Machine Work, Missing Anything?

Not gonna port the head too?

:dunno:

Head work - why are you having the valve seats enlarged? Unless you're going to build a high-RPM stroker, your money will be better spend on having the head ported and polished - which will improve flow, and reduce the bottleneck in the system (the intake ports.)

Block - "Check Deck - $100?" That involves laying a ground straightedge on the block deck surface (mating surface for the head) and checking with a set of feeler gages - takes about 10 minutes for an experienced machinist, IF he's being careful! Find out also if anything there includes replacing the cam bearings - which are wrecked when the block is tanked (and should be replaced anyhow.) They do require a somewhat specialised tool, so it will be good to make sure.

Rods - don't see any trouble here.

Camshaft - Polishing makes some small sense, but "balancing?" You don't have enough "throw mass" for that to be an issue, and it doesn't spin fast enough to be a big problem (since it spins at 1/2 crankshaft speed.) Since you'll have to get new lifters anyhow, and you're willing to pay for work on a cam, might I suggest just replacing the thing entirely? Crane makes a couple that look promising - and there has been a thread on the subject in the last few days.

Crankshaft - Balance and polish make sense here, to a certain extent. Especially the "polish" part.

N.B. - typically, you have parts balanced when you're going to build an engine that will live at 5kRPM or higher - like imports or small blocks. Given that most later AMC242 control setups have a rev limiter down around 5250RPM or so, they have a wicked harmonic problem ~5500-7000RPM, and they make screeds of torque at low RPM anyhow, there's not a lot of reason, I'd think, to go into a lot of work balancing things. Granted, it's a good idea (and an "attention to detail" thing) - but I'd spend less effort balancing an AMC242 - or a 242-based stroker - than I would if I was building an 11kRPM racing 383 SBChevvy stroker... It's the long crankshaft that causes the trouble - and no amount of balancing will really help. Granted, Barney Navarry ran an engine (based, I think, upon an AMC199 - I'd have to check) at Indy, but he still had the harmonic trouble, and had to make sure to stay out of the band where it caused trouble (from idle until you start to hit it, and once you get out of it, you're fine - but stay in that harmonic band, and you're going to break things...)

Even in stock trim, you probably didn't wind the engine up much. I probably touch 5000RPM about twice a year, just to make sure it can be done. All my rigs live (and live well!) somewhere below 3500RPM...

5-90

To me a rebuild includes boring the block, otherwise is is a re-ring job. If you are going to do a valve job, replace the valve guides, do not have the guides knurled.

Polish a cam????? Balance a cam???? Been building engines for 40 years and never heard of this.

Since you will be replacing the rod and main bearings, you will want to have the rods reconditioned. Shot peen, not necessary on a non-race engine, especially a low rpm 4.0L.

Crankshaft.....most likely you will want to have the journals ground. No need to polish. Personally I wouldn't worry about balancing. While it may make an engine last longer and run a touch smoother, 4.0L routinely last 200k without it.

The key is to ask yourself why are you redoing the engine. What usage will it see? If you are truly rebuilding, you want to bore the block and go with new pistons and rings. If you are going to turn the crank anyway, you might think about going to the 4.2L crank and different pistons and end up with a stroker. They are simple and tough as well as a ball to drive.

what if you are using a heavy 258 crank, and aftermarket pistons? lets say, the off the shelf speed-pro's. would the difference in mass require the rotating assembly to be balenced? it would make sence to me to have to have some meat taken off the counterbalences.


i have never built an engine

streetpirate said:

what if you are using a heavy 258 crank, and aftermarket pistons? lets say, the off the shelf speed-pro's. would the difference in mass require the rotating assembly to be balenced? it would make sence to me to have to have some meat taken off the counterbalences.


i have never built an engine

Click to expand...

Again, it's going to depend upon what you're building the engine for. OEM/Production small block Chevvies, for instance, are typically not balanced as well as racing engine - time, after all, is money. I'm sure they balance them to within a couple of grammes or so, but I've been involved in racing engine builds where a tenth of a gramme meant getting another part.

