EarlyCJ5.com Technical Library

A technical library for classic Jeeps

Engine Related Articles

The Dauntless V6 Has its Own Page of Articles and Resources

The Fireball 198 V6 has it's own casting numbers page now

Swapping a Chevy 4.3L into an Early 5 using a SM420 trans

Engine FAQ

  1. What does L-Head or F-Head mean?
  2. The Perkins 192 Diesel
  3. Dauntless V6
  4. General information on the F-134
  5. Engine - Rod Bearing / Spray Nozzle / Oil Pressure
  6. Cannister vs. Modern Oil Filter
  7. Lubrication at Low Idle
  8. Synthetic Lubes and Oil Additives
  9. Broken Stud
  10. Hardened Valve Seats
  11. Preventing gasket failure due to improper use of chemicals

What does L or F Head mean?

This is a reference to the valve train and cylinder arrangement for cam in engine designs. A L-head is a flat head and a F-head has the exhaust valve in the block with the intake valve in the head. For a more thorough explanation see the Wikipedia entry.

The Perkins 192 Diesel

Terry Howe's Jeeptech.com has a page on the Perkins Diesel.

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Dauntless V6

The Jeep "Dauntless V6" is a 90 Degree V6 designed by Buick in the early 1960's. All internal parts are interchangeable with the more familiar Buick 350, also called the "Dauntless V8" by Jeep in the Gladiators and Wagoneers. The only parts that are not interchangeable are the crankshaft, camshaft, and valves. Kaiser purchased the right to the Buick V6 to use in Jeeps in 1965, in 1966 they started appearing in CJ-5's, 6's and Commandos as '67 models.

See this page for more detailed V6 information The Dauntless V6 Page. Complete engine specs, casting numbers and FAQ's are available on this page.

The F -134

The F-Head 134 was the most commonly used engine in the Early CJ-5's. It featured intake valves in the head and exhaust valves in the block. This configuration produced 72 HP, up from the 65 HP of the venerable "Go-Devil" flat head or L-Head 4.

Derek Redmond's CJ-3B site has several pages dedicated to the F-134.

Guide to Rebuilding the F-134

F-Head Performance Hop-Up.

A brochure explaining to service stations the differences in the new F-Head.

The Carburetor

The stock Carter YF

The Solex Replacement carburetor, AKA the carb available from J.C. Whitney... Images of F-Head courtesy of the CJ-3B Page.

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F-134 Colors

Here's some info regarding F-head color codes. This is from a reprinted Master Parts List for the wagons and trucks, so I don't know if it applies to CJs. It is for complete engines and lists them as follows:

Could I use 3.73 gears with my F-head for a higher top speed?

AFAIK the F134 CJs only came with the 4.27 and 5.38 gears. I expect that you won't gain a lot of top speed with the 3.73s, because you will run out of power. What kind of top speed do you need? An overdrive will make an effective 4.04 final ratio - you're going to have to hit the gearing sweet spot to get that added 10-15 mph...

Two factors needed to go faster - revs and power. Let's consider 3 cases, where you increase your top speed to 1) 55, 2) 60 and 3) 65.

Here's what gearing you need to go each speed at the same engine speed that you have at 45 mph now:

  1. 5.38 * 45/55 = 4.40 final gear ratio
  2. 5.38 * 45/60 = 4.04 final gear ratio (same as Warn overdrive)
  3. 5.38 * 45/65 = 3.72 final gear ratio (axle swap)

So, if your top speed is 45 now (rev limited) and you want your new top speed to be 65 (again rev limited), you need a 3.72 final ratio.

You'll also need more power. Since wind resistance goes like the square of velocity,

  1. ((55/45) - 1) * 100% = 49% increase in power
  2. ((60/45) - 1) * 100% = 77% increase in power
  3. ((65/45) - 1) * 100% = 109% increase in power

Wind resistance is a considerable barrier - you can see why there's so much mpg change between 55 and 65 mph.

Oil Pressure

Good discussion from the CJ-3B Bulletin Board on high and low oil pressure.

More on low oil pressure from the Willys Tech List

A low oil pressure situation is dependant on two major things:

  1. How old the engine bearing and oil pump are. The older the lower the pressure the pump will produce at idle. At idle the oil going to the front main bearing is siphoned off to the oil filter, the front rod bearing, and the timing gear spray nozzle
  2. If the spray nozzle to the timing gear is the larger of two sizes you are risking burning the rod bearing. I don't remember the diameter or the hole in the spray nozzle but it is listed in the Willys repair manual that we have. It says in the book that if the front rod bearing is burning up the replace the spray nozzle with the smaller diameter.

