I’m not sure where to start but I have what I thought was a 1965 442 Convertible with a 400 in it. Way back, the machine shop said the engine had 4-1/8 inch pistons which they said makes it a 425 engine. The engine has a casting code of 389298B & a build date of 120. The heads are: "A" code 383821, with the stamp of V019841 on the pad from the 400.
We pulled the 4GC and put a 750 Holley on it earlier this year and then put it on the Dyno to see just what we had, 200 RWHP. I’m told the lower end is a low compression 425 and the upper end is from the 400. I have no record on what the cam is but it sure isn’t the right one.
The 65 442 ads back then, said they came with a high lift cam. Is this what I should be looking for or does anyone have a better suggestion. I want to put a 200R in it soon, so will have it down to cam it!

 

You really need to find out what you have first. Compression, rear end gear, cubic inch. Are you just looking for a little more hp or going stock?

 

Sorry to be blunt but 200 rear wheel hp is pathetic from a 425. Even s stock 425 2 bbl would make atleast 250 to the ground. Check your basic tuning issues & do a compression check on the engine before spending a dime.

 

Oops, sorry, I forgot to add the rest of my information: we did a compression check a week earlier than the Dyno: #1-141, #2-147, #3-146, #4-143, #5-143, #6-141, #7-142, #8-142. I have the Pertronix Ignition Kit installed and the timing was set about 12 BDC.
I was expecting to lose 20% going through the original Turbo 300, especially running the 3:08 gear set but I was shocked to see it max out at 200 HP @ 4200 with the torque maxing out at 290 @ 3000 rpm,. Blunt is not the correct word, sad is more like it.
But let’s be blunt, a stock 65 425 2 bbl, low compression engine was rated 280 hp @ 4400 with the torque at 425 @ 2400. So mine is hiding hp somewhere. I had a 1966 442, A/C car, bone stock except for a 350 turbo. My seat of the pants Dyno back then, said oh my! This one runs good, but not like it should.
The Holley and the 2-1/2 inch exhaust are the only visual non stock looking items and I’m not wanting to race it, but I’d like to see it to put out, what inside, hiding. I’m assuming (yes, I know) the cam was the original 425 replacement motor from back when. I’m trying to chase down the info (cam) from a shop long gone. There are just too many shared numbers and too many unknowns, between the 400 & the 425!
So, thank you all for your help & information.
PS: I’m new to this forum stuff, so I’m a newbie, it’s the info I’m after, from fellow Olds pilots!

 

The 280 and 425 figures were pretty happy back then. You may not be that far behind.
A Performer intake and cam upgrade will get you 20-30hp but your low compression ratio is holding you back.

How far you want to go it totally up to you.

 

Wow, the great information On Classic Oldsmobile forum and some others, has really helped me get edumacated. But, the more I read, the more D/S questions I seem to have.
I was told by my motor shop back in November 1997, so many things that were not true. They said the 1965 425 and the 400 shared the same block & casting numbers. So I was not to worry about the 4-1/8 inch pistons in my 65 block.
After many hours reading the info on this great site I have learned 1965 425 blocks would have a different casting of 386525A. My motor is the correct 400 casting number 389298B for 1965. Is it possible my motor had been bored .0625 over, twice over the years? I’m just guessing, but somehow the pistons went from 4 inch to 4-1/8 inch and the car does run hotter than I’d like. The shop just honed it and put in new rings and bearings and said it was good to go. Unfortunately it took me eight years financially to get it all fixed up and on the road for Friday Cruise Nights! Since then, I’ve added a little over 3000 miles on the clock, so it is broke it. The dyno run was the highest RPM since the overhaul. Shannon was there for the dyno run and said it was a 425.
In August I was able to find, contact and talk to Shannon (a real motor head, I’m not, but I’m learning) who was working at the machine shop back in 1997/98. She verified the piston size and said that they all thought it was a 425 motor. When I asked her about the cam and the numbers she said it was a 442 grind. I also asked about the “cba” and whether the cam for built for a 65-67, 45 degree Cam Bank angle, she went blank. Yes, I know that a long time ago and I barely remember what I did on Saturday, but she said she still had the books at home, on many of the cars and motors they worked on She called me with what she found.
So now I do know the cam info, in my car from so many years ago: But, to me it’s written in Latin.
Valve Lift Intake 0.448 Duration Int. 262 Cam lift Int. 280 Open 23 deg. / Close 59 deg.
Valve Lift Exhaust 0.472 Duration Exh 270 Cam lift Exh. 295 Open 67 deg. / Close 23 deg.
The info you guys supplied for the 1965 400, 442 cam: If I’m wrong please tell me. GM #387484 over lap 52, lifters .842 Dia.
Duration Int. 262 / Exh. 270 Lift Int. 280, Exh 295 Open Int. 23 deg, Exh 67 deg. Close Int 59 deg. Close Exh 23 deg
She had no info at all on my “cba”, but in reading the threads I see the wrong CBA can also make for more heat. If this motor has been bored out twice, much more heat given there too. I guess I’m in trouble. Any known options?
I say Thanks again to all you Olds Rocket Pilots, for all your help.

 

Compression #s look low its all relavent to hp #s.

 

Right you are, the larger the whole; the lower the compression. What kind of RWHP numbers should I see, if it was a stock 400?

Who knows what all went on inside the motor in the 32 years before I bought this car.

The motor is a 389298B, the heads are 383821A and the intake is 384439B. The exhaust manifolds: Right side is W389268RH and the left side is incorrect X389269LH. From the outside all are stock 1965 400 numbers from what I’ve read.

In January this year with the stock 4GC (515 cfm) carb on it, we did the first Dyno run. It came out at a little over 200 RWHP. The only real problem besides lacking 442 rocket power, it always ran hot.

