[chiphead]

My 400 refresh is coming together and I wanted to get y'alls opinions on it.

'67 400 block 4.155 bore, 3.75 stroke
Ross dished pistons, 9.3 compression
Total Seal AP ring set. stainless top, Napier 2nd, std tension oil ring.
6.8 BBC rods
670 heads ported 236/185, HR springs 160seat/370 open
KRE hyd roller, 224/230/112 520 lift.
RPM, Q-jet, 150 shot of nitrous
Butler M54DS custom pump
Milodon pan/tray
zero deck, line honed

3700 LeMans, 10" continential, 3.23 street or 3.90s strip.

[steve25]

It all sounds good, but for the pick of a Intake Manifold, as I would go with a rpm for the 3.23 gears , or a T2 with the 3.90s out back!

[chiphead]

I'm really debating the intake choice. I love the RPM, but there are so many good intakes out there now. I'm also running a Q-jet and spreadbore nitrous plate so that constrains intake choices somewhat. I'd have to change carb/spraybar horses to go squarebore intakes...

At what HP level of nitrous do I need to go from a dual-plane to a single plane intake? And what is the best spreadbore single-plane? It may be that I have to stay under a level of nitrous so I don't have to swap intakes. I'd hate to go single-plane and not be able to run a freeway gear. Those 3.90s get old on the street!

[steve25]

You need to make a decision that will enhance the greatest % of the type of driving you will be doing with the car!

[slowbird]

As someone who has built a 400, the RPM intake is a good pick with either gear.

[Tom Vaught]

Originally Posted by slowbird

As someone who has built a 400, the RPM intake is a good pick with either gear.

x2

Tom V.

[gtofreek]

In a recent 400 build I just did, the RPM intake with 670 heads, Q-jet, points distributor, and a VooDoo HR cam, made over 500 Ft. Lbs. from 2800-4200 RPM. Peaked at 525 Ft. Lbs. and 460 HP. Made a little more HP with a stock Iron intake, but less torque. It averaged 492 Ft. Lbs. from 2700-5500 RPM with the RPM intake. Made over 500 HP with a Victor intake and Holley.

[steve25]

Interesting info Paul!
From those HP numbers it would seem that with both the rpm and stock Intake each cylinder was able to access 223 cfm@28", and the Victor gave access to 243 cfm out of what the 670 heads flowed.
It would have been nice to see what a Edelbrock T2 or the like would have done!

[69FIREBIRD76MM]

Gtofreak, that's a nice 400, what size of holley carb and was that victor jr. Ported or out of the box?

[slowbird]

Originally Posted by gtofreek

In a recent 400 build I just did, the RPM intake with 670 heads, Q-jet, points distributor, and a VooDoo HR cam, made over 500 Ft. Lbs. from 2800-4200 RPM. Peaked at 525 Ft. Lbs. and 460 HP. Made a little more HP with a stock Iron intake, but less torque. It averaged 492 Ft. Lbs. from 2700-5500 RPM with the RPM intake. Made over 500 HP with a Victor intake and Holley.

And which intake will et/mph better at the track?

[HWYSTR455]

I say that 224/230 cam is too small. By about 10 degrees IMO. I'd be surprised if it made 375hp, even with the long rod. H-O through theory deemed the .060 over 400 with a 6.80 rod the best drag combo for a Pontiac engine, FYI. Check out the reasoning in their' design & blueprint book.

One advantage of the long rod with a 3.75 stroke is RPM, should be able to go past 7k with no problem. That cam is going to give up before you can take advantage of the combo/RPM.

3700 lbs is going to want some gear, and stall too, on top of the stroke wanting it. The 390s are good, maybe leave them, and save for an OD trans?

Current cam is good for the 323s though.

I sprayed an RPM intake with as much as 250, maybe more (can't recall at the moment), no issues. That was with a Holley though, not sure how much diff that makes, but felt it was worth mentioning. I've heard the argument of distribution on a dual plan with spray, but think the tech is much better these days, when it comes to spray bars, patterns, etc.

Last setup I had was an NX plate, perimeter spray, that certainly could care less if it's a dual or single plane. One before was a NOS spray bar, that one I ran on both (single and dual plane), and ended up keeping the RPM on it.

What are your ring gaps?

.

[slowbird]

It should make more than 375hp with that cam with no trouble.

[gtofreek]

Originally Posted by 69FIREBIRD76MM

Gtofreak, that's a nice 400, what size of holley carb and was that victor jr. Ported or out of the box?

The Victor was ask cast, no porting. The Holley was 750 HP that Jeff Koerner, the guy I work with, custom built for a Pontiac 400. It now flows 999 CFM. Engine made 505 HP @ 5900 RPM with that on, and 32° of timing.

The RPM intake made 460 HP @ 5400, while the stock, unported iron intake made 470 HP., @ 5400, then nose dived. The ported iron intake made 479 HP., @ 5400, and carried it out to 5900.

