BBC advice - Chevelle Tech
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post #1 of 13 (permalink) Old Dec 1st, 19, 12:12 PM Thread Starter
Tom
 
Join Date: Dec 2019
Location: Upstate NY
Posts: 6
BBC advice

At little history first.
Many years ago(38 to be exact) I built an L88 from parts minus the intake and block for my 68 Camaro. The car had a modded L78 in it at the time. Due to an accident and the unavailability of parts, the car was never put back together and the L78 was sold. The L88 Was parked in the corner of the garage to never be run.
I am now involved in putting the car back together as I can pretty much purchase any part I need.
I decided the L88 was Not feasible to use on the street with its 12.5 comp.
I decided to put a stroker crank in it and make it a 482 and lower the compression.

I would like opinions from BBC guys if something needs to be changed/altered.
Trans M21 Muncie
3.73 12 Bolt rear
4 bolt block 4.250 bore
4.250 forged crank-internal balance
6.385 rods with Icon forged 10-1 pistons
GM 074 open chamber rect port/rd port heads. 114cc polished chambers. Voodoo roller rockers

Holley strip dominator intake with Brawler 950 mech sec. Carb.
Comp cams 11-219-4 Solid FT .
MSD Mech adv dist and MSD 6AL Box
2"headers/3.5 collectors and Pypes X 2.5 system with Race mufflers.
Want to use pump gas.

Is this cam suitable or should I send it back for exchange? What should be my redline?
I know the new heads make more power,but I want to retain some of the old parts.
The car is just something to fool with on the street.No racing use.
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post #2 of 13 (permalink) Old Dec 1st, 19, 11:43 PM
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Tom Terrific II
 
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Re: BBC advice

I built an engine just like that a couple years ago. it idled OK, was on a 71 Vette that was like a museum piece, Thing ran pretty hard, had massive mid-range Tq.

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post #3 of 13 (permalink) Old Dec 2nd, 19, 12:42 AM
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Dan
 
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Re: BBC advice

Quote:
Originally Posted by 68RS/SS View Post
At little history first.
Many years ago(38 to be exact) I built an L88 from parts minus the intake and block for my 68 Camaro. The car had a modded L78 in it at the time. Due to an accident and the unavailability of parts, the car was never put back together and the L78 was sold. The L88 Was parked in the corner of the garage to never be run.
I am now involved in putting the car back together as I can pretty much purchase any part I need.
I decided the L88 was Not feasible to use on the street with its 12.5 comp.
I decided to put a stroker crank in it and make it a 482 and lower the compression.

I would like opinions from BBC guys if something needs to be changed/altered.
Trans M21 Muncie
3.73 12 Bolt rear
4 bolt block 4.250 bore
4.250 forged crank-internal balance
6.385 rods with Icon forged 10-1 pistons
GM 074 open chamber rect port/rd port heads. 114cc polished chambers. Voodoo roller rockers

Holley strip dominator intake with Brawler 950 mech sec. Carb.
Comp cams 11-219-4 Solid FT .
MSD Mech adv dist and MSD 6AL Box
2"headers/3.5 collectors and Pypes X 2.5 system with Race mufflers.
Want to use pump gas.

Is this cam suitable or should I send it back for exchange? What should be my redline?
I know the new heads make more power,but I want to retain some of the old parts.
The car is just something to fool with on the street.No racing use.
You're apt to kill that Muncie.
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post #4 of 13 (permalink) Old Dec 2nd, 19, 9:12 AM
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Bob
 
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Location: Pa
Posts: 1,324
I'd look for an L78 intake or an edelbrock air gap manifold myself and prob a comp 11-551-5
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post #5 of 13 (permalink) Old Dec 2nd, 19, 9:40 AM
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Eric
 
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Re: BBC advice

That combination should make 575/575+ all day long and be done by ~6K or so. And Dan is right, the Muncie won't be long for this world behind that, esp. if the car hooks.

Two things I would change (from personal dyno experience on a very similar combination):

-Go down to a 3" collector, but stay with 2" primaries. A 3" exhaust probably wouldn't hurt.

