Gentlemen, I need your wisdom or.. your madness for this 360

[toolong]

I'm new into the v8 Amc world, so I prefer to ask you how to do it.
I want to replace my very tired 258 by a 360 into my scrambler; why a 360? because,where I live 401 are really really rare. :smile:
My jeep has 35' Mtr, 4.88 diff gears, D300, NV4500 with 6.34 1st. I use it as a mild rock crawler,Rocks are not that huge here, in sticky mud, and a bit of sand plus the usual road trip indeed, but I don't use it for work,and to be honest, I wouldn't be against blowing some doors of :t: So torque is the go, but I like horses too, have cake and eat it too....
Here what I tought:
Head: stock 323344 but polished 2.08 & 1.68 valves with 11/32 stem, I like to put some HarlandSharp R/rockers #sv4004
Cam: Comp #A 252H or 270H
Piston: Well!! I dont really know,I aim for 9.5to1, but not many piston are available
Fuel & ignition: Edelbrock efi
But wait! the sticky point is : I wish to retain the stock exhaust manifold, because of the heat under bonnet :shock:
Ok what do you think?? if someone can Desktop this setup,I would be really happy. :!:

[Goose]

Well I will only make one suggestion.. you can achieve a greater heat reduction under the hood (Umm sorry, bonnet) by using a heat wrap on a the headers.. and get more performance..as to the build.. I will be quiet..vewy vewy qwiet..

[toolong]

Thanks Goose, maybe I should go for headers, and punch some louvres on the bonnet,hoops!! the hood! I'm just asking all this, because after reading all the posts, I have like an overload of informations, anyway, thanks for your input

[jeepsr4ever]

Well if your crawling you really want a over glorified RV camshaft. Now you can run a MPEFI from Edelbrock or a howell or holley injection system. The power will come from the MPEFI from edelbrock. I would run a mild camshaft (not a 270H that is a little large for the crawling) and a 252 is a real wimp. If your thrifty Summit's K8600 is an awesome RV camshaft and very inexpensive. You can look at many other cam mfg's as well. I would run a extra capacity pan and do some simple things like smaller hole cam bearings and/or smaller hole rocker arms to keep that crank oiled. Run a roller timing chain and if you really want to get exited try taking your heads in for some mild gasket matching and valve unshrouding and you can gain a little on the higher end without suffering too much low end loss. I love the 360's just as much if not more than the 401s

[toolong]

Ok, I'm going cam hunting again, by the way, I noticed when crawling that my rpm where often at 1200 or a bit more. And with deep gear it's easy'er' to rev.
MC do you have a special email for your shop? As I have lot of questions and demand for you.

[AMX69PHATTY]

Hello Down Under :sa:

The readily available AMC 360 stock replacement cast pistons have an
approx. 29cc dish top and a 1.581 compression hieght which is .020 shorter than stock.

If you are after 9.5:1 compression this can be achieved with these pistons
if you mill the block deck .020 to achieve 0.000 deck clearance
and mill the heads enough to get a 48cc combuston chamber.
For AMC Heads, .001 mill reduces the combustion chamber by 0.16cc,
with stock open chamber 58cc heads, they would need to be milled .063,
which is quite a bit but can be done, and provides NO allowance for unshrouding valves.
It's easier to get the 48cc chamber if you start with 1970 51cc heads, but those are hard to find.
They could even be 1970 304 heads, the valves are smaller , but the runners are the same .
Otherwise you are going to have to get custom pistons, or use Chevy Pistons.

Of course there are many things that can effect this scenario.
Rods shortened by re-conditioning, chamber rework, etc.
Optionally, rather than milling the block deck .020, only mill it .010,
and have the crank offset ground .010, which increases the stroke to 3.46.
Whichever approach is taken, the Intake Manifold would also have to be machined to fit properly.

A lot of variables are involved, but close to 9.5:1 can be achieved
using available cast ~29cc dished top pistons with a little creativity.
An assembled deck clearance of 0.000 is a good feature to have in any combination.
If flat top pistons areused then the combustion chambers must be opened up considerably.
If you can find an old AMC 343, they have cast flat top pistons same bore as an AMC 360.
Of course those would be standard bore size, but loose motors run good :mrgreen:

Not sure about thier reputation, but MadDog - Fast Engine Parts may have cast flat top pistons for the 360.
They are in Florida USA 1-800-792-9984 and use eBay a lot.

