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  #1  
Old 06-12-2017, 10:04 AM
WrenchMonkey WrenchMonkey is offline
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Cylinder head rebuild project

I know a bit about porting and polishing, less about the technicalities between bridged rockers, flat tappets and the like. I finally got myself some heads and it's time to build them up. Since replacing the heads is such an undertaking in and of itself I plan to replace the cam shaft while I'm at it.

So, suggestions, recommendations for valves, roller rockers, guide rods, valve stems, and cams much appreciated. For now I'm about to put them in a big plastic tub full of lye for about a week... I happen to have plenty left over from project de-anodize the grill... lol

I should add these were 360 heads with bridged rockers being built for a 360 block. I pull up the casting number when I get back from class.
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Old 06-12-2017, 10:22 AM
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SC/397 SC/397 is offline
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Cast valve guides for a street engine.
Stainless valves are nice.
http://www.ebay.com/itm/AMC-Jeep-304...rTkY9Q&vxp=mtr
Scorpion Roller Rockers are my preference.
https://www.summitracing.com/parts/scc-scp1097bl
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Old 06-13-2017, 07:28 PM
WrenchMonkey WrenchMonkey is offline
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Images





So, the casting appears to be 3231475-2 which makes them correct to the Chiefs model year, 1978, with intake valves 2.025" and exhaust 1.68" and 57.92cc

compared to my current early 1972, 58.92cc, intake 1.787 and exhaust 1.406 this should be an improvement (although the bridged rockers are not desirable).

SC/397 you say cast valve seats but what material? I've seen on one AMC hotrodding forum that bronze seats clearanced rather tightly for "sbc style" valves appear to be the cats meow.

stainless steel is a nifty material but is there any benefit to going stainless with valves? They are going to be coated in oil/gas anyways so rust isn't a particular concern, I'm curious what the advantage is.

Those scorpions are a little pricey for me
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Old 06-13-2017, 08:07 PM
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babywag babywag is offline
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the guides aren't a seperate deal on stock amc heads. When he says cast he meant cast iron, same material the heads are made of. They're just machined to accept the valves.
If you want new guides the heads will need precision machining for them.
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Old 06-13-2017, 08:34 PM
WrenchMonkey WrenchMonkey is offline
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Ah, that makes something else I was reading about make much more sense now.

Good lord, looking at the pricing just for head bolts is making me wish I had just kept the factory ones! Granted the engine currently has some, reusing bolts is frequently taboo in certain places and I reckon the cylinder head is probably one of those, thoughts?

Been looking at parts and what not and the more I look the less amused I am. The price seems to have no limit, and while a hot rod cam would be nice the difference between oem pushrods and +150 pushrods is a good 70+ dinero..

I can see why the appeal to just hand it to a machine shop and pay out the ass for them to handle the particulars is strong in many guys. But I've told myself if I want that other jeeps body I need to not spend too much money on these heads. I want new valves and springs, I need new pushrods, rockers, studs, valve locks and potentially guide plates? Some sources say they are needed, others not so much...

Since so much work is going into this already replacing the timing chain and camshaft seems worthwhile but I'd like to keep all of this under 500 and that seems to be an extraordinarily unlikely goal even without the camshaft.
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Old 06-14-2017, 07:37 AM
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stock new parts will be fine and relatively inexpensive.
when reading amc hotrod stuff, generally they're building for a higher reving car engine, or something that's going to hit strip.

with a $500 budget I don't see any valve train goodies being a reality.
I've reused head and other engine bolts many times on these.
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Old 06-14-2017, 07:51 AM
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It is rare that I don't re-use the stock head bolts. Find a set of of epay or I may even sell you a set if you get desperate.
If you are going to use the bridged Scorpion rocker arms, you do not need guide plates. The rocker arms are secured in channels which keeps them from moving around. sbf has a similar set-up.
I like the stainless valves because they play nicely with the hardened valve seats in the cylinder head. There is nothing wrong with the stock valves if you don't want to spend the money. Obviously, they would have to be checked for valve stem wear and have the normal valve grind done to them.
I would recommend that you have the heads machined for positive valve seals. Even the nylon seals on the FelPro gasket kit sometimes don't fit snug to the valve stem.
Like babywag states, you probably won't be spending money on roller rockers or new push rods on a $500.00 budget. Expct to pay $100.00 of that just for gaskets.

Last edited by SC/397 : 06-14-2017 at 08:27 AM.
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  #8  
Old 07-01-2017, 10:30 AM
WrenchMonkey WrenchMonkey is offline
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I'm back from my crazy vacation and it's time to get back to cranking on this mofo. The "new" heads have been sitting in a (relatively dilute) lye bath for almost two weeks and should be ready to see the light of day again.