Granted, most production engines are going to redline somewhere in the 5000-6000 range, and some racing plants can hit 12000 easy. More, if it's a Wankel rotary engine (I used to know a guy who specialised in Mazda/Wankel engines, and he could balance them to spin up around 22000RPM all day long.)

Bear in mind the maxim - "time is money." If you're going to build for high output or ultimate reliability, it could become worth it to have the entire reciprocating assembly dynamically balanced - but otherwise, probably not. Sure, you'll want to take time to balance your rods and pistons to each other (it helps to reduce harmonics,) but to what level? Within a gramme or so is usually just fine for a "production" or a "typical" engine - and if you're not going to see high crankshaft speeds, a gramme will serve neatly.

Sure, have the crankshaft itself spun - an unbalanced crank is a very good way to destroy an engine! However, if it was made properly to begin with, you're not offset grinding, and you didn't manage to bend the thing, "balancing" the crankshaft is probably going to be more just checking to make sure it's still balanced than anything else - unless you notice something obvious - like a hole in the side of the counterweight (where a plug of Mallory metal probably used to be... Lightening holes are usually drilled in the periphery of the counterweight - but "heavy plugs" are usually put in the side so they don't get flung out during operation...)

Unless you're planning on living at high RPM (anything over, say, 4,000RPM or so for "cruise" operation,) balancing the entire reciprocating mass as an entire unit probably becomes more an exercise in showing the depth of your pockets than anything else. Since we're not building 1500cc Honda "wind it up and move" engines here, save your money for tyres and lift. All the "common literature" doesn't show any need for special balancing when building a stroker - I'd have to check some of my old textbooks, but I don't see a lot of reason to do so offhand, either...

5-90

old_man said:

To me a rebuild includes boring the block, otherwise is is a re-ring job. If you are going to do a valve job, replace the valve guides, do not have the guides knurled.

Polish a cam????? Balance a cam???? Been building engines for 40 years and never heard of this.

Since you will be replacing the rod and main bearings, you will want to have the rods reconditioned. Shot peen, not necessary on a non-race engine, especially a low rpm 4.0L.

Crankshaft.....most likely you will want to have the journals ground. No need to polish. Personally I wouldn't worry about balancing. While it may make an engine last longer and run a touch smoother, 4.0L routinely last 200k without it.

The key is to ask yourself why are you redoing the engine. What usage will it see? If you are truly rebuilding, you want to bore the block and go with new pistons and rings. If you are going to turn the crank anyway, you might think about going to the 4.2L crank and different pistons and end up with a stroker. They are simple and tough as well as a ball to drive.

Click to expand...

X2- Bore block, get pistons.

Umm im to lazy to quote everyone so Ill just try to keep everything in order.

Head - port and polished, yes I thought thats what porting to gasket is? I want it to breath, but high revver not really. I dont even know what my RPMs are when I drive, but I can tell you how much gas is in the tank with great precision.

Why enlarge the valve seats? Im woundering if 1mm oversives valves will help with the breathing?

Check Deck - Should I just have them shave the head a bit, and get some higher compression, or go stroker(4.2L, keep in mind this is my daily driver).

I am interested in getting a higher lift camshaft, but the one person ive talked to that about says its a waste of mulah.


What the engine will be doing when the Heep is completely done?
Mostly daily driver, and weekend warrior. I do want to take a couple trips to Moab once I get the lift and new axles in. Figure bigger is better. 3.5" lift, and disco some dana 44s. Id like to run 31x9.5x15, maybe 10.5 forgot the right number. Then for gearing Ill keep my trusty AW4 and regear to 3.73 or 4.10. Cruising speeds I was told should be right at or slightly below 3k RPMs so yea, not looking at hauling ass. I do want to keep my City economy above the 16MPG mark, right now Im at 18. It will tow a few things, mostly light weight crap, and the heavy roof rack and recovery gear. I do have a lead foot, but Im learing to leave the boots at home(limited the throttle to only 3/8). Since this being a city driver acceleration is always awesome, but I have plenty right now, and I LOVE IT!


Reason for the rebuild? The engine is at 212k, and Id like to just be prepared for when it goes out around 300k. Also Im doing this to have fun, I love taking things apart and putting them back together, figure Ill start with something simple, then move up to my blown Camry-Supra(Cressida) :'(

Anything I miss?

