I know this gets asked all too often, and I did a search, but didn't quite answer my question. Looking for cam/engine guru's to see if I'm about to over-cam an engine I'm having built. Currently have a 305 with a poser....errrr, thumper cam. Sounds great, but is completely gutless. I'm about to purchase a 350 short block, bored .30 over, with flat top pistons. Will be putting 194 double hump heads on it as well. Rear end is .308, and running TH350 - the car weighs 1900lbs and I'm running a 2400 stall. Guy at the machine shop said he recommended a "151 grind" cam. I asked for more details and he ended up giving me Melling Part number 22200 so I could look up the specs. Duration 290, Lift .298 Thats more duration than the thumper (279 I think), but am unsure what the lift of the thumper is. I'm jsut worried about putting it in an overcam situation again where I have no low end power once again. Sorry for stupid questions - I'm new to the motor game, and have been completely confused and baffled about what cam to use. I want a good lope, but don't want to lose too much low end.
Dude, go look at the top cam makers sites. They break it down for you. Lunati, Comp, Crane , ect. A .454-470 lift intake will be a good driver w/ power and a lope to the idle. Duration will be high 'teens low 20's. on the .50.
You may consider a GM grind for your small block I like the L-79 cam for a street motor, with good heads and moderate compression it should net you a good flat power band and still have a mild lope. Crane makes a good blueprint of the L-79 there are others but I like the crane personally. if there is a brand that you prefer you may find that they make a boueprint cam of the same grind. Is the cam you are looking at 290 duration and 498 lift? 298 lift isn't comming open very far. I wouldn't be afraid to run a cam shaft with those specs either, I would want the lobe center to be between 110 and 112 for a steet motor though. Overlap will kill you on lower end.
If you want a parking lot cam, then by all means use a thumpercam,all noise and no go, duration should be at 220 -230@.050 and 112 -114 degrees , then it will Idle and run great , IMO
The specs of a stock GM "Hot Cam" for the 5.7 part number 12480002 is the following Cam Style: Hydraulic roller tappet Basic Operating RPM Range: Idle-6,000 Intake Duration at 050 inch Lift: 218 Exhaust Duration at 050 inch Lift: 228 Duration at 050 inch Lift: 218 int./228 exh. Intake Valve Lift with Factory Rocker Arm Ratio: 0.525 in. Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.525 in. Valve Lift with Factory Rocker Arm Ratio: 0.525 int./0.525 exh. Lobe Separation (degrees): 112 They have always worked well for me ...Sounds like an awful lot of duration on your cam .
Sorry, I failed to highlight the fact that I'm completely retarded when it comes to engines. I built the car, but outside of changing the cam and the intake a couple of times, I don't know **** about engines and am in the learning phase. Time to buy a book I spose. Here are the specs of the Melling cam. Would like to stick with melling if i can as I have a contact who has a contact who can supposedly get me a good price on one. <TABLE id=prodspecs cellSpacing=0 cellPadding=0><TBODY><TR><TD>Intake Cam Lift Duration:</TD><TD>290</TD></TR><TR><TD>Exhaust Cam Lift Duration:</TD><TD>290</TD></TR><TR><TD>Intake Cam Lift:</TD><TD>0.298</TD></TR><TR><TD>Exhaust Cam Lift:</TD><TD>0.298</TD></TR><TR><TD>Intake Gross Valve Lift:</TD><TD>0.447</TD></TR><TR><TD>Exhaust Gross Valve Lift:</TD><TD>0.447</TD></TR></TBODY></TABLE> Intake/Exhaust Cam Lift Dur: 290 Intake/Exhaust Cam Lift: .298 Intake/Exhaust Gross Valve Lift: .447 Is that information more suitable? My understanding is its suppose to be Mellings version of the L79. Which I understand is great in the 327, but gets a little mild in the 350? Don't want too mild though - still want to have some fun and have a nice little thump.
Think you better check those specs again. I think that cam is a copy of the old Chevy 350HP cam and it should be more like .447" lift and the 290° duration is at 0 (290° at .050" checking) and 107/117 lobe center (112 seperation). Not TOO MUCH cam by any means If the cam you have is the Thumper, not the Big Mutha, then the comparable specs are .518/.498 lift and 227°/241° (intake/exhaust) 102 centerline with a 107° lobe separation So compared to your Thumper you have less lift and more duration,the centerline is difference is where the lumpy idle comes from.
