I am building a 396 for my 64 nova with 320cc rectangle port aluminum heads. The valves are 2.25 intake and 1.88 exhaust. The cam is mechanical 300/310 degrees adv duration, lift is .540/.558 and rpm range is between 2500-6200.The stall speed on the tourqe converter is between 3400 - 3600. I used a chart from holley to figure what carb I should put on top of this and it put me in the ballpark of a 1050. This sounds excessive to me. What does anyone else think?:confused:

Since this cam is race oriented I would slap on a tunnel ram and two 660 center squirt Holley's. I assume your static compression is around 11.6:1 to 12:1. You will probably be happier with a lit bit looser converter (around 4,200 to 4,600 RPM). And I think with that high a duration on a solid you are leaving a lot on the table with that little bit of lift (should be around 0.710" to 0.715" in my opinion).

Big Dave

Use an 800 max. It will run just fine with a 750 vacuum carb.

Big Dave, how do I change the lift without changing the cam? May be a stupid question I dont know. Im not a top notch mechanic by no means.I want to run this engine on the street. What advantage would I get with a looser convertor? You think a stall that big would be ok on the street? I have victor jr for it that I used to run on it. Do you think I can stick with that with a dominator 750 mechanical?

You have what is known as a "bottom of the page cam". If you were to look at a listing of all of the cams listed by a grinder with the shortest duration cams listed to the longest, yours is down on the bottom. Those cam grinds are reserved for race cars not street cars. This is because as the duration gets longer (both the intake and exhaust valves are off the seat at the same time for a longer period of time) the amount of torque (horsepower is the product of torque multiplied by time) produced at lower RPM’s falls and is shifted to the higher RPM bands.

In other words think of a drag race. Cars are sitting in the staging beam waiting for the light to change to green so he can go. He brings his RPM up into the power band of his racing cam (which is generally around 4,500 RPM) and keeps the car from moving by locking the transmission into forward and reverse at the same time with the front brakes locked with a roll control. Light turns green and away he goes, foot planted on the gas to get the engine up against the top number on his cam grind to maximize his horse power.

Now imagine your mother is sitting next to you while you take her to the corner store for a gallon of milk and you are sitting at a green light with your foot on the brake. You bring your RPM up into the power band of your racing cam and keep it there with your foot planted hard on the brakes. Light turns green and away you go, wheels up foot planted on the gas to get the engine up against the top number on your cam grind to maximize your power horse power. What do you think will be her reaction? Your dates?, the cop behind you?

You will have to drive the car that way because it will be a dog other wise. An old air cooled VW with two burnt exhaust valves will be leaving you behind unless you drive the car this way. Why? Because the cam is letting all of your low end power flow out your exhaust pipes in the RPM range you drive at on the street. Now it will sound like a race car, with a radical rumpitty rump cam. Trouble is it will handle like one too (worse than a race car unless you properly size all of your components like carb and manifold with header tube size and length).

I was dead serious about the tunnel ram and carb suggestion (I’ve run this set up on the street and it isn’t as bad as you might think). But you will have to have a very loose converter (I had a four speed back then) to allow the engine to get high enough into it’s power band to generate enough torque to get the car to move. In my case I slid the clutch (which burns it up) in your case your slipping the torque converter which generates lots of heat so you need the biggest auxiliary transmission cooler you can find.

The number on the torque converter tells you approximately when it stops slipping, and starts to lock up or engage. The less torque you have the lower it will rev before locking up, if you had a 454 it would stall about were they advertised it. They call it stall because if you do not have enough stall built into your torque converter that is what will happen to the engine when you put it into a gear: Stall. With a small BBC (your 30 inches above the smallest displacement ever made with 810 cubes currently being as big as you can go) your converter will probably stall around 2,800-3,000 RPM which is way below peak torque with your cam. It may not stall the engine on putting it in gear, but it will not like trying to accelerate with it locked up either.

Unless you like the idea of driving this way on the street (it does have some appeal but it comes with a lot of tickets) then I would suggest changing your cam with something closer to 220°-230° duration @0.050" (236° maximum duration at 50) in about the 0.550" to 0.580" lift and buy and correctly install the recommended springs to go with the cam (the correct springs for your current cam (347-16 from CompCams) cost about $320). I go with duration measured at 0.050" lift because that way you can compare one cam with another. The advertised numbers are only used to compute dynamic compression and have no application to anything else outside of selling cams.

You made the right choice with rectangular ports for the race motor, but on the street oval ports make more overall power than rectangular ports which do not start to work below 4,500 RPM. Hopefully whomever you bought your parts from has a generous exchange program.

