After some 12 or so years of storage I've finally decided to pull my convertible out and start putting things back together.

Currently in parts I have 1971 chevelle conv. W/ fresh M21, 621 bellhousing, 11" flywheel, centerforce DF clutch. Fresh 12 bolt W/ 373.

I have a 71 pass. 402, all standard with the exception of heads being cut for bigger valves during a basic re-ring overhaul some 15 or so years ago.

Heads are oval, open chamber.

Being on somewhat of a budget I would like to put my money where best spent.

Plan on the basic to all engine performance upgrades, but specifically what do these engines like? How much will I be limited my these heads?

Car will be a weekend street warrior, few 1/4 mile runs, dunno?

Any advice appreciated, TIA, Kevin

Please do yourself a favor and put a roller cam in it. I am really tired of reading all the posts about wiped cams. I wiped a cam too, and since your building the motor from the ground up, it would be really easy to put a roller cam in. Its a bit more money, but more reliable and gives you some more Horsepower anyways!

The mans on a budget, and Rollers aren't cheap! I have had the same hydraulic cam in my car for 13,000 miles and many a 6K shift points. For a weekend worrier, I doubt he want to spin it very high, or build it to spin very high for that matter.

Dirtrocker,

The best advice I can give is to search for "396 or 402" motors in this forum, under Subject Only. Then you will see the many options unfold.

I think my setup is quite tame, yet performs very well. you can find it amongst the searching. Nothing too special thought, just basic upgrades. What these motors like is AIR. get the most in and the most out, and your ahead of the game.

With those heads you can have 400HP and 450TQ easy. I ran those same heads, with some bowl work (where intake runner meets the valve stem) and got to 105MPH in the 1/4 mile. That's between 400-450HP at the motor, easy.

Your stock crank and rods will do fine. I got ARP rod bolts for insurance. Stick with 10.3:1 CR or less. Keep the header primaries to 1 3/4" to a 3" collector. The rest of the details can be left seperate post. If you do replace a part, don't go the cheapest route! Too much motor/money at stake if an internal part lets go.

Like I said........poppin my cherry here :D Doubt I'll go with a roller setup unless I find a deal I can't pass up.

Already searched the archives.....read that these motors don't like big tube headers.

Heads are 3993820 castings........said to have larger valves cut in. Won't know what exactly has been done till I get it apart. I would imagine just a bit of blending?

Unsure in the piston department too.......been looking a bit. Don't want to HAVE to run race gas all the time. Detonation kills engines, what can I get by with? Thinking of playing with some thermal barrier coatings.........has anyone tried this with success?

Thanks again for any advice, Kevin

Hey Mike,

Went to your site and saw U had a bumpsteer kit installed. U running B-body brakes?

If you have 820 heads,you'll need pistons with a .319 dome to get decent compression (about 10.2)

Personally, i would build it with a dual-pattern solid flat tappet cam, let it rev up between 6000 and 6500 and have a little more torque down low compared to a hydraulic flat tappet (of equiv cam specs). I'd pocket port the heads, keep the actual intake runner volume to a minimum, and port the crap out of the exhaust side. If its in your budget, you could get some full roller rockers like Harland Sharps or Crane Golds, they free up some good horsepower. 2.5" exhaust max.

Originally posted by dirtrocker:
Hey Mike,

Went to your site and saw U had a bumpsteer kit installed. U running B-body brakes? No, net yet. The bump steer bars came at a very good deal, so I couldn't pass them up. I only have 3" of down travel, so I don't notice much difference at all in the steering.

My motor was my first motor build up, and it is a Big Block. You can do it, no problem. graemlins/thumbsup.gif

i agree with the .319 pistons, you will want compression to make power.

i have the isky cam, 240@050. pulls hard from 2500-6000 ish!

single plane (well, torker) and it is still pretty streetable, normal driving, i can keep it under 2500rpm and it drives very well.

Is there a "best bang for the buck" piston for this application. I see speed pro makes a set for around $375

well for what its worth..and keeping in mind the budget...the 402 bbc respond well to small tube headers....like the summit name brand headers for 80 bucks,a used intake dual plane of your choice, a nice 3310- carb that is a 750 vacuum secondary,hei that has been recurved,even a lower 9.0 to 1 compression is fine, split duration cam something in the 220/230 range @.050,and porting the heads.....just clean up all intake and exhaust runners of any casting flash and rough the intake runners completely with 80 grit sanding rolls and exhaust with 120 or finer grit.......blend and corners in the bowl area....along with a 3-angle valve job....


to give you an example

396 bored to 4.155
cheap $180.00 cast pistons small dome
closed chambered heads ported as described above that gave 8.8 to 1 compression.
284 crane cam 228@ .050 with .515 lift
eddy dual plane intake (performer)
750 holley vacuum secondary
open headers from summit
recurved hei 18 initial degrees 40 total
2500 stall th350 tranny
3.70 gears
3600 lbs car
ran 13.60's any time of the day at 103 mph on street tires

the 396 motor like to rev and running to 6500 rpms is not uncommon

i would recomend to run compression somewhere as you can afford between 9.0 to 10.3 so you can run pump gas with smaller cams (i have built them as high as 11.7 to 1 but used a big nasty cam ) , port the heads the best you can (this here alone was worth .3 e.t. reduction and almost 4 mph when i did this back to back test with no other changes) small tubed headers, 2.5" dual exhaust, 750 vacuum secondary carb, and dual plane intake, and cam in the range of 228/238 @ .050 with as much lift as you can get.......

i have built many 396 motors that range from 14's stock to high 10's on nitrous and they all have been on strict budgets and built with mostly used parts.......

my current 396 build has been somewhat of a challenge since im trying to get both performance, great idle quility, decent gas mileage, and a respectable top end speed, all with a 3900 lbs car that was carrying 2.41 gears but now i replaced with 2.73 gears so my shift point is more matched to my horspower band that i moved up.....instead of just a straight out performance car for the 1/4 mile.