New 4.6 won't run below 1800 rpm's

[xjchase]

I have a 1996 Jeep XJ stroked to 4.6L. The block has been deck 0.015 and the head shaved 0.010 with a 0.043 head gasket. The head has been port and polished and has Harland Sharp roller rockers. I have a 99+ intake, throttle body is 60 mm all the way through and 24# mustang injectors. The distributor, plugs, wires, cap, and rotor are all new. The distributor is in the correct spot and wires are in correct firing order. I am getting spark to the plugs, fuel in the cylinders, and the compression is 120psi which I thought should be higher but figured its not broke in and it should still run at 120. All the vacuum lines are hooked up correctly and could not find and leaks. The problem I'm having is the engine will start and dies immediately. The only way I can get it to run is bringing it up to at least 1800rpm's right away. Once I get it up to 1800 rpm's there is a miss and I can't get over 2100 rpm's, anything under 1800 and over 2100 rpm's it just stalls out. I can only let it run for a couple minutes before it starts overheating (230 degrees), then I shut it down. I have double and triple checked everything. I have gone as far as replacing the gas with 91 octane. I am going to replace the IAC tomorrow (don't know how to test it). I am completely lost and don't know what to do next. I greatly appreciate any help I can get.

[604rail_king]

sounds timing related imo

[Muad'Dib]

Are you triple sure that your distributer is indexed correctly?

[Cheromaniac]

I am going to replace the IAC tomorrow (don't know how to test it).

That won't solve your problem so save your money. I agree that the problem sounds timing related, which means that either the timing set was installed one tooth off or the distributor synch is off. Did you try indexing the dizzy according to my article?

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

[xjchase]

Yeah I had a punch in the distributor and put it in while the engine was on TDC of the compression stroke and the rotor is pointing at number one. I'll take the valve cover off and measure where the rotor is at exactly.

[SilverXJ]

I'm betting on the indexing as well.

However could be another sensor.. check the MAP sensor first. What is your fuel pressure?

[IH 392]

Sounds like a big vacuum leak to me.

[xjchase]

Well guys you were right! The site I found on how to index the distributor was completely wrong. I'm still having an overheating issue though. I'm also worried that my pushrods are to long so I still have some things to figure out yet. My temp sensor for my gauge could be bad because my Raytek infared thermometer says it's at 130 degrees and the electric cooling fan doesn't kick on. I can also touch the head without burning myself but for right now I'm going trust what the gauge say until I figure it out.

[Retlaw01XJ]

I'm also worried that my pushrods are to long .

Dino has a nice writeup on that, somewhere.
Here's a quick summary:
Put cylinder #1 at TDC on the compression stroke.... both valves will be closed at that point.
Loosen the rocker pivot bolt until you can feel play in the pushrod.
SLOWLY tighten the pivot bolt while spinning the pushrod back and forth with your finger tips.....at some point, you will feel resistance in the spinning.... that's your zero lash point. Now, count the number of turns it takes until the pivot bolt is seated....I believe the optimum point (gotta find my notes) is between 3/8 and 5/8 of a turn for the 0.020" to 0.060" lifter preload.
A cheap and easy fix is to put shims between the head and rocker pivot. It may not be the best method (depends on your whole setup), but it could be a quick fix for you.

But like others said, you more likely have a major timing issue is it's running that bad. If the timing chain is off a tooth, that's about 14 degrees.
Hope you get it worked out.

[xjchase]

I should have come here sooner to find my answers. It runs great now! The temp sender was bad so it was really never over heating. I still have to check my pushrods. Again thanks for all the help guys.

[cruiser54]

I am going to replace the IAC tomorrow (don't know how to test it).

That won't solve your problem so save your money. I agree that the problem sounds timing related, which means that either the timing set was installed one tooth off or the distributor synch is off. Did you try indexing the dizzy according to my article?

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

I've posted that link more than a few times on other forums. Thanks Dino.