Hello all,

Im in the process of rebuilding (frame off) my matching numbers 71 chevelle SS and was wondering if anyone had a recommendation on the engine build. The engine has never been built (original bore) and i have owned the car for 25 years and plan on driving it only on weekends. It has a turbo 400 with 373's (yes gears not stock) and now the engine question. I was thinking of a mild cam (300 duration / .500 lift) 10:1 and i need to buy an intake / carb setup (recommendations?) and i would like it to look "stock". 450 HP would be nice but not sure if i cpould get there with this setup. Any recommendations?

Stroke it 4" or even 4.250", hyd roller 230-238 @.050 duration, 10-1, perf rpm, Hughes 25 converter, 3:08 or 3:31 gears. Torque monster.

Hyd roller cam would be a wise investment, both in longevity and HP.

DC7432

Got a name?

What is the budget?

You could spend a lotta money on a roller set-up
or
You could do a basic rebuild, shave the heads or run a shim head gasket to raise the CR a tad, then your 3.73s would love the 60204 cam from Lunati
2500 stall
Performer RPM
1 3/4 headers

If you plan to keep the stock ext manifolds as this is a restoration.....go with the milder 60203 cam and either an Eddy Performer or the older C-396-QJ

If you have lotsa cash, you could stroke the 402 to 433 cubes.

or
Stash the OE engine, build a 454 and have some real fun

Since this should be an LS-3 I would put bump compression, throw bigger valves in with a good valve job, clean up the ports and install a mild cam with the same overlap as the stock POS for right sound.

Thanks all,

Yes its a LS3 and I have headers 1-3/4 that I plan on reinstalling. I forgot to mention the tranny is at the shop for a rebuild and we are looking at a 2500 stall with a shift kit pending the cam selection. I will check out the cam (60204 cam from Lunati) and shaving the heads is an option. Any ideas on HP with this setup?

Dale

Several ways to go. Question is what performance level do you want. Spirited street cruiser or weekend warrior. Spirited cruiser - simple. Freshen it up / basic rebuild. JMHO, I prefer hyd roller cams for street cars. Keep the duration short, but pack in as much lift as you can get. A hyd roller with no more than 218-220 (@ .050) on the intake side, lift in the .550-.570 range, will wake up that motor. "0" deck the block and cut the heads a good .030 in the process to get compression to about 9/1. Perfomer 2-0 intake with your choice of 650CFM carbs. Reassemble with a 2400 converter.

I am currently have my 71 LS3 done. I'm hoping to be in the 450hp range. Here is a list of the stuff. Going into a 68 SS 4 spd w/3.73 gears

71 LS3 2 bolt bored .030 over to 408 w/studded mains
cast iron 049 heads w/2.19/1.88 valves
Comp Pro Magnum roller rockers
UDharold cam 231/239 @ .50 .600/.600 lift 112 LSA
Morel roller lifters
forged pistons to get me @ 10 to 10.5 compression
6223 forged GM crank
ATI Super Damper
7/16 GM dimple rods w/ARP bolts
Edelbrock RPM Air Gap oval port intake
Holley list 4053 780 cfm vac seconday carb
Hedman 1 3/4 Elite headers w/2.5 exhaust
MSD Digital 6 ignition w/pro billet Dist.

Dale,

Some comments on the input that you have rcvd


GRN69CHV, you said "0" deck the block.:sad:..post #1 says matching numbers...
Original matching number block...even an LS-3, I say again, take it out, put it in the corner of the garage....build a mild 454.


BADRAD Jimmy, You said larger valves....
For a street 402, bigger valves are a waste of time IMHO. This money better spent on pocket port. "Doc" aka Team Member "FRYNTYR" has gone in the 10s with 427 and stock size valves and, bowl work. A bigger engine, more aggressive build....I'd then go for the larger valves.

You should have the good open chamber oval port heads

HYD roller, with all the stuff you need will run you $1000
I'm not convinced this is the way to go but I'm always on a budget. Yes, more lift on a given duration for sure.

With your 3.73 gears, look for duration at .050" lift numbers in the 228-235 range....should give your 402 power range from just off-idle to 6300 rpm or there about. Duration shorter than that and you'll run out of power band just as that 402 gets going. A shorter duration will give you impressive low and midrange power....so you gotta figure out how you are gonna use this thing.
No 'one size fits all.'
There are some DANDY mechanical cams out there if you do not mind setting the lash periodically

The thing about 396s is you gotta spin them up. If you are looking to not do this, as I said, park the 402 in the garage, build a 454 for the Chevelle

A no-frills build should be 400 horse with a decent cam, bowl work and a good 3-angle valve job on the heads

Yes, I am fully aware the "numbers" will be removed. But, in my experience, a '71 block that has never been apart is going to need the decks cleaned up in a rebuild. Once you clean it up, the numbers are gone anyway, so might as well cut it the .020 and be done with it. Otherwise, yes set it in the garage and find a 454 to drop in it.

