BOP/ Cadillac Demo Engines

[n8]

I noticed there wasn't a thread for Gm engines aside from the small block Chevys. Anyone have any experience with any Cadillac 472s or 500s? I remember years ago that there was a guy who ran 472s almost exclusively. Any common problems?

[7hemagician]

Yeah. Ive run em. No replacement for displacement.

[demo1]

I ran 79 Caddy it had the 425 in it. I thought the motor held up well even HOT. The rear end plowed dirt had a Crown Vic run across the back n bent it down. It happens.

[cowdoc]

I've ran a 472 from a 68 caddy multiple times-incredibly powerful, starts ok when hot but if I lose the radiator and it gets hot it loses all its power

[n8]

^ Think it's timing related or just gets that hot that fast. How fast roughly from when you first start steaming to no power?

[n8]

I was thinking about trying one in a stock class but wanted to hear some opinions first. I like the idea of not having the distributor on the back of the engine so I don't have to cut out the firewall. I also like not having to have tall gears which you can't have if you are running those stock GM 12 bolts anyways.

[7hemagician]

I've been doing alot if research on these lately. I love the torque. Love how they will move a car around with the stock gears. The more I run them, the more I find they are finicky and need some special tricks a little different than a chevy. The biggest disadvantage is that parts are expensive and you can't get any cheap used aftermarket derby stuff. Got to fab it all yourself.

[n8]

Those are issues i noticed as well. I know any 70's Cadillac engine would need a timing chain and gear to fix the fact it has a plastic gear stock. It appears just based on the rod and stroke ratio, a 472 would be a better choice than a 500 for our use. I found on one website that small block Ford valvetrain parts were mostly interchangeable with the Cadillac stuff, which would help the valvetrain issues these engines tend to experience. I remember reading here at one point that running alcohol instead of gas with this engine helps keep the temperature down to a point. Obviously alcohol will require more effort than gas though as far as tuning and maintenance. Given the location of the distributor, I am going to assume that RTV'ing the cap and covering it up as well as possible will only help. After changing the factory intake to an aftermarket aluminum version, the weight of the engine is 60 pounds or so more than a small block, so big block springs might not be needed. The blocks apparently have a higher nickel content than "average" which may or may not matter for derby use.

[cowdoc]

Jan 13, 2015 10:32:27 GMT -5 n8 said:

^ Think it's timing related or just gets that hot that fast. How fast roughly from when you first start steaming to no power?

Does fine as long as I have water but a couple minutes after destroying the radiator and it'll barely drag itself. I usually explode a radiator, not a slow leak lol

[7hemagician]

Interesting. The motor I ran lasted about 13 min without water. And ultimately the starter went out. Motor was still going strong.

[ron]

We have had good luck with with the 425s.
Lost front bumper once ran whole feature without it to 2nd place outta 19 over 30 min without water.
It still had good power and wouldn't die but we run 4.10s in it.
What ended up taking it out was the core support finally found its way to the cap and broke it.

[7hemagician]

410?? Wow. That's a tall gear with the torque involved in a bbcadillac.


You do any tricks to get it to run 30 min?

[n8]

OLDS engine info:
Has anyone had any luck with these? I bought a 83 that has a good running 307 but don't know much about them
Pretty much the same as an Olds 350. What transmission does it have? (400)
I have had a couple that ran great after ditching the factory dist. and carb. ran great hot, never shut down, just real gutless.
Ok thanks that's what I was afraid of after it got hot wouldn't have any power
Same result here thing ran and ran but man was it nutless
Stock olds motor mounts are weak. However, if you get a set out of a 77-79 trans am with a 403 olds or out of a 80-90 Fleetwood with olds 307 they are better and match up with Chevy frame mounts.
tune the carb up nice and it will have enough power for where you are going! wicket engine!

