Monzallac 425 Lives!

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Monzallac 425 Lives!

Postby HI WINDING MONZA » Fri Dec 07, 2007 8:46 pm

Well, before the bad weather hit, I made an attempt to fire up the 431 Cadillac today. Despite a bad fuel pump, some electrical issues and a slight tranny leak, it LIVES! :D Had to pour fuel down the carb to get it to run but my timing was dead on and it fired right up nice and smooth! Hopefully I can get a fuel pump tommorrow and the rain lets up so I can run it more than 30 seconds at a time. It idles like glass, just like a Cadillac should. Looks like a big hood scoop is needed because the HEI sticks up as high as the air cleaner. :( Should be ready for a test drive next weekend. Doug in AZ 8)
Last edited by HI WINDING MONZA on Sun Mar 30, 2008 12:10 am, edited 1 time in total.
My Old Cadillac Powered Monza Still Lives...........now on its 5th owner!..........Somewhere ?

The 90's just keep rollin' along........
1990 Chevrolet Silverado Regular Cab Long Bed 350 TBI V8 700R4 105k miles
1992 Pontiac Sunbird Coupe 2.0 OHC MPFI I4 TH125C 143k miles
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Postby v8astregt » Fri Dec 07, 2007 9:04 pm

Sweet! I love it when things go smooth like that. This is the first time I've checked your garage out, that's a pretty cool car! I love the Caddy motors. I still toy with putting a 500 in my Monte Carlo.
75 Pontiac Astre GT: 406SBC/TH350, roll bar, S10 goodies, down to 11.47 so far, more to come later.
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Postby cozwurth » Sat Dec 08, 2007 12:05 am

Lookin pretty good, Doug! I neverwould have thought that it would have fit so well. I can't wait to see the finished pictures.
Dave
And ye shall hear of wars and rumors of wars; see that you are not troubled: for all these things must come to pass, but the end is not yet. For nation shall rise up against nation, and kingdom against kingdom: and there shall be famines, and pestilences, and earthquakes in diverse places. All these are the beginnings of sorrows. MATT 24:6-8
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Postby PeerStalkHawk » Sat Dec 08, 2007 4:28 am

That's great Doug. I hope you have really good luck with that 431 motor in there. You sure picked a natural torque monster for an engine! It is surprising how well some of those big Caddy motors will fit into an h-body. I remember once when I was seriously thinking about putting in a 472 into a Monza and then thought of all the supporting work and modifications. Even looked at a late 60's Caddy with one in it. That car was loaded for it's time and was running still. Never did it in the end but it was surprising that it looked like it would fit. And, with all the low rpm torque those things make even stock........ yes Doug; I'm sure you're going to have some fun with it! :D...Dean
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Postby stage169 » Sat Dec 08, 2007 9:45 am

Wow, that is impressive. I have bench built an engine that size in my car a few times. Its much better to see it done! I've checked out a couple list of American V8 engine dimensions wondering if I could fit a Buick 455 in there without cutting the firewall. The list shows your engine Length from rear mounting surface to water pump pulley at 30.5". The big Buick is a .5" shorter hmmm.....
That is cool! Have you finished the front of your car? When you can show some more pictures and good luck with the shake down! Brian
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Postby hbodyfan » Sat Dec 08, 2007 12:49 pm

Wow. That is really cool. Is the motor all stock? I never heard of a 425 before. It would be really cool if you could overdrive it with a t-56. Does anyone know if cadillac cranks are drilled for a pilot bushing?
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Postby spyder_xlch » Sat Dec 08, 2007 1:52 pm

Does the 425 use the same basic block as the 429/472/500?
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Postby PeerStalkHawk » Sat Dec 08, 2007 3:00 pm

