86 la 360 build help

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Swanny253

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I’ve got a 86 la 360 in my 72 dart wanna do a top end build on it is it worth it to do heads a cam with the stock 8.what ever compression ratio can I get that to a decent number without getting in to the bottom half
 
Top end Job. A fresh valve Job will provide extra pressure on the old rings, accelerating power loss and oil consumption Have you done a dry, wet, or leakdown Compression test on the motor.??
 
Top end Job. A fresh valve Job will provide extra pressure on the old rings, accelerating power loss and oil consumption Have you done a dry, wet, or leakdown Compression test on the motor.??
Not exactly true.

If your bottom end is in good shape, not worn out, you’ll be OK. Do a compression test and look at your cylinder wear a second state of cylinder wall. Check the taper.
 
Hey man, welcome to FABO.

I basically did that with a 5.9 Magnum. Kept the same pistons and rods...but did hone and put in new rings. Then new Edelbrock heads, cam, intake, carb, and headers.

If your compression is good, go for it!! For a long time I just borrowed a compression tester from a parts store. But eventually bought one.
 
I’ve got a 86 la 360 in my 72 dart wanna do a top end build on it is it worth it to do heads a cam with the stock 8.what ever compression ratio can I get that to a decent number without getting in to the bottom half


Top end Job. A fresh valve Job will provide extra pressure on the old rings, accelerating power loss and oil consumption Have you done a dry, wet, or leakdown Compression test on the motor.??


Not exactly true.

If your bottom end is in good shape, not worn out, you’ll be OK. Do a compression test and look at your cylinder wear a second state of cylinder wall. Check the taper.


Just pop a Mancini Racing refresh kit in it for $205 and your bottom end will be good to go....

Clevite 77 Engine Kit - 360
 
As long as there is minimal taper in the cylinder, heck yea! There actually a good kit for the home builder. Let the machinist cut the crank and maybe bone the cylinder walls and slam dunk it with the kit.
 
Apparently you want peer approval. And I’m not going to tell you how to spend your $$.
BUT , Certainly any/all hot rodding practices will bring benefits.
Raise compression, increase flow, bigger cam, add carb. -
- I can’t see this from my house, but I say “Go For It”!
What ever your bank account can do!
- turn it on, and turn it loose.
 
Heads that are about 61-62 cc should do it...then a cam that closes in the high 60's or @.050 in the 40's on a 109 lsa and .500 lift.

Just get some eddy magnums... or mill .040 from the stockers
 
To the OP, is milling the head in the cards? It’ll move away from “Cheap Build” to new pushrods w/the head milling I think.
 
I’ve got a 86 la 360 in my 72 dart wanna do a top end build on it is it worth it to do heads a cam with the stock 8.what ever compression ratio can I get that to a decent number without getting in to the bottom half
For a DD, waste of time.
for a dual purpose with DD rear-gears, waste of time
For tire-fryer, waste of time.
For a track car, well it will be faster.

The point is this; you didn't tell us a single thing about your application other than
72Dart.
Here's the thing; Pressure is heat; heat is power; power is performance and could be economy.
Put a cam in it, with a later-closing intake event, and you are guaranteed to lose pressure. To get the pressure back, is gonna cost you money.
A bigger cam, with no other changes, will move the power to a higher rpm, but subtract power at the lower rpm. The power increase is a sliding window, about 1500 rpm wide. If you are running hiway gears, say 2.94s, and the stock cam that peaks around 4500rpm, that will be ~46 mph.
Getting a decent power increase will cost you about 2cam sizes. That will put your powerpeak at about 5000/51mph with those 2.94s. Will your car be any faster?
Probably not.
why?
Because at under; 5000 less 1500=3500, your engine LOST power. So the average power from zero to 46mph will be close to the same or maybe even less.
In second gear, it might be faster, cuz the rpm does not drop to the factory stall ever again. But Second gear does not start until 51mph and you gotta lift around 65/70 mph. 70 will be 4100... but your power is is just starting! So it's debatable if the car will be any quicker, in Second gear., and probably not at all.
So if you want to be quicker from zero to 70 , IMO, you need a different game plan.

