326 with 092 Heads
 

I am buying a 67 LeMans with a rebuilt 326 and it has 092 389 heads installed. Was this a good idea to improve hp to a 326?
Thanks for any input
Joe

Sort of good.
The chambers might be a little bigger to drop the ratio a bit.
Valves are a little bigger too. iirc

092 had same valve size as 093 , but different springs.
326 heads usually had smaller valves than those.

The 1966 092 heads have a 68cc chamber to make 10.5:1 on a 389, 1.92/1.66 valves.

The 1967 140 2-barrel 326 heads are 62cc to make 9.2:1 compression also with 1.92/1.66 valves.

So it’s pretty clear that someone was using whatever they had on hand, the 326 lost some compression and some performance with the swap to 092 heads.

1963 & 1964 326 heads had the smaller 1.88/1.60 valves, 1965 - 1967 326 heads had the larger 1.92/1.66 valves.

When the intake manifold to head bolt pattern changed in 1965 to the final design all the heads were upgraded to the 1.92/1.66 valves. Previously the only pre-1965 non-SD heads with 1.92/1.66 valves were the 1963 - 1964 9770716 Tri-Power 389, 421 HO and GTO 389 heads.

Since your looking for 1 hp per cid then I need to first ask what rear gears the car has out back, what trans ( hopefully not a TB300) and what type of driving will the car be used for 85% of the time?

What can tell you is with what those heads flow in stock form you will need to run a Cam of at least .525" lift to reach your 326 hp goal, and getting that .525" lift might come at the price of the Cam having too much duration to make for having a tolerable idle and a happy around town and highway car.

Unless they did some head milling it probably lost a half of point of compression against the stock 326 head. I think a 389 has about an 8cc bigger head chamber. But I am just going off of published numbers, sometimes they are wrong. But if it gains a bit of head flow, and probably lost some compression. It likely didn’t make much difference either way in performance.

If the motor was bored .030” over when it was rebuilt then that ate up 3.32 CCs of that bigger chamber size the 092s may have which would leave not even a 1/4 point of compression difference either way.

Call it a mute point is how I would look at it.

If there was a difference both head combos would still be .030” over, so the difference really stays the same. But that cc number is something I recall seeing from something from HOracing. Which I am not sure was even correct for that year.

I think Wallace racing.com has a calculator for CR ratio factors.
Don't know right off how much 6cc will lower CR but it should put it down into a real safe zone for cheaper pump gas grades.

I wouldn't worry too much about milking performance from a 326 engine.
Just a good smooth cruiser machine would be better in most cases.

Good info b-man

My 0.040” over 326 has 1967 400ci #143 heads on it. Should be a similar setup to you. Runs great, not a lot of juice, however. No idea what cam it’s got, moves the car pretty well from a stop, but not much top end. Still fun to drive.

From my research, there’s not a lot of great options for a peppy 326. I think you’re pretty much limited to pre 68 heads, most of the newer heads have chambers that are too big. You also want to keep the small valves to avoid shrouding. The pre 68 heads don’t flow as well, I believe Steve25 said the problem is mostly on the exhaust side.

Another option would be some custom KRE d-ports with small valves. But that’s $3k.

Really though if you have the heads off, a few minutes cleaning up the valve bowls apparently makes a difference. And if you’re gonna go that far, a Melling SPC-4 or -5 cam would probably be perfect. That’s my plan anyway.

Thanks for all the replies guys. I’m a 400/455 guy so I was wondering why someone would do this. I do not have any more info on the rebuild yet. I do have a 400 or 455 that will eventually make it into the car so it’s just a temp engine

I would use the 092 heads in a heart beat. I have been trying to find heads for a 326 for what seems like years. Now I just picked up a set. But now realize the intake port is almost a quarter inch lower at the top. than 389 heads. I had planned on using the 66 square bore intake but the ports do not match up.

A 326 with the bigger 1.92s likes a 068 cam and a qjet and set of 3.55s. Nice little tire burner