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500 Cadillac

nebraskaairboater

nebraskaairboater

Well-known member
I recently switched from a 350 chevy direct drive to a 500 cadillac direct drive. The difference is night and day. It runs great. The engine I got had sat for a couple of years. Now it appears that the rear main is leaking. At least the oil is hitting the prop and spraying over the back of the engine. It does not appear to be leaking from a valv cover gasket but the oil pressure tube looked like it could also be leaking. Is there a good way to check to see if it is the rear main with the engine on the boat? Also is the rear main something that can be changed while on the boat?

Thanks,

Dan Porter, Jr.
Fremont, Nebraska
 
They make dye that you put in the crankcase. Run it a bit and examine suspect areas with a black light. You can get this dye at NAPA
 
nebraska there is a low tech way to check for oil leaks and it works like a charm what i do is degrease the engine real good then let it dry completely then use women's secret deoderant aerosol spray the suspect areas real well when it dries it turns white then just run the engine and see were the oil is coming from and yes you can change the rear main on the boat
 
When you mention oil pressure tube do you mean crankcase vent or oil pressure sending unit and tubing? I used to have my vent coming out of the valve covers and running to back of engine and it always put out a little oil. Now I run the vents to the flame arrestor on the carb.
 
I'll try the deoderant first. Then if I can't find it I'll try the dye. The oil pressure tube is the plastic tube running to the oil pressure gauge. Any advice If I have to replace the main seal. On an Engine that sat for a while like this one are there any other gaskets or seals that I should change while I'm at it? And are there special tools or something I can make to push the seal out without removing the crank?

Thanks,

Dan
 
pcv valve in the valve covers with vacuum line to carb. Would the lines running from the valve covers to the headers be better?
 
I would replace the plastic oil pressure line even if it is not leaking. Plastic lines tend to get brittle and break and can leave you stranded at the worst possible times. You can find copper tubing at NAPA to replace it with. You should be able to remove the starter and drop the oil pan to replace the main seals and oil pan gasket while the engine is in the boat.
 
Hey nebraska i'm coming your'e way soon kinda lake of the ozark's but i lived in south sioux city neb. for 8 years never new there was air boats up there or i might not have left maybe i'll head your direction one of these day's is there some good riding and what part of neb. are you in i assume the west.
 
I'm in Fremont (30 miles west of Omaha). I run on the Platte River between Valley and North Bend. There is getting to be a bunch of airboats on the river. It's the only place I've ever ran so I think its a good place to ride.
 
A PCV valve is the worst thing for these reasons. 1 it robs vacuum from your motor thus hurting throttle response and power. 2nd it introduces oil into the combustion chamber. A header evacuation is superior it produces a good vacuum which prevents crank case pressurization thus preventing leaks. When a crank case gets pressurize the pressure on the back of the piston rings cause the ring to flutter or not make a good seal to the bore this poor seal kills bottom end performance. On the dyno I have seen 20hp gains on an iron block and up to 50 on an aluminum block just by adding a good crank case evacuation. I recommend installing a header Evac system. If you run mufflers you must install the pick up after the muffler they will not work when installed in front of a muffler.
 
Thunder,

Now you gave me some information I have been looking for, thanks. I understand some of the nascar guys use evacuation pumps.

Jim

I changed the screen name from cracker to jim to help eliminate confusion
 
I have heard where some drag race guys that use electric fuel pumps will leave the mechanical fuel pump on the engine and use it to pump the crankcase pressure out of the engine. I use the mechanical pump so it wouldn't work for me. Can I just drill the collector out on the header and weld a stub on it? I don't really have mufflers on my boat. We took a couple pieces of 4" stainless steel tube and welded it around a 3" piece to make it look like mufflers. The I welded in some sheet metal with a bunch of holes drilled in it. Looks like a screen inside the tube. It is actually pretty quiet like a muffler at idle. Would this cause too much back pressure for the header evacuation system to work?
 
On my higher horsepower motors and on all my nitrous motors I utilize a belt driven vacuum pump either a Moroso or an Aerospace components pump. Most drag racers and engine builders run these pumps now. You just need a MrGasket Evac kit they only cost $32 from jegs PN# 720-6002. Just weld the pick up into your header collector. They work perfect on airboats.
 
has anyone been able to find a gear drive for the cadillac engines yet? My timing chain is ok now but I'm sure it is stock so I expect to have to replace it eventually. Also how much weight can I get rid of with an aluminum intake. I just want to end up with a durrable engine that will last a decent ammount of time. I know that some of you were talking about different rocker ratios to give it more low end power but would this affect the durrability of the engine? What would the best combination be for this engine in direct drive application as far as cam, ratios, etc...
I'm not really a techical engine guy but there is a guy out here who rebuilds and builds engines for boat and he is willing to redo mine this winter and i'm just wanting to start thinking of what I can do to it to get the most power out of it that I can as a direct drive engine. I plan to run a 72" Sensenich Q blade prop when all is said and done.

Thanks,

Dan
 
The high ratio rocker arms make a huge difference they increase port velocity along with how fast the valves open and close. This all ads up to more torque and throttle response. Also purchase a Edelbrock Performer intake Jeg’s PN#350-2115 you should also install a Super Sucker spacer Jeg’s PN#555-15420 the next thing everyone will say is wrong or too big but purchase a 600CFM Holley double pumper PN #4776C see a dual plane intake only lets each cylinder see half of the carburetor then the above super sucker spacer drastically increases the velocity of the intake charge. I built a direct drive V/6 that swings more prop and snaps better than most 455 Old’s and 500 Caddy’s and it has a 700CFM Holley on it. You can turn that Caddy into a beast!
 
Waterthunder said:
The high ratio rocker arms make a huge difference they increase port velocity along with how fast the valves open and close. This all ads up to more torque and throttle response. Also purchase a Edelbrock Performer intake Jeg’s PN#350-2115 you should also install a Super Sucker spacer Jeg’s PN#555-15420 the next thing everyone will say is wrong or too big but purchase a 600CFM Holley double pumper PN #4776C see a dual plane intake only lets each cylinder see half of the carburetor then the above super sucker spacer drastically increases the velocity of the intake charge. I built a direct drive V/6 that swings more prop and snaps better than most 455 Old’s and 500 Caddy’s and it has a 700CFM Holley on it. You can turn that Caddy into a beast![/ WATERTHUNDER, I need your tele. number or your e-mail addres. Henry 229-723-5866 or h_maddox@yahoo.com quote]
Click to expand...
 
Thanks Thunder I dont have to ask them no more . I like the cads - Q and Answers . I can just sit back and listen . Thanks , :D check in the mail
 
waterthunder, everything else is there, but exactly which rocker arms ?
and which cam ?
looks like there's a few of us that need to know !!!
thanks in advance
 
Stage II (1.72:1) Shaft Rocker Assembly w/ Special Pushrods @ $525.00 Call CAD Company and buy the rockers but get the cam specs they recommend then call Comp Cams @1-800-999-0853 AND GO OVER THE SPEC’S I bet comp will come up with a higher velocity lob profile. I have Comp Grind all my cams. If you wish Email me @ 1320thunder@msn.com I will call my sales rep at Comp and get a custom grind for ya and save you a little money but the main thing is I get allot of cams from Comp and they will get more aggressive with lobe profiles for me.


CAD Company
The originators of performance parts for the Cad 472"/500"/425" !
You may order by phone, fax, or email.
Phone (505) 823-9340 - Fax (505) 797-0627
 
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