-Shelf the Strip Dominator and run a good dual plane such as a Performer RPM, Weiand Stealth or even an OEM 163. Removing the plenum divider on the 163 will trade some power downstairs for better high RPM power.

-You'll need a good oil pan with the 4.25" crank for windage control.

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post #6 of 13 (permalink) Old Dec 2nd, 19, 12:29 PM
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Gene
 
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Location: Buffalo NY
Posts: 14,415
Re: BBC advice

The cam is fine for a mid range TQ monster, could even drop it a bit in duration, but it ought peak near 6000. I personally would have run the 7118 crank, those sexy azz L88 rods with the boron bolts ( I swapped to ARP) flycut the domes off those heavy TRWs to get 10:1 and run a nice split duration solid cam to rpm the thing. But who wants a 427!

Windage is as important for a 7000 rpm 3.76" stroke, as it is at 4000 rpm, for a 4.25" stroke, so pay close attention to windage control with those big throws. It'll rob GOBS of power at rpm.

Not for nothing, but the old Chevelle ran [email protected] 118.75 with the old L88 done up that way. 12.24 as it's a clutch car with no gear ( 3.31). Ultradyne SFT 243/[email protected] .050, 153/[email protected]", .600" 110 LSA, 074s, 163 mani with Holley 850 atop. Monster power in a 427! Garage built to boot.. and had the choppy L88 idle.

The Strip Dominator dont dominate a friggin' thing. I reckon even an oem 163 would be better. And look all OEM and such to boot! Again, the cam is good for a mid range 481. Heads are a might big for that, but they are good small rectal heads. ALSO, I found mine moved lash 6 thou from cold/hot. Dont assume . Check it.

PS, if you havent replaced the factory rocker studs on those 074s, you need to run extended length ARP studs. Else you may blow a whole exhaust rocker boss off the head if you accidentally float the valves at 7500 rpm. Also, you'll need really, really good headers bolts/locks, as those old alum heads grow/shrink due to thermal like you cannot believe. Mine used to "spit" headers bolts out on the highway. BTDT!

I have ONE #6768 GM head gasket left, which were specifically designed to put their alloy L88 heads on iron blocks. All I ever used. You will need to retorque with those heads.

Gene
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post #7 of 13 (permalink) Old Dec 2nd, 19, 1:13 PM
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Re: BBC advice

Quote:
Originally Posted by 68RS/SS View Post
Holley strip dominator intake with Brawler 950 mech sec. Carb.
Comp cams 11-219-4 Solid FT .
MSD Mech adv dist and MSD 6AL Box
2"headers/3.5 collectors and Pypes X 2.5 system with Race mufflers.
Want to use pump gas.


Is this cam suitable or should I send it back for exchange? What should be my redline?
I know the new heads make more power,but I want to retain some of the old parts.
The car is just something to fool with on the street.No racing use.
Quote:
Originally Posted by Vintage Musclecar View Post
That combination should make 575/575+ all day long and be done by ~6K or so. And Dan is right, the Muncie won't be long for this world behind that, esp. if the car hooks.

Two things I would change (from personal dyno experience on a very similar combination):

-Go down to a 3" collector, but stay with 2" primaries. A 3" exhaust probably wouldn't hurt.

-Shelf the Strip Dominator and run a good dual plane such as a Performer RPM, Weiand Stealth or even an OEM 163. Removing the plenum divider on the 163 will trade some power downstairs for better high RPM power.

-You'll need a good oil pan with the 4.25" crank for windage control.
From what I've seen & read the 3' makes more power than a 2.5 so go to a 3" X and exhaust pipes and ad the Performer RPM either one, Air gap or not.They're basically both the same intake AFAIK.But I also like the idea of the OEM 163 intake cause that's what would probably come on the L88 from the factory.(or one just like it with a different #)

John
71 El Camino SS
406 SBC M21 3.31 12 bolt
"Quality is always remembered,long after the price is forgotten"
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post #8 of 13 (permalink) Old Dec 2nd, 19, 1:22 PM
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Rick
 
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Location: Michigan
Posts: 1,453
Re: BBC advice

Suggestions about the M21 are correct unless you use non sticky street tires. If your goal is good traction from a stop you will tare first gear out of it where first gear and the main shaft intersect. Ask me how I know, did this 3-4 times behind a similar 427/440cid.


