Technical What can i expect from a 355 with double humps and 30-30 cam?

Ive been on a few other boards and have found nothing but complete hate and discontent toward double hump heads. My wifes 79 Camaro has some 186 2.02s and its a complete beast! A lot of other forums bash them and act like just anyone can drop a G on some aluminum heads. I got 3 daughters and a wife, aluminum heads are not happening for me. Plus I like maintaining period correct. That being said I can get some cleaned up double humps with 2.02 valves all day long in the Ft Smith Arkansas area for like 300 bones. I was thinking of R and Ring this 010 355 I got, putting a re pop 30-30 cam to it, and a old 300-36 holley street dominator intake. What can I expect out of this combo? Am I going into the rite direction? I know it has probably been done a million times in the 60s. I got my eye on a couple early 50s chevys to put this in. This will be my first pre 67 build. Thanks much in advance.

 

Like many others I am not a big fan of the double hump heads, they work well enough though.

I think that what you can expect out of the heads is dependent on the short block. Well that and how well they cleaned the ports up with the new valves and if they went through the trouble to unshroud the intake.

With that combo I would look for a different cam shaft myself, especially if I could keep my compression in the 9.5 to 10:1 range. A Z-28 off road cam would be the bomb or even the original stock Z-28 cam. With the duntov cam I would not expect more then 1 HP per inch, if that much.

There that should get the ball rolling for you.

 

Compression is your friend. Shoot for high 9, 10.0:1 MAX with the iron heads. If you go less you are leaving free HP on the table seeing as how it's a complete rebuild anyhow. I'd personally run a Performer RPM... air gap if you can even, but at least an RPM. If you want it to look "period correct" grind off the raised lettering to give it a generic look. Use a BBC ratio full roller rocker under the valve covers (nobody can see it anyhow) to get another .030 lift out of that solid camshaft. Knife edge the crank before balancing, windage tray... it'll run well IMO.

 

I found what claims to be a replica of the off road z28 cam, crane part # 968821. Is that like the cam your talking about? it seams like those z28 off road cams are x nayed. I've got some 4 relief flat tops that where in the motor that look good, will that help me keep it in the high 9 to 10.0:1? What should I look for in heads to keep me in that compression ratio range? A good friend of mine races on the dirt track and has like 20 sets of those double humps, so I get my pick if I come by. Plus the 882 heads that were on this motor are now a door stop/ ash tray (don't ask im from Arkansas).

 

I've never ran roller rocker arms with a solid cam but I've heard it works darn good. The only reason i was thinking about the 300-36 manifold was because of the size of the runners and good experience in the past.

 

I have lots of friends in Ft. Smith, great town!
I can only speak from personal, seat-of-the-pants experience. From 1979-1992, I drove a '53 F-100 that had a .040 over 327 backed up by a Turbo 400 and the Ford rearend that came with the truck (3.92 gear ratio). I had a 350 horse 327 hydraulic cam, 2.02 double-hump heads with screw-in studs, Edelbrock TM-1 intake and a 650 Holley. The truck ran like a scalded cat. Even more so when I borrowed a friend's 780 Holley just to see what it would do with more carb. I would not hesitate to run the same heads again, not at all. One of the most fun vehicles I have ever owned. I sold it to a friend and have been trying to buy it back ever since. Oh, if I drove it nice on the highway, even with the steep rear gears, I could get 18+ mpg, and the inside of the tailpipes would be a nice light gray color.

 

Sound like a good combo. But I would shoot for a dual plane intake. You lose a lot of bottom end power with a single plane. And that's where a street car spends most of its life. As far as double hump heads. If you could get a set of 461 or 462. Ready to run. Go for it.


Posted using the Full Custom H.A.M.B. App!

 

derpr, you're absolutely correct about the dual-plane manifold but both the Holley 30-36 and thr Edelbrock Performer RPM are dual plane. I've used both with great results. If you grind off the Holley name the 30-36 looks a lot like a period correct Z28 manifold.