Personally, I don't give much thought to numbers matching, especially if you modify it.

George has some good points, I would stow the 402 and build a mild 454 short block, kinda have your cake and eat it too situation.

Hello all,

Im in the process of rebuilding (frame off) my matching numbers 71 chevelle SS and was wondering if anyone had a recommendation on the engine build. The engine has never been built (original bore) and i have owned the car for 25 years and plan on driving it only on weekends. It has a turbo 400 with 373's (yes gears not stock) and now the engine question. I was thinking of a mild cam (300 duration / .500 lift) 10:1 and i need to buy an intake / carb setup (recommendations?) and i would like it to look "stock". 450 HP would be nice but not sure if i cpould get there with this setup. Any recommendations?

Since you mention "matching numbers" I assume that is important to you.

If it is important you must be very careful of the machine shop. Many machine shops will deck the block, removing the "matching numbers", as standard practice.

If you don't want the block decked, give them instructions in writing about what they are to do and not do. Putting everything in writing is a good idea anyway so you and the shop understand exactly what is going to be done and how much it will cost.

Make the shop manager/owner sign a copy that you keep and give them another copy.

If they insist on decking the block, find another machine shop, one that will listen to their customer.

Back again.....

As GRN69CHV says, the pistons will be down in the hole....
Yes, 'better' shops can stop short of the stamped pad like Wolfplace's establishment. But....why chance it. If I was going to buy a number matching car, I'd want to see a whole, running, complete top to bottom engine, not an upgraded one...

Let me appeal to you with this....
Start changing stuff like carb and intake, it really loses originality. Do yourself a huge favor, Put the whole bloody 402 mess in the corner of the garage for when or if you sell the car. Here's why...

1. If you beef the 402, you'll want to explore its performance potential...just like every other rodder out there since the first guy went pedal to the metal. Sooner or later, shi+ will happen and your precious 402 will go bye-bye. Local kid Paul had the harmonic balancer come apart this weekend....lucky he was not on a 1/4 mile blast when it happened.....

2. A healthy 402 is 400 horse. At about 425 horse they (402) stop being really friendly street engines, start getting soggy low-end power.... There will be someone who will chime in saying they have a street-friendly 500 horse 396. I'll get right on it. Nothing they can drive in traffic or take on a nice roadtrip.
Short stroke BBCs need to be revvvvved-up to make good power,,,,then you start having to buy a lotta fancy valvetrain stuff...how much depends on some choices you make...my experience tells me the better stock stuff will last a long time to 6500 rpm, one shift at a time.

3. A lot of people INSTANTLY think Big Valve = High Perf. Think about the 396/402 engine. "Small bore" compared to the 427/454 and larger BBCs. Start throwing big valves in the heads and they are shrouded up against the cylinder wall. Sure, Chevy did this starting in 1965 but we have learned a few things since then.... I wish I had some numbers in front of me. There is a following for enlarging the EXHAUST valve. Was it "Mike 1241" or "GOSFAST" who mentioned using some slightly larger valves, less than 2.19/1.88 but greater than stock 2.06/1.72

4. A bud of mine Bruce Parent sold his 70 SS 396 last year. Always worried about dings and really not interested in 'rodding' his matching numbers 402/350. Are you headed that way, hanger queen? My 68 Vette 427 is pretty much a hanger queen, been there!
Either rebuild it totally stock and cruise it to the car show or take the 402, set it aside, build a 454 that you can thrash.

5. With a few parts, a 450 horse 454 is a no brainer...and just above idle it makes more torque than a 396/402 does at max rating. At max rating, a decent 454 makes roughly 30% more torque than a comperable 402. 500 horse, not an issue either.
A warmed-up 454 is a way better street engine than a built 396...no need to rev it to the moon or buy a lotta trick parts. Let cubic inches and good flowing BBC heads do the work.

Back to the ever burning question - what does he want the car to do? Which way to go?

OK Dale,

Do you want it to 'look stock' or 'go fast' or 'look kinda stock but go fast'
Street, street and occasional strip, street with regular strip use, more strip than street

Next, we need your budget.
Your skill level, doing this yourself or a shop build?