If you want to be quicker from zero to 70;
The very first thing you gotta do is up the stall rpm. And the second thing is to get rid of the hiway gears.
#1
Lets say your current stall is 2000rpm, and your engine make 270 ftlbs down there, which is 103hp
But by 2800, maybe she is making 290ftlbs=155hp... which is plus 52hp! There is nothing you can do to your Normally-Aspirated engine, that can match this change in this range. Which is why it should be your #1 go-to.
#2
Now you need to gear your car to be Reved out at at 70 mph, in Second Gear. so
Say your current combo tops out at 4500, but still makes decent power at 4800. Ok then to hit 70mph at 4800, in Second gear, with 10% slip, will take a road gear of 5.00, and divide by 1.45 Second gear in the trans, is a rear gear of 3.45, rounds to 3.55s. Now this will make your average power from zero to 70mph, about as most as it can be with your current engine.
Will it be faster than the current combo?
You better believe it!
Conclusion;
Go get you some 3.55s, and a 2800, and leave the engine alone; unless of course it burns more oil than gas, lol. If you already have 3.23s, then just get the 2800, because 3.23s will get you 70=4500 @10% slip, ending about right on the power-peak of the stock cam.
Now I realize that this doesn't actually answer your question. But you really didn't give us anything to work with.

Here's my thinking;
If you up-cam your engine, with a later-closing intake valve event, and no other changes; like I said, this is guaranteed to make your bottom end softer. One of the ways around that is to just put a higher stall TC in the trans, and the engine just never has to pull down there. So then, installing a higher stall TC is a given, and that takes care of blasting off.
But the higher-stall does nothing for you after the stall is reached and you are climbing up to the power peak. That will take gears no matter what. So since you pretty much HAVE to do the stall and gears thing, anyway; you might as well spend your money where it will make the biggest change.
Just maybe, stall and gears will satisfy your craving for acceleration.
Happy HotRodding
 
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Thanks for all the help I guess I missed some info haha it’s a 4 speed 3.91 rear gear 8 3/4 solid compression all around
Just debating on kinda build this la 360 or just swap to a crate magnum or gen 3 hemi id like to keep it la but if it’s not worth it than a swap will be it
 
You can make 350HP real quick with 8.5:1 compression and the right parts. There's zero need to spend lots of money raising compression.
 
You can make 350HP real quick with 8.5:1 compression and the right parts. There's zero need to spend lots of money raising compression.
What cam do you recommend for making 350HP with a 8.5:1cr? What should the ivc and lsa be?
 
Thanks for all the help I guess I missed some info haha it’s a 4 speed 3.91 rear gear 8 3/4 solid compression all around
Just debating on kinda build this la 360 or just swap to a crate magnum or gen 3 hemi id like to keep it la but if it’s not worth it than a swap will be it
Solid like like 125psi; or solid like 185? Those are two completely different engines, but hey, they're both"solid" whatever solid is.
With 3.91s and Dart wheel-wells, you should already be past the limits of your tires to cope with whatever power your current engine is making, and serious acceleration cannot begin until that stops, which might not be until after 40mph with street tires, a 4bbl ,and a free-flowing exhaust. , 350 hp will only make for more low-speed tire-spinning.
If that is what you want then as RRR sometimes says "I'd" go with the Magnum which was born with a higher compression ratio already,(which really livens up the bottom end); and it has better than stock LA heads, (which livens up the midrange and top-end.)
Your manual-trans combo, really likes compression, at below 3000rpm. And with 3.91s, there is no
substitute for compression from 3500 to 4500 except cubic inches. Skinny street tires are you limitation. 255s are gonna be roller skates, in at least the first two gears.
350hp is easy to get and cheaper with a Magnum, without the loss of bottom-end, cuz it already has decent compression.
Do you need the compression? ...........No.
But I guarantee that if you drove two identical combos, one at 135psi and the other at 185psi, you will never go back to the lower pressure.
The higher numbers mean that you could give up those 3.91s. I drive mine with 3.55s but only because it revs my engine out in Second gear just before or at the legal speed limit; I hate speeding tickets. I can live with tickets for excessive spinning of tires, lol. It was just fine with 3.23s
 
