Again with my searching around the net, I came across this website with some dyno numbers for a ZL1 427. We've heard for years that these engines make 550, 600, 650 horsepower!! But is it true? This may cause some debate since I bet there's a few that will swear on their soul a ZL1 makes close to 650 hp, but this is the closest to a real test I've seen.

http://www.camaros.org/copo.shtml

The ZL1 hp debates are another one of those great unwinnable battles, usually fought by those who have never tasted 650 hp.

Just like another legendary engine, the Boss 429, the ZL1 was never really raced in complete stock as delivered showroom configuration. The people who bought them usually had total domination on their minds - so even brand new cars had their engines yanked and reworked. Its kinda like that legendary HRM 396 Camaro that "somehow" received a 1/2" stroker crankshaft while it was disassembled for "inspection". "It's stock" is one of the great all time lines of poker faced racers everywhere.

Good link on the ZL1.

Thomas

SS454, This is an interesting bit of history. There was one ZL-1 that sat here locally at Bill White Chevrolet for quite some time. It was solid black and i think it had a black interior. At around $7000.00 it was way more money than normal people had to spend on a hot rod in '69. Mid tens would have been possible as these cars are only about 3055 pounds and blueprinted versions of this engine with that cam produced about 550 Horsepower with open exhaust. My 375-396 had that cam for a while and ran 11.58 @ 117.64 MPH at 3625 pounds. Another racer from the late sixties had a 432" open chambered Camaro that ran 10.60 with a L-88 and a tunnel ram.

If I remember correctly Jenkins Pro Stocker wasn't much faster than 10.50 with his brand of ZL-1 Camaro in 69. I really don't think a stocker could get even close to those numbers. The heads are really bad and the cam is completely wrong for a drag car.

It is an on going debate but here in the last 4 years there has been some stuff that has made some neat information available on this topic.

I'm involved in PSMCDR (Pure Stock Muscle Car Drag Racing) as my hobby. It kind of is a purist thing that reflects cars potential of going fast at the strip. The rules are at this website http://www.geocities.com/psmcdr/ The rules allow for an over bore and blueprinting to NHRA specs.

The ZL1 of Pete Simpsons has run in 2 modes, non blue print and Blue printed. Non blue printed at 10.8 to 1 compression with the GM ZL-1 made 465hp with stock exhaust manifolds (camaro). Headers turned I beleive 505hp. The problem with this motor was the cylinder pressure was only about 100 psi cranking pressure. The dynamic compression was dismel to say the least. It really only made power at high RPM.

He has since blue printed the motor and is right around 500hp with the manifolds (camaro). Obviously a corvette exhaust manifold would help greatly. The ZL1 camaro has run a best of 12.05 @ 116.05 on F70 x 14 Goodyear Polyglass restoration tires.

Petes cousin drives an L-88 Corvette under the same rules. dynoed at 535hp with Corvette exhaust manifolds and 572hp with headers. It is an NHRA spec setup motor as well. Quickest times are 11.60 at 121mph. JJ thinks it will go 11.40's this year. Yes, these are on the restoration Firestione Wide Oval tires pulling a mid 1.80's 60 foot time. The car weights in at 3400 with driver.

The guys are purest in the sense that they use GM parts. Yes, the cams are the GM stock cams that you pick up at the GM parts counter.

The camaro is an automatic and the Corvette is a 4 speed. Both run 4.56 gears!

Jim

Jim,interesting info you posted and good reading as well

smile.gif 4.56s make the old ZL1, or even the baby L88 cam TURN ON!

I can see around 550 hp from a stock ZL1, dyno tuned, good exhaust. 650? No way. Cam doesnt have the lift imho, heads **might** make that kind of number in a 427 with a monster cam and welded exhuast floors. Stopping the test at 6750 doesn't give the ZL1 full merit. As any of you who've driven an L88 motor can attest, it just starts getting interesting at 6000, the 6000+ pull is freakin' AWESOME! ( in a 67 Camaro/M20/4.56s on Remington tires, you'd go WOT and the thing used to break loose at around 5500 just as the motor was getting up its 'gumption' as we called it. )

Anyway, cool link. I can't imagine dealers pulling the ZL1 and putting a soft iron head motor in just to be able to sell the car. Lots of beans for that ZL1!

As a kid, L88s were the king sh!^! So I had to buy a used crate one! Would have been a bugger in a Chevelle in stock form unless I ran 4.88's. (Uncontrollable in a full street 67 Camaro with 88's!)

