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Unread 12-28-2013, 07:42 AM   #1
matt1980
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304 engine help

Hello everyone, I am new to the jeep world and have purchased a 1980 CJ5. I have completely disassembled my new found toy and am just about to begin putting it back together. This jeep will be used both on the street and in any mud that is between my family and I's fishing hole. I will be taking the 304 I purchased to the machine shop next week and am wondering what I need to do for parts. Obviously if anything is broken it will be replaced but I do not want to throw money at this engine if it is not needed. I am not looking for tons of power, I only want a reliable engine that I will not have to build again in the near future. Looking for recommendations, valve springs? connecting rods? pistons? My original plan was to re ring the engine and call it a day, again if nothing is found when I tear it down this weekend, after reading a lot of what is posted here I have a lot of concern that simply re ringing the engine may not be a good idea. I know that I will have a much better idea after actually tearing down the engine but looking for more amc specific recommendations. Thank you all.

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Unread 01-02-2014, 10:15 AM   #2
matt1980
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Ok, now that I have more info hope to get any recommendations you all may have. Crank is in great shape, all bearings showed nothing more than normal wear, plan to replace the cam. Where I am undecided is the rods. there is some rust in three of the cylinders and I am not sure of it will be able to be honed or need to be bored. The block is going to a machine shop this afternoon and will know more after they check everything. I have seen some postings that say to replace the rods and at least one that said upgrade to forged rods. I am again new to jeeps and amc motors but I thought that sounded like overkill for the engine that I am building. The options that I am looking at are use the rods I have now after sending them to the machine shop to be checked, buy replacement oe rods, or buy forged rods. Before spending the money on the forged set I would like to know if there is any specific reason that they would be necessary. I am looking at the edelbrock performer intake, 500 cfm carb,headers, and cam kit to match. I believe the cam will be a 2132.
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Unread 01-02-2014, 11:07 AM   #3
JeepHammer
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Low RPM V-8 AMC engines shouldn't need rods.
The guys that install bigger camshafts, ect. need to do something, but with mostly stock engine, it's not necessary.

I would recommend having a 'Bolt Stretch Gauge' be used when torquing rod bolts.
This will tell the builder if the bolt is still viable.
If it stretches too much before you reach the 'Torque' value, then the rod bolts are shot... And this is where you will have a failure.

If you replace rod bolts, then make sure they are SUPPORTED while you remove old bolts, insert new ones.
The best way in the world to screw up cast iron rods is NOT to use a rod clamp to support/square the rod while changing bolts.
Cast iron is BRITTLE, so a clamp is required.

DO NOT let a machine shop talk you into LARGER ROD BOLTS.
The bolts are steel, and already stronger than the rods, so removing more of the iron rod to put in a larger bolt makes no sense at all...
It's pretty common to go with larger bolts in STEEL rods, but they simply aren't indicated or recommended in iron rods...

If your RODS ARE HONED TO SIZE, make sure they are done IN PAIRS on the honing bar!
TWO rods will keep each other square, while one rod will cock sideways as it hones, and you won't have a square bore through the rod anymore, and that means uneven wear on the bearings/crank.

Stick with a reasonable camshaft,
On new camshafts, I STRONGLY recommend you use new lifters (Pretty much a requirement), and you use new valve springs.

Inspect the rocker arms CLOSELY...
Valve stem end, make sure the wear pattern is pretty much centered, doesn't have to be perfect, but reasonably close to center.
If the valve has worn a groove in the lifter you can catch a fingernail in, then replace the rocker.

Push Rod end,
Look for a polished wear 'Ring' in the pushrod socket.
If that wear ring gets into the oiling hole in that socket, replace the rocker.
When it wears enough the oiling hole gets covered by the pushrod, you are limiting oil to the rockers/valves.
No point in reusing something that is on it's way out...

Check both ends of the push rods, the ball ends.
If the wear pattern has 'Warbles' in it, instead of an even hemispherical wear pattern, scrap them and get new.
Again, you are through the hardened wear surface, and that pushrod is on it's way out very soon.

If you see any metal galling, then get rid of the parts and replace.

