Frequently Asked Questions

Parts and Services for the Universal Atomic 4 Engine
Parts: Phone: 610.421.4436 | 410.810.8921 | 610.928.3410 (fax)
Technical Service: Phone: 410.810.8920 | 410.810.8922 (fax)

To receive the FAQ's below by email, click the checkbox next to each FAQ group.
To receive a copy of specific FAQ questions, check the box to its left.

General Information: We removed our Atomic-4 2 years ago and had it rebuilt and tried to install it last week and once we got the motor in we found that we were 2in. out of alignment withe the prop shaft? the motor is setting to high. we had the rubber mounts installed even after removing them we are still too high. help; What would be the appropriate fuse and wire sizes for the main circuits within the engine DC power supply?; Have stuck valve on #4 cannot get head off. Managed to pry up about 3/8". Cannot get any looser. Just took off nuts. Studs are still on. Should I remove studs? if so, how do you remove them?; Looks like I need to remove the carburetor & exhaust manifold to adjust valves. Is that correct?; We recently purchased a 28 Newport with an Atomic 4. We were told the engine hasn't run in two years. What steps do you recommend to prevent any damage to the engine as we prepare to bring it back to life?; I'm planning a long trip, and although my engine is running quite well, I'm wondering what kinds of things I could check to make a breakdown less likely during the trip.; How can I tell the direction of rotation of my prop?; I have an Atomic 4 in my sailboat. I just measured the compression and got 0 for cylinder #1, 80 for cylinder #2, 120 for cylinder #3 and 120 for cylinder #4. I know the zero reading means a stuck valve, but does the 80 reading in the adjacent cylinder mean anything? Any recommendations on a plan of action?; What is the difference between an Atomic 4 and a Stevedore Atomic 4?; What is the proper torquing technique for head studs?; Where is the serial number on the engine?; Early or late model? How can I tell? What difference does it make?; A general approach to troubleshooting; Troubleshooting intermittent shutdowns; What would cause my engine to run with almost no power in forward, while it runs OK in neutral? It also seems to have more power in reverse than in forward.; What would cause my engine to falter, sometimes even backfiring slightly,as I advance the throttle too rapidly from idle?; Age; Things to look for when buying a boat with an A4; Starting with a hand crank; What would make my engine start hard, but then run perfectly OK once it starts?; Precautions when starting up an engine that has been sitting idle; How can I deal with head or manifold studs which fail to hold the specified torque values (35 foot-pounds for the head, and 25 foot-pounds for manifolds)?; Is it possible to use 3/8" coarse-threaded bolts in place of studs for installing heads and manifolds?; Knocking sounds in the lower part of the engine; Clicking sounds in the top of the engine; My Catalina 30 won't start.; I was coming back from a long trip with the engine on, when all of a sudden, the motor ran quieter. I quickly turned off the motor and raised the sails. I had to start the motor again when returning in the harbor, but it still was running poorly. Recently I checked it and found that it is only firing on 2 cylinders, but the plugs, plug wires and distrubutor all seem to be in good shape. Where do you think the problem lies?; Gas is ok, carb ok. Compression good on all 4 cylinders and I get spark ok, yet it will not start. Turns over ok with new battery. Do you have any suggestions?; What should the compression be?
Ignition System: I am interested in going to an electronic ignition system. However, there is a lot to be said about a point system when it comes to diagnosing problems and stocking spare parts on board. Any reccomendations? What would I need to stock on board to be assured that I could get it back up and running if I had a failure? How dependable is the igniter system?; Removing and replacing a Prestolite distributor; Is it possible to reassemble a distributor's mechanical advance mechanism in reverse order? I have a later model (1974) Atomic 4.; If my early model engine got out of time, how do I reinstall the Prestolite distributor?; Installed new depth/speed instrument on my C&C 27 last summer. I experienced intermittent "cycling" of the instrument when the engine was running, especially after long periods. I think that the problem is radio noise from the alternator or ignition. Any suggestions on how to correct?; I tried to remove the spark plugs on my boat. It looked like the previous owner had not changed them in a long time. I soaked them with penetrating oil for several days. However one of them broke off in the head. The part with the threads is still in the head. I tried an easy out but was afraid it was going to break without any success. Do you have a suggestion?; What is the recommended spark plug for the Atomic 4?; What coil is recommended for the Atomic 4?; What would cause my engine to have no spark?; My alternator is shot and I'm thinking about replacing it. Do you have suggestions on an alternator for the Atomic 4?; What is "dwell angle", and how do I measure it?