Big Dave

Thanks for all the info Big Dave. Thats a lot of information. I havent bought the heads yet but I was close. I ahve a pair of closed chamber rectangle port cast iron heads and I have a pair of open chamber oval port cast iron heads. Should I use one of those sets or should I buy a set of oval port aluminum heads. I guess what I am asking is what will I gain from having aluminum heads because thats what I want for some reason.Should I still go with a tunnel ram setup if I change the cam?If I go with a tunnel ram will I have to change hoods on my car,I will right?Thanks again for taking time to talk with me.:thumbsup:

The open chamber oval ports would be your best choice for this size motor. Aluminum hurts performance by as much as 14% by sucking heat out of the chamber (if they are thermal coated this isn’t a problem). The reason people use them is they are easily repaired if something happens to them (very difficult to get cast iron fixed), and they are much, much lighter than the iron heads they replace (shave an easy 80 pounds off the nose of the car).

I would put a fraction of the money you were going to put into the prospective aluminum heads into buying bigger reduced stem size valves for your current heads (2.19" minimum, 2.25"-2.30" if you’d like intake and 1.88" exhaust) and getting them gasket matched, pocket ported and rebuilt with new silicone-bronze 11/32nd inch guides. Be sure the head porter you use comes with a flow bench report of both before and after the work, and a couple of good recommendations.

An Edelbrock RPM manifold for an oval port head (gasket matched) and a Holley 750 CFM HP series 4150 vacuum secondaries Part # 0-82750 would be ideal for this engine. You do not have to buy a new hood unless you want to (see similar thread on cowl hood size).

As far as a tunnel ram and a hole in the hood that depends upon whether this is to be a street car or a race car (it can not be both). The hole in the hood would admit rain (not a concern to a race car because no one ever races in the rain). A tunnel ram is not out of the question on the street it is just impractical (that is why the factory bent them, squashing them down to fit under a hood; for a street driven car, and called them a cross ram).


Big Dave

Thanks big dave, Im going to stick with the oval port cast heads. You saved me some money there.The duration I gave you on my cam was the advertised duration. The duration at .050 is 247/255. The lift is .558/.566. Does this make a difference or do I still need to change the cam?Do I still need a bigger stall?Thanks Big Dave your being a lot of help to me, hope im not being a pest.

You are still close to the bottom of the page, will need at least 11.0:1 static to make power because you are bleeding off so much compression you are actually running closer to a 350 cubic inch engine displacement dynamically (before the intake valve actually closes). It will have a very rough idle and need headers and a gear to make it close to driveable (won't get much in the way of mileage).

Additionally is this a solid roller of flat tappet cam? If it is a flat tappet cam; read some of the prior posts on ZDP oil additives and flat tappet cam life expectancy posts (go to our sister board on Team Camaro's or Team Chevelle’s as they have a larger membership with more posts and more opinions on the subject to form a better idea of where you are going with this cam choice).

Big Dave

Try to find heads with the last 3 digits 049. They are the best oval port GM heads. If you angle mill these .100" and install the 2.25 and 1.88 valves with a little pocket work they will run GREAT.
If the budget allows, the Edelbrock 100cc chamber oval port heads are killer on the street and will KILL any OEM head, especially on the smaller engines.
Roller hydraulic is my first choice for cams. They run with anything up to about 6500 rpm and require no maintenance, no special oil or additives LIKE ANY FLAT TAPPET WILL!! Oil now is different than it was a few years ago and the lube for the flat tappet cams is not in them anymore, not even in synthetics.
Good starting point for a killer street cam is 235 to 245 degrees at .o50" lifter rise. Split duration cams seem to always run better with the exhaust 8 to 12 degrees longer than the intake.
If you do go roller, be sure to use a block thrust plate on the cam gear or, better, a Torrington bearing.
If you call any cam manufacturer or head company, they have people that get paid to help you and they're almost always knowledgeable and nice to talk to.

Big Dave: You bring up a good point on the heads, but it brings up another question in my mind and it sounds like you know a lot more about engine performance than I do. While I know full and well the material the head is made out of does not noticeably affect the air flow of the head, but doesn't an aluminum head allow you to run higher compression on the same grade of fuel compared to an Iron head? And if that is the case would the possible CR gained overcome the 14% loss?

While also I have to admit my knowledge of engines is limited to basic automotive knowledge and not performance issues I have done some research concerning heat dissipation and the emissivity of various surfaces due to training with thermal imaging devices. While Aluminum is much better at accepting or dissipating heat when in direct contact than Iron, Polished aluminum gives off less light in the IR light spectrum than a cast Iron head painted flat black given all other circumstances are the same such as surrounding air temp, surface area exposed, and temperature of the Iron/Aluminum. Due to this I would have to think the water cooling system is the major factor in the fact that aluminum heads run cooler than Iron heads since the water is a direct contact cooler. If this is true could you under drive your water pump to make up the running temperature of the Aluminum heads their by negating the 14% loss due to heat transfer and possibly gaining a little more since your water pump will not be stealing as much power from the crank?