What do you expect form the engine" (Sound good?, Loads of torque?, Top end performance?, ) Summit has a cam that I like (SUM-K1103) not too wild, great power with a small stall conv and mild lope. I have used it on several SBC with those heads and flat top pistons. Maybe the Comp 268 is for you. Small lope easy on valve train. Which Thumpr cam do you have? I'll pay the shipping to my door
Thanks for everybodies input. I really need to buy a book. When building my car, I bought an already complete engine - robbing me of a learning experience. Naturally, I'm buying antoher alerady complete engine - once again robbing me of another learning experience. But short blocks are just so damned cheap - its hard to justify building one on my own. I believed CompCams marketing line stating that it will give you a hard hitting lope while not sacrificing engine performance. I got the hard hitting lope that I wanted, but it absolutely killed my low end torque. I had the regular CompCam Thumper (not the mother thumper). Replaced my stock cam in the 305 which had OK power, but was too smooth of an idle. Fell in love with the choppyness of the thumper, but was disappointed in the power I seemed to have lost. Sound and low end torque are my two preferences. But don't want to be like the thumper where its all bark and no bite. Want to have something to back it up. So...i guess torque would be my first priority, sound a close second, and top end performance as the last priority. Finding something with solid low to mid rpm performance would be good - while holding onto a descent lope. Can you have both without getting crazy on power?
I am not sure how mild it is or what one considers to be mild, I drove a 4000 lb pickup into the low 13s on that cam (well not the melling) and drove 3 hours on way to do it. Had the same engine ( 355 cubes) in a 2800 lb car and was running 11s on street tires. Granted it I will never break any records with it, but it it is more than enough cam shaft for most of the street driven cars on here.
Part of the problem you had was the 305 is a low performance motor to start with and the Thumper was too big FOR THAT MOTOR.
I think 290 is to much for the street. It also seems your initial numbers are off. I have a stock cam, and .040 over engine. Head work, 110 valve seat pressure. I can fry the tires like no bodies business. Your stahl on your converter is half way through your present cams power range. You also got the advance or retard install option to. Bottom line. Less is more in most applications. Stick with a 230 to 250 duration, and maybe a 488 or so lift cam. A 1400 stahl converter. 194 heads arent gonna help your gain quest. If I am building a street burner, I always go 2:05's. Your runners are set up for smog control, not performance. Open the valves and get them closed. Hanging - um open is hurtin that engine power, cuz the runners and valves cant flow enough. Good luck
Ok...i'm starting to feel better about this melling cam now. i thought about a thumper for the 350 as well, but I really want more performance to back it up. Getting the impression that the Melling 22200 isn't too bad of a choice. May be hitting the book store after work. EDIT: Damn: after reading one post up, i took a step back and am questioning myself again. I would have prefered the 205 double humps, but the price was too good to p*** up.
I commend you Jmel for actually giving quite a bit of pert info!! Now you did leave out at least 2 importand factors- intake and carb, and even exhaust for that matter. Cam selection sorry to say, you won't really learn from a book. Perhaps understanding some terminology and basic functions, but chosoing a cam not so much. You are doing well by asking here on the board and of course next step would be the cam manufacturers. If you can afford a up grade to a retro fit roller lifters and roller cam, by all means do so. Also, cam selection COULD include a spring and retainer up grade and you should work with the machinist so he doesn't set up clearances and then won't be happy if you ask him to do it again because of your cam choice, so work together and ask him to wait and be patient with the cylinder head blueprinting and final ***embly. If you provide some of the above info, we can make a more knowledgeable suggestion for you, you are off to a great start!! TR
Thanks TR. I love this forum and community and have learned much from it. Also have taken something that I thought I understood, then flipped it upsidedown completely confusing me even further. But thats what I get for not starting this hobby into my 30's....old dog-new trick syndrome. Intake/Carb - running tri-power set up. Edelbrock manifold, 3 Rochester 2G carbs, progressive linkage. Headers - Open headers (lakestyle) EDIT: Upgrading to roller is on my short list...but I'm blowing my load in this engine as it is. Was all I could do to convince the wife to let me spend what I'm spending. That alone is somehow or another going to cost me big - and valentines day is coming up, so its not going to be pretty and will likely involve flowers, candles, and romance - and who has time for that???
