Hey Oldsmobrothers,

So I did it; I picked up a 455. It's the best of the best. 1976 Ka block, J heads, low compression dished pistons, EGR intake. Ooooh yeahhhh!

Okay, kidding aside. I did my homework and knew (mostly) what I was getting. The seller's "story" was that he pulled it from a sibling's Custom Cruiser before it was scrapped. It sat in his garage for some years, then it was hot tanked and magged with new cam bearings and the cylinders "bored a little" (I'm assuming honed), rebuilt, then it sat for three more years. What I know for sure is that he had to move and dumped it at his brother's house. His brother was tired of it being in the way and wanted it gone (I bought it from him but picked it up from his brother).

So far I've discovered it has all new gaskets and red assembly lube on the valve stems. The exhaust manifold bolts removed easily (maybe too easily). The underneath of the intake is extremely clean and the block has new freeze plugs. When I pulled a couple pushrods, some dirt fell out of the insides (puzzling, at best). The cam doesn't appear to have assembly lube but a few people asked to see it turned over (by hand). I'm going to pull one of the heads tomorrow so I should know more. Oh, and it was built in Kansas City.

The price was excellent (less than 1/3 of what he was originally asking, according to his brother) so I wasn't expecting much, if any, of the story to be true.

The "plan" is to pull it all apart, gauge the bores, replace what needs replacing, and upgrade the heads and pistons. Karma is paying off and I've been offered some G heads (that need work), a double roller timing chain, a lightly used cam and new lifters, and other odds and ends. All for the price of shipping and from CO members.

This time I know what I want. I won't be taking it to the strip, just tearing up blacktop. I want major (or acceptable) butt-dyno torque from 0-60. I'll do 93 octane if I have to but would prefer 91, assuming 87 is unreasonable for a high-9 to 1 CR. I have 3.73 gears and limited slip with a built 200-4r trans.

So, for some questions:

1. 442.com says the larger valves on some heads may sacrifice low end torque. So I'm taking that as saying "flow" is more important in my case? Will big valves NOT suite my needs if those heads are available?

2. I read that there could be clearance issues in my '71 Supreme, namely my shorty headers won't fit and maybe the brake booster? Is this true? Are there other clearance issues? I understand I will need notched valve covers.

3. Is replacing the iron EGR intake a must?

4. I have the stock rocker arms from my 350 (fairly new, maybe 1k miles). Will they fit the big block? Although the rockers on the 455 don't look terribly worn.

5. What other goodies can I pull from my small block (that are all fairly new)? Mechanical fuel pump?

6. Will the oil pressure switch, water temp sensor, and other small block intake goodies fit the big block?

7. Does anyone know what jets I should run in a respectably built 455?

8. I'll cc a head when I get it off but does anyone know what a good piston would be to bring the compression up to the high 9's? Do I need forged for my purposes or are cast okay. I won't be racing but I do want the option to romp on it if I wish.

9. Do I understand correctly that my current accessories and brackets will fit, using the second set of holes? Can I still have my AC? Same configuration as the small block?

10. Other pitfalls I haven't considered?

I'm really excited about this build. I'm hoping to get most of it done this winter, as long as the budget holds out. if not, I can take longer. I want to do it right this time around. Best part is I can still drive my car while I'm doing it. At least until I start scavenging parts from the small block.

 

I think you can go 10 to one pistons and run pump gas. No doubt 9.5 to 1.JMO

 

So, having a low compression small block for a few years now, I'm very used to playing with the timing, pushing it pretty hard. I think i'm running 21* initial right now. I'm assuming having more compression is better than pushing the timing, yes?

 

Dude even a 9 to 1 bbo will be fun. dont underestimate the tq. 9.5 to 1 would be ideal and allow you to run a decent cam. a mild 455 will put your car in the low 13's high 12's no problem at all and when i say mild i mean like towing cam mild.

 

Hence the old saying "Ain't no replacement for displacement"? Lol!

I talked to a guy last night that had lightly used Sealed Power flat top pistons on reconditioned rods for $75.00. Nobody wanted them so he scrapped them! Ugh!

 

Be aware that aftermarket cast pistons are short on compression height, which will dramatically affect the compression ratio (and quench, if you care about that).

The iron EGR intake is probably fine for your application, but an aluminum one will be a LOT lighter and your back will thank you if you ever have to pull the intake with the engine in the car.

