ClassicOldsmobile.com - Big Blocks

Finally got er done

Tirediron — Thu, 28 May 2026 14:36:53 GMT

I got this motor a year ago to put in my 56 studebaker goldenhawk restomod project. I wasn't planning on a major rebuild, but you know how that goes! Two spun rod bearings.
So began my first Olds overhaul. I actually got off real easy as I found a old-school machine shop that was liquidating lots of old(s) stuff and I got a reground crank and a set of Ga heads completely gone thru for 350 bucks! Mine were Js in bad shape.

So new crank, pistons, fixed up con rods, reground cam, NOS american lifters...kinda boring, I know, but I wasn't looking for performance.

And, a really great retired machinist who only takes on a small number of projects was willing to do the work. So for a bit less than 3k for everything, I've got a rebuilt 455 and a TH400. Can't wait to get it in the hawk and fire it up!

It's been quite the journey, and you all have been super helpful along the way. Thanks for all the good advice and patience with an Olds big
block newbie.

I know the colors are wrong, but I wasn't gonna put anything blue in this!

64 394ci valve guide woes

Tyroma — Wed, 27 May 2026 15:30:19 GMT

Hey Gang...

Noticed the engine ticking a few days back, and after tracking the sound down with my engine stethoscope, I popped off the driver side manifold.
Well, uh oh...found that the number three piston exhaust valve seal was burned, AND there were metal shavings around the spring. I just installed new valve seals last summer.
I was stumped on figuring out the source of the shavings thinking that the valve guides were bronze. My research yesterday taught me that these engines used steel guides.
Last night, Hudson and I removed the rocker arm shaft and confirmed that there is A LOT of play with the offending valve.

Damn. A screwed valve guide with the Homecoming show around the corner. I have decided not to take the chance with the 4.5h drive to Lansing and risk dropping a valve or seat into the combustion chamber. We are still gonna go, but we will just drive one of our other cars.

I have read that the factory valve guides can be tricky to remove and the is a risk to cracking the head casting. I am going to have the work done by the engine shop. For those of you that know, would I be better to have original style steel guides installed? Or, replace them with bronze guides? If the heads are a the shop anyways, i may as well have hardened seats installed as well. Any wisdom you can impart on my next steps would be appreciated.

Guess I'd better get a parts list sent off to Fusick for pickup at the show!

Oh well, small inconvenience in greater scheme of the hobby.

Waterpump to frontplate fasterners stripped threads.

GCH — Tue, 26 May 2026 06:01:45 GMT

Mounted the new waterpump yesterday and i stripped the threads on the two lower screws that
hold the pump to the front plate. So i took all apart again and i,m thinking to weld nuts on the back
of the plate instead.

Was very careful , oil on the screws and tried less tourq than recommended 13 ft.lbs .

Have all the 455 engines this thin frontplate also ??

Roller rocker recommendations to fit under stock valve covers? (455 Build)

jpaulwhite — Sun, 24 May 2026 23:07:27 GMT

Hey everyone,

I'm in the middle of putting together a '74 455 build and could use some advice from the collective wisdom here. My goal is to run roller rockers, but I really want to keep the stock look and have them fit under my factory steel valve covers.

I know clearance can get tight with roller setups on these heads, so I wanted to see what brands/models you guys have successfully run without hitting the baffles or top of the covers (even if it requires using extra thick gaskets).

Here is the breakdown of the top-end and internal parts I'm working with:

Camshaft: COMP Cams XR262HR Hydraulic Roller Kit (CL42-413-11)
Heads: Speedmaster Aluminum Heads PCE281 2170
Pistons: Speed-Pro Forged Coated Pistons (L2323F)
Intake: Edelbrock Performer Aluminum Intake (standard, not the Air-Gap)

Has anyone done a similar setup with the Speedmaster heads and stock covers? I'd love to hear which rockers worked for you, or if there's a specific brand (like Harland Sharp, COMP, etc.) that offers a lower profile body that clears easily.

Appreciate any insights or tips you can throw my way!