Fuel System: Our engine starts and runs fine for about an hour. Then suddenly stops. It can be re-started immediatly and runs fine for another hour or so. The only thing we have done mechanically is add an electric fuel pump.; There is a tube going from the intake manifold to the bottom of the carb...what is its function?; On my atomic 4 motor starts up ok, but then dies. Does this indicate water in the gas? What would you recommend?; Is it OK to mix other additives to the fuel (like stabilizers and moisture inhibitors)?; My fuel tank is higher than my engine. Do I need an anti-siphon valve? There is a small round valve installed just above the tank where the fuel line leaves the tank. Could this be some sort of anti-siphon valve?; What are the indications of a lean fuel mixture, and how does one correct it?; Why does it seem that adjustable main jets are more susceptible to becoming partially blocked than the fixed main jets of later model carburetors?; What are the pros and cons of removing the fixed main jet found in late model carburetors and installing an adjustable main jet?; Why does dirt get trapped in the float valves of carburetors, rather than move on through as the floats raise and lower the needle against the seat?; What is the proper float setting for Atomic 4 carburetors (early and late model)?; What is a good initial setting for the idle mixture and the adjustable main jet?; I notice that while running the engine rpms change without my doing anything to the throttle. Sometimes it runs faster and some it slows down. Any suggestions as to what could cause this?; Can the A-4 use unleaded regular gas, or should a lead substitute additive be used with the unleaded gas?; Octane ratings; I installed a new oil pressure safety switch and fuel pump, and I'm not sure if I wired it up correctly! Should the fuel pump be running before the engine is actually being cranked, as mine does?; Starting fluid; What would cause fuel to drip out of the mouth of my carburetor?; Fuel pump pressure; Recommended additives for gas and oil
Oil System: I HAVE A SMELL OF GASOLINE IN THE OIL AND THE OIL LEVEL RISES AFTER SHORT PERIOD OF RUNNING ENGINE(15-20 MINUTES) I also have gasoline in the exhaust water, it leaves a slick on the water behind the boat.; My oil pressure is somewhat higher and the engine seems to run a bit quieter when I use 40 weight oil, or even 20-50 in a multi-viscosity. Is there a downside to using heavier than recommended oil?; Is it OK to install other oil pressure safety switches on "T" fittings along with my original oil pressure gauge sending unit?; My oil has turned "milky". How can I troubleshoot to determine how much water may have gotten into my oil, and what can be done to remedy the situation?; I am getting some oil leaking into my bilge, but I can't seem to locate the leak on my engine. Where are some likely spots to look?; What could cause a smell of gasoline in the crankcase? I noticed a slight smell of gasoline the last time I checked my oil.; Water in oil (Catalina 30); Erratic oil pressure in late model engines; Recommended normal and minimum continuous duty oil pressure for the Atomic 4?; What type of oil is recommended for the Atomic 4, and how many quarts does it hold?; Recommended additives for gas and oil; I am getting some oil leaking into my bilge, but I can't seem to locate the leak on my engine. Where are some likely spots to look?; Minor oil leak right by the water pump; Oil leaking from the bottom of the flywheel cover
Cooling System: I am getting ready to acid flush my engine and was wondering about the themostat. Do I remove the thermostat before the flush, or can I flush the engine with the themostat in if I warm up the engine first? Will the acid do any damage to the thermostat? Any precautions I should take, aside from the normal acid spill warnings?; We have a 1972 Columbia 30 with a RWC A4 that was rebuilt in 1997 and is now overheating when at cruising speed (1700). I recently did an acid flush (as per your manual), but the engine still overheats, though not as much as prior to the flush. During the flush, it took about 5 minutes to empty the acid bucket which would indicate blockages in the cooling passages (impeller and thermostat are fine). How do I go about manually cleaning the passages that I can access without removing and stripping the engine down to have everything chemically cleaned out?; When is the thermostat housing spacer (OVWJ_13_241) used? I haven't run into one on any engine I've worked on. And do I need one with the bronze casting and current 180 deg stat.; Knowing that your freshwater cooling system requires at least two inches of space in front of the flywheel cover to accommodate