Are all Jeep 4.0 heads the same?
Not so! The heads will swap mechanically, so they'll bolt right up to the block (the 258 and 242ci heads, 1975 and later, use the same screw pattern and can use much the same gasket.) Yes, the 0331 head (1999-2006) will have the coil rail bosses that the previous heads will not.
What ratio are stock rocker arms?
The rocker arm ratio is the relationship between the 2 halves of the rocker arm. The halves are: The center of the valve stem to the center of the pivot point....How do I know what my rocker ratio is?Engine TypeStock Rocker Arm RatioChevy LS71.8Gen. 5 Chevy LT Engines1.8Big Block Chevy1.7Small Block Ford1.62 more rows•Feb 6, 2019
How loose should rocker arms be?
SIXTSVN, It is always better to have the rockers a little loose rather than too tight. If they're a little loose, the valves will close completely, if not, they will burn, not seal properly and you will lose compression.
What does 1.5 mean on rocker arms?
One of the most popular ratios is 1.5, and what exactly does that mean? It means the rocker arm will open the valve 1 and a ½ times the amount the cam moves the lifter and the push rod, or what cam manufacturers refer to as cam or lobe lift.
How do I know what rocker arms I need?
The ratio of a rocker arm refers to the amount of movement on the valve side of the rocker arm in comparison to the pushrod side. A 1.5:1 rocker arm will move a valve 1.5 times the lift of the cam, assuming all things are in proper working order. If your cam has a lift of . 4 inches, multiply by 1.5 to get .
How do I know what rocker arms to use?
2:5916:04How to Choose the Right Rocker Arms - YouTubeYouTubeStart of suggested clipEnd of suggested clipThese are probably just fine for that if you're going to spin it any higher than 5000 rpm you needMoreThese are probably just fine for that if you're going to spin it any higher than 5000 rpm you need to look at a different rocker arm and a different style. And certainly strength.
What happens if rocker arms are too loose?
With broken or loose rocker arms, the exhaust valves and intake valves can't function correctly and the cylinder associated with the faulty rocker arm will be disabled. This will ultimately limit the performance of your engine and your ability to drive the car smoothly and safely.
How tight should lifters be?
The answer? Weightlifting shoes should be long enough so there is NO room at the heel with just enough space in the front to fit your foot without having to curl your toes, while width ways the shoe should be very tight.
What happens with too much lifter preload?
and keep the valves open when they should be closed. Or, as engine rpm increases, the bleed down rate inside the lifters may be too great. If this happens, then there will not be enough time to refill with oil between each valve cycle, causing the lifter to collapse.
How much HP do roller rockers add?
You can easily gain 20 horsepower with a rocker arm swap, but installing them isn't quite as simple as removing the stock rockers and bolting on new ones. For seasoned car guys, it's a quick process, but if you're new to the task of setting valve lash you might want to take some notes before you tackle the project.
How much more lift does 1.6 rockers add?
With a 1.6:1 rocker, this gives us 0.508-inch valve lift at max lift, an increase of 0.031 inch. It doesn't sound like much, yet it was enough to show a sizeable gain, mainly because it increases the amount of time that the valves are open at higher lifts, allowing more air to flow through the heads.
What do high ratio rockers do?
A high-ratio rocker arm increases valve lift at every point. It boosts gross valve lift by several hundredths of an inch, but it can make a camshaft seem a few degrees larger as well.
What is the stock rocker arm ratio of a 5.3 LS?
CHEVROLET 5.3L/325 Rocker Arms - 1.7 Rocker Arm Ratio - Free Shipping on Orders Over $99 at Summit Racing.
What ratio are stock LS1 rockers?
For example, a stock 1.7:1 (advertised ratio) LS1 rocker actually pushes the valve off the seat at a ratio of 1.54:1, and as the pushrod seat rises on the valve opening cycle, the effective rocker ratio finally rises to 1.69:1 at 0.280-inch lobe lift (0.473-inch valve lift).
How much lift does a 1.6 Rocker add?
With a 1.6:1 rocker, this gives us 0.508-inch valve lift at max lift, an increase of 0.031 inch. It doesn't sound like much, yet it was enough to show a sizeable gain, mainly because it increases the amount of time that the valves are open at higher lifts, allowing more air to flow through the heads.
What is the stock rocker arm ratio for a small block Chevy?
1.5:1 ratioEven though Chevrolet made the decision easy for us when it engineered the small-block to run around a 1.5:1 ratio, (Comp Cams says most stock rockers are actually about 1.46:1), it's well known that the inconsistencies of stock rockers and the friction and heat they create mean there's power lost with them.
What is hub bore?
Hub Diameter or center bore is the hole at the center of the wheel. Backspace is the distance from the backside of the wheel mounting pad to the outside of the rim flange. Offset is the distance from the centerline of the wheel to the mounting surface of the wheel.
What is negative offset on a wheel?
Negative Offset is when the back of the bolt pad is closer to the inside of the wheel; when the mounting surface is inboard of the rim centerline. Positive Offset is when the back of the bolt pad is closer to the street side of the wheel; when the mounting surface is outboard of the rim centerline.
qkcuda Well-Known Member
My twisted mind wants to see what it will do bolted onto a 4.2 Gremlin.
Cuprum-74 Moparus Fanaticus
Funny how some of the 4.2 and 4.0 parts can be interchanged and be made into 4.5-4.7L strokers.
magnummopar Well-Known Member
They changes the port design along with intake/exhaust manifold redesign. The earlier design was a carry over from the 4.2 which was designed in the 50's. It was a tractor engine no matter how you sliced it...the port changes were so it would meet stricter emissions requirements. They do last a long time if you dont spend much time on freeway.
sscuda The best there is, the best there ever will be
I seem to recall Horse Power TV did a build on a 4.0 Jeep motor and I think they used the Edelbrock head. When they were finished building the motor they stuck it on their dyno. It made some stout numbers but I can't recall exactly what those numbers were.
Cuprum-74 Moparus Fanaticus
On their website they advertise gains of about 25 hp and 24-34 foot lbs over stock.
Cuprum-74 Moparus Fanaticus
I remember one of the members of a local Jeep forum putting a 4.6L stroker in his rock crawling wrangler, Lets put it this way, he was able to easily keep up with or even did better than the chevy V8 CJ's and even the dodge V8's.
magnummopar Well-Known Member
I have pulled a dozen stroked 4.0's out of TJ's during the last 18 years of doing Magnum swaps into Wranglers and never had one impress me nor have I ever seen one get better than 12mpg. Same with the Avenger SC's that were all the rage for a few years until everybody figured out they didnt work.