If you are going to shave anything, shave the block when you do a stroker to adjust the quench height. That will allow you to run lower octane fuel with a higher compression ratio. Shaving the head isn't that great an idea on a 4.0L.

all great and accurate advise, but like what was said, build a stroker, its not much more and you will have more useable torque and hp. Do a search for stroker on Google. You will turn up Dino's pages. It is one of the most definitive sites on how to build a stroker. You are giving your self some time so read up and you can spec out your parts and get them for cheaper. I have all my parts,,,I am still waiting for mine to crap out..... getting close to 400,000. Gonna pull the motor this winter If I make it to 400 or not. Good Luck

Simply enlarging the valve seats and sticking in larger valves will not help flow. All this will do is make a "funnel" at the seat area...the port will flow less than it did stock. increased flow on the intake side is all about the bowl area under the seat and the shape of the valve guide in comination with proper radius on the port floor where it blends into the bowl. the shape of the port from manifold surface to valve seat (if you could stretch it out on a straight line) is a venturi or "hourglass" shape...this maintains velocity around the bend where the runner blends into the bowl. disturb that smooth shape and the port will go turbulent...i ruined a lot of heads in my younger years..they LOOKED like they should be awsome...but the flow bench proved me wrong. port work is not always intuitive...there are some motorcycle heads that you improve flow by making the stock ports SMALLER...

balance cam??? huh? you can gasket match the head in a hour or so with a die grinder, the gasket you plan to use, a magic marker and a scribe..save the 125 bux. I like the idea of quality refurbishment of the rods...ARP sells good rod bolts...in the catalog they are spec'd for the 4.2...they work fine in a 4.0 or a 2.5 (exact same rods as a 4.0).

Alrighty revised it.

The 4.2L Stroker sounds like a good suggestion. Im sure these are overly asked questions, but Ill ask anyways. Whats needed in order to make the 4.0 a 4.2 stroker? Which crank, how much bore, other mods, gas economy? Or just a link to all this info, Ill search after I get this posted.

Now for what Im looking at for machine work and new parts.

Head:
Hot Tank ~$25
Gasket Match ~$DIY
Port & Polish ~$125

Block:
Hot Tank ~$100
Freeze Plugs ~$25
Bore & Hone ~$180

Pistons:
Federal Mogul Cast Pistons ~$135

Rods:
Balance ~$125

Camshaft:
Instal Camshaft Bearings ~$40

Crank Shaft:
Balance ~$125
Polish ~$75

Gasket Kit:
R&L Upper/Lower ~$95

Total: ~$1050

you cant make a 4.0 a 4.2 stroker, you use the 4.2 parts to make a minimum of a 4.5 stroker

Okay, well the guy Im getting the engine from has parts to make it a 4.5L so Ill probally get those when he brings the engine down.

He says his hi dollar one does like 19 City, and 23 HWY, which is just about where Im sitting right now. Fuel economy is a issure, but I guess if you build it right, it wont kill out you gas. Although I have heard some people say they get 8City with their 4.6L.

As long as you don't get too happy with the skinny pedal, you should probably see similar mileage to what you're getting now (you'll increase displacement, but you'll make more torque at lower RPM, so you can cruise at a lower crankshaft speed...)

Check this link out - http://www.sa-motorsports.com/diyguide.shtm - for some useful information...

5-90

Anyone notice the $100 for hot tank of the block. My shop does it for $25.

Seems high for cleaning a block.

Then the port and polish...$125???

Anyone know of ANY shop that does a $125 port and polish?? Shops around me do it for $400 for really light work and up to $5000 for CNC work on some v8 heads. Average job is usually about $1000 for a good clean up and porting.

Im just using a online average price guide, to get my figures.

Dont have the site on this computer, but Ill post it up once I get back to my house.

i just got quoted a grand for the following

bored .125 over, 4.06 offset ground crank, hot tank, deck block and head, install cam bearings the price of 6 new forged 4" bore pistons, rings, and installed on the rods. Painted and ready to go.