Olds 307 help:
Ok i have a few quick questions, i thought the car would be a quick strip and go since it was already running well it has a carb fire and burnt some wiring up so i decided to to do a complete strip of all wiring and then just run a toggle and pushbutton but, is it the same wiring as a chevt as far as the hei, alternator etc? and there are 4 steel tubes that look like they screw into the heads by the spark plugs what are they? and can i just pinch them off? and theres a thicker tube by the trans dipstick that feels like it runs down to the transmission i cut the tube and pinched it off because i thought it was for a vacuum line but is it needed? and what vaccuum lines do i need coming out of the intake and into the carb? its a stock 4bbl quadrajet carb and stock spreadbore intake and i know i need the one from the brake booster to the back of the carb but what else can i strip and what do i need? thankyou so much if you can help, the race is tommorow so i need some help as soon as possible.
Yes, the wiring is the same. You can block off everything that you mentioned. None of it is needed for a demolition derby car. If that Q jet has a bunch of wires going to it, it will not be a good carb.
Depending on the actual year of the car your distributor may need the computer to work right as well as the carb
The 307s that I ran in the past had computers. I just left that harness unplugged. It will still run but it wont have any timing advance which is what the computer controls on the distributor. You will need to swap to a non electronic carb of some type. the computer controlled q jets are junk. They will run fine until they get hot and then will not refire, in my experience.
i also had a computer on my 85 delta 88 307. i removed it. i took the electronic spark control out of the distributor, and put a standard quadrajet carb on it.
the wiring harness is super simple.
i'll be using that motor for many years to come.
his one has an hei and just the 2 wires coming out of it so is it a regular hei that i can wire up easy? and i have a standard qjet now with none of the electrical connections and if i have time ill throw on the holley 4 barrel but i didnt get it done for either of the figure 8's and todays the derby so i need to get it done.
will a regular old 4 bbl qjet bolt directly on the same intake as an electronic 4bbl qjet? ...without any adapters or nonsense
It'll bolt. It won't work right half the time. Nothing wrong with electronic ones if tuned for the job.
There is no reason for it not to work correctly
i love the old vacuum style q-jet..no wires at all...and will run excellent if you tune them right...just wanted to know if they will mount the same!...thanks
How do you make them work without the computer hooked up? (the computer controlled carb)
Primaries are smaller on the electronic carbs, at least most that I know of. Switching to the older q-jets on a newer intakes is a crap shoot. The blades won't be able to open. But they did do a lot experimenting with these so you never know. Also switching qjets not a good idea because these carbs are tuned to specific motors. The wrong vacuum signal will not make a good carb work right. That's why everybody thinks they're junk. They think just switch it when it just makes the situation worse.
They work great when not hooked up. They actually run rich in a default mode which is better for the derby. But the problem with them is the solenoids inside take up room so less gas can be inside the carb which causes vapor lock much easier. Get rid of all the emissions stuff inside and now you have MUCH more gas available inside the carb. There's to much to explain , really got to know carbs to set these up. I can try my best here but the this will be as long as the car build thread after I'm done. These are awesome carbs if done right. These carbs when used with the ESC were getting the metrics up to 25 mpg on the highway. Which I think is pretty damn impressive considering they can be tuned to go on motors pushing 400 horse power and still sip gas.
So you are modifing an electronic carb to make it a non electronic carb?
All I can tell is from experience. If you attempt to run an electronic carb without whatever modifications on a 307, it will not start after a few minutes. Period. Do not attempt

[hemi1]

My dad and uncles have ran several Pontiac 400's in the past and never had a problem them.They have won several features with them years ago.Any engine will get hot once the radiator goes,some faster than others,but they all will eventually get hot.I have seen olds 455's,buick 455's and chevy bigblocks all win features.

[n8]

Olds engine info continued:
How good are the gm 307s? I've never had one, are they any good for demos? I have a gm 350 and that motor is one hell of a good motor. If the 307s are any good I may just hang onto it.
Some guys like them. I've personally never seen one do that good, seems like once they get hot they are gutless and don't like to refire. I junk them.
Yeah I get what you're saying. I have an olds 350, that has been in two derbies so far and it's still going strong. I agree that Chevy 350s are way better then the olds 350, but I figured I'm gonna run it till it dies. It runs to nice to not run it. Thanks for clarifying what motor I have.
350 olds are good motors if you have a good one. i have one that has been in 6 or 7 derbies and has been hot several times and still ran great the last time i ran it.
I'm going to be running my olds 350 again on the 26th of this month. I haven't put any money into it, other then buying the car it came in. Seems like the hotter it gets the better it runs. If it survives this derby season I might have to put some money into it this winter.
Yeah mine needs some work it has been sitting in a car that I havent finished off and haven't got it pulled out. I think it is due for head gaskets. Last derby I ran it in it was down to 3 cars and I got hung up and and couldnt get loose car was still running great. Would have had a good chance of second in that one because one of the other 2 cars with a built 360 chrysler overheated. Biggest problem is the cost of parts and the motor mounts arent very good.
The motor mounts are junk, I hate them with a passion. Haha I was going to make my own set, but just didn't get the time to.

