Cam too big?

[Mike C]

My 'vette is a project been sitting for 15 years. Was stolen and frame bent in '76. Frame been replaced with a '66 (good for my disc swap since the 65 and up frames have caliper clearing depressions) Originally engine tranny etc., but re-assigned vin due to frame swap, thus no value as a collector car. WHich is perfect since I want a driver. 1/2" in the chain is really no big deal. All chains stretch, but they have built that in. Some manufacturers actually offer pre-strectched chains that were originally slightly undersize. Get a dial indicator and rotate the motor counter clockwise and until slack is gone, mark where indicator is, then rotate clockwise until slack gone again. check indicator. If less than 2 degrees, your OK. Drive sid is tight under load which really matters as long as cam timing is not drastically altered (1-2 deg no big deal) Here is a photo of my 'vette.

[Guest Anonymous]

Very cool, the 63's and 64's are one of my more favorite vettes. It'll be neat when its finished. Good luck.

 

Regards,

 

Lone

[Two40MuscleZ]

Hey Pete:

 

Sorry to hear about your "Paint Jail" problems. Its almost as thought the Board of Prison Terms extended your sentence! If you were a bit closer, I would have been happy to shoot the finish in far less than the 3 month sentence you are now commuting. Please let me know if there is anything I can do. My last paint project was a $90,000 "S" series Jag, which went to Europe and recieved its share of awards. Hard pressed to beat that one.

 

Regarding your cam...go for it! I know that you, Lone and I recently discussed just this subject. I decided to go with the Solid Roller CompCam which I just recieved earlier in the week. It specs out at:

 

Advertised duration 280/286 and 242/248 @.050. Cam lift 570/576, 110 lobe seperation, effective range 2500-6500 rpm. Approx. 160 lbs. seat pressure. Matched to the 462's, and you already know how they have been built, seems to be a compatible match, and as you already know our engines are uniquely similar. In that respect, I really don't think that you will have much of a problem. A little light on the low end, but strong never-the-less. The cam specs you posted were slightly less than the one I have, primarily in the lift. But I really don't see a problem with it for you.

 

KMA as to the disposition of your final decision. I look forward to both the completion of your paint and Cam choice.

 

Compliments,

 

Van

[pparaska]

Mike C,

I can understand long projects. I love those vettes (C2 stingray) and always wanted one since I was like 10 years old . Looks like a good bit of work, but I'd love doing one of those. Especially if I modified a thing here or there to piss off the Bloomington Gold set .

 

I'll check the angular play between the crank and cam before I replace that timing set. Just read a HOT ROD article on this and they said many of the same things. I didn't know you could get a "pre-stretched" chain - pretty cool.

 

Van, I wished I'd thought to fly you out to paint it, but didn't know of your talent . I'd bet it would have been cheaper too. Cool on that cam choice of yours. You should be a good bit more powerful with your 327, as my heads are not ported and yours have the full tilt job. That cam ought to be sweet. Thumbs up on the solid roller, I love it .

 

I've talked myself into either the XS274S-10 Extreme solid flat tappet or the the CS282S-10 Magnum solid flat tappet. As Mike points out I could just swap in the Magnum with my existing springs, so I will probably go that way. I will probably not do it now, but if I see scored cam journals, I'll have an excuse . I'm going get another crank, new bearings, and have the block gone over and cleaned, new cam bearings, etc. I'll inspect it and clean it thoroughly (especially all the oil passages!) but I want another set of eyes on it.

 

KMA? What's that stand for?

 

Cheers,

[jeffp]

The 274 cam's Valve Events are as follows: .501/.510 Lift & 110 LDA

 

IVO = 31* BTDC

IVC = 63* ABDC

EVO = 35* BBDC

EVC = 63* ATDC

 

This is a good cam to run in a small block. I would go to say .550 lift on the valves. The opening and closing points are good of the intake valve.

 

The 274 cam's Valve Events are as follows: .501/.510 Lift & 110 LDA

 

IVO = 31* BTDC

IVC = 63* ABDC

EVO = 35* BBDC

EVC = 63* ATDC

274 intake duration

278 exhaust duration

56 degrees overlap

lobe center 106 degrees

 

The other thing I would change is to advance the lobe centers to 112-114 degrees. This will give you the lowend, and you should be making good power by 3000 rpm's

Here is a suggestion, Call Ron Iskiderian and talk to him about your application. Your cam is very similar to my cam for duration I am not convienced the 106 lobe center is going to be too your best advantage. I am sure Ron can give you a very good direction to go.

Myself, I am running my cam on a turbo application. The engine will pull to 7500 rpm's the cam works well for what I wanted.

