Cylinder head rebuild project

[WrenchMonkey]

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.

[SC/397]

Cast valve guides for a street engine.
Stainless valves are nice.

http://www.ebay.com/itm/AMC-Jeep-304-343-360-390-401-Stainless-550hp-intake-exhaust-valves-16-1-4-gr-/170799947420?hash=item27c4785e9c:m:mLHIR3BPUP-MK-EBZrTkY9Q&vxp=mtr

Scorpion Roller Rockers are my preference.

https://www.summitracing.com/parts/scc-scp1097bl

[WrenchMonkey]

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

[babywag]

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.

[WrenchMonkey]

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.

[babywag]

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.

[SC/397]

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.

[WrenchMonkey]

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-...l+mount+rocker
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

[yossarian19]

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.

[WrenchMonkey]

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/sum-k8600/overview/make/american-motors

Well reviewed cam and lifters for 120.

[440sixpack]

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.

[Ristow]

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.

[babywag]

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.

[mattmopar440]

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

[79 Wolfpack]

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.