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post #9 of 13 (permalink) Old Dec 2nd, 19, 4:22 PM
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Posts: 542
Re: BBC advice

Most BBC Strip Dominator intakes are terrible out of the box. After you port the plenum area they come alive. The one I sold to my friend made 25hp (ported) more than than the stock one did (tested both on the dyno) and he ended up with 571 with peanut port heads. If you extend the runners there is more torque to be had also. Most intakes work ok out of the box but a little finessing really helps them out.
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post #10 of 13 (permalink) Old Dec 2nd, 19, 5:26 PM
Tech Team
 
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Re: BBC advice

An M23 will hold more power if you want to run a manual

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post #11 of 13 (permalink) Old Dec 2nd, 19, 9:53 PM
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Pete
 
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Re: BBC advice

Quote:
Originally Posted by 68RS/SS View Post
At little history first.
Many years ago(38 to be exact) I built an L88 from parts minus the intake and block for my 68 Camaro. The car had a modded L78 in it at the time. Due to an accident and the unavailability of parts, the car was never put back together and the L78 was sold. The L88 Was parked in the corner of the garage to never be run.
I am now involved in putting the car back together as I can pretty much purchase any part I need.
I decided the L88 was Not feasible to use on the street with its 12.5 comp.
I decided to put a stroker crank in it and make it a 482 and lower the compression.

I would like opinions from BBC guys if something needs to be changed/altered.
Trans M21 Muncie
3.73 12 Bolt rear
4 bolt block 4.250 bore
4.250 forged crank-internal balance
6.385 rods with Icon forged 10-1 pistons
GM 074 open chamber rect port/rd port heads. 114cc polished chambers. Voodoo roller rockers

Holley strip dominator intake with Brawler 950 mech sec. Carb.
Comp cams 11-219-4 Solid FT .
MSD Mech adv dist and MSD 6AL Box
2"headers/3.5 collectors and Pypes X 2.5 system with Race mufflers.
Want to use pump gas.

Is this cam suitable or should I send it back for exchange? What should be my redline?
I know the new heads make more power,but I want to retain some of the old parts.
The car is just something to fool with on the street.No racing use.

Built a similar combination several years ago for a customer as an upgrade to his 454. Basically a crank, rod and piston change on a 460 setup that had gone 11:80's or so in a 3800lb Chevelle with 4.11s on a 29.5".

850 DP Holley, Holley Strip Dom with plenum lip blending and dividers extended about 1", 781 ovals with 2.19/1.88 and basic blend with valve job, 10:1 CR, Comp 306S cam, 260/260 @ .050", 110LSA, 2" x 3.5" Hooker SC Corvette headers, 3" mandrel bent exhaust with Dynomax Super Turbos, M-21, 3.70, 255/60-15 MT Drag Radial, in a '69 Corvette. 3450lbs, went [email protected] mph on pump gas pretty easy.

It idled pretty nice, drove really well, massive amount of torque for what is was. His biggest complaint was that it bucked a bit if he tried lugging it under 1600 rpm.

https://youtu.be/chOEexr2wGU
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post #12 of 13 (permalink) Old Dec 2nd, 19, 10:27 PM
Dennis
 
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Re: BBC advice

If your just building it for the street omit the Strip Dominator. RPM range where it makes power is 4500-7600. Put an intake on there that works with your cams power range. Been there and done that!!!

Too soon old and too late smart!!!
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post #13 of 13 (permalink) Unread Today, 1:57 PM
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Re: BBC advice

Do a little cleaning to the edges of the strip dominator and you will be fine. Mine works as well down low as a dual plane intake and i think it make more power when i rev it up. And it is more period correct to match the heads. With some very mild work they can run very strong. I have one on my 427 and it works very well.

RH
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