general rule of thumb is 1 compression point increase for aluminum. The main points for aluminum are the much improved air flow they offer as they were designed to go fast, not pull a trailer.
The aluminum also controlls detonation much better due to not developing hot spots so readily.
Coating the aluminum heads can help heat dissapation almost to cast iron levels and still not have hot spots.
Also, I have sent out aluminum heads broken into several large chunks and had them repaired, though expensive, it will usually save money over an expensive ported head. Cast iron is just junk after they break.
If you do any porting, alumium is WONDERFUL-just don't get carried away.
John Lingenfelter did a set of 049 heads for me not too long before he died and they were the best head I had used on a 454 street engine. Now, almost any small port aftermarket head will kill them.
I have had great success with Wrold Products Merlin oval port as well as any of the big company's aluminum parts.
Dart is very good, too.
AFR's will outrun anything out of the box, but Edelbrock, Holley, Dart, Brodix, and many others have given me good parts.
If you will black anodize the Al parts, heat dissapation will be greatly improved and NEVER run anything polished if you want to go fast!!!!

Thanks for all the input guys. Im not that worried about mileage right now as this car will just be novelty for my wife and I on the weekends. How large do you think the gear will need to be? I tried finding those hooker headers you told me about Big Dave and had no luck. Thanks again.

If you haven't bought the cam, a 396281 Isky will kill the cam you specified.
Also, consider the Comp Cams XE284H part no. 11-250-3 or maybe Lunati Voodo cam 60204 with duration at .050"lifter rise of 233 intake and 241 exhaust???
The Isky is my favorite for a flat tappet hydraulic in an engine like you described and they will easily turn over 6200 rpm.
Trust me, they will all beat the one you had on the street!!!!!
All of these will like 3.73-4.11 gears.
The one you chose will need 4.11-4.56 gears.

First thing I would do in your situation would be to sell your 396 to an owner of a Chevelle or Camaro that is attempting to build a numbers matching car. Especially if those closed chamber cast iron rectangular port heads came with that 396 motor (had a 425 to 375 horse rating on the 396 depending upon year of manufacture). Go to http://www.mortec.com/bbc.htm for information as to the year that the heads and block were all cast. If they were all from a ‘67-’69 year they could be worth swapping for a Brodix or Dart BBC block (about $2,300). Or more depending upon you horse trading skills. A numbers matching HiPerf 396 is a very valuable chunk of cast iron to driving on the street (take a gander at the Barret Auctions to see what I mean).

Either way I would not be building a 396 for two reasons. One they are too valuable to museum curators building number matching cars. Two it is too small of a motor to justify dragging around the added weight of a big block. A SBC 400 cubic inch engine is 160 pounds lighter and makes more horse power than a BBC 396. That and it will fit in your ’64 Nova with out sawing the shock towers off to make room to get it in there. (read some of the stories posted on line by people who have done this in the past. None of them said they would ever do it again because of how the car handled and the amount of work to put one in compared to the enjoyment offered by a small block).

Going forward with the BBC you can find a running 454 for the price of a set of Aluminum heads. If you were to build one from scratch, and it was to be a street motor only, then a 496 would be the ideal motor for a street cruiser. Most people who race a big block consider a 750 horse 540 cid to be a small motor (I personally drive a 582 cid BBC on the street and it has 396 decals, and looks just like one). So you see once you go big block it’s best to go with a BIG big block from a competition point of view.


Big Dave

I vote for the small block in this car, also. The 400 or a 383 makes a GREAT engine for your car. A big block will be very problematic to install, though I have done several.
Also, the 396 is not my first choice for the street and the bigger the better with 496 the deal of the week.
Having said that, Hot Rod, Super Chevy and some other mags have done back to back tests on 400 BBvsSB and IN EVERY CASE, THE BIG BLOCK
W O N !! :thumbsup: even when used in the same car.;)

Why would a 396 be good for a heavier car like a chevelle than it would be for a 64 nova?:confused:

The Chevelle has more room under the hood, they came with a big block so all parts necessary are readily available, and the weight distribution will not be as upset. The extra torque doesn't hurt, either.

Why would a 396 be good for a heavier car like a chevelle than it would be for a 64 nova?:confused:

Big dave was refering to the Chevelle and Camaro guys building #'s cars. A 396 was not available in 1964 so the only reason to install it is power and bragging rights. Your going to loose any power gains over a simple 383 stroker due to the extra wieght. As for the bragging rights, you can claim you got a BBC under the hood, but a SBC guy is going to grin when he figures out he has more cubes than you do in his light sbc 400 engine. If you are going BBC your not going numbers so make sure you go cubes, 454 or more! If you just want something with some get up and go on the street go with a sbc 350, 355, 383, or 400 as these are proven packages that will produce a faster car with less dinaro!

I guess I will stay with the 355 that is in it for now until I can gather up the stuff to build a bigger cube BBC. Thanks for all the help.