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73-87 Chevy _ GMC Trucks => Performance => Topic started by: harcorshe on July 23, 2015, 08:33:32 pm

Title: Increasing Compression- 454 Build
Post by: harcorshe 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?

Title: Re: Increasing Compression- 454 Build
Post by: 68post 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 .

Title: Re: Increasing Compression- 454 Build
Post by: harcorshe 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 ;)

Title: Re: Increasing Compression- 454 Build
Post by: scorpion on July 23, 2015, 11:00:49 pm

Quote from: harcorshe on July 23, 2015, 10:24:47 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.  ;)

Title: Re: Increasing Compression- 454 Build
Post by: ehjorten 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.

Title: Re: Increasing Compression- 454 Build
Post by: harcorshe 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...