Guys, all good points. I went to an automotive school so I could rebuild myself however without the machinery its hard to rebuild. The engine is at a shop that my family has used on numerous rebuilds and they are very trustworthy so I dont need anything in writing. I plan on spending $3,500-$4,000. They just finished a rebuild on a pontiac 400 (GTO) that included new pistons, valve seats, valve job, cam, lifters springs etc. and they ran it on a stand and dialed it in. Total cost $3,500 out the door.

I understand the point of putting the original engine on a stand and store it for??? who, my kids? they can buy their own car as I did with this car (paid $550!) I will never sell the car as I have owned it for 25 years and I believe you should drive the car and enjoy it even when its completly restored. Im not doing a frame off as an investment I just want the car to be soild and turn the key and go. Matching numbers is not important to me but its nice to say I have a real matching numbers big block! Car shows maybe, but after I put 15-20k into it I want to get something back so it will be driven not down the drag strip or...... maybe one time to see how it does!!!!!!!!!!

I want the car to sound good and have 400-450 HP on pump gas and look stock / original. I know the headers will not help with this but i can easly change them in a heart beat as I have a car lift in my garage and the underbody work is a lot easier when its 7' in the air. So with that being siad, I like the advice on the cam and I may shave the heads to make them true and decking the block wasn't something I was considering and I dont understand when they say the numbers will be removed if a resurface the block?

When you resurface the block, it is machined across the entire deck surface. As soon as you hit that surface on the milling machine, it machines the metal off - right along with the numbers. You won't know until it goes in for machining and gets sized up. Depends on how pitted the deck surface is and how square or out of square it is. You may not have to touch the deck, you may have to get away with cutting it as little as .005"-.007" which may leave enough of the impression in place. Your decision. All comes down to - do you want the serial number stamped on the block. For me, it's no big deal.

What shape is the original engine in?
Best to let the machinist decide if it needs decking....this is to say if you are getting new pistons, do the mock-up with the new slugs, see how far down the pistons actually are.
For reference, my "Super Budget 454" started with a $200 short block. Stock pistons, stock bore, stock nodular cast crank, HD thumb rods....all these goodies checked-out as reusable, as-is. Following cleaning and pro-honing, the stock pistons were only .022" down the hole, 1977 engine. Deck was true so no need to deck the block.

Look on the pad, passenger side, front of the block's mating surface with the heads.
Got numbers stamped there? You should have something there like T0122CLA, example here being T=Tonawanda 01=JAN 22=22nd day of the month CLA is the engine suffix code= 71 Chevelle LS-3. You should also find the abstract VIN info with the last digits matching that of your VIN plate in the window. As mentioned numerous times, if the block is decked, these numbers, the ONLY thing that IDs this as a 'number matching' unit to your car...gets wiped off.
The block CASTING NUMBER and CASTING DATE are raised numbers on the back surface of the block above where the transmission bellhousing bolts to the engine.

Check with your machinist if the standard bores are usable....

I was at the machine shop today and its going (in now) the hot tank for a good cleaning. After I wrote the reply I remember the location of the numbers and how it will be removed. he will be calling but no decking until we talk. thanks guys.

Different qustion, I was at Ground Up this afternoon and they have a low rise inake manifold (repo.) for a LS6 and L78. do you think it would fit on my 402 and have a good flow? I currently have a high rise torker 2 that i want to replace with a 780 holley. thanks again.

Dale

Dale, Dale, Dale,

OK, take a breath....
exhale
Time to PLAN since you have decided on the 402 apparently

re the Intake
This LS-6 re-pop intake would look 'correct'
Opinions differ as to how well they work.
I believe "Mr 4 Speed" Chris says they work well.
Be advised that the ports are RECTANGULAR on this intake and your heads are OVAL PORT. This does work, will seal with a rect port intake gasket. Most of the guys that DO use this mis-matched set have 454s or larger...

I do have a Chevy Alum hi-rise rect port intake that I will test in the future.

Intake of choice is the Edelbrock Perf RPM or dolled-up RPM A-G.
If you go mild, the Perf 2-O or older C-396-QJ

I'd only use a Torker or Torker II if I had a stock BB hood on my 68 RatVette. It came with the L-88 hood so I have a lotta clearance for the Perf RPM.

I had a Performer 2-0 here that I port matched to the stock oval ports. Very easy to grind the Edelbrock script off (flap wheel on a grinder). Install and paint orange to match engine for a very stealth look.