I already have head gaskets, in fact somehow I have two sets.

Considering that I should be able to use the bolts from the cylinder heads that are currently on the block that's 133 bucks saved from buying the full set from ARP.

I've just ordered the stainless valves for 90, so I'm looking at roughly 400 to spend on roller rockers, springs, pushrods, lifters and maybe a cam.

Pushrods look like I can find for around 60 but some cams require .150" over length and that pushes the price for rods over 100 bucks apparently.

I know it's idealistic but there are some rockers out there from reputable people for less than bend-over-and-take-it money, so I'm looking for advice given whats available. https://www.amazon.com/Competition-C...rocker+arm+amc seems like a decent set but I'd need machine work..

or https://www.amazon.com/Cams-1210-16-...mount+ro cker
these seem to be a "better than stock" option that can handle "high energy" camshafts and "Features a long slot for higher than stock lift camshafts"


Another option is cannibalising the old 304 heads for their stud mounted non-bridged rockers and paying the machine shop to mill and drill for studs on the "new" heads (since I'm probably already going to be making friends getting them machined for valve seals). This probably isn't the best solution but they are certainly the prefered rocker style...

I'm not looking for a crazy camshaft, just something that offers a bit more low end torque, nothing with insane lift or that would compromise reliability. Such things seem to exist and I'm not really counting it in with the price of the heads. Looking forward to y'alls advice/input
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  #9  
Old 07-01-2017, 02:11 PM
yossarian19 yossarian19 is offline
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If you are doing a cam & lifters, that's at least $120 spent. Figure springs are going to be another, what, $100? $180 left for pushrods & incidentals.

You *could* buy a set of Scorpion 1.7 ratio roller rockers for $300 at Summit, requiring no machining and bringing your valve lift from .457 " to .486 ", with a bump in duration as well (duration @ 0.050" will increase, the lobe profile won't change)
I don't know in real world terms what to expect from this on an AMC, but I have read dyno articles where a bump from stock to 1.6 ratio netted an SBC 24 horsepower. For $300 and very little hassle, that isn't bad.
It seems like a mod. that will benefit an engine that is limited by camshaft and not so much benefit an engine limited by it's cylinder heads.

I'd look at Rockauto.com or Summit Racing for parts, your estimate on what pushrods will cost sounds pretty high to me.
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Old 07-01-2017, 08:52 PM
WrenchMonkey WrenchMonkey is offline
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I detest summit online purely because their god damn "unusual activity detected" BS. Evidently browsing and opening more than one window is suspicious.. there website is a pain and thus I avoid it (despite loving them as a company).

But you have made me take a look at those scorpions again...

Here's the catch all, far as valve trains are concerned I'm a complete newb. I've never built one, I know enough to replace parts but otherwise I'm at a loss with a lot of this stuff. For example, I understand why 1.7 is "better" than 1.6 but I don't know how to figure out what the lift would actually be at 1.7, nor how much is too much, ect. I know the factory pushrod length but I don't have a damn clue how long the pushrods would have to be with a 1.7 rocker. I don't know how much spring pressure I'd want/need, what angle keepers to get, ect ect ect. This all seems to be a level or two deeper than I've dealt with before. I don't want to make stupid mistakes and I'm really good at doing that, so if y'all could dummy proof the whys and wherefores I'd really appreciate it.

It seems to me that fancy rockers are pointless without a good cam... and therefor I may ignore the budget ideology and allow this project to take a longer amount of time as a result...

https://www.summitracing.com/parts/s...merican-motors

Well reviewed cam and lifters for 120.
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  #11  
Old 07-01-2017, 10:50 PM
440sixpack 440sixpack is offline
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You'd be better off to stick to pretty basic stock stuff if you want to build a dependable street engine.

One thing leads to another when you start modifying things like rocker geometry. now is the time to decide what your goals are and how much you want to spend .

To answer your question, you won't know what length pushrods you need until everything is in place you're ready to install them. that's why they make custom push rods for performance builds. adjustable rockers or spacers under bridged rockers will let you cheat a little to set your preload. but to maintain geometry customs may still be required.
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  #12  
Old 07-02-2017, 06:56 AM
Ristow Ristow is offline
 
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the 8600 is about the worst cam made for an amc. i've built several of these motors,ive used a handful of cams,including that 8600 pos. that was the only cam that sucked so bad i took it out to swap in something else.

i wouldn't use that pos if they paid me 120.00

1.7 rockers work well. you will want better valve springs for the accelerated open/shut speeds.
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  #13  
Old 07-02-2017, 08:37 AM
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for lift it's simply multiplied by rocker ratio
take lobe lift x 1.6 or 1.7

Get an "rv grind" cam, Melling MTA-1, Elgin 912, same as Edelbrock performer w/o inflated price tag.