 

I have a similar set up in my '55 chevy and 4spd, 355ci , roller rockers, aluminum factory mid rise Vette intake, 2.20 valve 461 double humps because they are traditional and flow well, I am not sure the specs on the 30-30 cam but my Engine pro cam is .510 lift and works perfect with flat top pistons getting the CR around 10.5:1, The desk top dyno program said about 390 hp, but my estimate would be closer to 350hp which makes it alot of fun.

 

A duntov 30/30 does not approach a .5 lift. it is a .485 lift cam minus .030 for valve lash which puts you in the neighborhood of .450-.455 lift.
The L-79 cam ( what some call a 350 horse cam) is a good street cam but it is hydraulic and won't clatter like a loose running 30/30 cam. the lift ends up being close to the same.

With a flat top piston and the small combustion chambers depending on deck height you should be in the 9.5-10.5:1 range on compression.

I am going to stay with my estimate of 1 HP per inch as an estimate not knowing the entire build, there are just too many variables. The engine should be plenty healthy enough for a streeter.

 

I can't give you a horsepower number, but it would be a fun engine for sure. I have a similar setup in a 55 Studebaker, but a 327. It runs hard. I am running the z-28 grind solid lifter cam. There are better heads out there, but, like you, I cannot afford them, and I have been happy with my double hump heads for 20 years. At this level there will always be somebody faster, so build it and have fun. A little pocket porting and gasket matching won't hurt either. The heads I am putting on the 327 I am building now cost me $400, ready to run, although I had to replace the valvesprings.

 

With the standard 4 relief flat top pistons (-6cc) and a 64cc chamber, you should be at about 9.7:1 with a Fel-pro 1094 gasket and .025 in the hole. If the heads need to be cleaned up you could mill them to raise it a tad. There are better cam choices out now than the original Z-28 or Duntov grinds but IDK if it's a period correct build you're after so... The Edelbrock Performer RPM cam runs hard in a mild (tame), street build SBC. I had the combo with intake & springs in a '78 F body and it ran well even given the porky weight. Isky 201025 is another. Be sure to use proper valve springs and a good double roller chain. Do try to gear the ride properly to compliment the engine's power band. Otherwise it'll sound all lumpy yet be a turd.

 

The block i'm working with has never been decked. I was thinking about a l79 cam as well as the 30/30. And for the price I can gather these parts up for id be completely be happy with a 350 hp. I got till Friday to make up my mind, and gather some good info. The Friday after that is when I get to find a victim car for me to curse at and spill beer on for the next couple months

 

For the most part all you will loose with the 350 hp cam is hassel and valve train noise.

 

If you can get a set of double humps with 202 valves that has good seats and tight guides for $300, sure run them. Everything I found with double humps over the years is beat. They will get the job done, as a point of reference the iron vortec heads with stock valves will make more power with less cam.
So a 355 with double humps and flattops, if you can deck the block to get your compression up, a lot of rebuilder flattops are even farther in the hole than stock, measure your piston compression height and see where you're at. There's plenty on the Web on where to do a "little" grinding on the double humps to get the best out of them. If you can get 10-1 or even 9.5-1 out of the Pistons you have you'll be ok. Look for a cam in the 480 lift range, adv duration in the mid 230's. If youre running an auto that combo will like a 2500 stall. If you're running an auto with a stock converter back the duration off to the high 220's and lift will be around 465-470. Holley 650 double pumper, presmog Qjet, holley vac sec are all good choices in this range and really depends on how you want it drive it, performer to performer rpm style intake, again depends on how you will drive.
there's a lot better cams out there than the 30-30 that was designed for sustained rpm on a 283 when the valve trains available were basically shit.
At 470 to 480 lift you can run the Z28 rebuilder springs and be ok, it's a gamble on pressed in studs, you can pin them or install screw ins.
I've built basically this same combination at least 20 times, solid street small block, sounds great, performs well. With a decent gear in the car this will run hard.