I re-painted the partially painted PERF 2-O I had. Was fixin to install this when I rcvd a C-396-QJ, already has the full size oval ports.
'gotago' ported his like you did....

George,

The reason I was asking about the intake was that it looked "stock" as I will need to provide the shop with the intake and hopefully re-use the Holley 780. There's a local swap meet comming up that I have attended the last two years in search of the stock intake but it's almost impossible to find one with the right numbers and in good usable shape. I know I have oval ports but wasnt sure if the intake would work. I'll check into the intakes you recommended, thanks for the advise.

On another note, if the block has to be decked (I know I'll probably get a lot of opinions on this) can I "restamp" the block? Like I said previously, the car will never be sold so I don't want to deceive anyone and I may be able to maintain the originality of the car. Has anyone done this "openly" before and can you buy the stamps that GM used?

Dale

Most on this site 'poo-poo' restamps, even your own correct engine.
1. even the guys who re-stamp a lot to 'fake' engines...most do not do a perfect job and the stamping is suspect.
2. each plant did things a bit differently
3. I believe the size and style characters are reproduced/available on eBay or Hemmings

I'd prefer to not mess with it.

The Holley '780' can use some upgrades too. Take a few pics of that carb you have and post em. What is the 'list number' off the air horn?

I had a Performer 2-0 here that I port matched to the stock oval ports. Very easy to grind the Edelbrock script off (flap wheel on a grinder). Install and paint orange to match engine for a very stealth look.


That's what I had on my 402 in my Nova...stock compression, crappy rebuild kit...fireball cam...no balancing or blueprinting...ran on unleaded...low 13's in the quarter

WAY too much fun!:thumbsup:

All, update on build.... shop called and recommended the following setup:

Keith Black Pistons that will get me approx. 9.6-9.8:1 CR
Molly rings
Comp-Cam 11-242-3.....range 1,600-5,800 RPM, duration 268/280, lift.515/520.

Any thoughts?

We talked about the intake and he recommended the Edelbrock Perf. 2-0 and Avenger Carb. 770 cfm. with headers he thinks I should get 415-425HP that would be great!

Dale

The comparative benchmark would be the '70 402-350Hp motor. If you get the CR in the 9.6+ range, add in better flowing intake and some more cam, you can figure on another 30-40HP. I think 425HP is somewhat optimistic, 390-400HP is probably closer. Regardless, it will run a lot stronger.

Dale,

Looks like decking is not needed...

That cam will work well with your 402. Though on the tame side, it will be powerful and have good manners. It is way more cam than the factory 350 horse cam.....
Your OC heads flow a bit better than the 1970 closed chamber heads...balances out having a bit less compression.

Here is Brett's KB piston after an outing at BEREMERTON Raceway...
http://i52.photobucket.com/albums/g34/Brettd85/DSCN0967.jpg
KB HyperE. Dunno what the ring gaps were but he admits to a bit of overkill on the ignition. I believe the citical piston speed for a Hyper E and 4" stroke is 5700-5900 rpm, don't know where Brett was in this regard either. Do a search on KB HyperE and then see if the SpeedPro Hypers give the same troubles......

I think you will come out at 400 horse.....425 horse would require more cam, etc, etc

If you should ever race a 396/350 horse car at the strip, you'll easily dust him.

The AVenger carb comes with a lotta stuff you could add to your old 780 Holley.

On another note, if the block has to be decked (I know I'll probably get a lot of opinions on this) can I "restamp" the block? Like I said previously, the car will never be sold so I don't want to deceive anyone and I may be able to maintain the originality of the car. Has anyone done this "openly" before and can you buy the stamps that GM used?

Dale

You can "rent" a stamp set specifically for your engine. You will receive a holder with the appropriate individual stamps to create your numbers. The stamps are the correct size and correct font. It is expensive.

Once a block is decked it is no different from any other decked block. It could have come from any car or truck.

Stamping a decked block with information to match your car is a waste of time. Anyone with knowledge and training will immediately know it is a "restamp". Everything you tell them after that will be taken with a large grain of salt.

Just because you know it is the original block that came in your car doesn't make someone else belive it.

Some of us are interested in originality and some don't care. If you are serious about originality don't deck the block. If you want to go really fast, get another engine and preserve your original engine.

BTW, forgot to mention that modern decking is done with fly-cut, semi circular tool marks on the deck. Originally the BBC were broach-cut which left lines from front to rear on the deck surface.