 

Copper is right about 9.5 to 1 can run high twelves easy. Depends what you do to engine and rest of drive train it can run mid twelves with street manners.

 

WANTED: aluminum intake for 455! Yikes, I pulled that sucker yesterday and it's a whopper. Taxed my old body and that was with the engine on a stand.

Ken, do you mean aftermarket cast stock pistons or just cast pistons in general? I do want to shoot for the 9.5 CR but I'd like to reuse the rods if they check out. Pistons I have to buy either way I think. Check out the pic of, I think, cylinder #3.




It looks like the heads were reconditioned. Too bad they're J heads.




Copper is offering me a cam and new lifters. Cam has the following specs:
512/512 224/232 duration @ 050 0n a 110 lsa. It's a Howards and has 300 miles on it.
The lift and duration I think I understand but not sure about the rest. I have homework to do.

 

As far as I know, all aftermarket cast pistons are shorter than the factory cast pistons. The forged pistons are usually the correct height.

 

Well that won't do. That won't do at all! Thanks for the heads-up, Ken.

 

I got stock rods dirt cheap if your interested!

 

If it is the Fa block, it probably won't have a boss for a clutch Z bar attachment. Also, it probably has a cast iron crank--look to see if it has a big N or smaller CN for the better nodular cranks on the front counterweight.

 

Go find a set of stock factory hc 1970 455 pistons. Then you will be right where you need to be for good performance and good compression and cheap. Yeah cast piston but great for street/strip performance.JMO

 

Do you have any proof of which cast crank is better?

 

I don't know the condition of my current rods. Are you in a hurry to get rid of them? And how dirty is dirt cheap? PM me?

No Z bar but I have an automatic and am not real concerned about that. I will check the crank.

Thanks dude! Exactly the info I was looking for. Again, I'm not going to be taking this thing down the track.

I've read this too, maybe on 442.com but there seems to be some debate about this.

 

So these will be shorter? Then how can they be listed as high compression?

https://www.summitracing.com/parts/slp-w369p

My apologies to everyone. This is my first short block rebuild.

 

Wait, there is a discrepancy between Advance Auto and Summit on these W369P pistons. Advance shows a very shallow dish and states it's a high compression pistion:

Type: Cast Piston - Individual; High comp.; Cast; VINTAGE; .9806" Pin Dia.; 2 Ring[s]; 5/64 Groove; 1 Ring[s]; 3/16 Groove; 1.725 CD; Recessed Head .120 deep x 2.940 dia. - 9.75:1 C.R.; Standard Size; 8 Req.

Summit shows a deep dish and gives these dimensions for the dish:

Recessed piston head is 0.120 inch deep x 2.940 inch diameter.

That comes to 41.93 CCs, if I'm doing the math right.

My current pistons' dishes measure 7.79 cm X .904 cm which comes to a 135.4 CC dish.
Maybe Summit is just showing the wrong picture.

 

Yes, and much of the debate may not even need to exist as the metallurgists have said the cast cranks and nodular cranks are both the same thing: cast nodular iron.
But this is a debate for some other thread.


They are called "high compression" because of the dish size. What they are not telling is the pistons are short, so the compression will not be near the claimed value without milling material off the block deck surface.

 

That description left out an important piece of information - the compression height or compression distance (CD). The Sealed Power catalog shows the CD to be 1.725".

http://www.fme-cat.com/digipubZ/seal...ge/#?page=1548

Compare that to the forged L2323F pistons that have a 1.735" CD.

https://www.summitracing.com/parts/trw-l2323f

So add that .010" too-short piston to a thicker than factory head gasket (factory shim = .018" vs aftermarket Fel Pro composition = .041") and the factory piston-to-deck clearance (maybe .025") and you get a fairly large unswept volume that reduces the compression ratio. Using the numbers above, the pistons would be ~.076" "down the hole".

 

Keep it coming, Ken. I don't have my daughter around to do my math for me anymore, lol.
I think I have the formula in my "pulling the motor" thread for calculating compression (which, IIRC, made me rather depressed when I did that for my small block).

The real question for me is then; how much will the CR drop with those figures. The sealed powers are rated for, what was it, 9.75:1? I could be happy with 9.5 but don't want to go any lower. Does "Smitty" sell shim gaskets for the 455? I used his on my 350 with no problems. Were they $140 at the time? Maybe?

