Throw me some ideas! Low budget 360 build

[SlantSixSullivan]

So.. I tore apart a 360 LA to get ready for a swap into my old Valiant, and that went by the wayside when the car was totalled. Now that I have the Diplomat, I'm finishing what I started. ANYWAY... What can I do to make this thing giddy-up-and-go? I have a mild 340 cam to put in, and other than that? Basically just going through the engine and checking that everything is good. What can I do to wake this thing up, with a relatively low cost? I was thinking thinner head gaskets to increase compression, but would it be worth it? Headers and no cats, obviously. No bore/stroke.

 

[BudW]

There is three (3) things needed an internal combustion engine needs to run: fuel, fire and compression.

Four (4) things needed for an internal combustion engine to run better: more fuel (in correct proportions), fire, more compression and lots more air flow.
More air flow = more power (a direct proportional effect).

The first couple of questions are:
- Your budget
- Overall plans with car.

Once we have those two “guidelines:” the rest (should) fall in line.


I have never been one to rev a ‘60’s, ‘70’s or ‘80’s engine very high – unless car is set up for strictly racing (yes – I know others disagree – but this is my opinion on the matter). High RPM’s generally = (equals to) a lot more money spent (better flowing heads, etc.) and ultimately, the car is less streetable.

If car will be driven primarily on street and is more of a daily driver - than low end torque should be your goal.

Worn, as well as stock, camshafts is always a good place to start – just make sure if fits your build and your cars objective. Tossing a camshaft in, by itself, will be disappointing.

4 bbl setup or even better, a “4 bbl appearing” fuel injection setup.

No comment on 360 exhaust manifolds vs. headers, for now. That topic requires another thread.

There is no replacement for displacement. A stroker kit which would add 40-50 more cubic inches would be my number one recommendation. Most pulleys and engine brackets will work as is.

Higher compression ratio – one that fits the fuel you plan on using. These engines never have liked low compression (a result of meeting emissions). That might be fixed with stoker kit – if that is a direction you are going.

Magnum cylinder heads.

Stick with the 999 automatic transmission (has better gear ratios, which you want).

Install a 2.9 or a3.2 gear ratio into the rear differential. Note: if you are planning on much performance modifications, then you might want to obtain a lager rear differential first (8¼” or larger) , and have it under the bench for now. The stock 7¼” will handle things well to a certain point. After that point, you going to take off and leave a 200 foot path of oil and differential parts.
Getting rid of the current 2.2 or 2.4 ratio will do wonders – unless you drive a lot.

---

Back when I picked up my own 5th Ave (M-body), I had looked into installing a 340 (had talked my brother out of his 340 – which I later returned, unused). Then I was thinking about no replacement for displacement. You can get a 360 to run just as well as a 340. Then I purchased a couple of 360’s to perform a project very similar to your goal (which both still reside in my garage along with a police 318 engine).

I was going to go the stroker route with a “mild” camshaft to make car more streetable.
Note: I have to make the car where wife will be able to drive the car - without any objections.

I then got a thinking and continued with the “no replacement for displacement” thought. I also looked into costs to get a mild stroked 360 engine built and installed and said, why settle for 400 ci and why not shoot for a mild 500 ci – with a peak torque targeted at 1800-2500 RPM.
It will be a lot more work, but I think once done, I will have a “higher grin factor”. Budget will be a bit higher – but it will keep me in my garage longer (a goal of mine) and the sense of doing it the way I want it to be.

Still in the process of hunting/gathering parts for that transformation. Actually, I’m gathering parts for both projects (building both engines together, etc.) – but unsure about proceeding with same procedures for my wagon (I was thinking 500+ ci auto for the 5th Ave, and 500+ ci 5 (or 6) stick speed for the wagon – both built for daily driving).


Now I have another dilemma to figure out, before projects are completed. My ’86 5th Ave is currently a great winter vehicle. You have to work hard to spin the tires on ice, even when driving uphill – so it has been a great winter vehicle for me – which I don’t think will be, after the displacement increase.
I may have to find another M body add to my fleet, for winter usage.

BudW

 

[MiradaMegacab]

Blower

 

[Dr Lebaron]

Instead of all that block weight on the front, a cop Pentastar 6 and some hair dryers.

Bonus, they run easily on today's crap gas.

 

[kkritsilas]

I'm pretty sure that a Pentastar 6 and twin Turbos don't fit the "budget build" part of the desired end result.

 

[lowbudget]

Budget port the heads. Our sister site FABO has some great how to threads.
Up the compression by decking the block, new pistons or shaving the head.
Gears.