With $400 budget, skip fancy rockers, can always do them later.
The bill on your head work alone is probably going to exceed your budget.
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Old 07-02-2017, 09:41 PM
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Quote:
Originally Posted by Ristow
the 8600 is about the worst cam made for an amc.

100% agree I rebuilt the 401 mike game me after it had a lunch of bolts out of the air cleaner and changed out the cam in there and it lost a huge amount of low end power
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  #15  
Old 07-05-2017, 08:59 AM
79 Wolfpack 79 Wolfpack is offline
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I have the 8600 in my 401 ,with all stock valve train .

It is a little doggie under 3000 rpm . But high rpm power is good.

It works good for me with a t18a 4 speed manual.

I would not recommend it with a automatic and low compression.
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Old 07-11-2017, 05:55 PM
WrenchMonkey WrenchMonkey is offline
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Generally speaking I don't like to half-ass anything... it's whole-ass or nothing...

but given the circumstances I'm already going from 304 heads to 360 heads and that in itself should be a considerable upgrade. I'll be going a little of my own port matching work to smooth out airflow, I've got new stainless valves, new seals, I'll need to order keepers and pushrods..

so the couple things still in the air are, 1. rockers: can I reuse the current rockers? They've got 150k+ miles but I hate to get "new" parts if I plan on upgrading later anyways.

2. Lifters, can I reuse the lifters currently in the engine or is it worth it to upgrade? These are significantly more affordable than the rocker options so it's not a big deal if I get new ones, any particular recommendations for a mostly stock valve train?

Speaking of valve train, is it possible on these engines to replace the cam without removing the heads? Seems to me you should be able to pull the intake and rods/lifters, waterpump and bobs your uncle, am I missing something? Cause if it can be done then I can stop worrying about the whole logic of "since I'm already going to be waist deep in the engine I may as well..." and put it off for another time without stressing that I'll have to "re-do" all the work again at a later date to upgrade... your thoughts are much appreciated.
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Old 07-12-2017, 05:22 AM
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but given the circumstances I'm already going from 304 heads to 360 heads and that in itself should be a considerable upgrade. I'll be going a little of my own port matching work to smooth out airflow, I've got new stainless valves, new seals, I'll need to order keepers and pushrods..

That all depends. The 304 heads could very well have smaller combusction chambers which increases compression ratio. Also, some say that the smaller 304 valves in a 360 will increase low end torque. - I have never proved this out though.

so the couple things still in the air are, 1. rockers: can I reuse the current rockers? They've got 150k+ miles but I hate to get "new" parts if I plan on upgrading later anyways.
It depends on if they are wore out or not. Inspect everyone carefully.

2. Lifters, can I reuse the lifters currently in the engine or is it worth it to upgrade? These are significantly more affordable than the rocker options so it's not a big deal if I get new ones, any particular recommendations for a mostly stock valve train?
It depends on if they are worn out or not. If they are wore, throw them away and buy a new set along with a new cam. If they are pristine, keep them in the same order that you took them out in. Post up pictures.

Speaking of valve train, is it possible on these engines to replace the cam without removing the heads? Seems to me you should be able to pull the intake and rods/lifters, waterpump and bobs your uncle, am I missing something? Cause if it can be done then I can stop worrying about the whole logic of "since I'm already going to be waist deep in the engine I may as well..." and put it off for another time without stressing that I'll have to "re-do" all the work again at a later date to upgrade... your thoughts are much appreciated
It's possible. Don't forget there there is two bolts going in to the timing cover at the front corners of the oil pan. It's not fun putting the timing cover back on with the oil pan on. You have to compress the little gasket tabs at the same time you are trying to get the timing cover to align with the alignment dowels. When you put it all back together don't forget to prime the oil pump.
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Old 07-12-2017, 03:02 PM
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Woodchomper Woodchomper is offline
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One more thing to consider when replacing the cam is the cost of a new timing set and if you decide to do it, the cost of getting the needed tools to degree the cam.
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Old 07-12-2017, 06:30 PM
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My '90 is potentially getting a set of early non-bridged 304 heads w/ larger valves, if they check out ok.
I have 'em so gonna use 'em if good, if not well then guess need rebuild the 360 heads that aren't so good.

There are sites that allow a custom printout of a degree wheel.
If you have a printer cost is minimal to print one to degree cam.
Allows for entry of your specific cam specs.

HF sells dial indicators and reviews state very accurate.
I had one few years ago, but dropped it and broke it.
Got job done very reasonably.
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