What is your target rpm range?

[JMortensen]

Jeff I think he might have moved on a bit from July of 2001 when this post was last used.

[grumpyvette]

first Ill point out two factors here

(1)that comp cams tech guys have been consistantly the LEAST KNOWLEDGABLE group Ive ever dealt with. In fact I refuse to bother dealing with them if I can avoid it, it just raises my blood pressure, if you call back chances are really good that youll get a differant suggestion, even if you get the same guy.

 

(2)better cylinder heads with higher flow rates need a good deal less durration to fill the cylinders, don,t think youll need the same durration or get similar results with better heads, its a differant ball game once youve upgraded fron reworked stock heads to good aftermarket heads, especially if you consider most stock heads are about a 160cc-170cc size/ 200cfm-230cfm vs a 190cc-230cc / 255cfm-320cfm on the better aftermarket heads

 

every choice in an engine combos a compromise and requires some ballancing in what your trying to achieve

 

the 230/236 and 235/240 durration cams can make excellent power in your sbc, Ive seen well over 470hp on several occasions with roller cams in that durration range

Im currently running this cam in my 383

http://www.cranecams.com/?show=browseParts&action=partSpec&partNumber=119661&lvl=2&prt=5

 

ID TRIED THIS CAM

 

http://www.crower.com/misc/cam_spec/cam_finder.php?part_num=00471&x=34&y=11

and found it was just a bit too much durration for street use, it made excellent power in my 383, but it was a p.i.t.a. IN TRAFFIC

 

I CAN,T SEE THE 327 BEING SERIOUSLY UNDER CAMMED WITH THE 230/236

 

 

if you slightly over cam the car you may get slightly better peak hp but youll kill off a good deal of the mid and low rpm tq and drop the average hp

 

NOW KEEP IN MIND A CAM IN THE 240-245 INTAKE DURRATION RANGE WILL MAKE MORE HP THAN EITHER OF THE SMALLER CAMS but its only at near peak rpms that its superior , and with a good wet nitrous system any of the cams can produce more power than your likely to be able to effectively put to the ground without slicks

 

just a quick silly example,

try sucking in a mouthful of soda thru a small dia straw then try doing the same thing with a much larger dia straw, the larger straw with its greater flow rate will allow you to get the same voluum transfered MUCH QUICKER, far less time results in a much more effective fill rate

adding durration to the cam is adding time to fill the cylinders but it effectively reduces the amount of cylinder voluum compressed because the valves are closeing later in the compression stroke.

its a compromise, your trading effective torque from clinder pressure/volluum for a greater number of less effective power strokes

 

http://www.iskycams.com/ART/techinfo/ncrank1.pdf

 

look at the cam timing and the true cylinder voluum compressed from the time the valves actually close

[pparaska]

FWIW, in that application (327, 9.5:1 compression, ported 461 GM heads) that cam worked out to be just streetable. Driveability in traffic was not great, the power was good though, as I was able to run a 12.78@110.4mph with a bunch of tire spin and 1.95 second 60' times. It needed to be just a bit less radical to be truly streetable. I always wondered what 10:1 or more compression would have done in that arrangement as I never had detonation problems on pump gas. It may have brought the dynamic compression ratio up a bit to make it more streetable.

 

I have moved on, now with a 406 and Canfield heads that flow a lot better. Went from a mildish solid roller to one that was too big. I need to split the difference on the next cam. More info on that in this thread:

http://forums.hybridz.org/showthread.php?t=102280

[Kevin Shasteen]

first Ill point out.., that comp cams tech guys have been consistantly the LEAST KNOWLEDGABLE...,

 

Just to add my .02 cents worth. A few months ago I was surfing the net for articles that spoke about the inter-relationships between the cylinder heads and the cam profile.

 

I came across one of the Comp Cam's tech guys that had his own site. Pretty close to the opening of the article this guy says that Cylinder Head Intake Port Volumes are not important and irrelevant; and didnt further qualify his statement; he just left it at that.

 

I almost jumped out of my chair when I read that - just thinking about all the people that might be reading his site and w/out further explanation from the author of that statement, will never know what he is talking about.

 

I too had my doubts about a master cam grinder that would make a statment like that w/out further qualifying the comment.

 

Now, because of that statement there will be a numerous amount of tuners reading that comment who dont know that Cylinder Head Port Volumes are very relavant to the specifics of any performance engine.

 

He may know how to grind a cam, but based on that comment - he doesnt understand the intracasies of modifying an engine when a specific output is desired.

 

Kevin,

(Yea,Still an Inliner)