The Willys place I purchase parts from said that they remove the original filters and change the oil when it gets cloudy looking to prevent a chance of burning the rod bearing.

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Is my stock canister oil filter sufficient?

I've used (and continue to use) canister type oil filters in some of the dustiest and sandiest country you'll ever wish to see.

Never had a problem. I drive (and escort) MB's, GPW's, CJ2A's, CJ3B's over hot, arid and remote country, in trips that can take the convoy up to three weeks and cover 5000 miles. Never a problem. I've used a roll of toilet paper as a filter when I've been stuck without the cartridge. Never a problem. I only change the oil every 2500 miles in that type of driving and in normal driving I change oil at about 5000 miles. Never burnt a bearing or cooked a crankshaft. Provided the oil galleries are clean and the oil is a good product, the physics of hydraulic mechanics will tell you that the oil pressure will be constant throughout the whole flow area. As you probably know, the canister system was used in numerous vehicles (Chrysler, GM, and trucks) way up to the end of the 60's. Never heard of a starvation problem. Early Land Cruisers (with the copy of the Chevy 6 engine in them). I'm talking about FJ40's and earlier, had canister oil filters. No problems that I heard of. Upon reflection, I do know of someone who had an oil feed problem (now that I recall) but he was stupid and had used Silastic as a gasket sealer and the stuff was stuck in the galleries. But that shouldn't count.

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Do these little jeep engines lack oil when they idle.

No. There is documented evidence of Jeep engines being used as stationary engines in power plants, as saw mill motors, to drive household generators (thousands of them in the Australian Outback cattle stations), boat motors and I could go on and on. Most of these engines spend countless hours idling. Furthermore, the difference between idling pressure and running pressure (in normal use - not climbing mountains or getting over sand dunes) is not very great. Hydraulic mechanics tells any fool that. If you would like to run Taz for long periods at idle - do so. The only thing that may be better for him is to turn the idle screw up so he idles at about 800rpm. Not for the oil flow but for good coolant flow and correct engine temp control by ensuring that the coolant flows and the fan blows.

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Does anyone have knowledge or opinion on Slick 50 and some of these other oil additives I am thinking' about putting one or another in my 2A to enhance engine life?

Answer 1 [From various areas of opinion]: one of the best products

I've used. Highly recommended.

Answer 2: My opinion, based upon nothing, is that the best thing you can do is run a quality oil and changed at reasonable intervals. The definition of 'quality oil' and 'reasonable intervals' are left to the reader. Everything that I've seen suggests that it is almost impossible to execute a well designed experiment to determine what these are given the variability and time involved. Dyno juice has been run for years and there's plenty of older rigs with well over 100k on them. My Civic has been completely abused all it's life (I run Castrol GTX and change it when I get around to it) and continues to run very well. There are some compelling reasons to run synthetics, however you can change to oil twice as often for the money with petrol oil.

As for the additives, et al. My basic take is that anyone who uses marketing techniques composed of outrageous 'get quick rich' type claims and sensational video footage in the auto part super stores are looking for suckers. If their results are that night-and-day of a difference I'd fully expect Castrol, Mobile, etc to be on board not to mention GM, Ford, BMW, Mercedes, adnausium. Believing that to not be the case I've concluded that it's a smoke screen. It probably won't hurt but I'd be absolutely blown away if you could convince me that you've found it to be of any help.

My motorcycle has one known flaw in that the top end oiling is a bit weak and thus the oil thread has been beaten into the ground on that mail list. We've even a few petroleum chemists. Being a high performance engine I run synthetics and change the oil frequently, the best technique I know. All that being said, there are differences in oil and some of the learned members of that list do use a particular zinc based (I think) additive to help the oil designed for cars function better in the bike (where the engine and tranny use the same oil) instead of paying through the nose $5+ a quart for Honda Motorcycle oil.

In short: spend the money on another filter and change your oil more often.

Answer 3: Ford, GM, BMW, Castrol, etc., etc., (my opinion) are not going to jump on the band wagon for a great new product that last hundreds of thousands of miles and makes your engine last forever. They WANT you to buy products and parts FREQUENTLY. That's big money. Other than that I think you hit it on the head. I've used additives and synthetics and could tell no difference, except in the wallet.

Answer 4: The good one I heard was about ST. A mechanic I worked with told me that he had seen what it did: ran down the side of the filler tube, the pan, and lay in a puddle in the bottom.

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How can I remove a broken stud [in the engine]?