The iron intake made 504 FT. Lbs. peak, and only made over 500 at 2800-2900, and again from 4100-4300 RPM. The RPM made 20 more ft. lbs. and had an average torque of 492 from 2700-5500, while the iron intake averaged 487 from 2700-5500 RPM.

[gtofreek]

Originally Posted by slowbird

And which intake will et/mph better at the track?

That's a tough call. I would tend to think the RPM would based off the higher torque used to get it off the line, but the iron intake pulled harder on the top end, so that may make up for it. I don't have a lot of personal drag racing experience, so it's hard for me to say for sure. I think the RPM would make a better street intake for a heavy car.

[chiphead]

I'm wanting a car that I can get in and drive 55-75 without revving the snot out of the engine. It'd be great to drive it to work without my head ringing. It would be awesome to take it the 200 miles to the magnum opus hotrod drive-in movie freakout that is drive-invasion Atlanta without getting tired of the engine's war cry and burning entire epochs of dinosaurs.

That's why I chose the 224/230, I'm thinking that's the biggest shelf cam I can run and still get good manners with a highway gear and tall tires.

The secret sauce here is the Ford 9 rear. I can change pumpkins in a few hours, and vi-ola, 3.90s and 26" tall drag radials on nitrous. What's not to love?

The lunati cam that Paul dynod was 231/239. It made about 12" of vacuum at 900 RPM. That's with 10:1 compression that I don't have. So I went a little more conservative on the cam, for the street manners. I'd be super happy with 425 HP on motor and 600 on spray. Does this sound reasonable?

[Blued and Painted]

I like the cam pic for the daily driver and the 670's. I still should run circles around most hydraulic flat tappers.
Its the exhaust components that will give you the tinnitus.

[BruceWilkie]

Originally Posted by Blued and Painted

I like the cam pic for the daily driver and the 670's. I still should run circles around most hydraulic flat tappers.
Its the exhaust components that will give you the tinnitus.

X2 Full tailpipes and 4.10 gear with 275/60-15 tire isnt all that bad at 55-70 mph. exit at the axle and its quite annoying.

[HWYSTR455]

Originally Posted by chiphead

I'm wanting a car that I can get in and drive 55-75 without revving the snot out of the engine. It'd be great to drive it to work without my head ringing. It would be awesome to take it the 200 miles to the magnum opus hotrod drive-in movie freakout that is drive-invasion Atlanta without getting tired of the engine's war cry and burning entire epochs of dinosaurs.

That's why I chose the 224/230, I'm thinking that's the biggest shelf cam I can run and still get good manners with a highway gear and tall tires.

The secret sauce here is the Ford 9 rear. I can change pumpkins in a few hours, and vi-ola, 3.90s and 26" tall drag radials on nitrous. What's not to love?

The lunati cam that Paul dynod was 231/239. It made about 12" of vacuum at 900 RPM. That's with 10:1 compression that I don't have. So I went a little more conservative on the cam, for the street manners. I'd be super happy with 425 HP on motor and 600 on spray. Does this sound reasonable?

Yeah, I get it, and it does make sense. That's the same general profile I tossed in the 442, a Crane grind, it has 342s in it, RPM intake, and highway @ 60-65, it's at about 3k RPM. Tolerable. But I'm still going to an OD trans in it. It's pretty tame in an O 350, but pulls and performs good, and easy to tune. Once it goes over like 55-60 mph, the mpg drops off sharply. The loss in the 65-70 mph range is like half of the 50-55 mph range. Just to give you an idea. If you can keep it down to a lower speed, you can save a lot, but with everyone passing you, it gets more difficult than it seems.

It's nice to be able to swap pumpkins, but if it's just a trip to the track and back, same day, it's a bit of a pain. I have friends that go to the beach and swap while they're there for the week, swap and drive back. Even that's a bit of a pain, and many find themselves leaving the big gear in and driving back. Maybe a hangover effect, not sure. It certainly is nice to have the option though.

I could be off on the prediction, was going off similar grinds, and comparing to something like a RAIV. The long rod may make up the difference though.

How much you spray is going to be dependent on the ring gaps, which is why I asked. If you're over a 150 shot, based on that bore, you should be about .031 on the top, .027 on the second. You can get a little tighter on it the closer you are to 150 if you're careful, but it would be at your own risk. There's a formula for gaps, it's bore size x something like .0075/.0065, baseline. But guessing you're aware of that.

I think feedback from your build is going to allow others to make good decisions, think it's a great baseline. I'm looking forward to your results, and think the info will be valuable.

.

[tom s]

a long rod will be virtually no HP increase.Tom

[HWYSTR455]

Originally Posted by tom s

a long rod will be virtually no HP increase.Tom

Yeah, wasn't sure actually, if the rod angle would free some up or not. My 1st thoughts were based on a higher RPM potential.

Was hoping to dig up my H-O bible, refresh my memory, but can't seem to locate it at the moment.

.