Not having tons of play $$$ to throw down the drain, the 7600 rpm rev chip also gave me a small 'pucker factor'. 6800 is just fine thank you.

See what happens when you turn 40. I liked the 'go for broke - fix it tommara' adolescent attitude! As hard as I worked for it back then, boy I sure blew money at will on Chevy power!

The L88 cost me $650 if I recall. I had $600 cash and had to ask the boss at the machine shop for an advance on my pay to buy it!

IF I ever have it to burn again, a nice Donovan blocked 505 ( 4.6" X 3.76") ZL1 would be my ticket of choice. EFI-converted Crowers on top, of course. 7600 rpm rev limit.


SEEEEEYYYYAAAAA!

Hey, I can dream right! Oh, the road to a Jerico.... smile.gif

Well if fear of RPM is a sign of a wimp - might as well put me in pink sweater. I won't even run a 396 past 6000 nowadays. We should start a new thread just for old time sake, call it "Post your stories here of who has thrown a rod through the block, flywheel through the floor or other such tales of destruction".

Been there done that, the wife would kill me. Got to much invested, to blow another one up.

I have no proof, but I figure with good port and bowl heads, a good set of headers and 12.5 to 1 CR. with the L-88 or one step up cam and you are looking at 550hp in a package that weigh's less then what a decent, run of the mill, stock SB weigh's..

Now an all aluminum LS-7 is a different beast AND I can see 600hp, (or more), outta one of them done the same way!

pdq67

A good friend of mine built and dynoed a "stock" rebuild on a ZL1 for a guy putting it in a 1969 Corvette (making a clone.) I say "stock" rebuild because although all the components were stock GM and/or stock replacements, there was definately more care spent on tolerances and assembly than at GM back in 1969.

The pulls were done with an electric fuel and water pump, no accessories. I cannot remember the numbers exactly but I recall ~465 hp with the stock 'Vette exhaust manifolds and ~525 with a set of 1969 GM "off-road" Corvette side pipes (basically long tube open headers.) That's pretty much what that article came up with, and while far below the legendary claims of 650 hp, the figures are very reasonable and certainly not shabby at all.

Troy

Believe it or not the ZL1 cam is too radical for 12.5 compression. GM even suggested using the 375 horse cam when the Corvettes ran twisty road courses. The ZL1 cam starts getting good above 6500 and most or your time is spent lower than that. The 375 hp cam will bump cranking pressure to around 200 psi, the ZL1 cam only gives about 180 or even less. When Jim talked about Pete Simpsons' Camaro being "certified" it means everything was checked to be sure it was NHRA stock, including a real ZL1 cam. One of the hot tips for a pure stock cheater would be to use a smaller cam to keep from blowing the compression down. If you don't believe it, try it out on your Desk Top Dyno. I did it for real. It works. Just be sure you have really good gas or you'll find pistons and rods all over the ground !

let me chime in here being a copo owner myself unfortunaly not a zl-1 but an l-72 the bill jenkins camaro had extensive head work that was ahush hush kinda thing with intake porting as well there is a full article on it .. the motor didnt make 650 hp it on a best day made 550

Interesting... a guy just pulled in with a 67 corvette today at my work with a ZL-1 engine in it...

I checked it out, sure enough, aluminum block 427..

He said it's documented as #16 of 27 I believe, and the motor in its stock "race" configuration had 13:1 compression and a HUGE flat tappet. Early prototype maybe?
He told me it came stock with that engine, and and came with only a cage and buckets.
Anyone know of 67 vette's with aluminum 427? First ive heard... I thought they were strickly 69.

1967 Vette with a ZL1? I know there were 2 ZL1 1969 Corvettes, but never heard of a 67. I know there are cars out there with the GM 454HO and are being called LS6s, so who knows what ppl will say.

i had a factory ZL-1 grind cam in my 396 bbc for about 5 years with 11.8 to 1 compression......cranking compression done right! was given right at 150 psi in each hole.......with a sideways torker intake and 850dp holley, ported oval heads.....this car came on from 4500 to 7500 rpms.........bottom end was real lazy and sloppy.....took a lot of tune for idle and had to resort to locking out the timming......it really wasnt to bad for driving on the street.......i put a lot of miles on the short block thats for sure in 5 years

one thing is for sure with a 4500 stall and 4.56 gears this engine rocked when you slammed on the go peddle.......never lost a street race.