Doug, that oversized 425 looks to be a good choice for your Monza, as it is 100lbs lighter than a 472, yet still pretty close in cubes. You can tell by the shape of those intake runners that the 425 was built for a lot of low rpm torque. It's interesting that there was both a four barrel(L33) and an electronic fuel injected version(L35) of that engine when it came out in '77. The fuel injected engine made 10 more horsepower but raised the torque peak up from 2000 to 2400 rpm in stock form. Doug, that 431 looks like a really good engine with a lot of potential.......Dean. :D
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Postby HI WINDING MONZA » Sun Dec 09, 2007 1:16 am

Sorry to get back so late to this post .( wife had the computor tied up ) Decided to get the red Holley fuel pump today since it was on sale at Checkers and I saved $5 more by ordering online and picking it up at the store. Gone through 3 electric pumps in the last 10 years with the 151, At least this new one is rebuildable.

The 77-79 425 and its little cousin the 80-84 368 uses the same dimentions as its bigger cousins the 472 and 500 but both ( blocks and cranks ) are lightened by 100 lbs over the bigger motors ( mostly in the cam area of the block - not the main webbing as most latter engines were.) . Still the bigger motors weigh less than a SBC. ( Buick 455 are just as light too , I believe) The bigger motors have the hardest blocks and cranks of any stock manufacter. There were reliability issuses with the early 425 cranks but most were swapped out with the 472 crank which is the same stroke. ( 368 same stroke as well) The 429 is a different motor alltogether.

To save beating or redoing the firewall, I just moved the motor forward and installed the radiator ahead of the core support. If this was a street car , that would have to be done differently for a bigger radiator since Caddys are designed to run hot from the factory. My little 24 x16 radiator might not cut on the street.This way the original driveshaft and trans mount all fit in the stock 151- 4 speed locations.

The motor is completely stock other than a .030 overbore. It was rebuilt with a steel cam gear and had 15k miles on it when I bought it used not running, sitting in the guys garage off Craigslist for $150.

I'll post more pics in my garage shortly.

Dean , acorrding to the Caddy experts, there is a ton of work that can be done, one is getting rid of the intake and exhaust manifolds since 425 -368 are more restrictive than the bigger motor ones. The intake ( single plane) acutully flows uphill ! Getting 400+ HP is not too exspensive but I'm just going to run it like it is for now since I race to win , not to go fast . I built this combo because of the heat here also, so I can be more consistant with the bigger motor and not have to worry about things like climate . Plus it will run close to what everyone else is running and be relialble so I can focus on these damn L.E.D. lights they have. ( I love the old floodlights like they had in NY)


For more reading check these out:
www.cad500parts.com
www.mtscadparts.com
www.cadillacpower.com/forums/index.php
www.caddy500.com

Doug in AZ 8)
My Old Cadillac Powered Monza Still Lives...........now on its 5th owner!..........Somewhere ?

The 90's just keep rollin' along........
1990 Chevrolet Silverado Regular Cab Long Bed 350 TBI V8 700R4 105k miles
1992 Pontiac Sunbird Coupe 2.0 OHC MPFI I4 TH125C 143k miles
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Postby starfire383 » Sun Dec 09, 2007 8:50 am

Congratulations, that's a neat combination
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Postby HI WINDING MONZA » Sun Dec 09, 2007 10:47 pm

Thanks, heres an update: Installed new fuel pump, (works like a charm ) got the electrical all sorted out, it was a stupid glass fuse that I was taping off the center terminal of the fuse box for my accesories for the key on , ( other than that the fuel guage reads full and it isint) and have three leaks though.

One is the left valve cover is leaking on the lower left corner , looks to be a R & R.

Second is a small freeze plug in the rear of the right cylinder head , Will be an easy fix due to access through the passenger compartment where the heater used to be.

Third is one bolt on the tranny pan has got a slight drip.

Runs real good , took a while to get the air out of the cooling system, since steam was comming out of the hose fill and sprayed on the the distributer cap, it started to run crappy and one of the exhaust pipes started to leak. Got that all fixed up and its running about 170 degrees at idle with the fan on low. Turn the fan off and it gets warm quick. It was about 63 degrees out today and it never overheated. Trans is now full and all the gears work. Idles smooth and steady , gave it a little throttle ( about 4600 rpm) carb works great. Shut it off and it refires right up.

