66427-450

Since many of you guys have a lot of experience with BB build ups, I thought I'd ask for a sanity check.............


Use = general/all round, hi performance (66 coupe)

Key items.....
468 CID, 4 bolt block, with arp main studs
scat crank and rods, forged trw pistons
Merlin/Grumpy CI heads, 310cc, 2.30/1.88
Comp Cam 294S .595", 248@.05
true 10.2:1 static compression (may try 10.5)
427/425 intake, top 1" of plenum wall removed
850 DP holley (start with 82's all round)
headers??? (trying to come up with something that will flow, and fit under my sidepipe covers)
3.70's, 2.54 first
new Be Cool alum radiator, while i'm at it (w/160 thermostat)

Thanks ! :seeya


[Modified by 66427-450, 6:27 PM 10/25/2002]

427Hotrod

I love everything about it almost.

That cam is pretty good, but there a couple of others I'd seriously look at.

The Comp 11-604-5 is a stronger piece. Still rated at 294 adv., but is a much more aggressive lobe and .050 duration is more. It's .579/.605 lift on 110 LSA.

Better still is the Crane134691. It's .580/.600 also on 110 LSA. VERY strong cam and still streetable. Adv. as 290/300 duration, but also a more aggressive cam with .050 numbers in the 250 something range.

The next harier one is the Crane 134761. It's a .600/.620 one and I swear it NEVER seems to stop pulling. Adv. as 310/320 on duration.

Sorry. I don't remember the exact specs of these three cams, but take a look at them. I've run them all. All will run DEEP 11's easily or better in a 3500 lb car on pump gas.

Your head choice will make lots of power, but be aware, they will not "come alive" until the 5000 rpm range on a 468. They are great heads, but beg to be driven in the 6500-7000+ range. Your 3.70 gearing won't allow that for a drag strip run. You won't be high enough rpm wise at the end to take full advantage of them.

If you want to make the power those heads can make, you gotta spin it high. If you intend to stay in the 5500-6500 range max, don't be afraid of a good set of aftermarket oval ports. Merlins, Darts or Brodix. You might be happier with your gearing.


Either way, you're planning a handful!!

JIM

69 N.O.X. RATT

I agree with Jim. That is a pretty big set of heads for a 3.70 geared 468. The heads Jim listed are great. I would also look at the Chevy Ovals, they have the highest flow numbers of any of the oval ports, plus they only cost a little more than 1600.00 a set. The Chevy heads with a bigger cam than what you listed would make a lot of torque and good top end power. It would be a very good street engine.

A solid roller would be even better :chevy

66427-450

Thanks for the feedback guys, I really mean it

I'm just trying to understand.........

I checked on those bigger cams:

The CompCam 11-604-5 is listed at 108 LSA..... you think i could get away with that? with the 3:70s? I have been thinking about 4:11s, I ran them before....

And the 2 Cranes you mentioned..... they recommend 11.5-12.5:1 compression, does that mean with my 10.5 or so, the bottom end (~3000 revs) will be "deader" than if i had 12:1? I mean, big cams bleed off pressure at low rpm's, yes?..... so there'd be even less left down there, since i'm starting out lower.

Also, do you think i'd be ok with std jetting (with 1" off plenum divider)?, or will i need to worry about stagger jetting? any experience with that? I know if the plenum is completly out (like the L-88's) I'd need tabs, and stagger jetting.

Concerning the oval heads, I understand your point.... but seems like a sin; 427/big rect => 468/ovals????? I'll leave the rev limiter set at 6500.

Again, thanks for the insight Guys ! :seeya


[Modified by 66427-450, 10:42 PM 10/25/2002]

69 N.O.X. RATT

Do not discount Ovals, Jim ran 11.20's with Oval heads in a 427. I have not run mine yet but made 450 rwhp and 470 rwt with stock Edelbrock Ovals and a dual plane intake through full exhaust in a 454 +.030 (solid roller .646 .653 242 and 248 at .050). I pulled a full car length (full on 2nd to 3rd gear charge till I hit the rev limiter) on a buddies 496 Indy head and intake wedge motor that went 123 in a 1/4. 71 Challenger

The 108 will be fine if you do not have power brakes (without a vacuum tank) The power brakes may still work, but not for sure The bigger cam will be softer in the low end than the smaller cams. They will be fine for cruising around, then when you want the power it will be there.

sinistervette

Here's some food for thought. I built a 468 for a guy last winter very much like your plan;

GM steel crank
7/16" "dimple" rods with arp bolts
Dart pro-1 alum. heads 119cc chamber-325cc runner-2.30"I/1.88"E valves
Isky Z-33 grind .560lift-250*dur @ .050-108 lobe centers(solid flat tappet)
Edelbrock Victor jr
1050 dominator

