Building my 289: Edel heads too big, what do I do?

Hey guys,

In the planning stages of building up my '67 289 to a street machine from the ground up. It's all apart and at the machine shop waiting for direction from me. I thought I scored on a used set of Edelbrock performer 1.9" int. heads, under the impression they were ~60cc chambers and could be finessed to reach 54cc for around 10:1. Well, CC'd them and got average of 64cc! So that totally disrupts my plans. Options are to:

1) domed pistons: less efficient. Ideally flattop or dished would be best, can't seem to find -10cc domed pistons either
2) mill heads down -10cc: is that even possible with regards to intake manifold, valvetrain fitment, can of worms?
3) sell them and keep looking for heads with smaller chambers

Now I'm researching stroking the engine to fit the heads but I really don't want that much power as everything else down the line needs upgrading. I'm learning a lot taking on this project. Can't wait to get to making some decisions and moving forward. What are your thoughts?
Thanks!

rbohm said:

if your plans were for 60cc chambers, then just mill the heads enough to bring the chamber size down to 60cc.

the thing is though that you wont see any real power difference with either chamber size, so go ahead and use them as is, and tune around the issue as needed.

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Edited my post to include that key info I left out! I was hoping for close to 10:1cr (54cc chambers).

Guitylerham said:

Edited my post to include that key info I left out! I was hoping for close to 10:1cr (54cc chambers).

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Would stroking it to a 331 put my larger heads to good use?

rbohm said:

if you mill the heads, you can take the intake to the machine shop and have them mill it to fit. as for the valvetrain, you may have to get shorter pushrods to reset the rocker arm geometry, but you are probably going to have to get different length pushrods anyway with a cam change. you will have to check the rocker arm geometry to be sure though.

and yes, if you build a stroker engine you can take advantage of the greater head capacity. you will have to run the numbers to see what compression ratio you would end up with though. i also suggest running the numbers before milling the heads to determine what compression ratio you are looking at now and seeing how close to 10:1 you are right now. personally for the street i would run closer to 9.5:1 compression.

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Thanks for that. After looking more into a stroker, yeah it'd be cool to have more power but it's also more expensive to build a bigger engine and I should go back to the original scope of the build and just have the shop put together a kit of pistons/machine work to make those heads get decent power. I'll definitely be modifying the pushrod lengths and ensuring the valvetrain is good regardless. I'm used to driving a stock 289 C4 with 2.8 gears so this built engine with better heads/exhaust, a T5, and perhaps 3.55 rear will likely be all the oomph I'll need without having to stress squeezing out every ounce of compression.