New Member 454 questions

I have a 74 Nova that was a factory 350
4 speed car. I am building a mild 454 to put in it and use the factory Muncie and 3:43 10 bolt posi. The engine is out of a 1980 truck. The heads are some I picked up from guy who used to run a machine shop. They are 215 oval port from a 67 or 68 427 he doesn't remember which. Someone dropped the off years ago and never picked them up. With the stock flat tops it should be around 9.0 CR. He said they are good for around 6,500 RPM. I am building for street use but may run the 1/8 mile at the local track. Looking for carb intake and cam recommendations. It has power brakes so vacuum will be a consideration. Thanks.

What are the serial numbers on the heads?

The casting numbers are 3917215.

I'm not a BB expert, but those heads are common to '67-'69 396 engines. 2.06 intake valves, 1.72 exhaust valves stock unless someone has upgraded to larger valves. While they would work on your engine and get you around 9-9.5:1 with flat tops, your engine might run out of air before you achieve 6500 rpm. 5500 tops IMO.

I guess I wasn't specific. Valve springs are good to 6500 RPM. He made no claim to the flow rate. They have a three angle valve job and after market springs otherwise stock.

Call three or four of the major cam companies and give them your specs. They will give you some good suggestions for cams that would fit your requirements. One person from another forum suggests doing this and choosing the cam that is closest to the average of the three or four suggested. That's not a bad method. Post the recommendations and I'm sure other members will forum chime in.

A MILD 454 won't overcome the weigh added to your 350 Nova------Build a bigger cube 350--------406? etc or if wanting to do a swap (added expense of exhaust? accessories?? ) look at the new alum LS series------------

ALSO------the Nova has a special clutch pivot boss that you won't find on the big block------what are your plans to deal with that???

BOBCRMAN@aol.com is a shop owner on another forum. Here is some of his advice.....

These are early heads with the "N" series spark plugs. Small bathtub chamber. These were notorious for guide and valve stem wear. Check for wear and correct. Guide wear is a leading factor for dropped valves in big blocks, keep them snug. To be correct for modern fuel you will have to have hard exhaust seats installed. If you do, have seats for 1.88 exhaust installed and use aftermkt stainless valves. These heads are a bit restricted on breathing on the intake side because of the combustion chamber wall. Anything you do to relieve the wall around the intake(taper chamber into head face surface) will help, If you can handle a little compression ratio loss. I usually bowl hog the intakes and install 2.19 intakes. This will help breathing to about 5500-6000 rpm.

First clean your valves good in a degreaser, on the valve stem about 5/8-3/4" down from the retainer end, visually check for wear thru the chrome plating. If you can't see it take the valve stem between your finger tips and run the stem up and down, you will feel any wear. If you can feel it, the stem is junk. To check the guide, install a new or unworn valve in the cleaned, dry guide, all the way in, then pull it out about 1/2" and try to move it sideways and back and forth to the side. If you can feel any motion, you will need guides. the clearance is only .001-.004" on a cast guide, at about .003 jou can just barely start to feel the side motion.

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also a factor of installing hard exhaust seats in bbc iron heads is that the casting is thin around the seat on the end that has the exhaust valve at end------common problem of going thru when machining for seat so stay as small as you can on seat insert OD.

The older bbc from 65 to 89 mark 4 block as the two spots on the block for the clutch pivot ball and over 30 years I used the 215 .396 heads was a cheap way back in the early 80s was done with a flat top 454 to get the CR up there and small chamber head bath tub chamber and like Jerry said you need to watch the size of I.d of ex seat as you can cut thru head casting can easly pass 470 hp with them heads I built 396/489 out of.them heads still would not say it cheaper to go ls but it close I done many nasty bbc.over the years and some very good running ls engines still the swap and dealing with some of the ls is no free lunch were to swap a 454 bbc in your nova is much less as gm parts.and many parts used can be found to make a 454 a bolt in job