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Discussion Starter · #1 ·
Hi,am new here and wanted some help with my cam choice,have a 65 ss impala with 327,350 trans and 3-36 gears,has been running with wrong heads and today i finally scored a set of 186 camel humps with 2-02-1-60 valves,not easy to find here in new zealand,now i want to freshen the heads and change the cam as wanting more power up top,is running stock cam and 520 small valve heads,what camshaft should i run for good power and performance without going to high stall converter, was thinking comp 262 or 268, or summit 1103,any suggestions, have posted intro, cheers
 

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"more top end" and "stock converter" are diametrically opposed. You can't have your cake and eat it too.

Any cam you bolt into the motor has an operating range of around 3500 rpm's. You can put that 3500 anywhere you want to....idle to 4200 or....1000 to 4500 or....1500 to 5000 or....2000 to 5500 or....2500 to 6000 or....3000 to 6500 or....3500 to 7000 or....4000 to 7500 or....well, you get the idea I'm sure.

As you move up in the operating range, the intake closing point on the cam moves further away from BDC and you make less and less cylinder pressure because as the piston comes up in the bore on the compression stroke, compression does not begin until the intake valve is closed. So, if you close the intake later, you have to raise static compression ratio to make up for the loss of some of the intake mixture being blown back up the intake tract by the ascending piston. Also, as you move up in the operating range, it takes more and more valve spring and associated parts to allow the tappets to follow the cam profile and close the valves properly without float.

On a more or less stock 327 with a stock converter, I would bolt in a CompCams XE262H and be done with it.

If you want more top end, you're going to have to start spending more money to change other components in the motor and also shell out for a looser converter and shorter (numerically higher) rear gear.
 

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Now the facts

The specs on the Comp Cams 265 DEH and the Summit 1103 are the same as are some other companies,there are generic grinds that several companies use it's all a matter of profit for them( you can always buy a Comp Decal) if you read the fine print on Comps website a lot of the cams recommended here so far do require you change springs and retainers also once you exceed .450" lift you should change rockers also.So,best bang for the buck: Summit K1103.Summit 141506,Summit 174000 for a good match for an intake the Weiand 8120.
 

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Discussion Starter · #6 ·
ok,thanks for the info guys,am already running edelbrock performer intake ,eddy 600 carb and headers,with stock cam and 4520 small valve heads ,shift kitted turbo 350 trans i was running 15.5 at 89mph,the impala pulls from low and runs out at about 4500,was wanting to improve without too many changes,with getting the 186 heads with bigger vaves and better flow should improve,in two minds now about cam choice,my 186 heads have 7/16 studs and double springs ,i may consider a set of 1.6 ratio roller rockers and stick with the cam in it to improve lift and retain lower power,with the better heads do you think this will help my performance? cheers
 

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I wouldn`t keep the stock cam, especially with upgraded springs on the heads. The 268 as I mentioned would work fine. If you already have headers and I sure hope you do then a single pattern cam like the 268 is all you need. Chevy heads have almost always had a very efficient exhaust port, the intake isn`t as great so there is no need for more lift and duration on the exhaust side. With the better heads you`ll see some gains with a stock cam but nothing like what you`ll see with a better cam. If the heads breathe better as the 186`s will then the cam will also. If you go with a new cam you`ll need to use valvoline racing oil for the break in and there after. If you use regular oil without Zinc and other anti wear ingrediants the cam will go flat. Since you`ve mentioned the heads have 2.02 valves I hope the chambers were unshrouded.
 

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Discussion Starter · #8 ·
Thanks,heads were off a dz302 engine z28,owner had decided to put alluminm heads on,use to run these with roler rockers hence the 7/16 studs,will take your advice and go with 268, cheers
 

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Techinspector has thrown out some good stuff as well as others. I have done similiar to what you are attempting and there are a few things I will throw out for thought, even though you may have all ready made up your mind. You have an E-brock Performer intake which matches well with the smaller valve heads you have. Going with the bigger valve heads precipitates more changes to help your motor increase it's potential. Yes, a more aggressive cam is in the equation, but as TI said, you need to up your operating range to realize the benefits so you need to also go up with intake as well, say to the E-brock Performer RPM. You could go on E-Brock's web site and look at their packages that include "Preformance packages of Heads, Cams, Intakes, and Carbs". Look at the specs of each of these and go from there. You don't have to buy their products because you can get the same specs from other manufactuers. Balance out your components is the name of the game!!!

My 327 has a Comp Cams improved, dual pattern, regrind of the 300 horse Vette 327. I had a dual plane Bow Tie high rise intake and the same heads as you have with a worked Q-Jet. It worked great. I have since replaced the Q-Jet and Bow Tie with the E-Brock Pro Flow with the two barrel air valve and it is a little screamer (worth about 45 HP more over the carb) even though some of that comes from the intake which is virtually an E-Brock Air Gap modified for the fuel rails and injectors.
 
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