Answer I broke off an exhaust manifold stud leaving a piece in the block. It was the rear stud, about 1" from the firewall. I drilled a hole in it and used a screw extractor. BAD RESULTS! It broke also, leaving tool steel in the hole. About $75 worth of carbide drill bits later, I inserted a Helicoil and a new stud.

I would recommend just drilling the stud out and inserting the Helicoil, skipping the screw extractor and carbide bits. I hope your experience is more pleasant (and cheaper).

The thing that I hope everyone out there learned from this is that screw extractors don't.

If you are lucky enough to be the one that broke off the stud, then you should have some idea about how much torque was required to do it. If you were really leaning on it, or it was actually getting TIGHTER as you unscrewed, keep that in mind as you reach for the screw extractor. Remember the extractor will have to apply MORE torque than you did when you broke it. That is rarely possible.

If it broke because you bent it, or because you were trying to straighten it, that's different, and an E-Z out has a chance. I, too spent $75.00 in carbide removing a screw extractor. once the extractor is out, the stud removal goes pretty easy. (You know the drill...).

  1. Grind the broken stud flat and square if possible.
  2. Center punch the broken stud in the exact center.
  3. Pilot drill the broken stud clear through.
  4. Follow with the correct size tap drill. (Left hand if you have it)
  5. Tap with a 2 flute plug tap.
  6. Finish with a bottom tap.

Use lots of cutting fluid, or motor oil while drilling. Go slow, and stay square.

Another (more time consuming) option is to drill the stud with a small enough bit that you don't hit the block or threads. Take a die grinder with a skinny side cutting bit, and carefully grind away the stud from the inside, when you get to the threads, peel it out with a sharp pointed tool (I used the little pointy tools that comes with those small screwdriver sets). Somebody on the list suggested this a while ago and I had a chance to try it out - it worked very well, barely nicked the threads and it took about 2 hours.

Left hand drill bits are worth the investment in this case. You use them in reverse and a lot of the time they will catch and back the broken bolt/stud out for you. Soak the broken stud a couple a days w/ PB Blaster or some other penetrant, then start with the smallest left hand drill. Keep increasing in size until the bolt grabs and screws out or until you've e almost exposed the threads. Then you have a choice, either gently try an E-Z out or go ahead and over drill and put in a Helicoil. My own experience has been that 60 to 75 % of the time the left hand drill bits grab and back the bolt out.

A couple of years ago I found a local guy that had a "disintegrater" tool. For $50.00 (less than we can spend on broken tools) he removed the debris and supplied a new stud.

Here are a couple of tips I've learned about broken studs that might help:

  1. When using easy-outs, grind a groove around the shank just below where the wrench grabs it. The depth of the groove is trial and error. You are making a safety valve, so to speak, so the easy-out will break there first, leaving some material to grip to pull it out.
  2. Use a two-handed tap wrench if there is room. This keeps you from applying any side load, which is often what breaks the easy-out. I realize this might not always be possible, like up next to the firewall. In that situation, I've used various scraps of wood, etc. to rest the easy-out against, to prevent side-load.
  3. Years ago, I remember reading of a certain type of acid that only attacked a certain component in the steel in easy-outs and taps. It supposedly left the surrounding metal alone.
  4. [When removing my stuck stud] I opted for some reverse cut bits by Helicoil, sort of a drill bit and EZout combination. Sixty bucks for 4 of the bits. The EZout part didn't work too well, but the bit cut the broken stud like it was butter. I wound up drilling out the stud and retapping the hole, worked like a charm.

Most of you probably know this, but for anyone that hasn't heard of it, and has access to a mig welder, you may find it useful. I've found this technique to be far less time consuming then drilling and extracting, and more successful in terms of saving the original threads. Lets assume you have a broken off exhaust stud. It might be broken just above the surface of the casting, flush with the mating surface, or slightly inside the hole. If the stud is broken above the plane of the mating surface, that makes life very easy. Find a nut that fits over the little bit of remaining stud and hold it in place with a pair of pliers. Now take your mig welder and weld the nut to the end of the stud. You now have added a new bolt head to the broken off stud to give you a way to wiggle it and free it back up. The process of welding often puts enough heat in to the threaded section to make it come out much easier with a bit of wiggling and some penetrant.

If the stud is broken off flush, or inside the threaded hole, it adds a little more work, but with some patience, it is still quite easy. simply weld a little ball of weld on to the end of the stud to give you a place to attach your nut. I've actually been able to pull this clad welding technique off with a stud broken off several threads down in to the threads. I hope this can help someone out that hasn't heard of it before.