the belt drive for the sea water pump, how much space does the system require above the engine?; One of my freeze-out plugs has developed a slight leak. What options do I have in terms of repair?; I got caught off guard when the first snow storm hit our area the other day. My boat was taken out of the water earlier in the week, but I was not able to put antifreeze in the engine before the storm hit. How much damage do you think I have done? It got to the low 20's overnight two times.; How important is the internal fitting on the block side plate, the one directing coolant flow to the rear of the block?; My engine was running fine then started overheating. There is white billowing smoke or vapor coming from the exhaust. The engine seems to run smoothly but the smoke (vapor) worries me as well as the overheating. The raw water strainer is clean. Could it be the thermostat, and how can I check it?; I am getting steam out of the exhaust when running, but the temp guage says 140 to 150 degrees. I did a compression check and the results were 120 psi on two, three, and four, and 90 on number one. I am thinking of a crack in the head or something with the head gaskets. Any ideas.?; What type of grease to use in grease cup for water pump?; The engine temp goes way up and then falls back down over and over. I have replaced the thermostat three different times, and it still does the same thing. It seems to be the worst when I am motor sailing so the load is the least.; Zincs; What would cause my engine to run at temperatures below the rating of the thermostat?; Why does my engine run at 160 to 170 degrees (with a 140 degree thermostat), even after insuring that my cooling system is well maintained?; What would cause the temperature to go above 180 degrees in my late model engine?; Bypass restriction in a late model cooling system; Operating without a thermostat; Operating temperature; Re-plumbing raw water cooled engines for better hot water heater performance
Accessory Drive: Grinding or screeching noises in the area of the accessory drive; Rattling or clicking sounds in the accessory drive
Reversing Gear: What is the proper oil/lube to use in the v-drive? Should any type of additive such as Lucas Oil Stabilizer be used?; I just read your FAQ on reversing gear and see how I must have tightened the collar locksrew as you advised NOT TO! and broke off the cast iron base it was in. That was HOW so now WHAT can I do?; My customer's A-4 is very difficult to shift into fwd gear. Once it does, operation seems to be normal. Is the effort with which you can shift affected by the adjustment of the fwd mode? Could it have been over-adjusted to make up for worn plates?; Is it normal for a prop shaft to turn slightly while the reversing gear is in neutral?; The reversing gear shift lever on my A-4 completely slipped off the cross shaft (I think it is called cross shaft). Could you please tell me how I can reattach it, and why it slipped off in the first place? The cross shaft appears to have an open slot on each side about the size of a quarter. But I don't find any thing on the shifting lever that is designed to go into it. Not sure what is the purpose of the slots.; My reversing gear doesn't engage reverse.; Reversing gear adjustment procedures; Why does my boat move forward, even when I have the shifting lever in neutral in the cockpit?; Why does my reversing gear slip out of �forward� whenever I advance the throttle much above half power?; Grinding sounds in reverse; Why won't my reversing gear stay in reverse?; How long should the forward clutch disks last in the reversing gear?; How does the reversing gear get lubricated?; Pedestal steering issues
Exhaust System: I noticed smoke rising out of my A4 after four minutes or so at idle. It doesn't smell like exhaust, but it could be. The hot section of the exhaust is wrapped with fiberglass, so I can't see the leak. Is there a way of repairing a small leak in the pipe, or should I simply replace the entire iron section per chapter 7 in the manual? Also, in the event that I have to cut the pipe off, how do I remove the flange bolts in the exhaust manifold?; How do I go about replacing my exhaust system?; Exhaust system blockage
Propellers: I have one of the CDI props, but am interested in the Indigo one as a replacement. I have a O'Day 27 that (as you would guess) I motor more than I sail. Indigo claims their prop is quieter and more efficiant. I was wondering if you folks would have an opinion which prop would be better for my application. And btw, the electronic ignition I bought from you works great!; Prop selection
e-Mail FAQs to:
[Back to the FAQ's] ��-�� [Search our FAQ's] ��-�� [Question Not Answered?]��