wrong here if it's tight at all.

[Chargerguy74]

Yeah, something must be off. I get a diameter of 0.4365" for my pushrod, sound normal?

[A383Wing]

I have 3 new rods here, measures 3.25" overall length, .4385" diameter in the middle

[Chargerguy74]

Interesting. Well I went to town with some steel wool since the pushrod was a little tarnished (just cut it out of the packaging). Cleaned it up and got it to slide in with a little pressure. The bore for the pushrod looked clean, but it definitely will not drop free. A little tight for my liking. If the thing doesn't seize up when it gets hot due to friction I imagine all will be well. It'll be the first thing I think of if I stop getting fuel.

Well it's been 12 years in the making, and tonight I finally finished my 440! I started the project when I was 18, put it on the back burner for a while, stopped building and started collecting, a year ago I needed a replacement for my 340 so I pulled out the long block from storage (my dad's heated shop). I ripped out a perfectly good brand new cam, removed the new lifters, new intake, rebuilt, ported, and larger valved 516 heads, and replaced with a different cam, 440 source heads from Challenger340, new intake, EDM lifters, which required new pushrods, etc. As long as I don't wipe the cam during breakin the headaches will finally be over. Except after 12 years the paint on the block is in very rough shape. Might just leave it as is though.

[Dino]

I would pull that pushrod back out and double check things.  If it's tight now it's not going to get better when it heats up.  I really wouldn't take the chance that all will be well.

It took 12 years to get you here, but it may take you longer to get over not repainting it. 

Do it once and do it right.   

[Chargerguy74]

Lol, yeah, it's definatly not going into a show car, but an unrestored car. I know I'd love to repaint the block if prepping was easy, something I'll have to look into. I seem to be severely challenged when it comes to making paint stick.

As for the pushrod, how tight is too tight? My pushrod sounds like it's in spec, not sure what my options would be.

[Dino]

The old paint is no match for paint remover.  Or brake fluiid for that matter.  Once it's off you clean it with post paint stripper cleaner, available in diy stores like Home Depot.  Acetone or thinners work as well.  You can also do a second cleaning with hot water and dish soap.  Then dry it, mask, and paint.  If the paint calls for a primer, get a 1K etch.  I think the paint I've used goes onto the bare block.

Heck, scraping off loose paint and reshooting it would be an improvement but I'd spend the time to do it right.  Start early and you'll be done by the end of the day.  And let's be honest, what's one more day after 12 years?   

The rod should not be tight at all.  If you can't just slide it in with your finger then it's too tight.

[Chargerguy74]

Well, I'll probably repaint after the break in.

This rod has me concerned now. Maybe I should try another one first. Wish I had a spare, or an old one. Welp, out it comes, be back in a bit.

[ws23rt]

Lol, yeah, it's definatly not going into a show car, but an unrestored car. I know I'd love to repaint the block if prepping was easy, something I'll have to look into. I seem to be severely challenged when it comes to making paint stick.

As for the pushrod, how tight is too tight? My pushrod sounds like it's in spec, not sure what my options would be.

About your push rod fit.--I'm going to go with Brian's measurement.--.4385"--  If your measurement is .4365"  that says yours is .002" smaller than a new one.---Not a great amount to be concerned with. (I suspect your measurement may not be quite right). Check the zero ref on the mic.

If your measurement is correct you should have free movement in the bore.

As to the concern about things changing as the engine goes through heating cycles?----When the engine block heats up the bore for the pump rod gets larger as well and does so just before the rod feels the heat. The bottom line is the fit of the rod to the bore cannot become to tight because of any normal heat cycle the engine goes through.

Let's say that the bore is good and also clean.  The odds of it being too small are very low. In fact so low I would say it is not too small.

If the rod does indeed measure .002" smaller than what Brian has (new rods). The only thing left that make's it feel tight in the bore is it is bent.

[Chargerguy74]

Thanks ws23rt. I agree as long as the 2 metals have the same or similar coefficients of expansion, which I imagine the difference is negligible. Anyway, just what I feared, I can not get the pushrod to drop free. To give you an idea of how snug it is, I can't budge it with a magnet. It's starting to look like I've gotta rip the front end apart and remove the timing cover to get some pliers on this thing.

[Dino]

It's not my area of expertise by any stretch of the imagination but shouldn't the smaller object heat up and expand faster than the bigger one?

I don't suppose you could stick a smaller rod on the end of the pushrod with jb weld to yank it out?

[Chargerguy74]

Dino, it may be possible. I wonder how well it would bond.  I'd love to get in there with the mig and just tack it to a rod. Any slag would drop into the oil pan though. I think I'm gonna have to walk away from this tonight and come back fresh. I really don't want to open this thing up again.

[Dino]

I think that's a wise move.   

