: 1979 deville 425



bryan1970
04-14-04, 11:03 PM
i just bought my fisrt cadillac it is a 1979 coupe deville w/a 425. it has a ticking noise from what sounds like the front lifters for the front two cylinders. I have little to no experince with cadillacs specificly and was wondering if there is anything that might be a common problem with these engines. I think it is maybe clogged push rods or collapsed lifters or i was thinking that it also could be the oil pump not creating enough flow to feed the front lifters. Of course that is assuming that the pump is in the back like on small&big block chevys. Again i have very little experience with these cars. any help would be greatly appreciated. thanks in advance.

tripleyellow78cad
04-16-04, 09:36 PM
i just bought my fisrt cadillac it is a 1979 coupe deville w/a 425. it has a ticking noise from what sounds like the front lifters for the front two cylinders. I have little to no experince with cadillacs specificly and was wondering if there is anything that might be a common problem with these engines. I think it is maybe clogged push rods or collapsed lifters or i was thinking that it also could be the oil pump not creating enough flow to feed the front lifters. Of course that is assuming that the pump is in the back like on small&big block chevys. Again i have very little experience with these cars. any help would be greatly appreciated. thanks in advance.
hey bryan!
your oil pump is on the outside of the engine where the oil filter is located,
that means you can change the oil pump very easely with out removing the oil pan:woohoo:
and i have had the same type of lifter problem in my 78 deville
but only on start up or when its very cold out, also i read my service manual
and the oil pressure is only 10 psi at idel on 425 V-8's :wtf:
and only 30 psi max:wtf:
what made my 425's lifters make noise was the quick lube place puting
strait 40w oil plus an stp oil additive insted of just plain simple 10w30:fan:

i hope this new info helps

bryan1970
04-17-04, 12:02 PM
ahh ha this is interesting because there is a sticker in the window from a quick lube place and it says they put 10W40 in it! yesterday i tried running it w/ ATF to see if it would get the lifters to quit ticking but i had no luck. And it was late so today i'm going to put some new oil in it, and a new filter of course, and see how she does. by the way you wouldn't happen to know where the oil pressure sending unit is on the block? because i looked all over and couldn't find anything that really resembles an oil pressure switch. the closest thing i could find was what looked more like a coolant temp switch just below the distributer.
thanks for the help

lux hauler
04-17-04, 03:09 PM
ahh ha this is interesting because there is a sticker in the window from a quick lube place and it says they put 10W40 in it! yesterday i tried running it w/ ATF to see if it would get the lifters to quit ticking but i had no luck. And it was late so today i'm going to put some new oil in it, and a new filter of course, and see how she does. by the way you wouldn't happen to know where the oil pressure sending unit is on the block? because i looked all over and couldn't find anything that really resembles an oil pressure switch. the closest thing i could find was what looked more like a coolant temp switch just below the distributer.
thanks for the helpOn the 472/500's the oil pressure sending unit is just below the intake, at the rear of the block, just above the bellhousing flange......check there.

bryan1970
04-17-04, 09:35 PM
well no luck running the ATF didn't help nor did it hurt the ticking noise. I'll try putting a gauge on the oil sending unit port and see exactly how much psi is running. All though with the pump on the front of the engine it pretty much pushes my old theory on low oil pressure out the window. but it wouldn't hurt to know what it is running anyway. so know it sounds like i'll be putting in some lifters. does anyone know if you have to take off the intake to get the front lifters out or can you get them out through the heads? it lookes like a tight squeeze.:hmm: thanks for the help

P.S. does the 425 share the same block, heads, intake, etc. as 472's and 500's?

lux hauler
04-18-04, 01:41 AM
The 425 is a completely different casting.

bryan1970
04-18-04, 03:05 PM
all of it is different? that sucks for me. oh well i don't want to get to wrapped up in this car anyway i'm just gonna try and sell it. Thanks for the help

lux hauler
04-18-04, 07:30 PM
They are just about the same size.....so a 472/500 can be swapped in place of a 425 or vise-versa but the crank, heads and block are different. You may be able to swap intakes but I don't know of any real benefit to that. The Eldebrock intake for the 472/500 will fit the 425 though.

tripleyellow78cad
04-19-04, 09:59 PM
all of it is different? that sucks for me. oh well i don't want to get to wrapped up in this car anyway i'm just gonna try and sell it. Thanks for the help
hey, bryan1970,
i looked in my service manual and the oil pressure sending unit on 1978 425 v-8s
is located in the front of the engine near the water pump(on the passengers side of the engine)
also dont sell your cad, you can put a 472 or a 500 cad engine in there
and everything will bolt in and look competley stock only you will know:coolgleam:burn: :burn:

bryan1970
04-20-04, 09:36 AM
aww man don't tell me that! i've already got one project going and i definatly don't need another not to mention i've already got 6 cars at a house with only a 2 car garage. i.e. the driveway is only designed to support 2 cars not 5. Plus the whole point of buying this car was to re-sell for profit. by the way the ticking has returned. after i did all that fluid changes it got quieter but i started driving it to school on mon and it started again and was ticking on the way to school today. And i really don't want to put a new cam and lifters in it. so it kinda sucks right know.