Doug in AZ 8)

PS Yes John ,
Caddy cranks can be drilled out for a pilot bearing. Guys are using this setup in dirt track cars.
My Old Cadillac Powered Monza Still Lives...........now on its 5th owner!..........Somewhere ?

The 90's just keep rollin' along........
1990 Chevrolet Silverado Regular Cab Long Bed 350 TBI V8 700R4 105k miles
1992 Pontiac Sunbird Coupe 2.0 OHC MPFI I4 TH125C 143k miles
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Postby HI WINDING MONZA » Fri Dec 14, 2007 11:38 pm

Got all the leaks sorted out, the freeze plug was the hardest since it was in between a 1 1/8 and 1 1/4. so the brass ones I got at Napa wouldnt fit so I took a 1 1/8 rubber one on the 2nd trip just in case and that worked!

Took off the Super Coil and Accel module and installed a stock ones since I wont be reving past 4600 rpm anymore. ( Lo Winding Monza- :lol: perhaps )

Didn't want to start after I did that , traced it to a weak coil reinstalled the Accel module and another stock coil , it took a while to start because of no choke but finally did.( 40 degress outside)

Throttle kept sticking, thought it was the cable since its the original, took it out and lubed it , reinstalled, same thing. Traced it to the trans tunnel had gotten bumped when installing the motor and was holding the gas pedal from going all the way back. Got the ball peen and fixed that problem.

Drove it around the yard, everything good no overheating. Did a couple of acceleration tests ( about 200 feet) in the yard and went thru the gears. All ok.

Sits a little low in the front but with anything bigger than the 155/13's up front now, that should help. The oil pan is about 3 inches off the ground .( drain plug) Mufflers lowest (2 inches - turndowns)

Might need a shim on the starter ( started with none) a little hard to turn over when warm but still fires.

Will try it on the street in a day or two. ( with a "LEGAL" 3 day paper plate)

Overall , A great Day! :D

Doug in AZ 8)
My Old Cadillac Powered Monza Still Lives...........now on its 5th owner!..........Somewhere ?

The 90's just keep rollin' along........
1990 Chevrolet Silverado Regular Cab Long Bed 350 TBI V8 700R4 105k miles
1992 Pontiac Sunbird Coupe 2.0 OHC MPFI I4 TH125C 143k miles
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Postby HI WINDING MONZA » Sat Dec 15, 2007 10:28 pm

Got the hood clearance problem solved! The kid , who I helped build the Monaco for, came up with the idea of making an U shaped incision in the hood , and lifting it and rewelding it. It will take some body work, but its pretty much free , with the supplies I have on hand. Will post pics soon . Doug in AZ 8)
My Old Cadillac Powered Monza Still Lives...........now on its 5th owner!..........Somewhere ?

The 90's just keep rollin' along........
1990 Chevrolet Silverado Regular Cab Long Bed 350 TBI V8 700R4 105k miles
1992 Pontiac Sunbird Coupe 2.0 OHC MPFI I4 TH125C 143k miles
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Postby Sirshredalot » Sun Dec 16, 2007 12:08 pm

With all that caddy torque...youre defintely gonna break somthing Doug.
The buick motors and caddy motors where known for their torque ratings.
Some of the from the factory where upwards of 500 lb ft.

thats a monza twister for sure.....Hope you got frame ties.

God bless and good job
-Shred
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Postby HI WINDING MONZA » Sun Dec 16, 2007 10:55 pm

Time will tell.............................. new pics in garage. Doug in AZ 8)
My Old Cadillac Powered Monza Still Lives...........now on its 5th owner!..........Somewhere ?

The 90's just keep rollin' along........
1990 Chevrolet Silverado Regular Cab Long Bed 350 TBI V8 700R4 105k miles
1992 Pontiac Sunbird Coupe 2.0 OHC MPFI I4 TH125C 143k miles
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