Jeep Strokers

For a little background I built the stroker 3 years ago then I bought a house and had my first kid so long story short I just got it up and running after some wiring issues.

I used a 4.0 block and connecting rods with a 4.2 crank,hesco rvob6 cam, hesco FPR, 30lb/hr injectors, a 62mm throttle body, 7120 port/polished head. I can’t for the life of me remember what pistons I went with.. but I know I ordered a set of KB944-60 but they didn’t work for some reason and my machine shop ordered a similar set that would. I also can’t remeber what valve springs I used but I talked to hesco and ordered what they recommended for there cam. When I built the motor I followed the medium buck 4.7 build sheet from this site but it has changed since I built my motor. http://www.jeep4.0performance.4mg.com/stroker.html

Now that you know what’s done to the motor here’s my problem..... it will fire right up but sounds really rough at idle and has no power. I checked for misifires and found that I can pull the spark plug wires or fuel injector plug on cylinders 3 and 4 without any change. Then I checked for spark and power to the injectors and I have both. Next I did a compression check on cyl. 3,4,5 and all were close to 180psi (cold).

I’m not sure if I need to maybe advance timing or maybe the injector timing is off but there is something definitely wrong. I have an air fuel gauge and it’s running around 14.5-15.5 with the FPR set at 47psi.

Hopefully you guys can help me get this figured out. I would really appreciate it!

Did you check if the distributor is indexed correctly?

I did about a year ago but I will check it again tonight when I get home from work just to be sure.

Well I checked the timing and It was retarted pretty far so I moved it a tooth advanced but it wouldn’t start... Then I moved it a tooth back and it barely ran so I tried moving it back to the original spot and couldn’t find the sweet spot. So tomorrow after work I’ll put #1cyl at TDC and drop the dist. back in the right spot but this time I’ll cut the mounting point off so I can manually time the motor with a vacuum gauge.

Clocking the dizzy won't effect timing. It only effects injector timing. Get it on the right tooth though. That will change the timing!

SkylinesSuck wrote:Clocking the dizzy won't effect timing. It only effects injector timing. Get it on the right tooth though. That will change the timing!

Good to know! I assumed it would be like older motors that you would turn the dizzy to time.

Is there a way to check injector timing or will the ECM just set it correctly? I’ve heard of guys cutting the dizzy mount off and using a clamp to fine tune strikers... I just always assumed it was timing.

You will need to do that, yes. Dino had instructions in his sure.

Yup. Here:

http://www.angelfire.com/my/fan/dist_index.html

Cheromaniac wrote:Yup. Here:

http://www.angelfire.com/my/fan/dist_index.html

Great! Thank you!i will get this done then report back on how it runs.

Dino`s link while helpful may not be "correct" for your application.

The dist. needs to be indexed as shown in his link as a baseline. This gets the parts playing nice together.

Depending on the advance/retard ground into the cam. Or the advance/retard you degreed the cam with the cam timing set the dist. may have to be rotated slightly from the fixed position the tab/bolt provides.

Baseline as Dino says.
Mark the position of the dist and remove the tab.
At idle rotate the dist CW/CCW to find the sweet spot. The engine will tell you where it wants to be.
Tighten the hold down clamp.

My personal engine I run the cam 4 degrees advanced to bring the power curve down a bit. The dist. is rotated a few degrees away from where the tab/bolt would have been.
Life is good.

Setting the cam synchronizer can make a big difference in drivability, as mentioned above. Having it out of proper range can also set P300 misfire and other codes. Had this same problem on the first 4.0 I rebuilt, it was a shock that a one minute adjustment could make such a big difference.
30-lb injectors may be too big for your engine, probably should be in the 24-27-lb range.
Do you have a ported head?

jsawduste wrote:Dino`s link while helpful may not be "correct" for your application.

The dist. needs to be indexed as shown in his link as a baseline. This gets the parts playing nice together.

Depending on the advance/retard ground into the cam. Or the advance/retard you degreed the cam with the cam timing set the dist. may have to be rotated slightly from the fixed position the tab/bolt provides.

Baseline as Dino says.
Mark the position of the dist and remove the tab.
At idle rotate the dist CW/CCW to find the sweet spot. The engine will tell you where it wants to be.
Tighten the hold down clamp.

My personal engine I run the cam 4 degrees advanced to bring the power curve down a bit. The dist. is rotated a few degrees away from where the tab/bolt would have been.
Life is good.

Thanks for the help! I think I talked to you over on JF and on the phone when I was originally building the motor.

I can’t remember how I degreed the cam but I know I did when I switched to the RVOB6 cam. If I need to I can re degree the cam so I know where it’s at.

lazyxj wrote:Setting the cam synchronizer can make a big difference in drivability, as mentioned above. Having it out of proper range can also set P300 misfire and other codes. Had this same problem on the first 4.0 I rebuilt, it was a shock that a one minute adjustment could make such a big difference.
30-lb injectors may be too big for your engine, probably should be in the 24-27-lb range.
Do you have a ported head?

What air fuel ratio do these strokers like to run at? I just assumed 14.7 is what they ran at like other motors.

I do have a potted and polished head

14.7 is a lite throttle and idle air/fuel ratio. Your narrow band closed loop factory system should keep it there by itself. WOT should be much richer. Ballpark 13'ish.

Well tonight I tried to re time it using Dino’s link. I did everything to the T and it won’t start. Both valves were closed I even hooked my compression gauge up to make sure it was on the compression stroke.

Here is a picture with the rotor set like his instructions say. The black sharpie mark is where the #1 plug terminal is.



And here is a picture with it retarted one tooth.. still wouldn’t start.



I’m not sure how I had it running before I didn’t do anything different when I timed it.