Timing on my 455 Big Block

radiofellow50 — Sun, 17 May 2026 23:06:34 GMT

So I have a 75 Hurst Olds that has had all the pollution stuff removed. Took a run yesterday and it was running great until the 2nd leg and upon acceleration I noted (I think they call it a knock) which apparently would indicate - possibly- that the timing is off or maybe a vacuum leak? Anyway,...the tag on the fan shroud shows the timing should be 16 degrees BTDC! But, since the pollution stuff is all gone, would I want to set the timing of say a 71-72 Olds 455 which is between 12-16 degrees BTDC?

1965 425 Rochester choke

GCH — Sun, 17 May 2026 10:39:09 GMT

Hi , i looked at this video from Mikes Carburetor and he say, s maybe the choke not
working properly because of the wrong flange gasket ( 6.30 )

The choke in my 1965 425 Rochester 4GC does not work well so i have seen several types of flange gaskets , looked
in the Olds chassies manual but could not se a pic of the original gasket. Tha carb is an rebuild Autoline from Rockauto
and works well when engine is warmed up.

Have this insulator spacer to keep the heat away from the carb a little but have also seen this
more open gasket

Dashman's, Hot rod and custom speed equipment parts - Dashman's, Hot rod and custom speed equipment parts

Have also seen pics of carburators who have both styles mounted.

Quadrajet vacuum break adjustment

August442 — Thu, 14 May 2026 18:05:36 GMT

I have a 1970 442 with the stock Quadrajet & turbo 400 trans. I have the bogging problem when I really get on the gas. If I slowly push the pedal down the car has tremendous power.
I checked the vacuum break dashpot & found that it leaks. I got a new one. I adjusted the dashpot as shown in the repair manual. before changing the dashpot, I had been adjusting the
air valve spring to no avail. I set the air valve spring to 3/4 turns after the flaps just closes (like what it says in the manual). Again, no real change. My question is do I just keep making
the air valve spring tighter till it slows the flap opening? or is something else wrong. I'm sure this has been addressed before but my search didn't answer my question.

Looking for OLDS 455 Engine Rebuild near Grand Rapids

Jimmy_B — Wed, 13 May 2026 21:07:54 GMT

I've been putting this off for years, because I am too scared to take this car to just anyone. I have several oil leaks due to silicone breaking down from a prior engine re-build (before I bought car). Motor needs to be disassembled and put back together the right way with the correct gaskets. Might as well have it inspected and possibly re-built too. Pretty sure the rear main is leaking. Can anyone here recommend a shop that would do quality work near Grand Rapids, MI or Lansing, MI. Not necessarily looking for a quick fix.

455 water temp plug identification

Dippydocus — Fri, 08 May 2026 23:19:45 GMT

Hey guys, the re-wire effort continues. Can anyone help me identify the sensors/senders in the top of my engine.
There's a total of 5.

Looking around at other forum posts I believe number 5 is the oil pressure sender for the warning light in the instrument cluster.
On mine, this has been cut and was spliced together with another cable that went to a whole mess of wires that was potentially related to either a fuel pump relay (I believe I have an aftermarket electric fuel pump fitted near the tank) or the ignition system mess. Unfortunately I cut these wires and systems out before noting exactly what they were or how they were connected. Hopefully the sensor in the hole is still the correct one and I can just wire it back up to the lamp.

Also checking other posts I believe number 2 is for water temperature.
On mine it was attached to an aftermarket water temp gauge which I will hook back up again when I can. If it doesn't work properly or seems a bit rubbish I might treat myself to a new one.

The others have me a little stumped as they don't seem to be exactly the same as others mentioned in other posts. Just in case it's relevant, this car was originally fully loaded so had A/C, cruise control and a bunch of other optional extras, I have removed most of all of this now though.
1,3 and 4 (You can't see number 4 in the top picture so I've included a better picture of it's location below) have all been soldered together and run into the engine/generator dash connector (which has now had the entire cabin section completely removed). I've included a picture of the splice and labelled the wire that runs back to the fusebox/connector. I'm colourblind so struggle with the different green/red/brown wires at the best of times, let alone when they're all grubby. If someone could let me know what colour that is, it might shed some light on what they were wired into. It looks quite dark in that picture but it's definitely not black.