 

Notice you mentioned 882's, these are 70's smog heads with 76 cc chambers. The circle track guys liked them for claimer classes, run then with a large dome piston, 202 valves and hog the ports. The large chamber and pop ups pretty much put all the combustion activity on the piston dome and the thinking was the large chamber unshrouded the valve. If they were run on a 400 block I saw a lot of them with milled areas out to the edge of the bore to further unshroud. This was about 1990. Once the vortec came along they became the go to claimer head.

 

OK here is my thought on this as I have been there done that. The 30/30 Duntov cam is great in a 283 but in a 350 it is very mild. Also the "REAL" Z28 off road cam is really radical. Last 3 numbers are 754. I think the lash is Int 28 - Ex 24. It idles some what around 1400, It eats plugs like crazy. Pulls hard from 3k to 9k - Blows up at 9500.
If you want to make a good street engine use one of the Comp cams like they used when R&C built their 57 chevy. Man what a great sounding cam and pulls like crazy to 7k.
Double hump heads are OK if you were back in the 60s but a good set of Alum heads will greatly out perform them.

 

I'm also too cheap to get a set of high dollar aluminum heads so I waited around and got a set of World Sportsman iron heads used. 2.02/1.60 stainless valves, triple springs, screw in studs, 64 cc chamber - I think I have about 275 into them. I ground off the letters n such on an RPM intake and painted it all cast iron grey. No horsepower number to claim but they run better then the 487x that were on there before and at a glance looks kinda old-ish (if you don't know what to look for and don't see very well). Definitely can find a more appropriate cam than the 30-30 though (sorry Zora).

 

When I did the double humps in my old ladys Camaro, I put a comp 282 cam in it. It seams to be a stout set up, I just want to do something different. This was another thought http://www.summitracing.com/parts/isk-cl201281/overview/ a isky mega 280. Lets say I caved, could I run a set of vortec heads without having to screw with them too much? Will the stock springs in vortec heads accept the .485 lift from that cam?

 

Dude id do those 882s but they look rough! Ill soak them in gunk over night and see if they would be worth building. I guess that wouldn't be a bad idea though, I just heard everyone say they are not worth it.

 

For YEARS my back-up road race motor ( that I threw in when I blew up the big bucks motor) - has been an old 70 LT1 350 crate short block ( I think 11:1 cr ) , 2.02 double hump heads, and a hydraulic lifter Lunatic short track cam ( no Idea of specs anymore) , with an air gap single plane manifold and 750 holly.

It has been a wonderful motor - great torque, about 400 reliable hp, and sounds killer. I have had other competitors at a track come over and tell me how good it sounds.... Has seen temporary duty in a road car or two......may be going into the Devin build...


Posted using the Full Custom H.A.M.B. App!

 

Last year a friend put $835 in a set of double hump heads, Ex. seats ,exhaust valves ,guides, three angle valve job ,screw in studs ,surface,Springs ,retainers, cut for positive seals, hot tank and magnaflux. He could have bought a set of Iron Eagles that would have beat them face down on power for $700 new.I understand the nostalgia thing but in my opinion unless your building a 100% original car ,sell the double humps and buy a good set of heads.

 

I run double humps and even powerpacks. I use the old C3B edelbrock or Z28 dual plane intakes. carter AFB carb. and I like the solid lifter 30-30 cam. I set it a 28 & 28 lash hot. A 30-30 cam will work with a stock valve train and not collide the valves with the pistons. For Me Its all about not spending a lot of money and having fun. I installed a old set of 57 powerpacks on my 69 327 engine. that I built for my55. I used them because they came on the first 55 chevy I bought. And I have a set of the old cal custom finned aluminum stagger bolt valve covers That I bought when I was a kid and wanted to use them. Shure there are faster options. However this is the Hamb and guys will spend lots of effort to use inferior obsolete parts. Look at the money guys pour into a ford Y block or a buick nailhead ect. Build your engine and use your double humps and preferred cam. If its not what you want you can always change the heads and cam to something else. The best thing ive found aftermarket cams and springs are good for is wiping out cam lobes and circulating ground up metal through the engine.