Oldsmobile 350 engine worth a $#!^ for a derby motor
Hi is a stock Oldsmobile 350 (out of a 1976 Delta 88) worth a crap as a derby motor compared to a stock chevy 350? Is the Olds a true small block? I read some stuff that oldsmobile used the same block across several engine sizes. I don't want a big block size engine. I just sold a pontiac 400 to purchase a gm 350 and found a great deal on an olds 350.
Its all personal preference. I prefer a 350 Chevy.
We've ran quite a few of them, never did get a win. We got a 2nd and a handful of 3rd-5th's. Talking strictly stock they usually get better as they get hotter, but if they die when they are hot they are a pain to crank over. Good low end torque out of the box. Swap intakes and put a fresh 2bbl on them. Invest in a good high torque starter if you want to spend a little more. Dick Miller Racing has a website with Oldsmobile performance parts and he has a good one.
My dad runs one. It seemes to run good, and does crank when it's hot. But he only has like 7 minute heats on it, so nothing major
longest heat/feature we have ever had on a stock olds was about 40 minutes. when she died out, that was it
Most of the heats I have been in here in TX are 6-8 minutes with features going 10-13.
you should be fine then IMO, it takes that long just to get the thing warmed up lol
Yeah haha, he always starts it 8-10 minutes early and lets it idle
Are the olds 350s close in size to a chevy 350? Read that olds used the same block for different size engines.?.?.? I was using a Big Block Pontiac engine before and that beast didn't leave much room on the sides.
It is a little wider then a chevy 350 is, about the same length. This is just eye balling it I don't have measurements.
Also, and forgive me if you've thought about this or already have this on your list, but notice how close the upper radiator hose is to the alternator belt. Either splice in a piece of metal pipe in that part of the hose or sleeve it with a soup can. Sometimes even the slightest front impact can send the hose into the belt. Happened to me on my 2nd car which was a '77 88 with an Olds 350.
Thanks, but we won't be running a radiator on this motor. Will just be running Hose to Hose with the inline filler neck. So a little piece of wire holding the hoses up should keep them from getting into the pulleys/belt. Will have a picture posted this weekend of all this!

*also won't be running an alternator either.
Well car stood up good, just had some motor issues. In the heat the car went about half way through before it shut down and wasn't able to start back up. At the end of the heat it was able to start up and we drove it back to the pits. In the pits we saw nothing wrong with any motor components but noticed a spark on the one battery terminal on ignition which ended up being a loose connection which we fixed in time to put it into the concy. But again once we got it into the ring about 5-10 hits it shut down again but once again started when they cleared the track and was able to drive it to the pits. We still haven't diagnosed the problem yet. As far as I can tell it starts perfect but sputters for the first 10-20 seconds after ignition until it warms up then it runs just fine. After this it'll run good but then the motor just shuts off until it cools off a bit. Any opinions on what might be the problem would be much appreciated!
rhann123 - I had a very similar issue with a Pontiac 400 motor that I used. It ran great without issues the 1st couple of derbies and then started doing what you decribed. I could never get it to exhibit the issue outside the derby arena so I started replacing ignition parts but still never solved the issue. The only things left for me to do on the motor was replace the timing chain and try a different carb (it had a q-jet that did have a recent carb kit). I solved the problem by selling the motor and am going to use the money to buy something different or finish a EFI to carb conversion on a Ford 302.
We are planning on pulling the motor here soon so we will get a chance to have little better look to see if everything is okay. But we are currently looking in Starter, Vapor Locking, Some possible distributor problems which if its none of those I'm not sure what to look for.
Was wondering what motor mounts you guys use for the olds 350. I just removed the stock ones today and I'm looking for heavy duty ones. I checked on summit and they don't have anything that looks to be very solid. Any suggestions?
store.dickmillerracing.com/enginemounts.aspx Perhaps something like this?
I think those will work. I might have to get a set. Thanks!
If it still has the original timimg chain the cam gear is plastic and aluminum, which a known for going out, does that edlebrock have the off road springs in it for the float? It could be flooding out from hits if ya dont have them...
The motor rhann123 is talking about is my motor. Yes it is the original timing chain. How would I go about changing that? I do not have the knowledge to do anything with the timing, as for the carb I'm not sure about it having the off road springs. I borrowed that carb off a friend of mine. I will try to get ahold of him as soon as I can and find out tho.
Stock olds motor mounts are weak. However, if you get a set out of a 77-79 trans am with a 403 olds or out of a 80-90 Fleetwood with olds 307 they are better and match up with Chevy frame mounts.
Pontiac don't really have big block and small block 326-455 same physical dimensions on the outside.

On Oldsmobile the difference between small block and big block is that the big block is basically a tall deck version of the small block. Big block heads will physically bolt on a small block. Certain heads/blocks use different diameter head bolts, but it can work. All accessories and brackets interchange as well - just need longer belts on big blocks. All small blocks also have same stroke and ci is changed by bore size.

In my opinion the best olds engine in stock form (without getting into using diesel blocks or swapping internal parts) for derby would be a 330 followed by pre-76 350 (or even a 260) The worst for derby use would probably be a 403, or anything that has heads on it that have "PMD" cast into them.