 

[AJ/FormS]

While Buds suggestions are on the money,
I would drop it in,stock, and gear it up. More gear in the back is the quickest way to grins.
A really nice starter gear of 8 to 9,is good for about 50 mph at redline. Add a 2600 to 2800 TC and you will have fun for years.
If you have an A999 with a 2.74 low gear then the gear of choice would be about 8.85/2.74=3.23s would be the place to start.
But if you have an A904 with a 2.45 low, then you need to start with 8.85/2.45= 3.61s; so 3.55 would be the starter rear.
You can try the teener TC, but I think it won't be long before you will be wanting more, so before it comes out,perform a stall test on it to see what you didn't like. Then run the car up in about 5mph increments and do a flash-stall, to find out what stall your fire-breathing Dragon wakes up with.
I, on the otherhand would start with a minimum a starter gear of 10 to 11. This will be 2.74x 3.91=10.71. Unfortunately this gear requires about 8400rpm to hit 60mph in first, so for you a shift is mandatory. But if you have never had a 10.7 starter gear, you will nearly die giggling the first time you blast off with them!
For a city car, I like to gear them to be able to hit 50mph at shift-rpm. The stock 2bbl 360 cam, with nothing more than adequate spring pressure will go 5500 easy enough.At 50mpg,and 27" tires, this requires a starter gear of 8.85. So the above math works pretty good.
The shift rpm is not an arbitrary number pulled from a hat.The combo will determine it.
If you put that 340 cam into a stock 360,with less than an 8.85 starter gear and less than a 2800TC, I fear you will be disappointed. So if you insist on it, then at least get the TC right away. That 340 cam will also need the matching springs,and the matching DD rockers, and then the shift rpm will move up some 500 to 700rpm or so. This will probably get you 55 mph at shift rpm.Conversely you could throw a lil more gear at it and then maybe a lil less stall.I'm thinking 10% more rear gear and 10% less stall.So the math works out to a 9.74 starter gear and a 2600TC. That 9.74starter could be a 2.74 low and 3.55s, Shazzam! It's funny how those 3.55s always seem to pop up.
These 3.55s will get you 65mph = 2867rpm locked-up, with 27s.
But I wouldn't change the cam at all, unless a compression increase was done at the same time.I'll tell you this; a very low compression 360 with a 340 cam,and 3.55s will be a pig on gas. So get a second job for gas-money,lol.

 

[SlantSixSullivan]

My plans for the car are seasonal, of course, as I live in the rust belt and would prefer to keep it in decent shape. So I'd be driving it every other day or so, through spring, summer, and fall. So reliability is a concern, as well as overall comfort. I don't want to go crazy, just something fun to drive around. I will say this; I have a mild 340 cam, and the plans are to use an A904 with B&M shift kit and an 8 1/4 Sure grip rear end with 3.23 gears. One thing I did not take into consideration was the converter, which AJ/Forms mentioned. That will make a difference. Of course, I will be cleaning up the motor and reassembling it, basically from the heads up. So a head port job will more than likely take place. I considered stroking the 360 to 408, but I am on an even tighter budget than that. So it will stay as is. Thanks everyone for the advice!

 

[AJ/FormS]

If the stroker kit costs the same as porting,pistons,a crank clean-up,machining on multiple parts, and a TC,etc, ......... I would pick the stroker. This is for your application. The kit even with virgin big-port heads, will far out-perform the combo you just outlined. Putting in a 408 over a 360 is the same percentage increase as going from a teener to a 360,namely Plus 13.3%. And most of us have experienced that torque increase! But the stock heads will pretty much be at their stock limit with a 340 cam, so don't get greedy. Besides, as a streeter, you will never need more cam with a 408. That bad boy will already cost you a lotta suspension upgrades, if you wanna harness it for 60fts. And only a bit less if you like to go quickly from say20 to 50.
The 340cam into a 360 will need upgrades too. Starting with an 8.4 compression ratio, the Dcr will come in at about 6.67/126psi. This will make about as soggy a take-off as a tired teener.And the midrange will also be weak, and by the time the engine wakes up, it will be time to shift.
But not all 360s can make even 8.4Scr.
If you intend to use that 340 stick, you are looking at a big compression change.Ima thinking it will want about 10.5 with iron heads, and a tight squish. This is more than just pistons. Also that cam will want new springs to keep things together, and that usually means HD rocker arms, or risk punching the pushrods through the little cups. So this is starting to add up.
Do the math,pick your poison.

 

[BudW]

AJ/FormS shows that it is all about the math – which it is.

3.23’s is maybe the best overall gear ratio made (in my opinion – it fits most people’s needs nicely).

3.55’s will make you grin a lot bigger, though, and will make those trips to get grocery’s a bit more likely. It is a great city only use gear.
Have to drive between towns or on the interstate (?) then those trips become less frequent (not nearly as fun).