Enough to chew on there mate ?

:t:

[toolong]

Er..... yes a lot to shew on! :-| , I know few guy who are using 400 sbc piston,and tought that's wrong!, but I understand why now!! Yes I was really tempted by the 343 ones as I know where to find a set, but bad luck, standard size, and I need to rebore .30.
I dont know if even I use 343 piston I can enlarge the c/chamber enough to go down 9.5 to 1? What do you think?
I'm going to contact Ross to know a bit more about their pistons.
Thanks for your ideas.

[AMX69PHATTY]

If 3cc is used as the valve relief volume in the 343 flat top pistons,
a stock compression hieght of 1.601 instead of the 1.581 of replacement pistons,
and destroke the 360 crank by offset grinding -.010 for a 3.42 stroke,
which results in a .022 deck clearance, assuming no deck milling,
the c/chambers would need to be increased to 68cc to get 9.5:1 compression.
If the Connecting rods are shortened by re-conditioning, the c/chamber could be smaller.
Also, AMC 390/401 connecting rods are shorter, 5.858 vs 5.875, if you can find a set.
If they are used, .039 deck clear, needs 65cc c/chamber for 9.5 cr.
By destroking or using the 390/401 rods, the piston being .022-.039 below the deck surface
is less than optimium for quench and avoiding detonation.
Ross forged piston are kinda pricey, and forged pistons have thier drawbacks,
like a piston/bore clearance of .006-.009, and having to let the motor
thouroughly warm up before squeezin' hard on the go pedal.
Another option would be to O-Ring the Block and use thicker Copper Head Gaskets which are available.

The stock rods, 3.44 crank, replacement cast pistons, 1.581 CHt, 29cc dish,
58cc heads milled .033" resulting in 53cc with no c/c rework,
and milling the deck .033" to 9.175 to get get 0.000 deck clearance,
would result in a c/r of 9.08:1. This may be a cost effective option.

[toolong]

:smile: Why haven't I chosen a Sbc as my friends advised me ????
Nope!!, I am going to persevere! so back to the calculator and e-store.

[AMX69PHATTY]

SBC !?!! ........... that is that cheap shat .... er ...... stuff :?:

For the "cost effective option" mentioned above using stock parts,
if you're going to have the Crank turned, ground, and polished,
you could have it offset ground like +.010 and this would result
in not having to mill the block deck as much, would yield a few more cubes,
and would also bump compression a little bit.

If you use SBC Valves, and mill the deck and heads, you'll need different length pushrods.
I have 2.02/1.68 StnStl SBC 11/32" stem valves in the heads on my motor.
The head valve spring seats were machined for 1.46" dia. Double Valve Springs.
Crane offers Double Springs, Retainers, & Locks that work out very well.
I think they are actually BBC pieces, 1.46" dia, 1.875 installed Ht, 120 lbs closed.
Crane Part Numbers: Springs #99893-16, Retainers #99953-16, Locks #99097-1
I prefer the Machined Valve Locks over the stamped steel ones.
My Hydraulic Cam is identical to a Solid Cam Crane offers #861201 which they spec these Springs for.
Cam Specs - .512/.533 lift - 238/304 In - 248/314 Ex - 112 Lobe CL.
Not saying this is the cam ya need, just that those springs can handle that much.

While you're at it on the crank, have it crossed drilled and chamfered.
Be careful on the rear most journal cross drill,
that it does not intersect the pilot bushing passage in the crank butt. :?:

[toolong]

About valves I had the same idea, SBC valves like ManleyS/S 2.08 & 1.68, .3415 stem and profiled for a better flow, looks good.
For the pistons I found at flatlander a set of 400 chev with 15deg valve pockets, and a c/h of 1.425, I must admit I haven't done the math yet,but maybe, by as you said, milling and grinding I can go somewhere.
Thanks again for your help

[tufcj]

One problem I've heard of with SBC pistons is that if they are cut for valve reliefs, they won't be positioned right for AMC. You need to get them uncut, or specify placement when they're made to have the reliefs in the correct position.

Bob
tufcj

[toolong]

:(: OOOOHHH !!! crap, always something to p..... you off
Thanks Tuffcj, back to the drawing board.. again. ](*,)