Need help with a 4.6 build

[SilverXJ]

Check Maudib's build there are some good break-in recommendations in there. You did break the cam in correctly, right?

Ont he low oil pressure, what weight oil are you running? Was the front galley plug installed? I would be a bit concerned about that.

[hflmike21]

Looking for more info on the reast of the break in

CamShaft break in
http://www.youtube.com/watch?v=23sYBHH9fUA

Some say take it easy some say accelerate hard and decelerate hard to seat the piston rings to the honed cylinders walls, seems like one of those topics that do not have a clear answer the link below seems to have some pretty compelling arguments why to drive it kind of hard. So Ill probably follow that when mine is done. Hard take off and stop but not really take it over 55 for the first 500 miles.

http://www.mototuneusa.com/break_in_secrets.htm

[jbain]

Thanks guy's I'm at 600+ now and just ran it in back to back Mud Bogs.

[jbain]

My Stroker now has about 2k of racing and hard off roading on it and with fair season approaching I'm looking at bringing a few more ponies to the show. I built the Poor Mans but kept the stock head and Cam and I'm still running the factory injectors throttle body and exhaust (with exception of a hollowed Converter and a Flowmaster muffler. I've got about 800 to drop into it before May and I would like some opinions for what will give me the most hp gain for my buck. Thanks in advance.

[Cheromaniac]

Port the head (learn how to DIY), get a 62mm TB, and upgrade the header/exhaust using piping of at least 2.5" diameter from the downpipe back.

[jbain]

Thanks or the post, I bought everything to port the head last year when I initially built the motor but chickened out and didn't do it. Does it really give you a big boost in HP/TQ? I will definately redo the exhaust, buy the 62mm TB along with new injectors.

[Cheromaniac]

I bought everything to port the head last year when I initially built the motor but chickened out and didn't do it. Does it really give you a big boost in HP/TQ?

Yes. If you follow the Standard Abrasives DIY head porting guide like I did, you'll get very good results. I reckon I would have had ~20 crank hp less if I'd left my head stock.

[jbain]

Well then I definitely need to get it done before racing season, a local track is including sand drags this year and I'm pumped to run against the V8's. I run an AW4 transmission, 410 gears, 35 inch tires and as of now on flat pavement with a lincoln locked rear axle and no power braking I can leave two black marks maybe 2 feet long, for those running similar setups is this decent or am I missing alot of Stroker Horsepower?

[yuppiexj]

I run an AW4 transmission, 410 gears, 35 inch tires ?

Gears... you'd enjoy 4.88s even more.

I ran 4.56 gears and 32in tires. After the swap from 3.55s, I felt like I'd been driving with the parking brake on for the last few years.

[stroked'73]

On the porting - always err on the conservative side. It's far better to not take enough off than too much. You're not "hogging it out" - more like smoothing things out. Sorta like un-kinking a hose. The only place you wanna really cut alot is the valve guides - and that's only to make them more aerodynamic. Round out the "short side radius" and don't take anything off the floor. Try to be consistent. And leave the exhaust alone except for smoothing it out (and cutting the valve guides). You don't wanna port-match the exhaust - it needs to be half-moon shaped to keep exhaust gases from flowing back into the cylinder. Opening it up will kill performance. It takes alot of time but it's fun if it's the first time you've done it.
I read Dino's (cheromaniac) page on porting before I did mine and that was really all the info I needed to do a decent job (for a first-timer). It might be posted here, but I read it on his jeep4.0performance page. Thanks Dino, BTW!!

Oh - and obviously - do your porting job before you get the valve job, that way if you accidently nick up the seats, it'll get fixed anyway with the valve job.

[stroked'73]

There's a nice thread on porting just down the page from this thread - "Head porting - for Silver XJ". Some good info in there.

[jbain]

Thanks for all the input I really appreciate it, I've got an extra head lying around so I guess I should get started.

[jbain]

I had to swap out my rear spider gears last night so after I was finished I bolted up a set of bald 30x9.50's so I could take it out on the road and have some fun doing burnouts....Fail, I couldn't even break traction... I know I still have a stock Cam, Exhaust, TB and injectors but with 4:10 gears and single wheel peel I thought I could at least leave a little rubber. Is this normal?

[Muad'Dib]

Do you have aggressive tires?

I have approx 29's and 3.55's and when i first bought my General Grabbers i could burn rubber pretty easy... now on a dry asphalt surface i'm lucky if i can. (probably because they are broke in now) Those things hook up... It feels like i'm twisting the chassis and it breaks your neck but it doesn't start spinning the tires.

EDIT didn't see bald...

One thing i notice about my build is that i get more torque at a little higher RPM (cam choice). So its much harder to break the tires loose at idle.. once they break loose though its crazy town.