by the way anyone want to buy a 79 coupe deville? thanks anyway

Angela Desmond
04-21-04, 07:24 PM
I'm building a high HP 425 now, and there are a lot of differences between 425 and 472/500. The 425 stock intake sucks, it's a single plane that sits lower than the intake ports; all in the name of hood clearance...You didn't mention what kind of milage was on the engine. There is no adjustment for the lifters, like on a chevy. That's one reason people use different rocker set-ups on high output Caddys. And no, you can't get those darn lifters through the heads without removing the intake. My '79 425 has the oil pressure sending unit at the rear of the block.

bryan1970
04-22-04, 09:28 AM
:annoyed: the engine has 127k on it. and that whole intake design sounds prett shitty. i can't belive it even runs right. but i bet a new intake would make a world of diffrence. yeah i found out about the rocker design when i took off the cover to see if any oil was getting to the front rockers: it was. I guess oldsmobile uses the same design on some of thier engines too. where do you get parts for the 425 i havent even been able to find like a rebuild kit for one in any of my catalogs? i've triedsearching on google and can't find anything either.:hmm:

lux hauler
04-22-04, 10:46 AM
Most of the vendors that sell stuff for the 472/500 engines, sell stuff for the 425 too.

Angela Desmond
04-22-04, 10:56 AM
I've done all my parts business with "Maximum Torque Specialties" (MTS for short).They're in Delvan WI. Also, there is Cad Company by Flashcraft. Never did business with them, but many people do.Then there are some real race heads and intakes built by other folks, but you should start with these guys...Yes, the 425 intake is real crap and performance gains can be made just by changing to the Edelbrock dual-plane, but you have to watch your hood clearance 'cause it rises much higher than the Caddy design.Worse than the 425 intake is the exhaust manifolds! Just keep in mind, these aren't small block chevys ,where everybody and his mother makes hi-po parts for it and most things fit right out of the box. Anytime you switch parts with these things, measure what the parts people tell you to measure, or you'll be blowing up things faster than Chinatown on their New Year.... :crying2:

bryan1970
04-22-04, 09:07 PM
cool i'll have to check those companies out. Personally i'd rather look at a hopped up cadillac instead of a chevy just for the reason the they actually take some skill to make cool. Not knocking on chevy guys but they/we sure got it nice because it is so easy to find parts. but there is just something about doing something diffrent that makes a hot rod a hot rod. although sometimes you just don't want to deal withh all the hassel. but any way thanks for the info

Angela Desmond
04-22-04, 09:50 PM
You will become a more skillful engine builder doing the caddy. At the same time your knowledge will be, at times, sorely tested....Welcome to the club :welcome:

bryan1970
04-24-04, 11:52 AM
yeah thats why i'd really like to build up the caddy but it has come kind of at a bad time because i've already got a 1970 camaro project in the works. and of course high school isn't exactly giving me a lot of free time and work takes up a lot of time, especially the working full time in the summer. oh and by the way this forum is great and all the people on it. at least everyone i have met have been really helpful. unlike other forums like the 60degreev6 forum. although there was some people on there that were really helpful most of them were squirlly kids:bouncy: that think if you put a cat back exhast and a throttle body on a 3.4L v6 they are going to get 300hp out of it. i kinda got tired of saying the same thing to them: you have to build the whole engine to take advatage of your mods!!!. but any way everyone that has replied i really appreciate your help.:worship:

Angela Desmond
04-24-04, 12:04 PM
Those are the same pimpely faced kids I blow away with my 350CI Caprice.They think a noisy muffler makes goobs of power :p Your Camaro would be an excellent project to throw a big block Caddy engine into! Thanks for the kind words :)

bryan1970
04-29-04, 09:08 PM
yeah i don't know what i like more: blowing those kids off the street or listening to them talk about cars and then correct everything they just said right in front of all thier friends. A big caddy wouldn't be bad but i got some pretty evil plans for a 307 to make it into a 328.:lildevil: then when i beat some guy with a 350 or 400 i'll tell them they just got beat by a 307! by the way by chance and i mean a very small chance, does the caddilac use the same transmission bolt pattern as a small chevy. I'm pretty sure they don't but i figured it cant hurt to ask. :hmm:

lux hauler
04-29-04, 10:51 PM
yeah i don't know what i like more: blowing those kids off the street or listening to them talk about cars and then correct everything they just said right in front of all thier friends. A big caddy wouldn't be bad but i got some pretty evil plans for a 307 to make it into a 328.:lildevil: then when i beat some guy with a 350 or 400 i'll tell them they just got beat by a 307! by the way by chance and i mean a very small chance, does the caddilac use the same transmission bolt pattern as a small chevy. I'm pretty sure they don't but i figured it cant hurt to ask. :hmm:The 368, 425, 472 and 500 all use the BOP (Buick, Olds, Pontiac) bell bolt pattern. Chevy is different.