------------

Makes no sense to reuse the timing chain set.
Just makes sure there isn't any 'Flash' from casing in the oil passages, and clean it out, line up your oil holes...
If you are ordering a new timing set, don't try to save a few bucks here... Get a TRUE DOUBLE ROLLER set,
Your machine shop will know what that means...

Once you have things up to 'Snuff' you are ready to get another 50,000 or so miles out of it!

Remember to break in the camshaft/lifters like you have some sense, and that is the first 20-25 minutes of operation.
You will probably need to add a zinc additive for break in, flat lifters need that extra lubricant until they establish a wear pattern with each other.

Does any of this make any sense?
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Unread 01-02-2014, 11:12 AM   #4
JeepHammer
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Crap! Forgot valve springs!
If you are replacing cam/lifters, might as well retire those valve springs... They don't cost much and will pretty much ensure you correct seat pressure and camshaft pressures when the camshaft operates.

Most camshafts for this will have recommended valve springs, lifters, ect. for the camshaft you are ordering,
But if I can find Chrome Silicone springs instead of 'Music Wire' springs, I go with them.
Chrome Silicone won't have brutal seat pressures before the break in, and the don't weaken up nearly as much during the years of operation as 'Music Wire' springs do...
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Unread 01-02-2014, 11:46 AM   #5
swatson454
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As far as the cam is concerned, I highly recommend digging a little deeper. That "Edelbrock" cam; which is actually a reboxed Blue Racer or similar cam from the '60s, is decent on the duration measured at .050 but way too wide when measured at .006. They're also ground on crappy old cores long before we had our oil changes a decade or so ago. The lobe technology today is just far beyond that old stuff and it'll show up in torque and manifold vacuum.

I know the price is attractive (which should be your first clue to look elsewhere ) but I'd look into either a Comp XE256 or a Lunati Voodoo 256.

You might want to PM Rollbar and see if Ashley is pleased with her Comp cam. If she feels like it should make a little more torque, I can tell you how to get there. If she's good to go... fantastic! Either way, both of those cams are about a light year ahead of those old, reboxed cams that Edelbrock likes to push.


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Unread 01-02-2014, 12:12 PM   #6
Hbryant123
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For my amc 304 rebuild i just used a stock cam, i figured just make it good as new. When i broke mine in i used that zinc additive to be safe and valvoline motor oil. Something i wish i would have done was replace the pushrods, rocker arms and bridges.
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Unread 01-02-2014, 01:00 PM   #7
JeepHammer
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Quote:
Originally Posted by swatson454 View Post
As far as the cam is concerned, I highly recommend digging a little deeper. That "Edelbrock" cam; which is actually a reboxed Blue Racer or similar cam from the '60s, is decent on the duration measured at .050 but way too wide when measured at .006. They're also ground on crappy old cores long before we had our oil changes a decade or so ago. The lobe technology today is just far beyond that old stuff and it'll show up in torque and manifold vacuum.

I know the price is attractive (which should be your first clue to look elsewhere ) but I'd look into either a Comp XE256 or a Lunati Voodoo 256.

You might want to PM Rollbar and see if Ashley is pleased with her Comp cam. If she feels like it should make a little more torque, I can tell you how to get there. If she's good to go... fantastic! Either way, both of those cams are about a light year ahead of those old, reboxed cams that Edelbrock likes to push.


Shawn
Makes sense Shawn.
How about some specifics in difference and performance between the two,
Elaborate a little...

How do they work with these old uneven intake runner and smog heads?
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Unread 01-02-2014, 03:53 PM   #8
swatson454
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Quote:
Originally Posted by JeepHammer View Post
Makes sense Shawn.
How about some specifics in difference and performance between the two,
Elaborate a little...

How do they work with these old uneven intake runner and smog heads?
I can sure try but I don't think the short version is possible.

Let's start with the actual valve timing and work stroke by stroke from there (save it, I already know )

We'll start on the intake stroke but while the piston is still coming up on the exhaust stroke. I know that might be confusing but that's where things start to happen. The Edelbrock 2132 that the OP mentioned opens the intake valve at 33* before top dead center or BTDC. At low rpm, that's a lot of time for the piston to push spent exhaust gasses back through the valve and into the intake manifold, especially if we're dealing with a restricted exhaust and there's back pressure making the piston 'push' the exhaust out.

A very important point on the lift curve is how much lift is available at maximum piston demand: usually around 72 to 74 degrees after top dead center or ATDC, depending on rod length. The 2123 cam listed is pretty low on lift, especially given the exceptionally long seat timing. That means the valve isn't open as much as it should be when the piston is wanting the most air flow. That's also a product of intake centerline angle or ICL but more on that later... maybe.

Next up on the intake stroke is the intake valve close point or IVC. The cam listed above closes the valve at 65* after bottom dead center or ABDC. Again, at low rpm, that is an awful lot of time for the piston to push the intake charge back up into the intake manifold. That reduces the manifold vacuum like no other as the next piston on the intake stroke just takes that instead of pulling air through the carb.

Now granted, these scenarios are rpm specific but I'm trying to stay within the confines of what most guys here are after.

Moving on to the exhaust stroke, the 2132 cam opens the exhaust valve at 78 degrees. That's a good thing. Higher compression engines build more combustion pressure than lower compression engines but they also dump that pressure quicker. Point being, on a low compression engine, the longer you can keep the exhaust valve closed and let the cylinder pressure continue to push the piston down, the better. Here's the problem, that's considered the least significant of the other valve events.

Here's where things get pretty important again. On that cam, the exhaust closes at 30 degrees after top dead center. Again squared, that's a lot of time for the exhaust to be open when we're back on the intake stroke.

Now, these valve points aren't bad if you wanted to take a 12:1 compression, 304 to 6,500 rpm but there's more to it than that. The duration at .050 and lift for the "advertised" duration is as weak as it gets, except for stock cams.

Take all that into consideration and then compare that cam versus how I would cam this 304. It would be a Comp Extreme Energy, hydraulic-flat lobe, asymmetrical intake lobe number #5441 and a symmetrical exhaust profile from the same Extreme Energy family #5207. Ground on a 106 lobe separation angle (LSA) and installed on a 102 intake centerline (ICL). 256/260 advertised duration, 212/212 at .050 and .477/.474 lift.

So how do the actual valve events look? IVO 26, IVC 50, EVO 60 and EVC 20. Now match those up with the valve points I mentioned earlier for the "Edelbrock" cam (IVO 33, IVC 65, EVO 78 and EVC 30),factor in much more duration at every point and total lift and you should see why a modern cam (especially when ground correctly) will produce more torque, more horsepower with better manifold vacuum than any of those old things.

The way *I* would cam it compared to the 'Edelbrock' cam, the intake valve would stay shut a little longer, open more quickly and further for the piston at max demand. The additional intake charge seen on the first half of the induction stroke would allow me to close the intake valve earlier and trap all of that goodness in the cylinder, as opposed to puking it back up into the manifold. That would give me the same dynamic compression ratio (DCR) at a lower rpm that you'd typically expect to see above 6,000 rpm. Think low-speed torque and throttle response.

The exhaust closing point and intake opening point (overlap triangle) when timed correctly with piston position, will make or break the torque curve. There isn't a whole lot we can do with aftermarket intake manifolds. Luckily, at the rpm we're dealing with here, it doesn't seem to matter much. This post could go on for days.

I hope that helps a little. There's so much more but I'm tired of typing


Shawn
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Unread 01-02-2014, 08:20 PM   #9
BeastOfBurden
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Reading this thread made me wonder why so many people that I show my 304 engine have a negative comment about the 304.
It is a great engine.
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Unread 01-03-2014, 05:32 AM   #10
JeepHammer
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Excellent explanation Shawn! Good stuff!

It's a talent in it's own right to be able to explain what's going on in terms that about everyone can understand, and that's a pretty good job you did right there!

-------------

As far as 50's designed engine, with some 60s materials making it up, it's not a 'BAD' engine...

When you compare it to 'Small Block Chevy', the Chevy oiling system is what keeps them alive for ever...

Small block Ford usually makes more power, but they don't have the longevity a Chevy does simply for lack of the oiling system.

My two biggest complaints about AMC engines was they didn't offer forged steel rods for the smaller displacement engines,
And they have a LOUSY oiling system.

Anyone that has had a few of these apart that died of natural causes, or had one on a flow bench or dyno can name a few other things, but those are the big two for me.

The cast crank will take over 500 Horse Power, just like a lot of the cast crank versions from other manufacturers.
The block has pretty good main webs, so the block doesn't splay out,
The block is pretty rigidly made, it doesn't twist like crazy like some engines do when you make horsepower,
And for a 'Smog' engine, the heads/combustions chambers are reasonable.

The rods are weak, like a lot of cast iron rods are, and the oiling system is horrible.
I spend most of my time making sure the back of the block gets oil when working on one for myself...
Getting oil passages to line up, getting some oil delivery to the back of the block (Looping),
And trying to get those factory front covers/oil pumps to tighten up so they make volume/pressure.

If you still have a LIVING engine, then it was drilled correctly from the factory and oil is getting to the rear.
Not large amounts of oil, since no AMC engine delivers large amounts of oil to the rear in stock form,
But it's would have shown up any defects in the last 27+ years...
So you are starting with a good 'Core', and that's usually the biggest hurdle in getting a reliable engine.

Pay attention to care of the rods, and getting the oiling system in so it makes volume/pressure and can deliver it to the back of the engine and it will live for another 27+ years or more.
It's no power house, but it will move a light weight CJ around pretty good, and it won't break drive line parts in most cases, so the 304 is a pretty good balance between power and longevity of the vehicle.
We all know RUST usually kills CJs before the engine gives up, so that should tell you something!
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Unread 01-03-2014, 05:53 AM   #11
JeepHammer
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Shawn, that single post should be a 'Sticky' for anyone looking for a camshaft...

You address the two things I think are most important for CJ owners,
Operation RPM (Idle to lower end of 'Mid-Range' for most 'Racing' camshafts) and lower compression engines.

I used to get so sick of people dragging in 'Racing' camshafts for street driven engines that were going to be daily commuter vehicles it wasn't funny...
You install THEIR parts, then they have 'Issues', and you get the blame!
(They read an advertisement or saw it in a magazine somewhere and just HAD to have it!)

Please, when you have time, elaborate more, I'd like to see it.
I don't keep up with camshafts these days, I'm pretty much stuck with slapping down alligators when they pop up in business instead of being in the shop where I'm most comfortable.
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Unread 01-03-2014, 05:57 AM   #12
matt1980
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Thank you all for the info, I have not bought any parts yet and the cam is not something that I had put a lot of thought into, just figured that using the edelbrock stuff that was suppose to be matched to work together would be fine. Again, thank you for the info, I am sure I will be back when it is time to assemble this motor.
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Unread 01-03-2014, 07:50 AM   #13
swatson454
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Thanks, Hammer. If anything, I need to expand on *why* opening and closing the valves at those points is bad at low rpm. As you can see, this subject doesn't really allow for the short and sweet version


Shawn
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Unread 01-03-2014, 09:50 AM   #14
JeepHammer
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"Short & Sweet" doesn't teach anyone anything...
Sharing information is what this forum should be about, not worrying that someone casually looking through threads will get 'Bored'...

They want to be 'Entertained', there is always 'You-Tube'... Nothing like endless mind numbing crotch hit videos.
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Unread 01-03-2014, 10:08 AM   #15
swatson454
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Quote:
Originally Posted by JeepHammer View Post
"Short & Sweet" doesn't teach anyone anything...
Sharing information is what this forum should be about, not worrying that someone casually looking through threads will get 'Bored'...

They want to be 'Entertained', there is always 'You-Tube'... Nothing like endless mind numbing crotch hit videos.
It wasn't so much about keeping someone entertained as it was getting my lazy arse to do it. I'm having a little trouble getting my brain out of neutral lately. Perhaps you're willing to share some of that Jack Daniels


Shawn
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