Increasing Compression

[letank]

as for burning oil, what are you burning? 10W30 or 10W40...

[FSJfan]

That's a lot of oil.

Rebuilt means lots of things so don't put much faith in anything you don't know what was done and who did it.

If it's mainly on start up it could just be the seals . if they put the POS white Teflon seals on it you will burn oil and they need to be changed, they're crap . I fought this for a year on a fresh 383 Mopar before I figured it out . the blue green viton umbrellas are a good replacement.


you can change stem seals with the heads on the engine with a few simple tools.

Okay would you suggest putting new a rocker arm to get a few more ponies out of it?

[FSJfan]

as for burning oil, what are you burning? 10W30 or 10W40...

Burning Valvoline 10W30

[440sixpack]

A new rocker arm won't change anything. you could go to a 1.6 and get a little more lift as long as you don't get coil bind but again it will change nothing.

I'd pull a valve cover and look at your stem seals. sometimes they're cracked and in pieces. if they're the white Teflon seals it amounts to about the same thing. it won't give you anymore power but if they're toast and you change them at least you won't look like you're driving a Mexican diesel.

This can be done by just removing the valve covers, rockers and spark plugs.

To get any noticeable power gain you need to build a new engine with performance pistons. a turbo or blower is the only magic bullet for your engine as it is .

[FSJfan]

Alright so the only mods that should be done yo get any real improvements are intake, carb, and distributor?

[440sixpack]

Unless you increase your compression a manifold and carb are not going to increase your performance by 1/10 of a second. it's physics.

That's assuming you have a low compression smogger with a good 2V on it. they pretty much are what they are. if your ignition is a joke it's possible that would help a little .

Honestly if you want more power putting some 31x 10.50 tires back on it like it came with would give you the most bang for your buck. but I was a kid once and I know how it is, sometimes looks are worth sacrificing performance.

[FSJfan]

Well I bought it with like 1500 miles on the tires so I’d rather spend the money elsewhere.

[440sixpack]

Okay but that's part of why it feels gutless. not that it would be a fireball anyway.

[babywag]

The stock rockers are already 1.6

A holley 500cfm 2bbl will give a small performance increase.
Cheaper than intake+carb, because its a bolt on. Your MPG will suffer though. Needs off road needle/seat setup or won’t work well offroad.

There is also GM TBI, a good all around upgrade.
Better drive ability, increase in city MPG, and also small performance increase.

Holley also recently released a 2bbl EFI kit.

A good exhaust system vs. restrictive stock stuff also helps.

[fulsizjeep]

OK, we compression got covered.

Simple, cost affective things that will wake up a 360/401...

Exhaust:
True dual exhaust, 2-2.5" diameter pipes. The stock Y pipe is restrictive. Some have also moved the Y pipe back behind the transfer case where there is plenty of room to install a Y that flows better. Some prefer to keep single exhaust but have gone to 3" pipe after the Y for better flow.

Intake:
Edelbrock Performer. This implies you are going with a 4 bbl carb unless you want to use adapter for a 2 bbl. These intakes breath very nicely for the AMC motors. Other manufacturers have been utilized but Performer is probably the most widely used. The stock 2 bbl intake is fairly restrictive. The stock 4 bbl (square bore or spread bore) breath pretty well on their own but having swapped a spread bore for a Performer made a difference. On one of our Jeeps, we are running the stock spread bore intake, square bore adapter and Holley TA. It has dual exhaust and breaths real nice on road, towing and off road.

Distributor/Ignition:
We have been changing over to HEI on our Jeeps. It is an easy 1 wire solution and gives a hotter spark. There are other options for hotter spark. We have run a few different Jacobs ignitions but I think that is basically a waste of money. I have not personally felt a power difference except for maybe towing. They do start easier. I like the simplicity of a HEI and one wire solution.

OK, your motor is using oil. That is usually a sign of power loss alone. Something I have found to help them run better, is dump all the emissions crap if you don't need it by law. This opinion varies with others. Once all the emissions except for PVC are removed, tidy up the remaining vacuum lines. As in replace all the hoses. Even a vacuum leak on your heater/defroster controls can cause power loss.

My $.02...

[Stuka]

Ok, going to say this one more time. Compression does NOT have to be increased to gain performance!

Saying that doing X mod will do nothing because of stock 8.5:1 compression is complete BS. The mods mentioned here are all intended to increase VE. Compression has no impact on VE.

You can still have a 300HP 360 with 8.5:1. Which is plenty of power for most people. GM and Ford have both sold crate 300hp V8’s with 8.5:1 compression so that people can run 87 octane fuel.

[440sixpack]

300 horse out of a tired 8.25 to 1 smog dog by bolting ' modifications " on ? like a blower ?

Look at where a 300 horse 360 starts, and look at what it takes to go higher. yes it's a mopar 360 , but they run as good if not better than an AMC 360 so it's apples for apples.


http://mopar1.us/dyno.html



Nothing ruins a great story faster than a dyno. why do we have to keep going through this.

[babywag]

300 horse out of a tired 8.25 to 1 smog dog by bolting ' modifications " on ? like a blower ?

Nothing ruins a great story faster than a dyno. why do we have to keep going through this.

Why? because it can be done. Without a blower, with stock compression.