bryan1970
04-30-04, 09:18 AM
ok that isn't as bad as i thought i thought that cadillac would have thier own separate pattern diffrent from everything else. at least that broadens my searching capabilities now. because the th400 that is in there now leaks like a 2/3 qt. about every 100mi. and it is difficult to figure out where it is coming from. because the whole bottom of the transmission is wet. when i get a chance i'll take it in to work and put it up on the lift to try a find the leak. i have heard that the modulators are a common spot to get a pin hole in them then the engine sucks up the fluid but i have not seen any smoke come out of the pipe ever on this car. but i'm still gonna check that. the other two areas are the pan gasket and the torque converter seal.

lux hauler
04-30-04, 05:15 PM
I'm not sure what tailshaft your tranny has but, if you're going to get another trans, make sure it has the same tailshaft length or you'll have to buy (make?) another driveshaft.

bryan1970
05-05-04, 09:39 PM
:wtf: okay now it has nearly quit leaking. and all i did was NOTHING!!! the only thing i did do was fill up the transmission. in fact it isa little over full. but it runs just fine. Nothin special put in the tranny just valvoline's max life tranny fluid but thats what i've been putting in there all along. So i don't know, and honestly i don't care as long as it still runs and isn't leaking.

Night Wolf
05-17-04, 05:15 PM
So the intake and exhaust manifolds on the 425 are restrictive... so if someone was to get the Edelbrock intake manifold and a high-flow air filter system, and nice after market exahsut headers, along with a while header-back exhaust system (more free flowing) are we looking at a nice noticable increase in performance here?

Also, the 425 with the Edelbrock intake manifold and air filter will not clear the hood of a '79 DeVille?

Night Wolf
05-17-04, 05:55 PM
Are these any good:

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=7902115908&category=34203

they look real nice... and are pretty cheap, but I wonder if they flow any better then the stock exhaust manifolds...

bryan1970
05-17-04, 11:18 PM
that is exactly how you have to think when trying to get the most power for an engine modification. Basically any internal combustion engine is an air pump and if you can get a bunch of air in but you can't get it out then the pump won't be as efficient as it could be. It is like a balancing act. Those headers on ebay look okay. i'm not sure how long the chrome would hold up but performance wise they look okay. the only thing to think about is what size primary tube work best on a 425. too big of a tube can actally hurt horse power and especially torque.( which is a cadillacs best friend:coolgleam ) Even though the flow of the headers are better than stock. i have never seen the size of a 425 exhaust port but that might be one thing to keep in mind.because 1 7/8 really is a huge primary tube.

by the way out of curiosity what dose your deville run in the1/4?

lux hauler
05-17-04, 11:30 PM
Are these any good:

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=7902115908&category=34203

they look real nice... and are pretty cheap, but I wonder if they flow any better then the stock exhaust manifolds...make sure those headers will fit the chassis. they are block huggers (made to fit close to the block) and they dump downward and not back. they usually only work in street rods where there is no cross member behind the motor mounts.

Night Wolf
05-17-04, 11:56 PM
My stock DeVille, no tune up yet, K&N air filter, octance booster, empty trunk, 12/18gallons of gas, my first time racing, real crappy launch, brought me a 16.0 @ 83mph..... I thought it would be betterm but I launched it bad, and if I get the car i am looking at, perfomrance from my '93 wont matter any more....

cadillacdeville
05-18-04, 12:27 AM
about those ticking noises you hear its not the oil pump or the pressure the same thing happens on most every ones cadillac with a 425 what it is is the lifters on a 425 cadillac are hydraulic and the oil drains out pretty quickly if you use anything less than 10w-40 and upon start they will knock for a second I learned this from some original information cadillac serviceman news letter from 1976-77 that I got of ebay plus I have an origonal factory service manual that covers every thing on the car and explains the hydraulic lifters. to fix it you cant but however you can lessen it by adding a can of restore engine lube and good valvoline 10w-40 highmileage oil that will really help if you need any additional information on the engine or trans just contact me at cadillacdeville@aol.com (cadillacdeville@aol.com) I will be glad to help anyone who has any questions about the cars or mechanics of them and can even send you detailed instructions about almost any procedures for repairing, replacing, and finding parts for these wonderful powerful and best of all AMERICAN cars also I can send you information about the options and aproxament cost of the 77 cars.

Angela Desmond
05-18-04, 02:39 PM
As for the topic of primary tube size on the 425, 1 3/4" should be plenty for mods spinning the engine up to about 6500RPM. If your getting totally nuts and plan on spinning this thing over that, then, maybe you can consider 1 7/8" but you'll need to really open up those exhaust ports... :burn: