Cam help please.

[Datsun660z]

I am running a 30 over SBC 400 and my idle sux. I am looking for advice on a cam I could switch in for driving on the street to get a good to fair idle. I am running 76 cc S/R torquer heads from World. Speed Pro Hyper pistons with .100 dome Current Cam is * Advertised duration: 300 intake/300 exhaust * Duration at .050 in. cam lift: 246 intake/246 exhaust * Gross valve lift: .515 in. intake/.515 in. exhaust * Lobe separation: 108 degrees. Toped off With 3/4" raised Plenum Weiand Team G Intake With A Holley 4160 750 vac secondary carb. I will keep this cam for Playing But I would like to use somthing for just playing on the street Thank you All. Jon

[Guest the_dj]

This is the kind of thing I wouldn't understand because I've never been in a car with a rough idle like that. I need to be in one sometime or I'll find myself getting a cam like that not even realizing what I've done.

 

I just seem to see the extra power and none of the downsides from here in the computer chair.

 

DJSS

[Guest Anonymous]

Well the theres alot of factors to think of when choosing a cam.

1. What application (alot of people get 305 comp cams because of the duration, yet they do not have the carb, stall converter, engine combo)

2. Did you degree the cam? Degreeing a cam to the exact recommendation to the combo you have might be your solution.

3. Cams suck up alot of vacuum, I took care of that by getting a 87 Cadillac air pump to assist in the other vacuum needed items such as Brakes, Tranny modulator, distributor timing and other vacuum required parts.

4. Timing!, timing coincides with a degreed cam as well as primary and secondary settings on your carb.

5. Automatic or Standard transmission? it makes a difference

6. Ok finally the recommendation.

I have been pretty succesful with a Comp Cams 280, because I am running a Victor Jr., it is similar to the Team G intake.

Borrow a 280 stick (cam) from a buddy and try it out, also since I try different cams alot, I got the 2 piece timing cover that way I dont mess up my oil pan seal.

[grumpyvette]

ok first thing you need to understand is that that rough idle is almost intirely caused by the OVERLAP area in that cam, first read this

http://www.c4board.com/cgi-bin/ib3/ikonboard.cgi?s=3cb9702b026dffff;act=ST;f=10;t=94

, btw your present combo shows as 421hp/416tq

 

 

now you need at least 225 degs of intake duration to effectively spin that engine to 6000rpm but you really need a wide (112-114 LSA) to limit your overlap area to get that idle smoothed out, now a cam like that will have a wide torque curve but it will build slower as the rpms climb than that narrow LSA cam you have now, the CRANE# 113821 hydrolic flat tap cam will match those requirements

 

http://dab7.cranecams.com/SpecCard/DisplayCatalogCard.asp?PN=113821&B1=Display+Card

 

heres what the CRANE CATALOG SAYS "fair idle, moderate performance useage,good mid-range hp 3400-3800 cruiserpm 9.75-11 compression ratio advised basic rpm 3000-6000rpm"the computer shows 430hp/457tq

"

 

btw that comp cams #280h

 

http://www.compcams.com/information/search/CamDetails.asp?PartNumber=12-212-2

 

heres what the comp cams catalog says "hydrolic-great for street machines. needs stall,headers & gears,rough idle" the computer shows 421hp/458tq

 

now to be fair rememeber those are discriptions of the cam in a 350 displacement engine, because your running a larger engine the power will be higher, the torque will be better and the idle will be slightly better with both cams in your engine

I hope you noticed the wider LSA and lower durration capture more cylinder pressure for a wider torque curve, thats what the more efficient dcr does for you