326 Heads

[NeoGoat]

Can I put 1.65 ratio rocker arms in the stock heads of my 326 (which i'm going to have converted for unleaded and ported & polished)or would I be better off getting a different set of heads i.e. -
350 or 400 heads?

[NeoGoat]

Can I put 1.65 ratio rocker arms in the stock heads of my 326 (which i'm going to have converted for unleaded and ported & polished)or would I be better off getting a different set of heads i.e. -
350 or 400 heads?

[zedo]

We tried 326 heads once and only once, on a 350 Pontiac, every-day driver to work.

The engine went in my brother-in-law's '72 Nova, with a 4-speed, and 3.08 rear. It got new bearings, rings, cam, valve job, chain, oil pump, 3-tube headers, duals, and was topped with an iron intake and Qjet from a '69 GP 400 engine.

It ran well as a driver, but completely ran out of breath at any higher rpm at WOT. The ports are tiny, smaller than the 350-400-455 head, about only 3/4 the size. We didn't port them.

It also pinged on unleaded gas, as the chamber size is very small, and is a "closed chamber" design.

He ran it for years anyway, and when we finally pulled the motor and sold the car, it had 2 pistons with broken ring lands.

I'd get different heads- I pitched the 326 heads in the heap pile at the scrap yard.

[NeoGoat]

Thanks Zedo, It probably would be easier to find a newer set of 350 heads that wouldn't need to be converted for unleaded, and she'd breathe alot easier too!

[DHVoorhees]

While working on porting and polishing the stock heads for my 326 I had poked a small hole in the exhaust runner. So I'm either going to have it fix at the machine shop or buy new heads. Does anyone have a specific head model # that would work on that engine and also flow better than the stock ported heads.
I also plan on using 1.65 rocker arms with a mild-medium cam.
Thanks
Daryl

[Tim Corcoran]

There is really no reason to use 1.65 rockers since you haven't selected your cam yet. You can just pick a cam that has the lifte and duration you want to run and run 1.5 rockers. If you do run 1.65's you will need to open up the pushrod holes in the heads or the pushrods will hit the heads.

[DHVoorhees]

There is really no reason to use 1.65 rockers since you haven't selected your cam yet. You can just pick a cam that has the lifte and duration you want to run and run 1.5 rockers. If you do run 1.65's you will need to open up the pushrod holes in the heads or the pushrods will hit the heads.

The engine is a 326 from a 1966 LeMans. Head casting number 094.

I'm using a Lunati #10510701 Cam and Lunati #73949K2 Valve Springs.
Comp Cams CCA-RP1452-16 Rocker Arm/Pushrod Kit, Magnum 1.65, Hi-Energy Pushrods.

Thanks for the tip about opening up the pushrod hole. I guess I would have found out when I align center of the rocker with the end of the valve.
I'll also be converting the pressed studs with screw in studs.

I'm going to get a price for the cast iron hole repair this week and continue to look for alternate heads in case the repair is expensive. I was planning on taking the heads to the shop anyway for hardened valve seats and a valve job.

[CAM400455]

6X heads are a nice alternative to the 326 heads. They flow well and are made to run on unleaded fuel. IMHO

[Tim Corcoran]

With a 326 big valve heads may hurt low RPM performance. The small bore 326 would need the top of the cylinders chamfered to clear the valves with 6X heads and the valves would be shrouded. I believe you would be better off with small valve heads on that motor. There is a ratio between bore size and valve size for optimum VE and you would be way out of balance with big valve heads on that motor. If you use a different head I would use small valve heads and try to get your compression ratio between 9.0 and 9.5:1, get a nice 3 angle performance valve job. And zero deck the block too.

That is a great cam for your combo but it needs 125 lb on the seat because of the fast ramps and putting 1.65 rockers will put a strain on your valve train. Make sure your valve train geometry is 100% right on and don't use cheap off shore hydraulic valve lifters. If you want to avoid problems, like a flat lobe or ticking valve train I would only use Johnson Hy-Lift 951R lifters, make sure you get the R lifters. These are the only true Pontiac flat tappet hydraulic lifters I know of that are made in the USA with quality US materials that have a consistent leak down rate. If you do use 1,65 rockers I would break the cam in using 1.5 ratio rockers to avoid getting a flat lobe and making a mess of a nice build.

Sounds like a great build. After you get her running please post how she runs.

[CAM400455]

I stand corrected. I've never owned a 326 and had no idea about the work needed to use the 6X heads. I have only built the bigger CIDs. Thanks for letting me in on that.

[chaz069]

Need a test engine? I have a 67 326 WP engine no.573798. Removed from a running 67 lemans. If you are interested. chaz069