If anyone can shed some light on these that would be great, also if there are any I can remove and plug would be awesome.

Lifter concerns

Tirediron — Fri, 08 May 2026 14:57:26 GMT

Hey all. Getting my rebuilt 455 back together with reground cam and NOS American lifters. A couple of the lifters were a little tight in their bores. A little dressing of the top edges of those bores with a curved needle file seemed to take care of that in that the lifters in question can now slide up and down ok.
But I read somewhere that the lifters need to be able to fall down on their own. Some of mine do, but some lifters need a little coaxing (this is with a bit of motor oil on them.

After reading all the horror stories of ruined cams on start up, im worried. Is what I did enough, or do they for sure all need to be falling on their own? I just dont have a good feel for how loose they need to be.

I also read that I could rotate the crank and watch for lifter rotation. I'm kinda hesitant to do that because I don't want to wipe thru all the assembly goo that I've wiped on the camshaft lobes and lifter faces by spinning the crank a number of times.

Thoughts?
Thanks in advance.

455 Main bearing question

kjr442 — Wed, 06 May 2026 15:29:33 GMT

I bought a really nice Crankshaft from another member and it came with new bearings, both rods and mains that are 10 under.
I am not ready to start on the engine yet, but decided to go ahead and pop the crank in the block and just store it there for now.
This is a 1971 block out of a W30. The fella that I got this crankshaft and bearings from couldn�t remember what this set up was originally intended for.
Everything fit just fine until I got to the front main and that bearing would not fit into the pocket because the width of the block is larger/wider and the pocket isn�t as deep as what the bearing needs to flush out with the block.
This is really just a I�m curious type of question. I know I can buy a set of bearings for the 1971 block and there is no problem with that. I�m just curious when this change was made.
Every listing you see for a set of main bearings is sold as fitting 1968 to 1976
Thanks for helping to figure this out.

Crank no start help

timothypaul — Tue, 05 May 2026 23:21:19 GMT

Ciao Guys - curious how you all diagnosis a crank no start issue when you are a lone wolf. I have no one to assist me, so am having trouble identifying if I am get spark at the plugs. Car was running fine, when I decided to do some radiator and body modifications (i.e.- nothing mechanical). Now, it won�t start. Battery is good, and when I look down carb, I see gas - so I am presuming it�s not a fueling issue. I have a MSD blaster coil and an MSD distributor. I am getting 12 volts at the distributor terminals. Being all by myself, I am trying to figure out a way to check for spark at the plugs, I messed with it for quite a while today, but just could not figure out a way to check for spark�. Anyone ever go through this ?

65 400 pistons and cam

mrb2872 — Tue, 05 May 2026 18:10:38 GMT

Howdy. I got my 400 up with a builder. My talk with him yesterday went with him saying he can't find a roller cam to use and also he's advising to change to the 350 pistons for cost. He's not happy with staying with a flat tappet cam but he's stuck.

My question is does anyone have advice I could pass along for if and where to find a roller cam that could be used. And if there's a good source for somewhat comparable cost to what the 350 pistons might fetch?

I know through other kind of related posts there's talk about using the 350's, which is fine. I just want to try to keep close to the same power output. I also have a set of 425 pistons I was considering using instead. And I've read where some folks seem to have experience or know people who've bored out to use them. Heck I think I even asked the question a number of years ago. I'd seen conflicting opinions on other sites on whether it was ok to do or not.

Thx

Kenne bell camshafts?

tuggy — Sun, 03 May 2026 16:49:31 GMT

Does anyone have any information on Kenne Bell oldsmobile Camshafts, an old catalog they could scan or put up? Experience with using a particular cam?

Cam thrust washer issue

DanM — Fri, 01 May 2026 19:54:48 GMT

I got my new cam in, and slid the bronze thrust washer over it. The ID of the thrust washer seems a bit too big. OD seems fine. I'm guessing about 1/16" to 3/32" of movement around the cam bearing surface. Is this normal?

Edit:
Well its tight around the bearing but there is a tiny groove at the end of the cam that the washer slide in.. Is this all ok?