Big Valve Stroker Motor

[Maize583]

Are you generalizing that, or is that just for your particular build? I.e. the lobe separation issue.

The smaller the lobe seperation, the less vacuum you will have at idle. The idle will also be more 'lumpy' than a wider lobe seperation.

If you have a carb system, the lobe seperation really doens't come into play until you get so low that the vacuum accessories don't work.

In a fuel injection system, the vacuum level plays a part in not only the fuel curve, but also shift patterns for the transmission.

In my '94 OBD computer, there are no aftermarket programs available except a Unichip product. Since I want to keep my factory computer, I have to play within the boundaries that system sets. The 231's lobe seperation would not work with the stock computer.

[dwg86]

I agree with what you are saying about lobe separation...or I should say its a fact. A 113 lobe separation will have more vaccum and a smoother idle than say a 110 lobe separation. The only thing I don't understand it that all the specs I have seen for the mopar cams say a 108 lobe ceterline...even the 28ab, which is a small cam. The specs I have seen for the 96 and later are 107 lobe separation with a 114 intake centerline. That would mean the cam is retarded 7 degrees...makes no sense! http://www.angelfire.com/my/fan/Jeep4.0Camshafts.htm
I am going to have the mopar 30AB cam I have profiled so I can see all the specs @ .050 and to find out if the 108 they list is the lobe separation. I am thinking maybe its intake centerline. Reed cams is close and they only charge $25.00 to profile a cam.

[SilverXJ]

While it may be true, the 68-231-4 cam causes no idle nor vacuum issues. I have run both cams in a 4.6L stroker and noticed no differences in idle, nor any issues with the fuel injection or computer. I did notice a bit more top end on the 231 though.

As for the programmers the unichip isn't the only option. Splitsecond's FTC1 or PSC1, Perfect Power's SMT6 and the Apexi SAFC all work on the 4.0L engine. Most piggy back programmers do the same basic thing, on the 4.0L it modifies the MAP signal based on RPM and throttle position. The 231 will cause no more issues than the 232 will cause with the stock PCM.

[Maize583]

While it may be true, the 68-231-4 cam causes no idle nor vacuum issues. I have run both cams in a 4.6L stroker and noticed no differences in idle, nor any issues with the fuel injection or computer. I did notice a bit more top end on the 231 though.

As for the programmers the unichip isn't the only option. Splitsecond's FTC1 or PSC1, Perfect Power's SMT6 and the Apexi SAFC all work on the 4.0L engine. Most piggy back programmers do the same basic thing, on the 4.0L it modifies the MAP signal based on RPM and throttle position. The 231 will cause no more issues than the 232 will cause with the stock PCM.

I did not have the benefit of having used both cams. I took the advice of the Comp Cams tech line. The 231 was specifically stated by the tech line NOT to be used with the factory computer. I wasn't going to challenge that recommendation.

I want to build this motor once, and not keep tinkering with it. Nor do I want to keep replacing cams and lifters. I am not trying to draw every ounce of power it is capable of producing. I want a reliable, daily driver that can tow my 3-place enclosed snowmobile trailer 7 hours to Wisconsin, 12 hours to Wyoming or pull my Sea-doo twin engine jet boat 2 hours to Lake Delhi.

The stock computer will work just fine for my application with my larger injectors, adjustable fuel pressure regulator and adjustable MAP sensor.

[SilverXJ]

Your AFR isn't fat in upper RPM?

[Maize583]

Your AFR isn't fat in upper RPM?

Not with the adjustable MAP sensor.

[RAPTORFAN85]

Maize if you dont mind me asking, how much $ do yu have in this project so far?
What do you think the final tally will be?

thanks
jake

[Maize583]

Maize if you dont mind me asking, how much $ do yu have in this project so far?
What do you think the final tally will be?

thanks
jake

I was originally designing this to be a production based business oportunity. But the interest was not really there. I had bunch of products given to me for the research, and other stuff sold at cost.