the pulling power was fantastic!!!! i swear there was no limit in the rpm range for this combo......i only ran it to 7500 rpms a few times at the track and it was still pulling hard......

not wanting to risk loosing the stock bottom end with 25+ years of use out of the bolts and crank and rods.....i kept the rpm chip in for 7200 rpms........

in street trim with 3600 lbs it ran a best of 12.18 @ 110 thru the mufflers and on a set of regular 275/60-15 tires with a 1.72 60 ft time........take the exhaust off and add a victor jr intake with some more carb tuning and that engine comes alive to mid 11's at 115mph with slicks.........

that was the closes i came to feeling what a ZL-1 engine felt like.......since i heard a great deal about them......

the zl-1 motor could be ordered in any chevy body you wanted to pay the extra bucks to put it in..

Yes, but the ZL1 didn't come about until late 1968...after Fred Gibb pestered Chevrolet to come up with a motor to go drag racing with.

Wasn't the big ZL-1 cam, if it is the .600"/.600", the one that was best in the Crower mechanical F.I. motors that were about 494/510 or so inch CanAM motors that Bruce McLaryn(Sp?) drove??

The "calliope" stacked jobber..

pdq67

Just a little more history. Sometime around late '68, Kurt Dixon (don't know if i spelled that right), from Prue, Ok. held the AHRA record with a '67 Ralley Sport Camaro and at the time it wasn't much slower than Jenkins then emerging Pro Stock car. It ran 10.46 @ 134 at Green Valley and routinely ran 10.60 @ 130 at Tulsa. I don't think it would be much of a trick to make one of these cars run mid tens as i personally have seen a single four barrel, flat tappet cammed, 427 run 10.7 @ 127 on our mediocre track. By the way SS454 i think your right about the corvette as any '67 should only have been a L-88 at most. NHRA only lists the '69 as having been factory produced and were declared illegal because only two were made. Another interesting thing, my '67 Chevelle had two different fender identification flags on the front fenders. One side said 396 and the other said 427. I heard some time back from a friend that the factory offered dealers the option of getting a 427 which could be dealer swapped into a 375 H.P.-396 car, thereby changing a Chevelle to a 425 H.P. - 427 at a cost of only $100 and that cars destined to get this dealer swap would have one of each flag until they decided which they preffered. Don't know about the authentisity of this story but mine had two different flags.

pdq67, The McLaren 494/510 big motors had the bigger mechanical cam designated the "Can Am". It is .600 lift on both sides and has 366/360 degrees duration at .015 lift. The ZL-1 cam has .560 int./ .600 exh. lift. These figures are net lift as lash isn't subtracted on the factory figures like aftermarket cams. Mine measured .606 lift on some valves. The ZL-1 cam has an effective duration at .050 lift of 263 int./ and 272 exh. duration with 110 degree lobe centers and has a powerband of 3500-7500 in a 396 or 427. My son's car had this cam in his 13-1, 482" motor which ran 10.48 @ 128 MPH at 3540 pounds and had 4.10 gears and 10.5" slicks. It wasn't one bit faster with a roller cam.

to deennis, You should have wound it a little tighter. Mine saw the far side of 8000 a couple of times, (missed gears). The reason most people lose engines is because they use the stock Chevy valve springs, bad mistake, these springs fatigue rather quickly and then work the top of the valve off from insufficient seat pressure. With good springs and the oiling system working properly this little motor is nearly indestructable. Mine went 11.58 @ 117.64 at Tulsa and i had a run that was both quicker and faster than this but the clocks malfuntioned. The car went through a couple of hundred higher on the tach and it was the perfect run but no time and i feel more could have been had with 5.13 gears instead of my 4.88s as the car had a slight bog down low. Wish we had had one that ran like my son's back in the sixties we could have cleaned house.

You guys should have tried different cams. We played with the ZL1 cam and found yes it will RPM forever but it really doesn't make a lot of power anywhere. The best of the old style cams we tried was the Comp CB 310. In the dragster we ran it straight up in the door slammers we advanced it 4deg. Super power everywhere.

Mike,

I just looked and CC has several 310B cams so please come back with spec's if you have them.

Just curious is all..

thanks,

pdq67

In his book titled " American Muscle , Muscle Cars From The Otis Chandler Collection " he has a featured story about Jack Cheskaty's ZL-1 Corvette he managed to buy new.... $ 500.00 deposit and a balance of $ 9,819.00...... Suposidly one of only 3 produced.