Heres something else important to think about friend. The converter you have in a car as light as yours, will not handle much of a aggresive cam. 2400 stall in a 1900 pound rig will start to flash well under 2000 RPM, so that must be considered as well. It not's fun fighting the brakes and cam when the converter is mismatched for the app. You will be OK with examples as the 151 GM cam with your converter, no problems there for instance. The 3:08 gears are not helping either but a good cam is still doable.
Mind elaborating on "flash well under 2000 rpm"? ***uming this melling cam is a 151 variation - I feel better about my choice again. At least until the next person tells me that it ****s and I'll freak out all over again like I have a couple of dozen times over the past week. The cam decision seems to be the hardest choice I've had to make in the entire car build process.
That's what I mean when I say fighting the brakes. The converter is starting to do what it does by definaition. The converter does 2 things, Multiplies Torque. It is a Hydraulic Coupler between the engine and trans. In laymans terms, it want to start moving the car forward, hence your forced to holding it back with firm brake pressure.
JMel, something you might want to consider: You live "local" to our LT1 head porter/cam guru, Lloyd Elliot. I don't know if he does anything besides LT1 engines, but is certainly one of the best in the world with them. He specked me out a custom grind cam that does exactly what I wanted for only a few bucks more than an off the shelf cam. If you want to visit him he's in Red Oak...barely southwest of you, and his phone number is 972-617-5671.
Dog cam, good back in the day but with todays modern grinds you will make more horsepower and torque with a recommended cam from Comp or Lunati. I have built many 327 small blocks and made the mistake of using the L-79 grind once, It just did not have the torque like the Comp cams 268 XE.
I agree w/HOTRODDON. The 305 was never enough motor, especially if it was a stock head and compression 305. My last cam experience was a 4.3 V6 which we used a Comp w/325 dur and 513 lift, .030 over, cleaned and gasket matched intake and heads w/TH350 and 3000 staff. Even though I should have built a SBC, the V6 ran pretty darn good. You already have the stall so don't go down in cam size. Then you will not have enough power to benefit from the stall. If you go down in stall you will want closer to a 1800 stall. Run that cam in the 350 crank some timing in it and let it eat! Those are good heads and cleaned up a little will work great with that combo. Just my 2 cents.
Here you go; The Comp cams NOSTALGIA PLUS 12-671-4 N+L79H this is my recommendation, TOTALLY HAMB friendly cam!!! You will need springs and checking the usual clearances for the cylinder head ***embly, TR
With the light car ya got and that 3:08 rear gear ,any cam you pick will respond better by simply adding a 2500 stall convertor.....that will help your launch and thats the most satisfying part of accelerating......The 73 75 Z-28 camshaft[350 horsepower -350cu in] is a great cam and not to jumpy/bucky....GM spent a lot of dollars to get the 350 to perform,and they didnt give a **** how lumpy the sound was....sound is not speed.....go with the engineered cam it will out perform the poser aftermarket cams.
The L79 cam is a good cam if used how it was designed. The 350HP 327 with that cam had 11:1 compression and used the 2.02 version of the Double Hump heads and a 585/600 Holley. When equipped with a 4 speed this combo was tough to beat on the street back in the mid 60's. There is quite a bit of overlap in that cam, so If you ran an automatic you needed a 2500 RPM converter. Grumpy Jenkins was a national record Holder in C/S in the low 11's with a L79 Chevy II
Sure, but if you are going to run that cam make sure you have enough Compression for it to run right, especially with the smaller valves. That cam also wants to see better exhaust scavenging then a set of lakester style headers is going to produce. If you don't have the compression and a good set of 4 into 1 headers, I would run something smaller.
Based on displacement, pistons, "recommended" cam from machine shop and 194 double hump heads - the machine shop estimated around 10:1 or 10.25:1 compression. Don't know enough to validate or agree with him, all I can do at this point is smile and knod.
Here's a calculator to do your own CR ....hopefully you have all the raw data http://www.wallaceracing.com/cr_test2.php
You also need to consider your highway cruising RPM with a 3.08 gear w/tall tires and a high stall converter may not work.
The Jalopy Journal