The idea was to have this completely done ready to drop in completel with roller rockers for the $2000 mark.

I have more time than money invested at this point. I might have $1500 in it when it is done. Probably less. Some of that expense was non-performance stuff like a new flex plate, a new harmonic dampner, double roller timing chain.

I used the machine shop at Recreational Motorsports to bore out my TB. I made the throttle plate at our local CNC Class at our community college.

I got a set of Doug Thorley headers, I think those were $375 from Summit Racing, with my discount. I also got a 2000 intake manifold for like $100. I modified that to fit the 94 motor configuration.

The valves, valve springs, titanium keepers and retainers were sold to me at cost from Engnbldr.com. It ran me like $120 for all that. The abrassive kit was given to me by Sperry Engines. The Super Flow bench time was donated by Sperry Engines, as well as most of the machine and balance work. I also did alot of the machine work myself. I left the performance valve-job to Sperry Engines.

I spent about 3.5 hours polishing the rods.

The pistons I got off ebay. It cost me $115ish to have the pistons dished. The rings, rod, main and cam bearings I got at cost from Sperry Engines, along with brass frost plugs.

I have about 60+ hours in the head with the chamber, intake and exhaust runner work, flow bench time and machine work.

The engine work was pretty straight forward after the pistons were dished. I have the pistons coated with a thermal barrier coating on the tops, and a poly coating on the skirts at Cool Concepts for about $100ish.

If somebody were to pay to have all this work done, it would be expensive..especially the head work that was done. The machine work for getting the block completely done (ready to put on the head) would probably run about $1000. I know I wouldn't do the chamber and port work on another head like this for $600.

To have somebody build a motor like this, with everything being hired out....I would guess in the range of $3500-4500 maybe a little more.

[jeepinwi]

I did not have the benefit of having used both cams. I took the advice of the Comp Cams tech line. The 231 was specifically stated by the tech line NOT to be used with the factory computer. I wasn't going to challenge that recommendation.

I want to build this motor once, and not keep tinkering with it. Nor do I want to keep replacing cams and lifters. I am not trying to draw every ounce of power it is capable of producing. I want a reliable, daily driver that can tow my 3-place enclosed snowmobile trailer 7 hours to Wisconsin, 12 hours to Wyoming or pull my Sea-doo twin engine jet boat 2 hours to Lake Delhi.

The stock computer will work just fine for my application with my larger injectors, adjustable fuel pressure regulator and adjustable MAP sensor.

I think you'll be VERY satisfied with the performance of your stroker when towing. With 3.07 gears, my XJ pulls a 3,000 lb car on a tow dolly comfortably in 5th gear. Your ZJ with 3.55 or 3.73 gears should perform wonderfully. You'll probably be pullng about 2500 lbs with 3 sleds, and the boat is about the same weight. Your ZJ is also a heavier tow vehicle, so it should handle the trailers fine. I've found the limit of my XJ's towing ability without trailer brakes. I can make a safe stop even towing 3500 lbs...as long as I'm going straight. If I try turning while braking, I've had my rear end get pushed to the side by the trailer. Your heavier ZJ should not have this problem.

[Maize583]

I did not have the benefit of having used both cams. I took the advice of the Comp Cams tech line. The 231 was specifically stated by the tech line NOT to be used with the factory computer. I wasn't going to challenge that recommendation.

I want to build this motor once, and not keep tinkering with it. Nor do I want to keep replacing cams and lifters. I am not trying to draw every ounce of power it is capable of producing. I want a reliable, daily driver that can tow my 3-place enclosed snowmobile trailer 7 hours to Wisconsin, 12 hours to Wyoming or pull my Sea-doo twin engine jet boat 2 hours to Lake Delhi.

The stock computer will work just fine for my application with my larger injectors, adjustable fuel pressure regulator and adjustable MAP sensor.