I took the head off my 1947 L-Head, and broke 5 bolts in the process. Not sure what to do now, (wanted to get it going again is used for daily transportation to work). I started digging through my pile of small block Chevy parts, and found that the outside 4 Head bolts on a small block are an exact match for the L-Head bolts (minus the nut on top that rusts on). So after cleaning out the threads in the block and applying a little Teflon sealer to the threads the head was back on and she was running again. Didn't have enough bolts to replace all the head bolts but will at a later time. I feel these are a superior bolt. Have taken heads off dozens of Chevys never broke one bolt.

Here's something that worked pretty well for me for taking out a broken EZ-Out. I put some carbide dental drilling tips I bought at a garage sale in my Dremel tool. Used lots of WD-40 and a few tips but they cut very precisely. The best way to get the EZ-Out out is to cut away at the soft metal of the original stud.

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Where do you get hardened valve seats (to handle extra heat from unleaded gas)?

Your block has to machined and the valve seats installed by a machine shop. Any good one will be able to get them for just about any size valves.  

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How to Prevent Gasket Failures Caused by the Improper Use of Chemicals

Most modern no-retorque head gaskets have a solid or perforated steel core faced on both sides with a soft material such as nonasbestos aramid fiber or expanded graphite. The steel core provides strength and rigidity while the soft facing material allows the gasket to conform to minor irregularities in the head and engine deck surfaces.

To improve the gasket's ability to "cold seal" the engine so it doesn't leak coolant until the engine is first started, most gaskets are also coated with Teflon or silicone-based materials. The cold-flow characteristics of the coating material allow it to creep as the gasket is loaded to seal small scratches and imperfections on the head and block surface. The anti-friction characteristics of the coating also help the gasket deal with the shearing forces created by differences in thermal expansion between the head and block -- which can be especially severe in bimetal engines with aluminum heads and cast iron blocks. Were it not for the protective surface coating, the shearing action that occurs in these engines as the engine undergoes repeated heating and cooling cycles would soon cause the gasket to degenerate and fail.

The non-stick characteristics of the anti-friction surface coating also allows the gasket to come off clean when the head is removed. This reduces the amount of cleaning needed when replacing the gasket.

Many gaskets also have raised elastomeric sealing beads (such as Fel-Pro's "Printoseal") around critical sealing areas. The added thickness created by the raised bead increases the clamping force for improved sealing.

NO CHEMICALS, PLEASE!

Under no circumstances should any type of chemical sealer be applied to a soft faced, coated head gasket. This includes adhesives, shellac, tacky sealers and RTV silicone.

Use Fel-Pro's "Blue Gasket Sealer" (BLU4) for metal or fiber pan and valve cover gaskets - but never on coated, rubber or silicone gaskets.

If a chemical sealer of some type is used on a coated gasket, it may react chemically with the coating material. This, in turn, may prevent the gasket from cold sealing properly -- or worse yet, it may cause the gasket to deteriorate and fail. A sealer may also undermine the anti-friction characteristics of the surface coating, causing it to stick when it shouldn't. This would increase the shearing forces on the gasket which could also lead to failure.

If RTV silicone is applied to a head gasket, it may flow when the head is clamped down and enter the combustion chamber and/or cooling jackets. What's more, RTV silicone is not resistant to gasoline and would quickly dissolve leaving gaps that could become leaks.

The added thickness of a heavily applied sealer on a head gasket could also cause uneven loading and loss of torque retention which could also create leaks or cause the head to warp.

So never use any type of sealer on a coated gasket.

USE SEALERS FOR THEIR INTENDED PURPOSE ONLY

The embossed steel head gaskets that were used years ago by engine manufacturers required the application of a sealer to cold seal the engine. But except for the new shim steel rubber coated embossed (RCE) head gaskets that are used on certain late model Japanese and domestic engines which should be coated with sealer when replaced, sealers are not needed and should never be used with soft face coated gaskets.

Sealers such as Fel-Pro's "Blue Gasket Sealer" (BLU4) is a good choice for metal or fiber pan and valve cover gaskets. But it should not be used on coated, rubber or silicone gaskets.

Fel-Pro's "Yellow Gasket Adhesive" (YEL5) is a quick-dry contact adhesive for holding cork or rubber pan, timing and valve cover gaskets, intake manifold end seals and oil pan end seals in place during installation.

Fel-Pro's "Red RTV Silicone" (RED3) can be used for a variety of sealing purposes, but should not be used on head gaskets, rubber valve cover or pan gaskets, or where it will come into contact with fuel.

In addition, it's a good idea to use a product such as Fel-Pro's "Gray Bolt Prep" (GRA2) on bolts that enter fluid passages to prevent fluid leaks.

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