This is my first time here so hi everyone.
I have a 67 396 with the era-correct heads port matched to the original cast iron intake. I was just given(not a typo)a set of completely rebuilt heads with the good guides and hardened exhaust valve seats. Trouble is they are off of a 366 engine and have slightly (.050") smaller intake valves. They have HI-PER cast into them. Will I lose alot of performance compared to the stock heads if I use these with the addition of an aluminum intake?
Also, am I the only person who has a problem with roller rockers hitting the sides of my valve covers?? I think I'll have to fabricate my own sheet metal covers to fit unless there's another solution. :confused:

Double gaskets

Thanks milehiss.Cheaper and less time consuming than my solution.

Double gaskets leak and need to be re-tightened often......I just went with "tall" aluminum cover to clear my rollers.

[What is the casting number of the truck heads?

By chance -236's or -864's??

This is being asked b/c the old -236's are the really small "peanut port" intake port heads with 2.06"/1.72" valves.

Whereas the -old 864's have either 1.84" or 1.94" intake valves and 1.66" exhaust valves but do have regular large oval ports so they can be opened up to take up to a 2.25" intake and 1.88" exhaust valve, if not mistaken??

pdq67

Double gaskets and bend the drippers up if you're using stock valve covers,roller rockers don't need the drippers.

Thank's folks
The heads have the same size ports as the originals, it's just the intake valve that is smaller by about .050" total. I'll check the casting # when I get home. Buddy the mechanic tells me intake velocity should increase(but flow will decrease)with these heads. Guess I gotta run somthing till I get the old heads re done.

Truck heads won't say "Hi Perf" they will say "truck"

HI-PER Is cast right into the top of the head. This surprised me too. However, they do not say PASS or TRUCK anywhere.
They are out of a school bus and I know bus small blocks have alot of good parts in them(x rods, steel crank, double hump heads etc)Maybe this could also be true for the 366 bb.

Here's the numbers from the top of the head.
216 in one place
CFD in another
Were the old heads say PASS the heads in question say HI-PER
Casting # is 14092359
Maybe these heads are only used in Canada

No comment on the heads, but I bought and installed the double layer sandwiched valve cover gaskets. Think Felpro. Double cork with steel inner core.

They must be square port heads then..can you post a pic?

86-90 oval (can be peanut they don't say exactly) open chamber 366-427 truck they are marked HiPerf.

Whew!
GRN69CHEV-Thanks for the double gasket tip, but I started making the tooling for aluminim sheet metal covers today. I'll post a pic when they're finished.
mr 4 speed & Mike Feudo-They're definately oval port, but with a closed chamber just like the originals.86-90 should be right on for the mfg date. The only difference I really can see and measure is the intake valve size. They have to be odd balls. smile.gif

NO, they are just tall deck, truck motor "Torque" heads with small valves is all..

Install bigger valves and i bet they do fine for you.. Imho...

It took me forever to verify they even existed and now know they in fact do b/c everybody always said that the smallest valves installed stock in BB heads were the standard 2.06"/1.72" ones which we now know is only part of the story...

Check the amotion web site out and you will find SMALL BB valves listed like is being talked about here.

http://www.amotion.com/amcat.html

pdq67

I think its all pretty clear on the heads now.Thank you all for your input and research.
I'll try them as they are(bottom end grunt is what I'm after)and let you know in the spring how they work.
Thanks again
K

Actually,I have a pair of BBC heads that fit this description..they have 1.94 intakes and 1.60 exhaust valves,and the exhaust seats are hardened.
I talked to the local machine shop,and the intakes can go up to 2.19 on these and the exhaust can go 1.72,but any larger and the seats will have to be changed.
The combustion chamber looks like the old 290 and 215 heads