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Discussion Starter · #1 · (Edited)
Alright, I have my whole front end off and I can hug the radiator fan. With all this room, I decided its time to pop it off and swap out the restrictive stock cam with something else.

Engine: Stock 400 SBC (All stock) 4bbl Rochester
True dual exhaust
30,000 miles on engine
TH350 trans (stock)
Stock rear end

What I am looking for in the cam

Torque to me is worth more than Horse power
Economy is always great, gas is expensive
That rough idle sound is pleasing to me (Comp Thumper perked my interest in that category)
Performance boost

But I'm open to everything and all ideas
Looking to keep cost down to as little as possible
Not looking to create a nascar engine
Just a nice driver
I plan on driving the elco daily

So, Begin the choosing of my new cam! Internet links always help but not necessary!
Help me choose this cam!
 

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the thumper is a good choice, but may be tamed down somewhat in a 400. depending on your compression ratio at the rebuild. if you are at 8.5 to1 i wouldnt go any more than the thumper as you wont have the compression and will make the motor doggy down low.what pistons and heads are you running
 

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If I am inferring correctly that you have a 4000 lb cruck, stock converter, 2.73ish rear gears, 8.0:1 compression, I would say something mild like a 214/224 would drive better than something lumpy that sounds mean would. I've run a nasty sounding 241/241 in a 10:1 Buick 455 with headers and 3:55 gears; when I dialed it back to a 224/234 I lost the mean sound but gained leaps and bounds in vacuum for brakes, low end torque, off idle punch, etc. Not to mention it's quicker in the quarter mile, too. Go mild.
 

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Most people try to run too much cam for the compression ratio they have. What ccc (Carl) said is good advice. Lumpy cams usually mean lower vacuum for power brakes etc.
My 400 has flat top pistons, and I'm running a Comp Cams 280 Magnum cam with 230 degrees @ .050 lift. With stock type dished pistons, this cam wouldn't work well at all, and the engine would be a real dog ( woof, woof ) !!:smileyb:
!
 

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I believe that with the stock dished pistons, like 8.5 to 1 compression ratio, even that duration at .050 might not be the greatest set up, but it may work OK.
Do you know what chamber size the Vortec heads are ? Some research should turn up that info. If they are smaller in CC size, you can use a longer duration cam.
You will need a different intake manifold for the Vortec heads also.
 

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COMP Cams HYDRAULIC − Factory I.D. #3863151 for:
factory 350 hp. Hyd. Hyd. 1800 to 5800 151H 342 342 222 222 .447 .447 114°
I had this cam in a 400ci with 2bbl....:beer:
 

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While your brainstorming, look into the lunati voodoo series cams. In the ls engine version I,m interested in , they made more overall power & peak power using less duration than their older series of cams. Hmmmm?
 

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I would listen to what they are saying about the aggressive cam. I don't know what cam is in my 77 305 but it is way to much. My car idles in park at 1,500rpm and drops down to 800 when in gear. The rear gears in mine are 2:56. I would guess yours are the same. Also as CCC & Steelybill said my brakes have no power assist at idle. Its a real pain when parking it almost did not pass saftey because of how hard the brakes are. I two foot drive it because they are so hard. Your motor will make more power than mine with any cam your choose but if I drove my car everyday I would go with a smoother cam. The thumpy idle is sweet but you look kinda foolish backing into light polls because you cant stop from 5mph, I almost hit one at a cruise night.

I did not see it mentioned anywhere, are you looking to go to a roller cam or are you sticking with a flat tapped cam?
 

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Just keep in mind that any cam with more than 220-225 degrees of duration will require at least 10-1 CR to make good power. It will also kill your available manifold vacuum and cause you to fatten up your idle mixture due to intake dilution. Chose between "thumpin" and running well. Big cams and big carbs to not necesarily develop big power. Keep it mild and you will have the best of both worlds> good performance and good economy.
 

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Thanks Steely, I'm not worried about the cam in my 305. My big block is at the engine shop as we speak. Block fluxed out ok, waiting on word about the heads. Should be done sometime this year.

Back to F3nderbass' question, i'm in the same boat as you are right now for my aforementioned big block. It gets confusing when for every good thing you read about a comp, edelbrock, or lunati cam you read another bad thing from someone who had their motor blow up on them. I was leaning towards a Thumper roller setup for the longest time but the lunatis are starting to grow on me. I am going to talk to the engine shop to get his input.

You should check out this catalog from Lunati it has some good general advice about cams. I'm sure comp, crane, and edelbrock have similar catalogs as well. http://www.lunatipower.com/PDF/Lunati-Catalog-2012.pdf

The Bare Bones hydraulic roller packages seem very fairly priced. $600 for the cam and lifters.
 

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Discussion Starter · #15 ·
I am looking into more mild cams now, or at least something smoother.
Trust me, ive driven low vacuum now that I think about it in my uncles 72 GS 455, and man was that scary stopping that thing!
I Like the suggestion of something round 214/224
And I'm looking to keep a flat tappet cam, as I said, lower cash > spending more haha
 

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For cams with low vacuum for brakes, a vacuum tank can be plumbed in, as a reserve vacuum source. I see that Summit carries them. Another way is an electric vacuum pump. The electric pumps are pricey though.....
Another alternative is to find a belt driven pump off a diesel pick up and make up some brackets.
 

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look here,, you start talking vacuum canisters and roller this and that you might as welll throw your check book out the window,,, do yourself a favor,,,, ask this //????
what is the realistic goal for this build???
call a cam company----like comp cams ,, 1800 cam help...
they will ask you tons of ???? be honest in your answers and you will be happy
if it was mine i would go no bigger than 215/220 duration @.050 and no biggger than .430 lift
this will give you more torque down low,, keep the revs down also , no need to spin past 5000, rpm
a good 750 cfm quadrajet fom sean murphy or mountain man,,, and be happy----remember you asked:poke:
 

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It's according what you're looking for in a cam. If you are going to be racing then buy the cam for racing. If you are going to be going to the car shows, sounding good and looking good, then but a thumper. Some people call them the "show car cam" becuase they sound so good but don't run as good as they sound. I personally thing mine runs great. The thumper cams have alot of valve overlap which gives it that deep chopping sound. From what I understand it cut backs on the performance and also the manifold vacume. I can speak for the low manifold vacume. I tried the vacume pump but it didn't work for me. The only place I had to mount the vacume pump is under the hood, mounted to the plastic fender liner on the drivers side. When I cut the pump on it sounded like my motor was coming apart. The vibration of the pump against that plastic fender liner made a hell of a racket,,,,,is racket a word?? Anyway, I ended up getting a vacume canister. I got mine from Comp Cam for a little over $100, it works for me. You can run low on vacume if you pump your brakes alot or have to use them alot but so far mine has worked well. You can also get what they call a hydroboost. It's a brake booster that runs off your power steering pump instead of your mainfold vacume. It's pretty neat, kinda pricy but neat. Google "hydroboost"
I don't care what they say about the Thumper cams. I love mine. I'm not going to the drag races with it, I don't race everybody up and down the road with my El Camino, I like to cruise through town, lookin good and sounding even better.
 

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I would stick with something in the 214° - 224° as well. You need compression and stock rear gears are the worst for a higher rpm cam, seems like it takes forever to rev. If you dont want to increase comp and do a 355 or better rear gear I would go mild. GM used to make a cam they calles the "performance RV cam" i will try to look ip the specs on it, but it was a great street cam.
 
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