Thanks Ken, really

 

That is why i said get some 1970 hc 455 pistons. Then order you a steel shim gasket game over.As for your rods they will need to be sent to a machine shop to be checked and recondition. The key word here is recondition. Always send the whole rotating assy to be checked. Also you may need bores checked. The word here is may. I always have all of the rotating assy checked then balance it. Heads need to be checked if they are unknown and not fresh. I hope this helps.JMO

 

That sounds like a lot of cam for your application. Especially if your compression comes in at less than 9.5:1.

 

It's not really much bigger than the cam in my 350, and his engine has 100 more cubes.

 

I have a 496 lift in my mild 455 and 512 isn't much of a stretch.JMO

 

This entire engine is an "unknown", unfortunately. It's a weird mix of good and bad. The cylinders all have crosshatching in them but there is still a tiny, and I mean tiny, ridge at the tops. I can sort of feel them with the skin of my index finger but can't catch a fingernail on them. One of the pistons is in backward with the indentations facing the back of the block. The block has been hot tanked, at least it looks to be so. Absolutely no residue in the water passages, and not a speck of crud under the intake. Red assembly lube on the valve stems and the same cleanliness of the heads. Double roller timing chain that's nice and tight with a pitted cam. Red assembly lube on the fuel pump arm. It's driving me crazy! Lol.
I'll call the machine shop tomorrow but we only have one. They're good but it could be months before they can take a look. How does one lift a bare block into the back of a truck? What I mean is; what bolt holes should I use?

As for the cam, I'll look into that.

 

Just to reiterate; I'm shooting for 9.5 CR or above. But less than 10.

 

I'm not following. Do you mean original '70 pistons? I did a search on Summit for a 1970 442 455 motor and those are the pistons that came up.

 

Well, due to the nature of the engine and the fact that I'm running factory manifolds, the cam in my 400G is 218/224 @0.050 with .462/.470 lift and a 110 LSA and I can sometimes see the fenders shaking when I'm idling at a light.


As they say, just sayin.

 

That howrads cam will be perfect in a bbo. It wasnt too crazy on my sbo when i had it. The extra cubic inches will tame it down . It was a great cam even for my sbo on the street.

My current cam on my sbo is a 522/523 lift 233/241 duration the steel bumper shakes lol. Same cam on an bbo with a well tuned idle should not shake much.


this was about a 750 idle.

 

With a well tuned idle?! Well, I'm screwed.

 

Dude you know how to atleast get a q jet running. You can tune a holley all day. like i told you you can have my 750 holley 3310 vac. secondaries carb.

 

Yes good used original hc 1970 pistons if you engine is standard bore. Why is because they are the correct pin height for your rods. No guessing check the bores and measure before you buy pistons! Good luck on your build which ever way you go.

 

I ran cast flat tops from a ram rod 350 in a engine i built. No blancing no machining it ran very well , But that whole cast brittle thing with .0055 clearances knocked the skirts right into the oil pan lol it lasted a few years lol.

 

I appreciate the offer my friend but the Holley would need a $150 linkage adapter for my trans. Maybe I could fabricate my own? When are you coming down? You should come to a car show with me, Ralph, and Brian; all Cutlass owners. We could talk about working on cars and complain about the award winners, lol.

I honestly didn't think of that as an option. I'll keep an eye out.

 

when is the car show. also my buddy had a 700r4 with this carb. thats who i got it from.

 

Car shows most every weekend, just let me know. Brian is Dalilama(sp?) here on CO. Has a 72 vert. Ralph has the gold/copper 71 vert you see in my pics.

Maybe that carb DOES have the correct linkage. I could get lucky, once, right?

Let me know and I'll find a show.

 

i will start planning. there is a few breweries i wanna check out that way so for us it will be a weekend trip lol.

 

Sounds good, bro.

 

I bet if you made a post in the parts wanted you would find someone who has a good used set of 1970 hc pistons. I had some but didn't think i would ever use them again and tossed them in the junk pile years ago. I could have used them twice now.

 

Like me, you never need something until after it's gone
I'll post an ad as soon as I know more about the condition of the cylinders.

I called our machine shop and like I feared, they're 6 months out, at least. Copper, do you have a reputable shop up your way that could get to it soon-ish?