Prevously he had been raceing a 1965 327/375 HP FI Corvette and running low 13's with it.

A quote from the book...

" When he ran the ZL-1 up to 6000 RPM and popped the clutch , the slicks spun." So what " I thought
my old car did that.The slicks started to burn " So what my old car did that too ". But then the slicks grabbed and it was all I could do to grab onto the shift lever to get second before the tach needle hit 7000 RPM.I Knew this was something different ".


Adding nothing more than a set of headers ,a larger carb , 5.13 gears and slicks.... and learning how to drive the car....he ended up running mid 10's @ 130 MPH.

It appeares by the pictures the car has been restored.

When we used the CB310s they made 2. A 108 and a 110. The 110 we put in the Super comp car straight up and the 108 I tried straight up in the 10.50 Super Street car but it ran better advanced 4deg. I don't know what they have now they probabily are better this was a long time ago.

ddeennis and Harold Sutton.

I too know what you guys are talking about with the old ZL-1 cam. I ran that cam in my '69 396 Nova "many" years ago, with 11.5 c.r., Tarantula manifold w/ Holley, and 4.88 gears/4speed. Not alot on the bottom, but didn't really matter with the 4.88's. Twisted mine to 7200-7400 using the Crane triple springs. What a screamer! I just never could get enough tire under the Nova body to get it to hook up.

Dave

Hi Novadad, I used to run mine 7500 RPM or a little harder if neccessary. We put it in a lightweight Camaro once (2895 with the cast iron 396) and it ran a 11.40 @ 122.44 but wouldn't bite at all. Things happen real quick with 5.38 gears and a four speed. I personally think the cam works pretty good as it was about nine MPH faster than the stock cam. You ought to see it in a 481". One local ran one in a little open chambed 396 and ran 10.90 @ 124 in a vette that weighed 3300+ pounds with the driver.

Harold
yes they happen quick with the 4.88's, too! I can only imagine how quick with the 5.38's! It was surprising how fast my .060 396 would rev.

If I remember right, I think it only had about 6" manifold vacuum at idle. :eek:

I took it to 7800 one time just to see if it would go there, but didn't have the guts to take it any higher. I do remember that it was still pullin' when I lost my nerve!

I think those cams, 4 speeds, and gears were meant for each other. ;)

I think that was the most fun of any of the cars I've had.


Dave

Hi NovaDad, mine when to the moon a lot. When we put it in the Camaro we used a magneto and a rev limiter which started out being set at 8000. After hitting it a couple of times i decided it was better to turn the limiter up than have the motor bouncing up and down. The car would initially bite then when the front end started to come down it would spin badly. With the limiter set at 8200 i could get it shifted into second without hitting the limiter. This car spun worse than any i've ever driven and had new 13 x 30 M&H Slicks.

Harold
I never could get mine to hook. The Nova body was so wheel well limited I couldn't get any rubber on there unless I jacked the back end up. I think that only made things worse. Blowing the tires off was just a way of life for me and the Nova. The only time I ever got it to leave without smokin' the tires, I broke an axle!

Like I said, it was a lot of fun!

I drove it a little on the street with mufflers and street tires. Loved the way that ZL-1 cam sounded through the Hookers and mufflers, but between that cam and the 4.88's I didn't pass many gas stations.

Dave

hey harold and novadad, that ZL-1 cam in my 396 idled with 4.5 inches of hg .......sounded real tough at 800 rpms...but sure enjoyed 1000 rpms for idle a lot better....i got 11 mpg out on the highway with that combo and 4.56 gears i would run down the road at 4000 rpms......maybe if i would have spun it up higher i might have ran faster at the track .....but not having a balanced bottom end and running stock bolts and rods with cast crank i sure didnt want it flying apart anytime soon......and would you believe me i ran about 5 years on the same springs......and would you believe me i ran just a single spring and damper.......a lot folks thought i was full of......when they asked what springs i was using......infact i didnt even know what name brand......i bought a set of used heads off an 11.80 396 and used the heads and springs ..all i did was make sure the spring would handle up to the .600 lift........i did run a lash of .018 on that cam.......i cheated my way to 10 second passes with a 150 hp shot of spray on the motor.......thinking about it...i cant beleive that motor lasted as long as it did....i built it in summer of 1996 and retired it from the streets in 2001 for a bigger 454 engine.....i took that 396 apart and built the milder 396 i have now in my z28 i bought in 2001......dang where does the time go......