Solid like like 125psi; or solid like 185? Those are two completely different engines, but hey, they're both"solid" whatever solid is.
With 3.91s and Dart wheel-wells, you should already be past the limits of your tires to cope with whatever power your current engine is making, and serious acceleration cannot begin until that stops, which might not be until after 40mph with street tires, a 4bbl ,and a free-flowing exhaust. , 350 hp will only make for more low-speed tire-spinning.
If that is what you want then as RRR sometimes says "I'd" go with the Magnum which was born with a higher compression ratio already,(which really livens up the bottom end); and it has better than stock LA heads, (which livens up the midrange and top-end.)
Your manual-trans combo, really likes compression, at below 3000rpm. And with 3.91s, there is no
substitute for compression from 3500 to 4500 except cubic inches. Skinny street tires are you limitation. 255s are gonna be roller skates, in at least the first two gears.
350hp is easy to get and cheaper with a Magnum, without the loss of bottom-end, cuz it already has decent compression.
Do you need the compression? ...........No.
But I guarantee that if you drove two identical combos, one at 135psi and the other at 185psi, you will never go back to the lower pressure.
The higher numbers mean that you could give up those 3.91s. I drive mine with 3.55s but only because it revs my engine out in Second gear just before or at the legal speed limit; I hate speeding tickets. I can live with tickets for excessive spinning of tires, lol. It was just fine with 3.23s
Yes, magnum
Good heads
Hyperuetetic pistons
Piston skirts special anti friction coating
Superior gaskets and sealing
Moly rings
Better factory machining
Factory hydraulic roller camshaft
Cheap cores, easy to find, Last one I got $150 for Complete engine
 
The above posts assumes you have no control over your right foot when depressing the pedal. 255’s are plenty of tire. Hammering the go pedal until you just spin the tires is fine for just the burn out. While fun and cool to do and watch, if your interested in hooking the rear tires up, work on your suspension. It will take only a little time to find out where on the pedal is to far and a little longer to know how far you can hit it on the initial as well as how fast you can proceed to push it to the floor without spinning the tires.
 
Dang, I hit reply…. As I was saying…

You said a solid 8.75-1 compression. When it was questioned, it was questioned back with PSI. This is dynamic compression. You can’t answer that. Nether can AJ. No way, no how. Static ratio is just the measurements and dynamic is the actual, when in motion which the cam used. It changes with every cam. The higher the PSI the better and more snappier and stronger the bottom end will be. This is where closing the valve early helps. Also why you see these timing events on the cam card.
 
Thanks for all the help I guess I missed some info haha it’s a 4 speed 3.91 rear gear 8 3/4 solid compression all around
Just debating on kinda build this la 360 or just swap to a crate magnum or gen 3 hemi id like to keep it la but if it’s not worth it than a swap will be it

Very ROUGH ballpark, variables such as you doing the work change it a LOT. And I'm figuring low because you will say to yourself, "While I'm here, I may as well do _______." New heads, intake and new carb(s), headers, radiator, torque converter, Caltracs, brakes, suspension rebuild required for increased power, move from column shifter to floor, headlight relay kit, relocate battery to trunk, et cetera. It's never JUST an engine build/swap.
  1. Keep the 360, $2k-$4k
  2. Magnum crate, $4k-$6k
  3. Gen 3 Hemi $10k, plus wiring and computer
your call.
 
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It’s minitubed and leaf’s mounted inboard on frame full hotchkis suspension and stage 3 chassis stiffening so I shouldn’t have a problem with tire size or suspension and I miss spoke in ratio it’s a 3.55 now with the 489 case, old was the shorter ratio
 
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