Re: L88 cam in L78?
 

Not to be argumentative, but...

I had this very discussion with both Crane and Comp. Know what they told me? Stick with the "143". The guy at Comp told me he *might* up the lift to around .530", but that it had plenty of duration. This was after I filled out both companies' forms for a blueprinted L-72 running through manifolds and faxed them back. They both said it had PLENTY of duration (.316"/.302" advertised, and .240"/.240" @ .050"), and Comp said the only thing they *might* do is bump the lift to .530". Comp's "Magnum Muscle" cams have almost the exact same duration (242/250), but have quite a bit more lift and a tighter LSA (110 vs. 114), which is gonna bring a pretty hefty lope with it. Any more duration/lift gets into their "drag race" section of cams, with power bands starting at 3500, and you know what that's gonna do to your drivability.

You have to remember, though, that the exhaust manifolds change the entire equation, and require a little different mode of thinking. They will only flow so much. And, like I said above, I'm not being argumentative, just passing on what I've had to learn the hard way (but I'm not alone!). Like Steve said, all of the cam manufacturers can offer you a respectible cam, but I'd just about bet that when it gets down to "brass tacks" that you'll be back where you started: good 'ole "143".

In a slight bit of irony, I was reading the tech section of SS&DI and someone asked about changing cams in a '66 L-72, and the reply was to stick with the "143" cam. They also ended with these words of wisdom: "an engine will run better with too little a cam than it will with too much". Just curious...what kind of power you looking to get out of this L-78?

Re: L88 cam in L78?
 

Sam, I remember those cars running mid 11's with headers and a pair of 9' slicks back in the 70's. I don't feel that any porting or anything of that nature hurts originality. All parts and numbers will still be correct. If you can find an NOS camshaft of the 375hp variety than I would use it. They are better than todays GM stock ground cams. They just where! Too much cam with little else wouldn't make it run any better. It is the combo that you need. Kim is correct about the stock specs of their B/S Nova, the lift has to be the same BUT..... ask him about the duration. Also the Schubeck lifters help. If you build your camaro to basically stock 1970 specs with a little clean up of the distributor add a set of headers and traction bars with 9" tires ,some good gas, at least a 4:10 rear that car will probably run 11.80's with practice. That to me would really be considered stock.Remember, No matter what these guys tell you here, small tires and the smog equipment was off the car before the first tank of gas was empty. No body kept that stuff on! Good luck! I would think by basically using Rob's set up and adding headers and slicks you would be right there. Good luck! Sam [img]/ubbthreads/images/graemlins/3gears.gif[/img]

Re: L88 cam in L78?
 

Sam,

Let me say that almost everything that I can think of has all ready been said except this!

The L-88 cam is marginal at best in a 427 in the street and you're running 31 cubic inches less.

The cam was designed for headers.....no doubt about it! Wayne Nelsons L-88 corvette that just went 11.99 at Stanton 2 weeks ago dynoed the motor at 571 hp at 6700RPM with headers.

With the manifolds it pulled down 505 hp @5800 RPM with 480+ lbs. Wayne shifts at 6100 RPM because he is going slower and wasting motor if he goes more with the manifolds.

Are you ready to have the neatest sounding car but get beat by an average Joe because it wont run strong except the last 2000RPM before redline? What you have read on the above posts are the truth. Do you want to go fast or have a neat sounding car?

Jim [img]/ubbthreads/images/graemlins/burnout.gif[/img]

As far as running some of the really fast ramp lobed cams, the valve train must be in good working order. Lots of spring pressure must be used to keep the valve train stable at high RPM. Find a good machinist if you go that way.

Re: L88 cam in L78?
 

Jim:

Any idea what Wayne's car weighs? Or what his best MPH was?

Re: L88 cam in L78?
 

Thanks for all the responses, I would pity the fool that puts an L88 cam into a 396 with cast iron exhaust! [img]/ubbthreads/images/graemlins/no.gif[/img] [img]/ubbthreads/images/graemlins/eek.gif[/img] [img]/ubbthreads/images/graemlins/no.gif[/img]

At least, I will be sticking with the 143 cam. My goal is to blueprint the motor when I pull it out, and do a few things to improve air flow (like port matching the manifolds). I plan to drive this car on the street a lot, but I would also like to see 12's on bias-ply tires with it..