Hi ddeennis, I had a 454 that i bought from a guy that he couldn't get to run in a 3000 pound gutted Chevelle. Best he ever got it to run was 12.20s at 115. I started checking things and found all the exhaust valve's springs were coil binding. They wouldn't go over .560 lift and the springs were stacked up tight. I put some Isky 8005s springs and associated hardware in place of the Chevy springs and the first time down the track the car went 11.87 @ 118 with a passenger, ( they used to let us do that sometimes). This car eventually went 11.15 @ 126.76 and it spun on that run.

You guys bring back memories of the huge cam that I ran in my 396 in a 68 Chevelle.

Not sure what brand it was, I bought it from a friend, but I do remember it was .323 duration and .612 lift solid lifter beast.
I was runnin aone of the twisted phlenum torker intakes with a 780DP Holley. Bone stock bottom end.


And, I was 19. It's a wonder I did kill my fool self in that car.

More that once I sidesteped the clutch at 5-6k rpms and hungon for the ride! I blew up a couple of trannys but I could'nt hurt that engine.

ddeennis

I idled my ZL-1 cam around 1000 as well. My 4.88's just wouldn't let me get much better than about 5-6 mpg, though. Seems like I used to lash it about .020/.020-.022 approximately. With that cam, bottom end was not a problem as long as you had enough gear. Put enough gear with it and it would twist to the moon.

Getting my Nova shut down at the end of the quarter was the biggest problem I ever had with that cam because I had to get it out of gear and get on the brake as quick as I could while keeping the revs up with my other foot (4-speed) to keep enough vacuum to operate the power assisted brakes! Yikes! :eek: Talk about adrenalin rush. :D

Dave

A ZL-1 in a '67 Corvette? It never happened. That's about as phony as the guy who said he had ordered a '66 Vette with an L-88. Actually, there were a couple or so '66 L-88 Vettes that went out the back door but they were not regular production options. There were only two "RPO" ZL-1's that came off the assembly line and that was 1969. I use exclamations for "RPO" because two is hardly a regular production item. Zora Duntov and his engineers spent a lot of time designing the ZL-1 and here's an interesting story. When Duntov gave the order to build the first one he was calling Tonowanda every day for a month to find out when the !*#\! thing would be completed and shipped to him. He finally got his call and it was to be shipped out "first thing next morning". The next morning when they opened shop the ZL-1 had disappeared! No doubt it was an inside job and that motor was never recovered. Zora went ballistic and when the second motor was finally completed, almost another month later, they placed the motor in a caged area with an armed guard watching it. I had the extreme pleasure to meet Zora in Bloomington and I asked him about that incident. The old Russian had nothing to say.

Originally posted by Rain Man:
A ZL-1 in a '67 Corvette? It never happened. That's about as phony as the guy who said he had ordered a '66 Vette with an L-88. Actually, there were a couple or so '66 L-88 Vettes that went out the back door but they were not regular production options. There were only two "RPO" ZL-1's that came off the assembly line and that was 1969. I use exclamations for "RPO" because two is hardly a regular production item. Zora Duntov and his engineers spent a lot of time designing the ZL-1 and here's an interesting story. When Duntov gave the order to build the first one he was calling Tonowanda every day for a month to find out when the !*#\! thing would be completed and shipped to him. He finally got his call and it was to be shipped out "first thing next morning". The next morning when they opened shop the ZL-1 had disappeared! No doubt it was an inside job and that motor was never recovered. Zora went ballistic and when the second motor was finally completed, almost another month later, they placed the motor in a caged area with an armed guard watching it. I had the extreme pleasure to meet Zora in Bloomington and I asked him about that incident. The old Russian had nothing to say. I agree there were 16 L71/L89 Tri Power aluminum with heads and 20 L88s 67 Corvette made according to the books.

Quote from Motown/Malibu: "the zl-1 motor could be ordered in any chevy body you wanted to pay the extra bucks to put it in.."
No, you could not "order the zl-1 motor in any chevy body". You may have been able to buy a big block car off the lot and have the dealer install the ZL-1, if you could find one and could afford the motor on top of the vehicle cost. If what you said was true, we'd see ZL-1 Biscaynes, Caprices, Impalas, Novas, and hey, even Chevelles! You might want to contact Ed over at copo connection to get your info straight. You are one lucky guy to own a copo, but why not try to restore that irreplaceable piece of history and build another, Plain-Jane 69 Camaro? What if you crack it up? :eek: God Forbid.