[bullen!]

spec on my engine:

Block: 402 ci .030

pistons: Keith Black Silvolite hypertectic med 4.5 mm dome (.180")

Kam: Lunati Voodoo, intake lift .515, dur 213, out lift .530, dur 219 1000-5500 rpm

heads: 820 ovalport, matchported , 113 cc , 255/114 komp 9.4-1

intake mainfold: Edelbrock Performer 2,0 1000-5500 rpm, matchported to heads

distributor: accel HEI super coil

carburator: Holley 750 vaccum


headers/exh: 1,5/8?? and 2,5" crosspipe.

sorry. but its all spec i´ve got at the moment. some say it´s 350-400hp is that possible? it´s very well tuned in and runs perfect. will test it at 1/4 and 1/8 this summer.

 

[Tom Mobley]

seems like it ought to do 350 OK, 400 might be stretching it a little, the cam is on the small side.

Measure the header tubes, should be at least 1,750.

 

[onovakind67]

The 1-5/8" headers should be good for well over 500 horses.

 

[SWHEATON]

Thats a very mild cam thats not much more then the stock 396/350hp came with but with your motor setup with headers i would think it would be approx 365hp-370hp/430-440 lbs trq + - a few hp/lbs trq but not 400hp MHO,need more cam for that unless maybe you'r running professionally ported heads.

Scott

 

[Belair]

Here's my numbers for your comparison.
402 c.i.
10.5 compression
.510 lift
intake duration 230
exhaust duration 236
lobe seperation 110
2" Hooker Headers
750 Edelbrock
Brodix raceright heads
Pertronix ign.
Performer intake
435 hp
443 tq
this on a conservative dyno
a Holley 750 got 6 hp more and 7 tq more, I gave up about 1.5% for driveability

 

[bullen!]

tnx!

 

[Bubba's 69]

The dome on those pistons are the same as my stock 402. You gain alot of power from compression.

So, given the numbers from Larry, I would say350+ hp is about right.

 

[trmnatr]

The 1-5/8" headers should be good for well over 500 horses.

Huh? 1 5/8" on a BB ? Small blocks that i have ran over the years ET quicker the larger you go without exceeding 1 7/8" , 500hp i would use 1 3/4" on a 402cid

Bill Jenkins ran 2"+ header tubes on 331's, MP and guys back then thought you had to have huge header tubes, it is clear they didnt hurt Jenkins and others

 

[GOSFAST]

Hi Sam, the combo below may give you an idea of where your are with your build!

It's along the lines of many we do here for 100% solid resto's, on both the Camaro's and the Chevelles, where we aren't specifically "chasing HP".

Here's an excerpt from a recent similar build. I had posted it up here a while back.

This particular build used a 9.2:1 final (measured) C.R.

(Quote) Here's a list of components, the dyno "numbers" follow:
Pistons: KB130's
Rings: E243K's gapped at .030" top and .022" second.
Bearings.: Clevite's mains-.020"s F/M's rods-.010"
Oil System: Stock pan/screen, Melling pump #M77 w/M77020 HPspring (Idles @ 25#, runs @ 55#)
Cam/Lifters: Blue-Racer "hydraulic" 214* @ .050" x .500 x 114 L/S (In @ 109 C/L) / Johnson #817's
Gaskets: Corteco's #32377CS
Valves: G.M. Stock 2.060" and 1.720". No back-cuts (seats located at outer edge however).
Springs: G.M. Stock "singles". Customer's choice, we recommended dual's. Pressure’s at 110# / 285#.
Rockers: G.M. Stock "stamped" with a set "slotted" balls and new lock-nuts (16 new studs also).
Fasteners: All stock, the original's were retained.

Unit came off the dyno at 362 HP @ 5650 and 420 Ft.Lbs. Torque @ 4100. We tested this with the only headers we had available at the moment, which were 1.750", and a 750 Holley. There was absolutely no "traces" out the exhaust ports. Everything seemed fine and it's been delivered. Thanks, Gary in N.Y. (End quote)

With your 1.625" pipes I would suspect some very slight increase (possibly) in the final torque numbers. The pipe size is fine for your application and also makes fitting them under the hood little easier!

Thanks, Gary in N.Y.

P.S. Just for future reference on these type builds, by changing over to the "retro-hydraulic" platform with the identical (as close as possible) cam specs, you will "see" approximately another 30 (nominal) HP.

 

[SWHEATON]

WELL I EST 365HP/430LB'S TRQ FOR HIS COMBO AND GARY GOT 362 HP @ 5650 and 420 Ft.Lbs. Torque @ 4100 on the dyno with a very similar build/cam,not too shabby (LOL!!!!!)

Scott

 

[65cayne]

spec on my engine:

Block: 402 ci .030

pistons: Keith Black Silvolite hypertectic med 4.5 mm dome (.180")

Kam: Lunati Voodoo, intake lift .515, dur 213, out lift .530, dur 219 1000-5500 rpm

heads: 820 ovalport, matchported , 113 cc , 255/114 komp 9.4-1

intake mainfold: Edelbrock Performer 2,0 1000-5500 rpm, matchported to heads

distributor: accel HEI super coil

carburator: Holley 750 vaccum


headers/exh: 1,5/8?? and 2,5" crosspipe.

sorry. but its all spec i´ve got at the moment. some say it´s 350-400hp is that possible? it´s very well tuned in and runs perfect. will test it at 1/4 and 1/8 this summer.

Wish I had a dyno sheet, sorry...that is pretty close to my combo except I have a few more cubes...454, 9.4:1CR (rounded), same cam, 770 vac secondary, ... Nice street motor.

 

[onovakind67]

Huh? 1 5/8" on a BB ? Small blocks that i have ran over the years ET quicker the larger you go without exceeding 1 7/8" , 500hp i would use 1 3/4" on a 402cid

Bill Jenkins ran 2"+ header tubes on 331's, MP and guys back then thought you had to have huge header tubes, it is clear they didnt hurt Jenkins and others

Did Bill run a 213° hydraulic cam?

 

[trmnatr]

Did Bill run a 213° hydraulic cam?

All im stating is 1 5/8" headers on a 402cid are not gonna support well over 500 horses as you say they will

Today, 6:56 AM
onovakind67
Senior Tech Team Join Date: Jan 2001
Location: Fairfield, CA
Posts: 4,077

Re: is there 400hp in my bigblock?

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The 1-5/8" headers should be good for well over 500 horses.