Author Topic: Increasing Compression- 454 Build  (Read 6713 times)

Offline harcorshe

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Increasing Compression- 454 Build
« on: July 23, 2015, 08:33:32 pm »
I didn't want to hijack another thread, but I have some questions about my first attempt to "build" an engine.

Here is what I have:
454 with '049 heads.
Headers with a 3 dual exhaust and H-pipe.
Edelbrock 1407 carb (750 cfm)
14 bolt with 4.10:1 Gears and 31 inch tires (but I want 33s!)
I just got an RMP Air Gap intake and I figured that I would get some work done on the heads (maybe bigger valves) and a more aggressive cam and I should be good to go.

I called COMP CAMs and they asked about my compression ratio. According to what I found on the web, it is probably 8.5:1, right? If so, they said that I shouldn't bother with a more aggressive cam unless I can get to about 9.5.

Is this true? How much can I increase compression by shaving the heads? (I don't want to pull the block.) Any other ideas?

'78 K20
454
TH400
14 Bolt
205 Transfer Case

Offline 68post

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Re: Increasing Compression- 454 Build
« Reply #1 on: July 23, 2015, 09:35:17 pm »
Are your pistons flat top ? I doubt you can gain enough by milling - unless you are angle milling them also. How aggressive of a cam are you looking for ?

There are aftermarket heads with small chambers , or factory vortec heads also. Those heads will take a flat piston/stock bore 454 from 7.9 to approx 9.0 .

Offline harcorshe

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Re: Increasing Compression- 454 Build
« Reply #2 on: July 23, 2015, 10:24:47 pm »
It has stock pistons which I think are flat topped.

I guess changing the heads might be the best way to increase compression but I hate to get rid of these oval port heads.

I'm really not looking for anything too aggressive. It's a 78 K20 and I will mostly be driving it to Home Depot--I just what to get there faster than anyone else ;)
'78 K20
454
TH400
14 Bolt
205 Transfer Case

Offline scorpion

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Re: Increasing Compression- 454 Build
« Reply #3 on: July 23, 2015, 11:00:49 pm »

I'm really not looking for anything too aggressive. It's a 78 K20 and I will mostly be driving it to Home Depot--I just what to get there faster than anyone else ;)

Well it looks like we'll be racing each other to Home Depot.  ;)

Offline ehjorten

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Re: Increasing Compression- 454 Build
« Reply #4 on: July 24, 2015, 09:21:39 am »
049 heads are open chamber heads with about a 122 cc volume.  They flow the best of the 3 early big oval port heads that were available.  They flow best with bigger valves (2.19 and 1.88).  Your best bet for increasing compression would be new domed pistons.

Alternatively, you could ditch the heads and go with a closed chamber head.  I guess it depends on if you are going to tear into the bottom-end of the engine.
-Erik-
1991 V3500 - Gen V TBI 454, 4L80E, NP205, 14 bolt FF, D60, 8" Lift on 35s
1977 K20 Silverado - 350, THM350, NP203, 14 bolt FF, D44, Stock Lift on 31s
1969 Chevelle Malibu Sport Coupe - EFI350, THM350
1968 Chevrolet Step-side Pickup - 300HP L6

Offline harcorshe

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Re: Increasing Compression- 454 Build
« Reply #5 on: July 24, 2015, 02:22:39 pm »
Thanks.  I was hoping to avoid work on the block by upgrading the top-end and adding headers, but it seems like there is only so much I can do.

I better start preparing my patient wife...
'78 K20
454
TH400
14 Bolt
205 Transfer Case