Ghinmi was kind enough to dyno one for folks.http://www.ifsja.org/forums/vb/showpost ... stcount=19
Headers(edlebrock shorties)
Intake(edelbrock air gap)
Holley carb(750dp)
Comp cam(270H), and springs
255hp/364tq, but then the dyno ruins a great story.
Apparently so do Jeepers, with all their useless bolt on talk.

If someone wants to add the useless stuff, let ‘em. Obviously you never have to a stock engine. It does make a difference.
Comparing it to a Mopar is apples vs. oranges.

[rocklaurence]

Babywag: thanks for the post... I was reading another build on the net and they said that they were able to increase the head chambers almost 10cc. Dose anyone know where the material is removed from? This would help drop the compression when using a Cast set of 343 pistons, I would love to install the intake/cam combo mentioned in the previous post but with the 343 pistons and not have to run 92 octane.

[Stuka]

300 horse out of a tired 8.25 to 1 smog dog by bolting ' modifications " on ? like a blower ?

Nothing ruins a great story faster than a dyno. why do we have to keep going through this.

Why? because it can be done. Without a blower, with stock compression.

Ghinmi was kind enough to dyno one for folks.http://www.ifsja.org/forums/vb/showpost ... stcount=19
Headers(edlebrock shorties)
Intake(edelbrock air gap)
Holley carb(750dp)
Comp cam(270H), and springs
255hp/364tq, but then the dyno ruins a great story.
Apparently so do Jeepers, with all their useless bolt on talk.

If someone wants to add the useless stuff, let ‘em. Obviously you never have to a stock engine. It does make a difference.
Comparing it to a Mopar is apples vs. oranges.

Exactly, thanks for finding one of the posts I was thinking of. 255hp at the wheels is over 300 at the crank if you count a 15-20% drive train loss.

[babywag]

Exactly, thanks for finding one of the posts I was thinking of. 255hp at the wheels is over 300 at the crank if you count a 15-20% drive train loss.

Yep, but they won’t ever make any power...sigh.
They are turds in stock tune, and stock setup is beyond a joke.
With same standard formula and methods used for decades by folks much better.
Sure you can tear the engine down and go balls out, lotta guys don’t have the $ or desire for that.

[REDONE]

Right? Here's some other pics I was going to rip of the interwebs and share. First is a dyno of a Howell injection done by 4wheeler on a 360.

Now the OP is a highschooler that's not looking at FI, but look at those stock curves. He's running stock gears and oversized tires, so he's not even getting close to the paultry power his engine already makes. He's way down in the lugging RPMs.

This overly-simplified dyno from Edelbrock is more in line with what he's looking to do:


he can throw the whole Edelbrock catalog at his engine, and down where his engine lives and breaths, he'll LOSE power.

Babywag and sixpack, I'm right there with you guys. I like AMC engines for what they are, but what it takes to get anything out of them isn't worth the money or the milage. I have another 401 on the stand right now, and I'm debating whether it's even worth the space it takes up.

[Fast Eddie]

Thanks for Torque and HP curves, VERY interesting. I have much of the same on my 360, Edelbrock Intake and Carb, Comp Cams cam and NO headers, BUT true dual exhaust. Very good performance and driveability, but I agree, never really get into those higher RPMS!! I Jeep friend told me I should go to a Y or H pipe (or even X pipe) crossover to improve my torque and pulling power! I have heard pros and cons, what does this group think?? THX

[REDONE]

Nope. At low RPMs our engines rely on the "scavenging effect" to produce torque. The phenomenon is that the velocity of the exhaust gasses leaving the cylinder create a vacuum that draws in more intake charge (fuel&air) than it would otherwise.

Before you file this under "hokus pokus", you have to recognize that 2 stroke motors run, so it must exist. When an engine "breaths better", you lose the scavenging effect, which is why torque drops at low rpm.

The reason that first graph (the Howell dyno) shows significant gains in torque at low rpm is that fuel injection is WAY better at maximizing the fuel/air ratio. The reason to starts to equalize towards the right side of the graph (high rpms) is that's where the limiting factor is how the engine "Breaths".

In the second graph (Edelbrock dyno), you can see that all of the significant gains are above 3000rpm. This is because the Edelbrock bolt ons allow the engine to breath, but it doesn't make better use of fuel, it just lets more in.

[Stuka]

The edelbrock gains are that way because its a 304, not a 360 or 401. The edelbrock cam is a side grade for a 360, and a downgrade for a 401. But its a big upgrade for a 304 in terms of mid to top end power. Plus edelbrocks chart is not a "real" dyno chart, it was created for marketing.

Ghinmi's chart shows wheel power with his stated mods, which I feel is a more reliable chart.

Oh, and scavenging in a 2-stroke can't be compared to a 4-stroke. Scavenging works on a 2-stroke because exhaust exits on the power stroke. So the burning fuel/air is allowed to expand into the exhaust, which is why 2-strokes have a big expando type exhaust.

To my knowledge exhaust velocity has zero impact on low end torque. Wide open exhaust and full exhaust have nearly the same torque curves (As proven by engine masters). However, intake velocity has a HUGE impact on torque curves. Which is why single plane intakes are BAD if you want any sort of torque.

Edited for clarity.

Second Edit: Forgot to mention that when it comes to exhaust, you can get scavenging with an H or X pipe exhaust. This can effect torque in a good way. Engine Masters also had an episode on this.