Camel Humps

[rpounds]

I need some opinions here . . . I know that nobody has any strong opinions on this board . . .

Anyhow, I have an opportunity to pick up a set of camel humps (291's) with 1.94 intakes and 1.5 exhaust, magnafluxed, rebuilt, ready to bolt on for a very (emphasize VERY) reasonable price. They have 64 cc combustion chambers, compared to my stock 76 cc smoger heads. They have had some mild port work done, mostly in the bowl area. Is this a worthwhile improvement, or do you opine that I should save my time . . . would it be worth while to pop these suckers on?

How about opening up the bowls further and installing larger valves? Maybe 2.02s and 1.65s? I will stand on the sidelines here and humbly await your musings.

Ron

 

[Hib Halverson]

Replacing heads with 76cc chambers with units having 64cc chambers will significantly increase the compression ratio of your engine. That is a good thing BUT only IF you can run that high a compression ratio and not have the engine in detoantion. With a maximum of 91-octane gas available in the western U.S., it's unlikely you can do that.

Your choices are to up the compression and start running a mix of pump gas and race gas or do some port work to those existing "smogger" heads. In fact depending on which set of big-chamber small-block heads (the L82 units are best) you have, they can be made to work pretty good with 2.02/1.6 valve and a street port/polish .

 

[69MyWay]

What Hib says is true. Cast iron heads don't work as well in higher compression scenarios on pump gas for street cars. Those heads worked very well back in the day of leaded gas and high RPM flat tappet cams.

I think you could get away with it, but your overall gain will be minimal because you will have to reduce your total timing curve, and or richen the mixture up significantly reducing other driveability areas. If you were to install a wide band O2 sensor in the exhaust with a rich/lean meter, you might be able to set it to the optimum fuel/air mixture and with a few other goodies pull an extra 30-45 hp out of that engine with those heads. You would feel that in the seat of your pants. If you are getting them for a steal of a deal, it might be worth giving it a try.

The 86 1/2 Vettes and up have pretty high compression for street engines. Believe it or not those aluminum heads only have like 58cc chambers on flat top pistons. They do have a pretty thick head gasket, but other than that they push up to 10:1 range. They are able to work well on the street due to the fact that aluminum heads do a better job absorbing the heat and reducing detonation. Plus, with the advent of the knock sensor they can retard timing as needed to avoid any damage.

If you notice, most of the high output street engine packages designed by Edelbrock push about 9.6:1 compression. This is basically a flat top zero deck piston, thick head gasket, and aluminum 64 CC heads. They get over 420 hsp from a small block with that compression ratio for the street.

I will tell you a little secret that I did on my 85 Vette. Believe it or not (I forget the casting #), I built a set of 305 HO heads with 1.94 1.5 valves ported and polished and dropped them on my 383 stroker motor with an otherwise stock TPI and accell fuel injectors. I had a difficult time getting the perfect fuel/timing setting. However, I picked up 3 mpg and went from 13.8 in the 1/4 to 13.0 with no other mods. My compression was well over 10.5:1 and I ran it on street gas. So, don't let these opinions totally scare you off. Sometimes the strangest things can work. Heck, I drove that car to and from work, cruising on the weekends, and it saw regular drag strip duty for three years in that combo. In fact, I could rip a 1.58 in the 60' with those heads on street tires and a 3.08 rear gear!

Good luck and keep us posted!

 

[vigman]

I have 461's

Which are the 2.02 version of yours.

Where I got stuck was NO ACCESSORY BOLT HOLES!

My 73 has ac and I was going to transplant these heads in mine. OOPS


So I'm going to build the Mystery 327 engine & crate it when I'm done, and continue the C-2 search.


I would buy the edlebrock aluminum heads for your ride! Bout a grand, everything new life is GOOD! ( don't forget the new cam!)

Mike

 

[rpounds]

The engine is from a '75 Chevelle. The heads that are on it now are the 333882 's. Static compression, based on my volume calcs is a very weak 8:1. If I use the same head gasket thickness, pistons, etc. as the current setup, I calculate the new compression ratio to be roughly 9:1. Does this calculation sound correct? Do you think that this ratio would be problematic as was indicated in Hib's and Chris' post?

I'm not really sure that the power gain is going to be significant enough to warrant swapping the heads out. I told myself that I was going to purchase a set of Edelbrock Performers in the next couple of months. However, there are some people who absolutely rave about the camel hump heads . . . my father included. Of the two camps, one side says that it's foolish to waste money on the Edelbrocks when I can have these Camel Humps for a 'song'. Others say to throw the Camel Humps in the trash and get the Edlebrocks. Part of this may be personal preference . . . but I'm more interested in the end results . . .

Any further comments in light of this?

 

[69MyWay]

Oh, with that kind of compression you will benefit from those heads. I was thinking that you had a more flat top type piston that would be typical for the stock vette motor.

I say go for it then. You will pick up MPG and performace with this combo. However, I would not suggest putting in any larger valves. With lower compression (and yes you are still on the low side at 9.1:1 or so) you can loose bottom end torque by installing the 2.02 1.6 valves.

Otherwise, I think you will be very pleased with this mod!

 

[rpounds]

Chris,

That's exactly what I was thinking. I need to keep the fuel/air charge velocity up for decent low end. You've confirmed my suspicions . . .