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CID Symmetrical Port Big Block Chevy Cylinder Heads.

  At CID we wanted to address the issues associated with the factory BBC heads. First of all we wanted to make our head a symmetrical port head. No more left and right unequal length runners. We straightened up the valve angles to move away from the factory bath tub chambers and to a smaller more efficient combustion chamber.

In order to facilitate this, the valve angle has been stood up to 9.5 degree with a cant. We added 0.750” thick decks. and valve train stability was also a priority so the rocker gear posts are robust enough for the most demanding applications. Everything you would come to expect from the experience gained manufacturing and developing the world renowned 3V Cleveland Cylinder Heads and Intakes.

With an As Cast port version developed by Jon Kaase - (JK 390) for small bore engines (4.250” – 4.310”) as well as As Cast or CNC port race version by Darin Morgan - (DM 500) (designed to work with 4.600” bore engines) some exceptional performance outcomes have already been had.
The CID Big Block Chevy cylinder heads are designed to run with shaft mounted rockers that are available from both T&D as well as Jesel, depending on the cylinder head. The JK 390 takes individual stand rockers that are available from both Jesel and T&D and are existing shelf items. The DM500 takes a one piece stand that is currently available from T&D Machine. Another option we have seen, is a customer cut and shut BB Ford guide plates, and used rocker studs along with existing stud mount Big BLock Chevy arms on our JK 390 cylinder heads. This however will not work with our DM 500 heads.
The cylinder heads come with 2 matching CID intake options, one for the JK 390 heads and one for the DM 500 heads.  Both intakes utilize the same exterior casting, with one having larger internal runners passages than the other to suit their individual cylinder heads. A primary consideration when designing the manifold, was that it fit under the hood of most cars. To facilitate this the intake measures just 6 3/4" from the bottom of the valley pan to the top of the carb pad, whilst still retaining excellent HP producing characteristics.
 The small runner system 4500 single plane intake pictured below has a clover leaf pattern carb pad for the Jon Kaase - JK 390 inspired standard bore cylinder heads. This intake is designed for engines looking to make somewhere in the mid 700's, to mid - high 800 HP range. It features the smaller of the 2 runner systems and wont match up to the DM 500 heads.


 The larger runner 4500 square carb pad version was designed by Darin Morgan to match his DM500 cylinder heads. This intake is suited to engines aiming to make 900+ HP. This intake will not match up to the smaller JK 390 cylinder heads.



  • The CID Big Block Chevy heads unique valve angles require their own piston design. Pistons are available from CP, Ross and Diamond pistons. For those wishing to use another brand we can send CAD files or chamber molds to your preferred supplier.

    Chamber volume for the Jon Kaase - JK390 designed cylinder head (suits 4.310” bore engines) is around 88cc’s. The Darin Morgan - designed DM 500 (4.600” bore cylinder head) has a 60cc chamber.


    • Symmetrical intake port design – no more left and right unequal intake ports
    • Matching 4500 carb CID intake manifolds available in both 9.8’ and 10.2” deck heights for both the JK 390 and DM 500
    • STD Exhaust flange design raised .375” will accept factory headers.
    • 9.5 Degree Valve angle with a cant – Factory bath tub chambers are replaced with a efficient modern chamber design. Engines in testing are running with just 24 Degrees of Total Timing.
    •.750” thick deck face
    • Oversize rocker gear posts for maximum rigidity to suit shaft mounted rocker gear. Completely new rocker gear setup is far superior to Factory BB Chevy valve train.
    • Affordable As Cast ports JK390 version. Cast inlet & Exhaust port version by Jon Kaase to suit small bore engines (4.310”) flows 334CFM@.500” and 390CFM@.800. 86CC CNC chamber
    •Affordable As Cast DM500 version. Cast Inlet & Exhaust port version by Darin Morgan to suit 4.600" + bore with a 60cc CNC chamber. (Details soon to be released)
    • CNC ported DM500. Will flow 500CFM with 2.450” valve. Flows 495CFM with 2.400” valve with 440CFM@.600” lift.
  • 60CC CNC Chambers
Take a look at some of the results our customers have had recently.
This dyno sheet below is courtesy of George Haddad of Haddad Race Cars from Melbourne Australia. Georges customer Kim wanted a streetable 638 he could enjoy. George chose our DM500 CNC ported heads and the matching CID DM 500 intake manifold and used a solid roller cam. Neither George nor Kim though were prepared for the increase in HP over their previous combination. The engine went on to make 1088HP & 917 FT/LB.



Below is a 540 CI BB Chevy built by Dandy Engines of Melbourne Australia. Another engine destined for street duty, this BB Chevy uses a Flat Tappet camshaft, our JK 390 cylinder heads with matching intake to make 810HP and 700 FT/LB on pump gas. Dandy Engines used the customers existing rocker arms to keep cost down and ran them with a set of modified BB Ford guide plates.




How about 1000HP & 800FT/LB @ 4500 RPM from a Pump Gas Flat Tappet 632" BB Chevy?

Well...Almost...Another impressive engine from Dandy Engines of Melbourne Australia.


Cut and Paste the link for a closer look.