Timing Gear And Engine

I have a 78 Dodge motor home, with a 440. First question is which timing gear pattern do I need to order. From what I've found on web sites there is a single bolt and thrre bolt pattern. Question 2 What is the differance between a 440-1 and a 440-3.

All the big block Chrysler engines I have worked on have a single bolt, in the center, holding the cam gear on the end of the camshaft. The best way to know what you need is to pull the timing cover and take a look.

Having said that, what leads you to believe you need to replace the timing chain set on your motor home??

I really have no special reson to replace gears and chain, except that I am replacing bad harmonic balancer. Have to take the timing cover off anyway for new seal so, being that close better now than later.

The 440-3 is the 'industrial' version of the 440-1. The 440-1 went into cars, vans, pickups. There were 440-2's, used in some military gensets and in boats. The 440-3 went into motorhomes and medium weight trucks. Anyway, the 440-3 uses different heads (with different spark plugs) has better bearings, a mild camshaft for better torque at mid range rpms, more cooling passages from block to head (so the head gaskets are different), had better valves, and induction hardened valve seats. I think the exhaust manifolds are different, but am not sure. I know the distributors had a slightly different advance curve - though not so different as would make it unfeasible to get a used dist. from a car. I believe the compression ratios were generally lower than used in the 440-1. The carburetors had different jets; and the water pumps, water pump housing, and radiators were bigger in the motorhomes, along with the radiator fans. Also you should be using a 'skirted' thermostat. You can see what the thermostat should look like here: www.stewartcomponents.net/Merchant2/merchant.mvc There will be an image of the correct type of thermostat in the middle of that page. If you double click on the image you get more info. And contrary to what is says on that page, you can use it with the original mopar water pump - which is already a high-flow pump. I ordered my thermostat from www.summitracing.com, where it is summit part # mrg-4367.
My impression is that motorhome engines dont go through timing chains very often. Mine has 103,000 on it, and the timing chain was like new when I replaced the front crankshaft seal about 90,000 miles. Its because they run at fairly steady rpms, unlike delivery trucks. Especially delivery trucks with standard transmissions driven by young drivers who do snappy shifting. I know of two Winnebago owners with over 160,000 miles on their original unrebuilt engines, and with the original timing chains.
I cant recall whether the cam had one bolt or 3 bolts on the 440-3 either. Dont lose the woodruff key.
While the engines used the same rough castings (which is why you might see a 440-1 cast into the side of the block), they used enough different parts to make getting engine parts a bit of a mystery sometimes. Its always best to take the old part in with you. There may have been crankshaft differences too - but I think they are interchangeable if the number of bolts holding the flywheel on are the same as what you have.
I make it a point to get the parts for the mopar big block in my motorhome from places who know the difference between the engines in passenger cars, and those in trucks. (mine is a 413-1, while the cars used 413's with no dash number. Different parts.) The places that provide parts to fleets and delivery trucks. Many auto parts places wont have listing for vehicles of one ton or more capacity, let along for a vehicle over 30 years old.
I replaced my clutch fan when it was about 25 years old, because it was sort of feeble. They never just die, they slowly lose their 'force'. Its insidious. If the cooling system on your 440 is as it should be, with a 50-50 mixture of coolant and antrifreeze, you will be able to drive anywhere in the USA or Mexico, up any grade - without overheating. If you are going to bo towing anything - I would add an auxillary tranny cooler.
Be sure to put a drop or two of oil on the felt wick that is inside the top end of the distributor shaft, under the rotor. This is the only lube the centrifugal advance ever gets. If it 'sticks' you can lose power when it doesnt advance, and can have goofy timing problems when it doesnt fully retract at lower r.p.m.
In the winters we are in far southern TX, near the MX border and the Gulf. VA in the summers.

Thanks Guys for your imput. I've gained a lot of knowledge in the past few days researching blocks. I found on 440source.com what the castings on the side mean and mine being 440-9 makes me feel a little better about it having improvements made to it. Anyway back to the reason for all this is when I bought my motorhome I was told it was a 440-3 and I thought I remembered the emblem on the valve cover saying 440-3. It has since been scratched and unreadable. So while digging around I found a site for decoding vin #'s. Mine with a D means 440-1. So with all that said and with everyone's help I figure with 96,000 miles on her what does it really matter. I'll look at the gears and chain when I get to it and just go from there. What really started all this was a vibration I could not find until I noticed a piece of rubber coming out of the balancer while changing the oil. Glad I found it though because the vibration was driving be nuts and surely wasn't good on the engine.Also it having a cast crank made the balancer hard to find also. So thanks again guys. You have been a great help.
Larry Ray
Littlefield, Texas

Thanks for the info about the balancer coming apart. Hopefully its what was causing the vibration, not the -result- of an imbalance elsewhere. The 'truck' engines seemed to have the cast cranks, since they werent going to spend much time above 4000 rpm; while some of the 440's in the muscle cars could wind up to much higher rpm - so had the forged cranks. The 440-3's I dealt with all had the small spark plugs - with the tapered seats. The 440-1's seemed to have the usual spark plugs with the flat seat and a washer.

Since you need to remove the timing cover to change the seal, I offer the following suggestions:

The oil pan attaches to both the block and the bottom of the timing cover with one gasket. Although it is possible to remove and reinstall the timing cover with the oil pan in place, I no longer recommend that method. The timing cover aligns on two metal pins in the block at the bottom of the cover. More than once, when I used this method, I ended up deforming the timing cover trying to reinstall the cover over these pins with the oil pan in place. This caused oil leaks from the cover. I recommend dropping the pan before reinstalling the timing cover, then replacing the pan with a single gasket. Though it may take a little longer, you don't have to go back and do it again to correct the oil leak.

Removing the timing cover will give you the opportunity to visually inspect the timing chain set. Some cam sprockets were all metal while others were metal core with plastic teeth. If you find you have a plastic tooth cam gear, I would recommend timing set replacement on general principal. Otherwise, you can inspect the play in the chain set by rotating the crank with a wrench clockwise until the timing marks align, the slowly rotating the crank counterclockwise until the slack is taken up. If you observe more than 1/2 tooth (at the cam) of slop, I would recommend timing set replacement.

Replacement timing chain sets come either as single row or double row and include new sprockets. Single row chains are least expensive, but double row chains are more durable. I prefer double row chains, but you need to decide for yourself.