Tossing a camshaft in, by itself, will be disappointing.

I mentioned this early on. I don’t want to stop you, by any means, but there is more to the story and a camshaft is best for a certain set of perimeters or otherwise it is making a square peg to fit into a round hole.
Compression, air flow, gears, converter, vehicle weight, intended purpose, street OR strip, etc. all have a big influence on camshaft selection (as well as another dozen or so items).

Man, I wish installing a 340 camshaft into my 318 would fix things – life would be so easy.
It can work, but not without changing almost everything first.


By the way, I highly commend you for asking first. Granted humans learn more the hard way, but in my opinion, it is less expense on you, to learn from our mistakes (or trials, or whatever you want to call it).
BudW

 

[AJ/FormS]

OOPs, I missed the part about "from the heads up".
I guess that means the short block is not coming apart?
In that case, forget the stroker. But forget the 340 cam Too. And if you are not going to extend the operating range of the engine,nor boost the compression,then there is almost no point in porting the heads.So then we are back to my first post,#7 above; namely put the 360 in as a stock item, with just a set of valve springs to safely allow a 5000/5500 shift rpm, and then gear it for fun; like minimum 3.55s, with a 2.45low tranny.
The 360 2bbl cam will take an 8.4 engine down to about 7/1 Dcr and 135psi cranking cylinder pressure.To be sure this is no powerhouse. But check out what the 340 cam does to it. From post #9 we got 6.67/126psi. That's way soggier than the 2bbl cam. The numbers don't seem that much different, but they really are. If I was gonna leave the engine alone, I think I would sooner put a teener cam in than a 340 cam. The 240/114 teener cam will pull up the bottom end to 7.33/143psi, now we got some off-the-line giddy-up.Let me stack 'em up for you;
...340 cam...6.67/126...soggy off the line,needs TC and 3.55s
...360 cam...7.06 /135...normal
...318 cam...7.33/143...snappy with stock TC and 3.23s
Of course each successive cam will pull down the power and torque peaks, but all will pull 3.23s to 50mph. However I doubt the 340 cam will make up at the top, what it loses off the line. And I doubt the teener cam will slow down at the top,enough to negate the strong off the line surge.
And where is like 80% of your city driving? That's right zero to 35 mph. So for me it would be teener cam, 3.55s and a 2400ish TC,like the teener TC will be with the added 42cubes of PercheronPower. You will have that 7.25 split open in no time.

 

[BudW]

I’m no expert on the longtivity of his existing 7¼” differential, but for a 360 4 bbl and stock camshaft and low compression – I think he will be fine, but I would emphasize on finding a 8¼” (or bigger) and at least have it under the bench – just in case.

Also, finding gears for the 8¼” is easier (a notch above "hard to find – but is out there"), than finding much of anything for the 7¼” (“you’re looking for a WHAT?”).


I was messing with camshafts, for fun, thirty years ago – before I even heard of DCR (Dynamic Compression Ratio).
SCR (Static Compression Ratio), I did know about and was easy for me to figure out/how to calculate.

I first heard about DCR a few years ago – which answers a lot of questions and proves a lot of theory’s I had from thirty years earlier – but just wasn’t thinking on that level (of not building compression until valves are closed).

The math is there – and it’s all in the math.

 

[AJ/FormS]

There is,or was yesterday, a 8.25-SG for sale right here on FABO. A fresh reconditioned unit. Case only. Get while you can

 

[SlantSixSullivan]

I was fixing to ask about DCR, but looks like it has been answered

 

[SlantSixSullivan]

I'm assuming "teener" refers to 318? I may have a cam in that case, from a 318. So what I've gathered so far, is leave the engine alone pretty much, except for maybe a 318 cam instead of a 340? And gear it with 3.23s, so I can still use it on the highway. The reason I want to use a 904 is simple: it's less tranny to turn than a 727. Cope Racing has been very good to me in the past with slant and big block parts, and I would like to get John Cope's opinion on some of the parts that may need to be "beefed up" to handle the 360, not that it will be a power house, but just in case I feel like being irresponsible with it.

 

[BudW]

The 904, 998 and 999 transmission is from the outside view – is the same exact thing.
On the inside, the 998 and 999 (you should already have a 999 in your ‘80 Diplomat) is almost the same - except for 1st gear uses a different gear ratio (which is needed behind those highway gears that M-bodies use).

With the low-gear gear set, you can convert a 904, to a 999. Sense you already have one – one less thing to worry about.

It is not so easy to change the low-gear get in a 727 – but it is possible.