In March we installed a 750 Holley and the throttle response was so much better, but the power, seemed about the same. The second Dyno run, with the 200 RWHP is attached showed no gain with the new Holley. Wow, now what?

Even with my very limited knowledge of motors, I'd never bore out more than .060 unless I was showed proof it would last. I've never heard of anyone boring any car motor out by 0.125 but it seem that is just what I have. I have seen other stock, low compression motors, build decent amounts of HP.

I'm thinking it has to be the wrong cam, wrong CBA maybe. Mine hits 3200 and drops right off the chart, that can't be right. But then again, I really don't know what I should be seeing.

I would imagine, if I ever really put the whip to it, all I'd have left would be pieces.

 

I'm not a motor builder, guru however, you do have the right casting numbers for the rare 400 block, the casting numbers for the heads-386525A the 400 and 425 share those heads. The 425 is actually a tall block 330 block casting from Olds. It sounds to me the 400 could be over bored and that's why maybe, just maybe it"s running warm perhaps? How warm is warm? Best to my knowledge the 400 after being sonic checked first for wall clearance etc. can be safely bored .057 and then you can use Olds 350 pistons in the rebuild.Everything else in the thread is there, past rebuilds could have placed a LC pistons in, thicker head gaskets? Just some thoughts.

 

What if you were to put a degree wheel on it and record the cam timing events and see how they compare to the specs?

I think a cba mismatch would be VERY noticeable. Not much power in the upper ranges. Rough idle, low vacuum, stuff like that.

 

Using a degree wheel is a good idea, has TDC been confirmed when the balancer is on zero? How much total ignition advance and at what rpm? Does the timing chain have much play in it?

The compression numbers are quite even, that is good!

 

Thank you all for the information and recommendations.
Thinking back to when I found this car, I should have known things were very wrong and could probably get worse.

I popped the hood to get the motor numbers and was shocked to find everything under the hood was spray painted black. I mean everything was black, all but the carb and air cleaner. I had forgotten this detail until I found an alternator box with the original black (spray painted) alternator in it. So I guess finding out the 400 block was over bored by .125 shouldn’t be that much of a surprise.

The machine shop, reputable at the time, is long gone now, but I’m hoping they did a sonic test, but we’ll never know. The fact he told me it was a 425 lower end make me wonder. It is what it is, a 400 bored to 425.

I do agree, most of my heating problems are starting in there with the wall thickness. But I just need to deal with the extra heat. Last year on a typical cruise night I would see temps of 220 to 230 at idle speeds, running without a shroud. As soon as I would pull out and get air to the radiator, the temps would fall to under 200. This spring we put a pusher fan in front and it now holds pretty steady at 205 degrees when idling along. I’ve also found a place to get shrouds for the 65 Cutlass A/C cars, so if needed; I’ll go to that option.

This car runs and idles pretty good and has good vacuum, fact is; I’m the only one who is not satisfied with the power. Then again, I’m the only one who has had two others 442s, both 66s with autos and the one had A/C, would run circles around this one!

When I get this thing in to the shop, we will put a degree wheel in and check to see just where we are. I will check the timing chain at that time. I would hope all that stuff was new 3000 miles ago, but we’ll see.

I guess my ignorance about motors is catching up to me, in my old age, but seeing the Dyno sheet with the low Hp & torque numbers shocked me. That and the fact that adding a Holley didn’t do much of anything to help, gives me pause to ask for help. Being over bored isn’t good, and it is going to cause overheating, but is that why the number are so low?

I’m still thinking it’s the “cam” but knowledge wise, that’s my weakest area.

 

The 66 and 67 400 engines can be safely bored out to 425 cubes. Likely the 65 400 is the same because that is what you have. I dont think it is critical to your hot problem. Thing is to get more air thru the radiator get a bigger one. It has been proven that that is what it takes to get the temp to drop. You are on the right track....

 

I would suggest doing a leak down test, your compression results are low by 25-30 psi. You definitely have a 400 by casting #, it would be a 45 degree Tappet Bank Angle motor, if the builder but in a 39 degree cam you be off 12 degree bank to bank or 6 per side if put in straight up.You'd be having serious idle issues. (see Oct. 12th. "Wrong Cam") Your cam specs are the same as, the ones you quoted, were given to you on this site. I'll be interested in what you find when you check the chain and valve timing, I think that's where your problems might be. Running retarded can cause heating problems besides being low on power.

 

Boring one of those blocks that far should be no problem, granted it is huge amount.
I would check the distributor for working order, is the timing set, what is the total advance? With work being done on it so far, i would run more timing (14*-18*) check you mechanical advance, make sure your vacuum advance is working. Set your initial timing numbers at 850 rpm, then run up to 2500 and see what it is. Should have a total 34* to 36* with vacuum advance hook up. When you set your initial do NOT have vacuum hook up. Vacuum advance should be hook to ported vacuum port on the carb. Just make all your adjustments a little at a time. making sure you can start easy.
Second make sure your radiator is up to par, all hoses are in great shape, a good thermostat. Make sure the water pump is working. I have seen impellers broke off or just plain wore down. The best, I think, is the cast impeller. Also is there a fan shroud and a 6 blade clutch fan.In good working order. NOT the cheap *** flex fan.
Do all your home work before getting the engine. If you still can't make the engine run good and all you bases are covered, then pull the engine and see exactly you have a tear it down complete and start all over, plan your budget. Just my thoughts.
Also the lower compression numbers may be do to the use of the thick Fel-pro head gaskets. I just cut .020 off the heads and .020 off the block to make up the difference and cut more to get the compression I want. I know all say the heads are 80cc's but i have never seen one less that 84cc's. That include the A,B,C,E, G, Ga.
Gene