4.6???
- Thread starter Jeepr89
- Start date
Snitty
New member
1071106
IF you can bore the 4.2 that much, then you can keep it carbed... there is no availible crank to stroke the 4.2... but it can be bored to a point... if it stays carbed, you don't have to mess with any computer stuff... only have to adjust the carb to make up for the increased displacement[addsig]
IF you can bore the 4.2 that much, then you can keep it carbed... there is no availible crank to stroke the 4.2... but it can be bored to a point... if it stays carbed, you don't have to mess with any computer stuff... only have to adjust the carb to make up for the increased displacement[addsig]
Snitty
New member
1071166
>b>IF[/b] the 4.2 intake will fit a 4.0 head, which it should, at least with minor mods... then you have got yourself a good block which can be bored and stroked... the 4.2 crank will have to be machined at the front to use the 4.0 harmonic balancer... i'm not quite sure if you can use the 4.2 balancer... after you get that machined, you will need to get the entire rotating assembly (crank, balancer, flywheel) balanced to each other or vibrations can cause some nasty outcomes... you will be using the 4.2 connecting rods, and will retain the 4.0 pistons... that alone will give you a 4.5... if you overbore, you can achieve 4.6 with .030, or nearly 4.7 with .060... your TDC quench height will be slightly lower than the deck of the block, but that will be fine.. or you can get the block milled to compensate for that, but your compression ratio will increase, and may get in the cautious range for pump gas... the stroker alone will bring your compression ratio up, but should be safe with 87 octane with minor ping if any... i would suggest using 89+ for any stroked 4.0... you may want to replace the camshaft to make up for the increased displacement, crane cams sells one perfect for this application... and since you are staying with a carb intake, you don't have injectors to worry about... if you have any more questions... keep them coming[addsig]
>b>IF[/b] the 4.2 intake will fit a 4.0 head, which it should, at least with minor mods... then you have got yourself a good block which can be bored and stroked... the 4.2 crank will have to be machined at the front to use the 4.0 harmonic balancer... i'm not quite sure if you can use the 4.2 balancer... after you get that machined, you will need to get the entire rotating assembly (crank, balancer, flywheel) balanced to each other or vibrations can cause some nasty outcomes... you will be using the 4.2 connecting rods, and will retain the 4.0 pistons... that alone will give you a 4.5... if you overbore, you can achieve 4.6 with .030, or nearly 4.7 with .060... your TDC quench height will be slightly lower than the deck of the block, but that will be fine.. or you can get the block milled to compensate for that, but your compression ratio will increase, and may get in the cautious range for pump gas... the stroker alone will bring your compression ratio up, but should be safe with 87 octane with minor ping if any... i would suggest using 89+ for any stroked 4.0... you may want to replace the camshaft to make up for the increased displacement, crane cams sells one perfect for this application... and since you are staying with a carb intake, you don't have injectors to worry about... if you have any more questions... keep them coming[addsig]
1071176
I had an 87 Wrangler with a 4.2 that I bored 60 over and put a perf. cam into and went through the entire motor. Thing ran incredible and never gave me a problem. I just finished doing it to an 89 for a customer. We finished it with a weber carb. The Jeep can pull the front wheels of the ground. I have been debating doing the 4.6 to my TJ I just haven't worked up the nerve yet to rip apart a great running engine yet with no problems. Usually we start into something like that when there is a problem that has started at 250K mi. Let me know how you make out.
darrin@eastcoastoffroad.com
ECOR[addsig]
I had an 87 Wrangler with a 4.2 that I bored 60 over and put a perf. cam into and went through the entire motor. Thing ran incredible and never gave me a problem. I just finished doing it to an 89 for a customer. We finished it with a weber carb. The Jeep can pull the front wheels of the ground. I have been debating doing the 4.6 to my TJ I just haven't worked up the nerve yet to rip apart a great running engine yet with no problems. Usually we start into something like that when there is a problem that has started at 250K mi. Let me know how you make out.
darrin@eastcoastoffroad.com
ECOR[addsig]
