396 Build Up

[VintageMusclecar]

Kurt;

With your vehicle weight and limited gearing, you're going to want to concentrate on low-end and mid-range torque, not higher rpm HP. You're looking at a usable power range of ~3000-6000 rpm. Anything much over that is going to be wasted here.

In that regards, you might want to consider shelving the rectangle port heads and going to a set of open chamber oval ports, such as the 049's or 781's. (A set of 820's might work as well, but you'll have to watch the dome-chamber fit). You're also going to have to keep the cam timing fairly conservative as well to keep the power range down where it's going to do you the most good. Again, a flat tappet will suffice at this level. (FWIW, look at how quick guys are running with the factory L78/LS6 143 cams, and they're only .520" lift and 242° @ .050)

A wide ratio trans will be a benefit as well here due to the additional torque multiplication. You're going to have to concentrate hard on covering the first 60' and 330' as quickly as possible as that's where your e.t. is going to come from.

Again, the weight and limited gearing are going to make things a bit more difficult, but if you concentrate on keeping the power range down where you can use it and spend a little time to refine the combination, you'll get there. Keep one key factor in mind throughout this--the car itself has to work...there is a lot of e.t. to be found with the hood closed.

And you're welcome, I'm glad to help however/whenever I can.

Eric

[69 Post Sedan]

One of the reasons I want to run rectangular port heads is they really don't start working until the rpm's get up there. So, I won't be frying the balonies out of the hole...just hooking up. By the time I get the real HP going I'll be moving.

I know that there are guys out there running the 198 intakes to keep the power down out of the hole just for that reason.

That's how I ran my 427 Nova that I built and it worked wonderful, even with P215/70R14. I never got a chance to take it to the strip to see how quick it was...I sold it but here is video of my Nova from a while ago when it had a tired 69 396 325HP, M20 with 3.73 gears.

https://www.youtube.com/watch?v=B4hJS...feature=digest

BTW I ran a 13.93@100mph with the air cleaner off. Earlier I ran a 14.08 and a 14.06 with the air cleaner on. That was my first time ever at the track. And the brake lights were coming on every time I pushed in the clutch.

[VintageMusclecar]

Read this. This is what a well-thought-out relatively mild oval port 396/402 can do in a 3600 lb A body.

The 7.10 e.t roughly translates to 11.20's or thereabouts. Granted this is a dedicated bracket car, but that also goes to show how important the overall combination (i.e. "the <u>car</u>") is set up.

As far as trying to soften the hit off the line, that's only going to make your 11 second goal that much more difficult.

E.T. comes from covering the first 60' and 330' as quickly as possible, and what you give up in short times you can not make up down track (at a given HP level).

There's a thousand ways to skin a cat. Some are far more effective than others.

[Chevy454]

[ QUOTE ]
Originally posted by: 69 Post Sedan

One of the reasons I want to run rectangular port heads is they really don't start working until the rpm's get up there. So, I won't be frying the balonies out of the hole...just hooking up. By the time I get the real HP going I'll be moving.

[/ QUOTE ]
Wishful thinking, believe me...our class [and especially the FAST class above us] is the masters of killing bottom end power and moving elsewhere, and those huge ports still make enough grunt down to make things interesting to the 330' mark (and beyond, sometimes!)...

Listen to Eric, he's giving you great advice...with decent tires &amp; hook this should be a no brainer.

[markjohnson]

That's an interesting link that Eric posted and I'd love to see what the 454-468 version would be capable of! I know that it's the correct sum of parts that gets you down the Dragstrip faster than the next guy but if I had to pick one the "magic" part in that comination, it would have to be that Comp Cams XR274R Solid Roller. I've actually had my eye on that very camshaft for an upcoming project and it looks very promising. I've built and owned MANY Big Block Chevys and I've had 9.00 Comp. Pump Gas/Oval Port/Solid Roller motors that would just flat out embarass my 12.5 Comp. Race Gas/Rectangle Port/Solid Flat Tappet Motors. I had the good fortune to talk BBC's with John Lingenfelter quite a bit in the back in the Nineties and he's the reason I'm sold on Oval Ports for applications under 496 CID and .650 Lift camshafts. Your 396 CID would be very happy with a set set of oval port heads with the big 2.19/1.88 valves fitted to them with some nice bowl port work and a Performer RPM Intake Manifold. Don't worry about trying to kill of low-end power with those giant Rectangular ports on such a small CID engine. Make all the power you can.....and then worry about getting it to hook. That's the fun part!

[VintageMusclecar]

There was a fairly well-known poster over on the TC forums years ago who had an exceptionally well scienced-out `68 Chevelle with an oval port 468 in it. (I'm not going to mention any names, and for those who know whom I'm referring to, please follow suit)

The 468 used prepped oval port closed chamber heads, ~11-1 compression, several different roller cams along the way, an Edelbrock Perf. RPM and a ProSystems prepped Holley backed by a TH400 and a 4.10 gear. The car reportedly weighed in over 3800 lbs and regularly ran well into the low 10 second range with 60' times consistently in the 1.30's.

Again...lots of ways to skin a cat, but e.t. is in the short times.

[Xplantdad]

Eric, I think I remember the guy you were talking about. He always had a picture of his Chevelle with the front way up in the air...

[SuperNovaSS]

Isn't there a member here who has a Blue 69 Chevelle with a similar setup? I remember a thread where he was thinking about returning it to L78 specs?


Jason

[68427imp]

Don't mean to hijack this thread,but I have a '65 Impala SS with a 468 with 781 heads(no port work),2.19/1.88 valves,Comp Magnum 292 cam(.550 lift,244 duration@050),Edelbrock Performer RPM intake,9.5 to 1 forged pistons,out-of-the-box Holley vac.750,1.7 ratio roller rockers and 2" headers.Anybody know how much h.p. and torque this combo makes? Eric? Jim

[JLerum]

Bob West has the 9.98 wheel standing 71 chevelle. It's 505 cubes. oops!!!! I gave it away...!

Jim