I think you'll be VERY satisfied with the performance of your stroker when towing. With 3.07 gears, my XJ pulls a 3,000 lb car on a tow dolly comfortably in 5th gear. Your ZJ with 3.55 or 3.73 gears should perform wonderfully. You'll probably be pullng about 2500 lbs with 3 sleds, and the boat is about the same weight. Your ZJ is also a heavier tow vehicle, so it should handle the trailers fine. I've found the limit of my XJ's towing ability without trailer brakes. I can make a safe stop even towing 3500 lbs...as long as I'm going straight. If I try turning while braking, I've had my rear end get pushed to the side by the trailer. Your heavier ZJ should not have this problem.

I had a ring and pinion go south on the front last summer. So, as long as I had to rebuild the diff and ring and pinion, I decided to go through both axles and convert from the stock 3.55's, to 3.73's.

The sled trailer weight is about right, but my boat is just a SeaDoo Speedster twin engine jet. It's only a 14.5' boat, the boat and trailer weigh about 1900lbs.

The old modified 4.0 pulled all of it just fine. I just wanted to test a theory I had with this head, and gain some grunt.

I ran into a little problem with the cam bearings yesterday. I went to install the cam, it fit fine until the last bearing. It was VERY tight. Too tight. I ordered another set of cam bearings, and we are putting them in the morning.

Hopefully, I will doing final assembly tomorrow, or Sunday at the latest. I should have some updated pictures after that.

I also have to drill a 2" hole in the hull of my SeaDoo for the depth finder. After that, I can start putting that back together after a complete teardown and rebuild of all the mechanincals. I am installing it under the gas tank. I had the whole engine bay apart to clean it out.

Both engines were rebuilt, I got rid of the plastic veined jet pumps and got bronze veined pumps, rebuilt them and put in new impellers. This afternoon I finished the rebuild of the throttle/trans block. The center throttle just flopped around, it wouldn't hold in place. So I rebuilt the entire assembly.

I installed a second full sized deep cycle battery to run the depth-finder and the stereo. That is seperate from the starting battery. I didn't want to be stranded without being able to start the boat, so I set up a second circuit with a Guess shot-off switch.

[RAPTORFAN85]

any updates? I NEED PICS

[Maize583]

OK.

It was back to work on the stroker motor this weekend.

I got the whole motor platicgauged, just to check all the clearances on the mains and rods.

I ordered the Clevite MS704P-10's, and then found that they are the other mains, the MS1947P10. After making about (what seemed like) about 40 phone calls, I found a set.

Then got the hardened Grade 8 washers for the stud girdle, and mounted up the oil pump and pickup. Then I used some Silly Puddy to set the depth on the oil pick up.

Then I checked the deck height on my cylinders. They are all around the 0.008" to 0.010" that I wanted.

I then moved on to the Cloyes double roller timing gear/chain. I got that degreed in to straight up with my degree wheel.

Then put the head on. I got to the number 11 position head bolt, torqued to 22lbs, then to 45lbs, then on to the 100lbs. It didn't get to 100lbs before it snapped off. I had to take the head back off, and drill it out. It came out easily. Luckily, I had more head bolts laying around the shop. I put the Loctite sealer back on it, and put the head on.

I need to paint up the timing cover then install the cover. I need to install the Flow Kooler water pump, and oil filter adapter. I also need to get an adjustable push rod to get the proper length push rod. Mine is too long to measure these.

I should be ready to drop it in the Jeep, hopefully, next weekend.

[SilverXJ]

Its surprising that the +11 bolt broke so easily. Did it break flush with the block deck?

[Maize583]

It is the one over the water jacket. I think it leaked into the bolt hole. The bolt didn't look the greatest. I probably did me a favor by breaking now. I should have replaced it before I put it back. It broke off where the threads started.

[Muad'Dib]

Dont forget those head bolts are TTY, meaning they can only be re-used once.