This engine dyno'd 586 hp@7100 rpm 558.7tq@5100.
It is in a 68 camaro convertable, B/W super T-10 4spd, dana 60 4.11 rear, hoosier 10.5X28.5X15 quick time tires. Car weighs 3712 with driver.
It was a challenge to tune this thing, and had best 1/4 times with 80 pri. jet, 4.5 hi flow powervalve, 88 sec. jets.Shifting at 7000rpm. Best et 11.06@124.6mph. The car did not 60' very well, I believe it was 1.7something. I had all along told him for street/strip to avoid the huge ports and the "damn"inator carb, but he way paying for it , so I built what he wanted. After talking to many BB builders(best advice I feel came from the guys at REHER-MORRISON) and playing around with my own 454 BB's, I talked him into letting me remove the Victor JR and "damn"inator, I replaced them with a Holley Strip Dominator OVAL PORT INTAKE and 850dp(modified-flowing 930cfm)! YES OVAL PORT INTAKE! I had mildly ported just 1" into the runners to enlarge them closer to the rectangular ports shape that is it. As soon as we fried it up, it was noticeably different. It idled much better and throttle response was incredible. It used to idle with 6-6.5" vacuum, now idled at 8". After some minor carb adjustments, we were off to the track, fisrt pass 10.96@123.0mph 1.64 60'. Car needed more jet. After a days worth of tuning his camaro ran a best ever 10.36@133.8mph and a 1.56 60'! now shifting at 6800rpm. Hopefully this winter he is going to pull it and run it on the same dyno again to see what he now has. I would suggest going to an aluminum oval port, I'm running a set of Edelbrock performer rpm 454-O oval ports(290cc flow 300cfm@.700 289cfm@.600) gasket matched to a Edelbrock performer rpm(dual plane) intake and a 850dp(modified-flowing 890cfm), on my own 454 with a CC X-energy #11-246-3 hydraulic flat tappet cam .552I/.555E lift-230*I/236*E dur@.050, 11-1 compression, cast crank, and it dynos 515.2hp@5700rpm 554.8tq@4100rpm. This motor has 500+tq from 2700rpm up to 5400rpm. It has incredible throttle response and is very streetable. Just a suggestion, but with the way the modern day oval ports flow(high velosity/high cfm) for smaller cc runner size, they will make serious hp and tq and will still be very streetable. Good luck with your build, it is going to be strong. :cheers:

66427-450

OK so potential changes (i'm now considering) are:

Just a bit more cam = CompCam 11-604-5 -- 108LSA, 580/605 256/260@50. (And no, I don't have power brakes, or power steering, or air, and have NO plans to add anything like that... or white walls, or curb feelers... LOL)

More Carb = ???? I do have a 1000 CFM Race Demon GC, as well as the 850 Holley DP, but I'm think'n the 850 for this engine (now, if it was a 541 or bigger...)

Heads = Sorry Bro's, I just gotta stick with the 310cc Merlins :) But I understand what you are saying (maybe I'll change to 4:11's again later)





[Modified by 66427-450, 10:15 AM 10/26/2002]

sinistervette

Cam will wake it up considerably.

Start with the 850dp carb, it will give you better throttle response with the merlins. If it is modified it should provide enough up top also.

Merlins, they are a great head, just tend to give up a little bit below 4500rpm. If you put this combo together and you do not have the drivability, throttle response, and low enough useable rpm, consider using an oval port intake manifold. This will greatly improve the throttle response and will not give you an noticeable top rpm losses either. I know it doesn't seem right, but using the oval port intake manifold will increase velosity due to the smaller int. man. runner, therefore creating a much more responsive and driveable motor. Just an idea, something you could try if you want. Good luck, and put some money aside for tires! :D :cheers:

Glenn454

66427-450, I'm looking at building a new 468 short block and using a mechanical flat tappet cam. A couple of cam grinds I'm looking at are Ultradyne's 625/625 259-267@50 110, 3000-6800
or 612/630 255/263@50 3000-6000. I'm looking to make 625-650 horse power. I'll probably have to run about 11.5 compression, single plane intake,1000 hp carb.
The 460 that I have now has a comp/hydr R 236/242@.50,521/540 110.
Ported ovals,10.2comp,830hp holley,Performer RPM intake. Makes good power 430RWH/466RWT. But I want 500+RWH. :)

66427-450

Thanks for the info Glenn...... Are you going to bigger heads?

Oh, and if you need a big carb, I have a 1000 CFM Race Demon GC, in like new condition (only used on a couple dyno runs).

Glenn454

I'm going to use the ovals I have now. I had a lot of work done to them.
Proflow 2.25 intakes/1.88 exhaust valves,bowl blended,gasket matched,exhaust completely ported.
So they should flow pretty good. I'm really just wanting to swap blocks (I'm running the original matching number block) and do a few up grades.
Have you used the 1000 race demon on your car?
What would you like to get for the carb?

66427-450

check your mail Glenn

427Hotrod

You're right... I had a little brain fade. The Comp is on 108 LSA.

It was the last flat tappet I had in my 427 before I went roller. I swear I literally went through 20+ cams over the 20+ years I ran that motor. Some worked well, some not so well.

That Comp is good, but for my money, the two Cranes run better. They are actually a pretty old design, but don't let that fool you. They work great.

Depending on the heads I was using at the time, I had compression from 9.8 to 12.0 in it. And I ran everything from rectangular port closed and open chambers, to the same in oval ports and even some of the "inbetween" "semi-open" chamber ones.

The cams I listed worked fine with the 9.8-10.6 combos regardless of heads. The last Crane does need some gear to make it work well, but a buddy of mine runs that same cam ( I gave it to him) in a pretty mild 396 Nova and it flat flies on the top end.

The 310 cc heads will work. My Merlins were heavily ported and flowed 324 cfm. But as everyone is saying, ovals can work well. I have another buddy with a home built pump gas 502 in a Camaro. The car runs 10.30's at 131 on pump gas and 3.73 gears and 2500 converter. It has a set of GM iron ovals that have been heavily worked, but they do run!

Keep checking around and asking for real world experiences from folks running these deals.


JIM