That is still considered fine.
It is still about 15 psi.

I see no one explained why the pressure drops when engine is warm.

The space beteen the cam and crankshaft bearings opens up from metal expansion.
This opening up action..lowers the pressure.

Much like you blowing a mounthful of water through a small straw ...and then again a mounthful of water though a short piece of garden hose.

 

ok ok that makes sense. Thank you. U guys have been a great help!!!

 

Maybe.Like I said-the gauge shooting up then dropping when warm is a good indication that that is your problem.The gauges arent that great in these trucks,but that shows you that it works,and when it heats up,it drops,and thats when the noise starts.I think thats exactly what your problem is...poor oil pressure,leading to failing crank/bearings.Again-VERY common with those engines.

Best bet is to a get a mechanical gauge on it,and see what you have for pressure.A good guide is to have 10 psi per 1000 RPM.

The bearings and oil pump CAN be done while the engine is in the truck,if you decide to do that.If your going to pull the motor,scrap that 400,and drop in a 429!

Good luck!

 

There is also a fix for this considered weak oiling system.

It involves securing a smaller orifice at the back of the block.

 

lol i wish i could.....to pricey for my budget(rememer im only 15)> my guage will peg then drop and stay in the "oil" lettering. It doesnt fluxuate. how much hourse power do these trucks have. no offnnse to u guys but these trucks have no ***** lol

 

No offense taken.You're right-no *****.IIRC...150HP.Dont forget,they were made from 77-82...BIG-TIME emissions era.Nothing in those years had *****!These were made to be emissions friendly.

Headers and a 4BBL wake them up a little.Remove all the unnecessary pumps etc,and you'll get a little more.

 

Yeah lol mine wont go any faster than 80mph. MY friends alwasy own me when i race em. THey all got fgrand ams and grand prixs

 

Kid, tell a bit more about the knocking... once the truck has warmed up, after driving for a while, if you shut it off & go to start it, does it crank hard? like it's hard to start?

if it is then this is also a sign of too much advance in your timing.

as for your heater, your blower motor. there should be a "blower relay" under the dash probably over towards the glove box area. I't a square metal relay with a metal mounting tab. it will be screwed to something metal like the underside of the dash itself because it need to be grounded to work. It has a 3 prong spade conector type harness that plugs into the relay. your relay may be bad. it's about a 10-12 dollar part.

See, there are 3 wires leading to that relay, one is a constant hot wire, it's always powered up. if that relay is sticking then your fan wouldn't shut off even after turning the key off.

the only other thing short of some creative wiring alterations as someone else has already mentioned.... is the possibility that the contact switches in your heater controls aren't breaking. i don't think that's it though. i've seen them fail to make contact but never seen them fail to break contact, besides, when you shut the key off the power to the heater controls should be killed.... so it's gotta be that relay.

 

as far as your lack of power... yeah, they are dogs. I had a 400 in a 78 halfie, I rebuilt mine & made some pretty good power improvements, I now have a 77 with a 351M, that's a serious dog there. The good news is that both of these engines have potential.

the biggest areas that need improvement, the areas that will net the most bang for your dollar are as follows in this order:

compression!!! compression ratio is 8.4:1 in that 400 of yours, that's not a lot of squeeze. the 1971 400 came with 9.1:1, much better and still low enough to run modern pump gas. Basically you will want to look for repro's of the 1971 pistons and then surface your heads while you are rebuilding the engine. even cutting them 10 thou will help. Badger Pistons by Dyna Gear (http://www.dynagear.com/) manufactures a 9:1 flat-top cast aluminum piston for the 400. Also, Ohio Piston & Pin manufactures a 9:1 flat-top piston (P/N 1282P) for the 400.

put those in & shave the head a little & you'll be at around 9.5 (much better)

secondly, the cam. pretty much any of the popular brands such as "crane" or "comp" is going to have a better cam for you, just don't get crazy, choose by rpm range & keep it from a 1000 rpm & up, you don't want to be targeting power from 2500 & up, just look for an "rv" type cam designed for the lower rpm ranges.

next is the intake & carb, i'd suggest just going with a dual plane aluminum such as the edelbrock performer & stick a $220 dollar holley 600 cfm 4 barrel on top. just a plain jane single feed square bore with vacume secondaries & maybe an electric choke if you like.

then if you still aren't happy loose the cast iron exhaust manifolds for a set of headers & 2.5" dual exhaust.

 

I bought mine off the side of the road almost two years ago. Keeps on keepin' on. Complete with medium poor oil pressure and a regular drum solo coming from the bottom end...

 

It isnt hard to start once its warm. starts just like a new car. It was that relay for my heater.Works fine now. I just cant afford to rebuild my motor right now. I want to get true dual exhuast to just make it loud:-) and for power gains. also some hedman headers. Ill porlly end up junkyard scavenging for headers off another truck liek mine that had headers on it. My dad has a couple holleys(idk what they are... ill save up for alluminum intake.

 

Well, glad to hear your heater works properly again.

if it starts nice for you when warm then it's probably not ignition timing. in my experience with these engines by the time you have pushed it too far with the advance in ignition timing to make the engine ping or deisil under load you will also have a hard time cranking it to start when warm because she'll be sparking the plugstoo far before the rod jounals on the crank come to the top of the stroke, she'll basically be fighting herself on start up, kicking back on the crank.

It could be so many things bud, it's possible that you have a little play in the bottom end that shows up after the engine is warm & the oil visc is down, it could be that you've got a little bit of play in the valvetrain when the oil thins out.... could be a little piston slap like someone else mentioned, but actually the slap & the valve train noise are going to be evident on idle... hard to say with out hearing it for ourselves.

 

Hahahahaha Ha Ha Haaaaa.... 400 M that bugs Me 2

 

Actually only the first year 400s had the small block bellhousings and not all of them had it either, Ford went almost immediately to the 429/460 bellhousing on them and by 72 ALL had it with the exception of a few engines that were put into 72 MY cars with carry over block ( you can check the actual date casting code and find out they were cast in 70 not even 71 when they were officially released)