Flat top 454 or domed 427 for a rering job - Chevelle Tech
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post #1 of 12 (permalink) Old Apr 6th, 17, 8:46 PM Thread Starter
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Flat top 454 or domed 427 for a rering job

Well summer is right around the corner and I'm looking for something to do that's not crazy expensive. I have a std bore 454 block, also have a set of 69 427 piston rods and crank. One piston was bad but thanks to ebay I found a replacement (correct dome and side) this is the .140 dome pistons used on the 335 and 390hp motor.
Also have a .030 over flat top 454 short block in the shed.
Using the same closed chamber heads, would I be better throwing rings and bearing in the 427 or 454? I guess I'm wondering is a more compression better with less displacement 427 or lower compression with 20 more cubes? 454
It's eventually going in my 66 4 speed 3.08 gears to cruise around. Jim

Jim

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post #2 of 12 (permalink) Old Apr 6th, 17, 9:14 PM
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Re: Flat top 454 or domed 427 for a rering job

With gearing and cruising I would go for the cubes. My vote 454!

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post #3 of 12 (permalink) Old Apr 6th, 17, 10:55 PM
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Cool Re: Flat top 454 or domed 427 for a rering job

Maybe it's just me, but there's something magic about the number 427.
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post #4 of 12 (permalink) Old Apr 6th, 17, 10:57 PM
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Re: Flat top 454 or domed 427 for a rering job

2 cars same gear(3.08) same trans (TH350) and same heads( 624) I built both cars one for father-in -law #1 was his 64 Elcamino 3840 LBS. He got the generic 214-224 @ .050 cam On a 112 LSA .447-.475 lift 388 cubes. 1.52 rollet tip rockers.

Same pistons in both blocks.. But my car was a 78 nova at 3300 lbs with a 350" and the [email protected] .050 .454" lift stock rockers.

He had a little more compression with the extra cubes I was lighter.. I swapped carbs and distributors around looking to give either car an edge.

The 2 cars ran exactly even until 120+ MPH and the 388" would pull away.

I later got 186 heads milled them to 54cc chambers and used the 224-224 @ .050 cam and of course I ported all the heads and all ran the RPM intake.

With the change to 186 heads and the larger cam the 350 would run circles around the 388".

With this I thought a smaller engine with more compression and a step larger cam could hang with something with 30 more cubes.

At the same time I ran the 3300 lb nova and 218 cam (268H) my buddy had a 78 camaro with stock 454 No porting and his had the same 3.08 gear and 268H.

My Nova would beat the camaro.
I tuned and tuned that 454 and it was still a putz. This was Battle of the slow cars.. My nova ran 14.7 then with the 268H.
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post #5 of 12 (permalink) Old Apr 7th, 17, 1:52 AM
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Re: Flat top 454 or domed 427 for a rering job

Quote:
Originally Posted by davewho1 View Post
Maybe it's just me, but there's something magic about the number 427.
I think the same, my vote goes for 427.
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post #6 of 12 (permalink) Old Apr 7th, 17, 9:08 AM Thread Starter
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Re: Flat top 454 or domed 427 for a rering job

Going to drag out the std block this weekend to give it another once over and at least get the rings and bearings ordered.
I've done 6 of these hill Billy overhauls and got lucky on all of them. Jim

Jim

70 chevelle, SS clone 454 4 speed
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post #7 of 12 (permalink) Old Apr 7th, 17, 2:54 PM
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Re: Flat top 454 or domed 427 for a rering job

Quote:
Originally Posted by davewho1 View Post
Maybe it's just me, but there's something magic about the number 427.
Yeah, but its mainly the nostalia of the "number... based on all the L72, L71 and L88 stuff... Then with the 454, there was only one year of max performance, and all downhill after that... Too many years of "truck motor" 454s...

Sure, a 427 will technically rev higher, because of the shorter stroke, but realistically, how much higher? The 454 will have more torque because of the longer stroke, but how much more?


IMO, it should come down to the goal of the engine... If you just want a cool Big Block in the '66, then what makes the most sense for the way you use the car?


My questions would be:
  1. Will you need to run a higher octane fuel for the higher compression?
  2. Are you willing and happy to spend that extra money on higher octane fuel?
  3. Do you EVER plan to utilize the higher rev capacity of the 427?


Quote:
Originally Posted by Jim
It's eventually going in my 66 4 speed 3.08 gears to cruise around
With the 3.08s (3.07s?), and more of a cruiser, I'd probably lean toward the 454, with more torque, without requiring the more expensive fuel...

And add a "427" decal/emblem or two, and 99.9% of people will never know...


I have a similar dilemma; I have two 454 shortblocks needing a rebuild, but I have a "std/std" 396/427 Forged crank (6223?) just sitting, along with old closed chamber heads... I had the crank wet-mag'd and polished about 20 years ago... If it goes into my '66 (4-speed, currently 3.42 gears),I'll probably go 427... If it goes into the El Camino (automatic, 3.08s?), probably go 454...

Once you go RAT, you never go back...
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post #8 of 12 (permalink) Old Apr 7th, 17, 3:17 PM Thread Starter
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Re: Flat top 454 or domed 427 for a rering job

The 66 has a 3.08 ten bolt now, have a choice of 3.31 or 4.10 12 bolt in the future.
I still have the original 230 six cylinder emblems on the fenders those are staying.

Jim

70 chevelle, SS clone 454 4 speed
71 camaro. (owned since 1978!) 6-71 blown small block 400
66 chevelle 350 4 speed 3.55 12 bolt
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post #9 of 12 (permalink) Old Apr 9th, 17, 10:02 PM Thread Starter
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Re: Flat top 454 or domed 427 for a rering job

made the decision. Went with the 030 over 454 with the flat top pistons. Not sure what the compression will be but probably better with premium than the pop up pistons. went with the plain rings and bearings from northern auto, new std oil pump. Next up is to decide on a budget cam, lifter and spring kit. maybe something like the comp 268H or similar just low end torque a step above a RV type cam is fine. jim

Jim

70 chevelle, SS clone 454 4 speed
71 camaro. (owned since 1978!) 6-71 blown small block 400
66 chevelle 350 4 speed 3.55 12 bolt
66 el camino 350 th350 parts hauler
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post #10 of 12 (permalink) Old Apr 10th, 17, 12:20 AM
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Re: Flat top 454 or domed 427 for a rering job

Jim, 454 with flattops and open/large chamber heads will be in the low 8s/ high 7s on compression. you need an old closed chamber head for that. think 396 heads with the small "bathtub' chambers. They work no sweat on flattops.

actually, the CSG CR calc said 7.7:1 for this.

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Last edited by Tom Mobley; Apr 10th, 17 at 1:35 AM.
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post #11 of 12 (permalink) Old Apr 10th, 17, 1:27 AM Thread Starter
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Re: Flat top 454 or domed 427 for a rering job

Tom, I picked up a set of 063 heads off a 69 427 335bp motor I plan on using. To bump up the compression. The 66 has manual brakes and steering so dropping the 454 in should be a piece of cake. Jim
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70 chevelle, SS clone 454 4 speed
71 camaro. (owned since 1978!) 6-71 blown small block 400
66 chevelle 350 4 speed 3.55 12 bolt
66 el camino 350 th350 parts hauler
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post #12 of 12 (permalink) Old Apr 10th, 17, 1:36 AM
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Re: Flat top 454 or domed 427 for a rering job

yeah, that's what you need.

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