The 727 is a larger and heavier transmission. I think the amount of HP robbing power is a very small amount (727 vs. 904/999). A 727 will carry more torque than a 904/999 will – but even with that said, you would have to have a monster small block to out-torque a 904/999 to begin with. So you will be fine with your existing 999.

Both sizes of transmissions (727 and 904/999) will both wear out in about the same time, as well – but in most cases, a soft part overhaul will fix most transmission issues.

For a stock, mild, mid-level or even super HP small block – I don’t see any advantage of using a 727 over a 904/999.
I do see the advantage on using a 999 over the other two versions (727 or 904).

“Beefed up” refers to installing clutch drums that will hold more clutch disks/plates – in addition to a soft parts overhaul (bearings, bushings, clutch disks/plates, and all seals/gaskets) – which is a good long term plan (each clutch plate carry’s less torque and therefore will/should last longer.

Big blocks are a completely different story.


"Teener" does refers to 318. I prefer just to use 318 (less typing).

If the original 318 camshaft has quite a few miles on it, it might be wise to get another cam/lifters as well as “plan on” replacing the timing chain while there (yours may be good – but always budget on the high side).

If you do remove lifters that is to be (or might be) reused – always keep them in order of the camshaft lobe they came off of! This very important to do – for any lifter mismatch WILL CAUSE pre-mature camshaft failure (no If’s, And’s or But’s about it).

Checking lifters for wear is not hard to do. If a lifter is worn, then there is a 100% chance the camshaft lobe is also worn out, I have seen lifters go 200k miles and look new and others go 30k miles and look horrible (it comes down to maintaince and keeping engine oil level out of the “low” zone.

BudW

 

[AJ/FormS]

It's starting to come together. I agree with BUD on all points except the 274-1.54-1.00 of the A999. If you already have slam it, in there.But I wouldn't go out to find one. And here is why.
If you put that lil teener cam in there, you will have about one of the torquiest 360s around, and for it to pull 3.23s with the regular 2.45-1.45-1.00 A904 will be a breeze with the teener TC.
But here is the real reason. If you re-spring the factory 240/248/114 cam to buzz up to about 5200, then with 27" tires, first gear will get you; 45mph with the 2.74s, and 50 with the 2.45s. I always like to hit 50MPH at the top of first. If you gotta shift before the race is over, you lose! And the reason is when the Rs fall into the basement, that poor teener cam will have to claw it's way back from 2922 with the A999, and from 3078 with the A904.That throws 156 rpm in favor of the 904. Doesn't seem like much, but if you got money on it, you may go home hungry.
Take off will be about the same if you have tire-spin. And if you don't,your engine is probably sick.With the Dcr up around 7.33/143psi, and the 3.23s rocking out back, and the stock TC now stalling in the 2200to 2400zone,and 245s about the biggest tires you can fit out back, and WITH an LSD, there should be plenty of tire-spin!!
In any case the 340cam will be a dog down there comparatively speaking. There is about a 10% difference in Dcr between the 340 cam and the teener cam, which translates to a cylinder pressure difference of 17psi. This is the equivalent of the 340 cam having about 126/143=88% as much pressure, or 1 minus 88%=12% cylinder leakdown! That is rebuild territory.
That is why the 340 cam needs a compression boost; JUST TO KEEP UP AT LOW RPM!
Anyway IMO,either tranny will be fine.If you use a regular 904 and you want a bit more oomph,jack up the stall a tad.Just try and keep it below your hi-way rpm;which with 3.23s and 27s is about 2600@65. Unless your hi-way useage doesn't add up to much,annually, then hit 'er hard!
I once swapped an entire teener top end and cam onto a 340 short block.I had received the 340 short block in payment for services, and I had this old teener kicking around, so I said what the heck! I was 22. I still have fond memories of that combo, in a 65 long-roof. 2bbl and all!
But I gotta stress that on every other point I agree with Budw.

 

[SlantSixSullivan]

The general plan of mine is slowly coming together, with the help of this new information. Basically I know this: I will be using a 904 trans with 8.25 and 3.23s. One question I am left with is, rather than using the 340 cam I already have laying around, should I instead use the stock 360 cam or perhaps buy a 318 cam? Is it worth the $200 to use a 318 cam instead of the 360? I will be using a 4bbl setup, not 2bbl, and the tranny will be "beefed-up" when I do the B&M shift kit. I have had GREAT luck with B&M in the past. And with the 318 cam and 4bbl carb, how do I go about choosing my converter? I want low gear power, but highway driveability

 

[BudW]

Unless someone had replaced his transmission with an older version, he should already have the 999.

 

[SlantSixSullivan]

Unless someone had replaced his transmission with an older version, he should already have the 999.

It's a slant six bell housing though, so it will not work with my small block