CPMotorworks Inc.

CPMotorworks Inc. Performance Engine Machining and Assembly,
Custom Cylinder Head Fixture Manufacturing CPM is owned and operated by Pete Graves.

Our goal is to provide first class machine work and engines that perform at their potential. We want to provide you with service and results that makes you, the customer, feel good about your investment with us.

05/30/2026

489ci BBC with L72 #163 intake and Terminator X.

05/30/2026

489ci BBC with LS6 / #569 intake & Terminator X TB fuel injection.

Had a last minute chance to get this one on the dyno, another 489ci BBC for a customer in Scottsdale, AZ for a 1973 Cor...
05/30/2026

Had a last minute chance to get this one on the dyno, another 489ci BBC for a customer in Scottsdale, AZ for a 1973 Corvette.
The low rise GM #569 intake with zero porting is no slouch, 627hp with the Holley Terminator X doing it's own learning curve, and I think there's more in it with fine tuning.
The GM #163 has a milled plenum and mild porting to match the BRODIX Cylinder Heads RR294 heads, and managed 658hp with 2° more total timing, all on 91 octane gas from Kwik Trip.
Both intakes benefitted from a 1/2" open spacer.

Results of yesterday's testing on the 489ci RR294 headed build.This was built as a replacement for the 496ci engine in m...
05/23/2026

Results of yesterday's testing on the 489ci RR294 headed build.
This was built as a replacement for the 496ci engine in my wife's 1970 Chevelle that was updated as an experiment back in 2014.
The 496ci is a converted 750/1050 Dominator, ported Victor intake, ported 781 heads (290cc, 367cfm @ .800" lift) a healthy SR 27x/28x, .700+ lift cam, 10.2:1 pump gas combo that has run [email protected] with a 3.31 gear (only 5400 through the lights) on a 275/60 drag radial @ 3800lbs, ZERO tuning as she only made about 5 passes after not driving her car for 5 years .
I'll add this 496ci made 712hp corrected on 91 octane with a Pro Systems 1150 Dominator on the dyno.
The 489ci is 10.6:1, Brodix RR294 heads, a small HR cam (24x intake lobe), makes 11-13" vacuum at idle, with heads that flow about 30 cfm LESS than the 781s under .650" lift.
The initial TQ dip of the Vic Jr is not an accurate representation IMO, some tuning issues and loading the dyno is really all that is.
Either way, this package will let me put her stock Cowl Induction hood back on, swap the 8" 4500 converter for the 10" 3500 converter she ran 11.50s with in the original 496ci build, that was just an AG/781/SFT cam setup, that only made 550hp/570lbs.

Another round of intake testing today on a pump gas 489ci build. More data to chew on while I question my life choices 🙃
05/23/2026

Another round of intake testing today on a pump gas 489ci build. More data to chew on while I question my life choices 🙃

L-35 325hp 489ci build
05/03/2026

L-35 325hp 489ci build

05/01/2026

I'll put this out there, and no doubt I'll get some heat, hate, "I just run solids", "Morels are junk" ,etc.
But FWIW, I've been using Morel Street Series HR lifters since 2010, and I've had one lifter fail in service, one stick a plunger on the dyno, other than that, pretty good results for the amount I've used, which is pretty much every street V8 I've built since 2010.
This is what my typical setup sounds like with a performance style lobe and decent spring pressure, link bar style lifters, steel roller rockers, .050" of preload.
Johnsons sound the same, the one set of Gatorman I used were noticeable louder, one set of Johnson Hylift HR sounded like these, a budget set of Sealed Power a customer used was also loud.
Smaller cam profiles with less spring can be a little quieter, one I used stock rockers and a tiny lobe was really quiet, but NONE of them are dead silent.
I have run solid rollers on hydraulic profiles, but honestly it takes a pretty careful lash setting and it's still a maintenance item. I try to make a lot of these as maintenance free as possible for most customers, because it's way more fun to drive them than work on them.

Cleaned out a cabinet.. prices have changed just a bit since this was just a side hobby for me.
04/29/2026

Cleaned out a cabinet.. prices have changed just a bit since this was just a side hobby for me.

04/25/2026

Iron Intake/Heads 489ci BBC for a 1985 C10 shop truck.

04/25/2026

Pump gas 489ci BBC on the dyno today.
Quadrajet, OEM iron 325hp Qjet intake, OEM 781 ovals, small CPM custom hydraulic roller cam.
Should rock a '85 C10 pretty good!

Address

4611 N Katherine Drive
Janesville, WI
53548

Opening Hours

Monday 9am - 5pm
Tuesday 9am - 5pm
Wednesday 9am - 5pm
Thursday 9am - 5pm
Friday 9am - 4pm

Telephone

(608) 290-4456

Website

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