I thought about tack welding it and you sure could with some prep, but I'd try the chemical route first...or sacrifce the rod and drill a small hole in it...but that's a bit more involved as well.  Got a spray lube you can squirt in there to let soak overnight?

[Chargerguy74]

Yeah I'd love to drill a hole in it, I'm just worried about the filings. Not sure what I'll do yet. I just know I need to stop for tonight before I do something stupid.

[Dino]

Correct!  You have all day tomorrw to do something stupid!  Well that's my moto anyway.   

Drill with a vacuum hose next to it and regularly spin the drill the other way to eject the shavings.  A magnet next to the bore may help as well.

Call it a day, have a beer.

[A383Wing]

you will never be able to drill a small hole in the rod...you don't realize how hard the metal the tip of the rod is made from...you will not have a drill bit sharp enough

[Chargerguy74]

I was wondering that, I know it's hardened. Time for a timing cover gasket set...again lol. I don't think the cam will have that hard of a time moving the rod, but I'm not too sure about the fuel pump pushing it back up. It would be so easy for me to put the fuel pump block off plate back on right now and go electric. The pushrod can just chill in there lol.

Dino you read my mind, I was half way through a beer when I read your reply.

[Dino]

you will never be able to drill a small hole in the rod...you don't realize how hard the metal the tip of the rod is made from...you will not have a drill bit sharp enough

I was afraid of that.  Got any diamond tip drill bits laying around?   

I'd still try jb or some epoxy first.  I'd hate to have to open an engine to get the rod out.   

I think I'm gonna grab a cold one myself now.

[A383Wing]

needle nose pliers....or the round tipped rubber hose pliers will also remove it

[Chargerguy74]

Yeah I tried, couldn't open them up wide enough. The hole is slightly bigger up top. I'll have to remove the alternator to really get in there. I might actually give that a go soon.

[Chargerguy74]

No dice, not enough room for needle nose pliers.

[ws23rt]

It's not my area of expertise by any stretch of the imagination but shouldn't the smaller object heat up and expand faster than the bigger one?

I don't suppose you could stick a smaller rod on the end of the pushrod with jb weld to yank it out?

Hey Dino-- This just happens to be one of my areas of expertise. I appreciate your observation about the rod being smaller and therefore being of smaller mass it would tend to heat up quicker than a larger mass such as the engine block.
In this case the heat that will expand the small rod comes from the warming of the engine block. That heat comes from the combustion chambers and migrates out from there. The water jackets tend to help spread this warming out as well. The rod will only warm from the bore it is in plus a very small amount from oil (which is still warming as well).

Since the question of expansion rates has been raised and many people are aware of it this may be a good place to give an example.

For steel (cast iron is so close as to be a non issue) the rate of expansion is --about--  .000006" per degree (temp f.) times distance in in.

The tem. rise from 70deg to 190 deg. is 120 deg

the dia. of the rod is .4385"

So ---.000006" times 120 (deg) =.00072   Times dia. .4385"= .00032"

If the rod got all the heat first it would get larger in diameter by three tenth's of one thousandth of an inch. This amount is so small as to be a mute point when talking about the fit and tolerance of the rod to the block.  If one were to put the rod in an oven and heat it  to 250 deg. let's say it should still slide in the bore. --Hmm this should be worth at least three cents.

[Dino]

It's not my area of expertise by any stretch of the imagination but shouldn't the smaller object heat up and expand faster than the bigger one?

I don't suppose you could stick a smaller rod on the end of the pushrod with jb weld to yank it out?

Hey Dino-- This just happens to be one of my areas of expertise. I appreciate your observation about the rod being smaller and therefore being of smaller mass it would tend to heat up quicker than a larger mass such as the engine block.
In this case the heat that will expand the small rod comes from the warming of the engine block. That heat comes from the combustion chambers and migrates out from there. The water jackets tend to help spread this warming out as well. The rod will only warm from the bore it is in plus a very small amount from oil (which is still warming as well).

Since the question of expansion rates has been raised and many people are aware of it this may be a good place to give an example.

For steel (cast iron is so close as to be a non issue) the rate of expansion is --about--  .000006" per degree (temp f.) times distance in in.

The tem. rise from 70deg to 190 deg. is 120 deg

the dia. of the rod is .4385"

So ---.000006" times 120 (deg) =.00072   Times dia. .4385"= .000032"

If the rod got all the heat first it would get larger in diameter by three tenth's of one thousandth of an inch. This amount is so small as to be a mute point when talking about the fit and tolerance of the rod to the block.  If one were to put the rod in an oven and heat it  to 250 deg. let's say it should still slide in the bore. --Hmm this should be worth at least three cents.

Way cool!  I had no clue this was your niche!   

That was a great explanation, I learned something new again.