 

4thhorseman, the Holley 300-36 is the same high-rise, dual-plane intake manifold that was patterned after the Winters Foundry aluminum intake that they cast up for use on the '68 Camaro Z-28. Same as the Weiand 8016 and the Edelbrock Performer RPM. The new design Weiand 8150 has almost the same exact carb pad height as the RPM, so it would also be a player. I would hesitate using the Air Gap in any climate where it gets cold and the motor will be for use on the street. It's just more hype and bullshit, like the roller-tip rockers that Comp markets, the ones with a sliding ball fulcrum. That debacle was designed bass-ackwards. They should have been made with a needle bearing fulcrum and a conventional walking shoe tip. The roller tips slide around on the valve stem and don't add a damned thing, except to Comp's bottom line. As far as hump heads, after you get through replacing valves, guides, seats, springs, magnaflux, and a flat mill, you will have as much or more invested than you would have in a new set of Pro-Filers that will outflow the humps 2 to 1. And they're still made of iron, limiting your static compression ratio on pump gas to around 9.5:1 to prevent detonation.

 

1969 301 30-30- duntov camel hump heads lots of farmer tricks, in a 63 2dr. biscayne running wide oval tires. Best 1/4 mile at U S-30 13.60 Don in Indiana

 

Was that "in 1969" or a "1969 301"?

 

I bought a set of larger stainless valves on the internet and put 202,s &164,s in my 66 camel humps. You don't need both hard valves & hard seats. Just one or the other. If you use stainless valves you don't need hard seats for unleaded gas. A three angle valve job leaves a narrow seat that doesn't collect carbon as easy. I cant understand the negative bias against the camel humps? good grief this is the Hamb we put dual carbs and split manifolds on 216 chevys blowers on flatheads ect. 1964 is the cut off year. the camel humps where the best heads available in 1964. the 30-30 cam was pretty good back then also.

When I was little I lived at Portage Ind. At a place on Domby Road across from Domby Lake. It was nicknamed Hillbilly Haven! We went to the Us 30 drag strip.

 

the last double hump heads i did about 10yrs ago cost the customer $1000.00 we changed everything, valve,guides, angle milled, screw-in studs and guide plates.victor jr intake 2" spacer and a 750 holley, custom ground cam.
i've run the GM 754 off road cam in a street car with double bump heads, a powerglide and a vega torque and 4.88 gears pulled to 8000rpm no problem

 

I know this might be obsolete Info, but double hump, power pack head it Mickey Mouse heads, was hands down the best avalible stock head. Was good enough then, and should still be. To a degree, but there is better heads avalible in this day an time.
If you got a good set and you are going time perfect, do it.
If you go all time perfect, 327 block small journal/front mounted, no acc. holes in heads and Road draft tube, by all means use them.

But for any other aplication, go on to craiglist, search low mile/resent rebuild(paperwork)/project abandont etc. Paint them same colour as block, and dont look back.

Same with cam, 30-30 is good, but not the only good one. price, avalibility and aftermarked help is more important. You can do what ever you want cam wise, and the eight people in the whole wide would that can call your bluff, buy them a beer, and move on.

Make you wallet happy, use the money on making your outside look fit the time frame of your car.
Nothing stick out more then a billet valve cover or a or goodwrench stikkers.
This might set someone a blaze, but then let this the one thing on top of the other.
I'm out -0-

 

back the truck up....
what are you building ?
street strip car?
drag car?
cruiser?
parts chaser?

these are the questions you need to answer first
will the car have power brakes?
automatic or stick ?
how much will it weigh?
any 350 chevy will make 350 hp with flat tops , 2.02 valves, 9.5 to 10 to 1 compression and a reasonable cam choice

and if you don't want the hamb police after you ... don't mention your 79 Camaro again