Seriously, I started looking at the specs as listed in the Chevrolet by the numbers book, and the L88 and ZL1 have tons more duration than the L72/L78 cam, as well as more lift.

Lift and duration, per Chevrolet by the numbers 1965-69 These must be at 0.000" lift..

L72/78 cam, pn 3863143, lift .520 intake and exhaust, duration 316 degrees intake 302 degrees exhaust.
L88 cam, pn 3928909, lift .562 intake, .584 exhaust, duration 354 degr intake, 360 degr exhaust
ZL1 cam, pn 3959180, lift .579 intake, .620 exhaust, duration 354 degr intake, 360 degr exhaust

I do have a question about the duration of the 143 cam, Chev by the numbers lists duration (from .000 lift I assume) as 316 / 302, the aftermarket cam sellers list their "143" cams as having 240 deg of duration for both intake and exhaust(I assume this time at .050" lift). Does this mean that the 'ramp" in the factory cam for the exhaust side is steeper than the intake side? What do you think the intended effect was for this steeper ramp?

The other two (bigger) cams have more lift and more duration for exhaust over intake (at least at the baseline), what is the benefit of this configuration?

I think I have read that at high RPMs the open exhaust valve can create a low pressure zone within the cylinder, helping to draw in the intake charge before the piston starts the down stroke - is that it?

Thanks again,
-Sam

Re: L88 cam in L78?
 

You could lighten up your valve train with stainless valves and push rods.Or you could put the larger valves of the L-89 in your cast iron heads.--- JoeG----good choice 143 cam.for your application.

Re: L88 cam in L78?
 

Waynes car weighs 3600lbs with driver. The car should be 160lbs lighter but because of the special drive shaft loops that he uses to protect the car their is the weight penilty.

His best MPH was 119.02! His reproduction cam is if I remember right is 6 degrees and 8 degrees less duration on the intake and the exhaust from the chevy grind and yes he is running the 12.5 compression.

JIM [img]/ubbthreads/images/graemlins/3gears.gif[/img]

Re: L88 cam in L78?
 

Sam;

The reason you find more duration on the exhaust side of the cams are because only until recently cylinder heads big restrictions were the exhaust port. Chevy has a really good one for a stock head compaired to the other manufacturers. On a flow bench they would flow about 70% of the intake which for their time of design was really good. You will find that alot of the after market manufacturers are around 80%. To compensate for the lesser design you would hold the exhaust valve open longer to help it out. The kicker again is the longer you hold the valves open the more compression that is required to aid in cylinder filling. Keep in mind we are talking about a cam made for all out performance for the L-88 and ZL-1 cars. [img]/ubbthreads/images/graemlins/beers.gif[/img]

If you look at Buick stage 1 motors their exhaust is an extra 10 or 12 degrees. The 440-6 pak motors from Mopar also have an extra 10 degrees designed in. These are just a couple off the top of my head that I know of that com from the factory with a cam to aid the exhaust port.

JIM [img]/ubbthreads/images/graemlins/headbang.gif[/img]

Yes...........those cam numbers are off the lobe not at .050 which seems to be the standard today.

Re: L88 cam in L78?
 

With all due respect for Waynes car, the cam is is running is a made up cam. We really don't know much about it. If he had a GM L88 cam in it, it would peek around 6800 rpm or more with his manifolds. I shift a 7000 rpm and go through the end at around 7200 with my lesser manifolds. If I shift at a lesser rpm, the car slows down a lot. His lobe separation and ramp speeds must be quite different than a GM L88 shaft. He has obviously done his homework, but it would be real interesting to see what the car does with the GM shaft!
Peter

HOW many lbs. ??
 

[ QUOTE ]
...The car should be 160lbs lighter but because of the special drive shaft loops that he uses to protect the car their is the weight penilty....

[/ QUOTE ]

WHAT ? 160#'s in driveshaft loops ? The HEAVIEST loop that I have ever made was 11 lbs. That was a 5" diameter loop, with 1/4" thick plate, and gussets. What is he doing, running the shafts thru black pipe ? [img]/ubbthreads/images/graemlins/confused.gif[/img]