Agressive Cam....Ruin timing?

[Stallion]

If you put in a more agressive cam, it would keep the valves open longer for more air flow, resulting in more hp, correct?

But, if you were to do this, what would it do to the timing? Wouldn't the spark plug need to be delayed for the combustion to take place? Or would you not have to fool with that?

In other words my question is, as a result of cam change, would you need to monitor/change other things? I don't understand how if you would put in a more agressive cam that the timing would still remain fine.

Thanks!

TR

 

[Stallion]

Also, if you would change your cam, what part of the engine would keep all of the timing calibrated? Thanks!

TR

 

[AKRAY4PLAY]

there are two ways a cam allows more flow, lift and duration. with more lift the valves open farther resulting in a bigger hole to flow thru. with duration they stay open longer giving more time to flow. now you start getting into trouble with lift when it gets too high; lifter bind, rocker stud pulling, valve spring stacking, valve stem side load at ends of rocker arm swing, etc. the problems with duration are cylinder pressure bleed at low rpm, loss of fresh fuel/air charge, poor vaccum, poor scavenging, reversion, etc. the trick is to balance your lift and duration with the configuration of the intake manifold, heads, rotating assembly and exhaust. generally speaking, the best running motors have the cam as the limiting factor in the "equation" of flow. but the cam can not be lacking far behind the motor combo, or you will have a very poor running motor.
generally speaking, the more duration you throw at a motor the higher the usable rpm range will be. manual trannies and high stall converters are band-aids for the absent low end of high duration cams. the bonus is you can usually run more ignition timing without detenating, thus allowing you to spin more rpm. if you want rpm, go with higher duration and if you want torque go with lower duration and higher lift. the guys at Crower Cams and Crane Cams have been very informative and enlightening for me in the past. give them a call and i am sure they will be happy to answer any questions you have with better terms than i do. as for keeping the timing calibrated, i am sorry i don't understand your question. Brian

 

[Stallion]

I see, so you can't take the extreme of duration and/or lift, or you'll run into common problems from the cam. That sounds like a lot of factors that you have to consider (intake manifold, rotating assembly, and exaust) to get this sort of mod working right. Is it worth it?

 

[AKRAY4PLAY]

if you like more performance, any mod is worth it! assuming you have the factory motor, the order of price vs. most hp is usually as follows. cam, exhaust, heads, intake and finally rotating assembly. this is based on relatively stock engines (under 250hp). intakes don't do a lot for you until your motor is built pretty well (350-375hp), and the stock Chevy intake flows quite well. rotating assemblies can dramatically improve volumetric efficientcies with longer rods and lighter parts, but it costs a mint. cam, exhaust and heads generally give about the same increases on stock motors, that is why i rated them in that order. if you want over 1hp per ci. then the list gets tossed around. this is were you need to have a power goal and at what rpm you want that power. there are quite a few guys on the forum that are good with small block build-ups, and lots of old threads purtaining to the subject. if you want to build a motor, it would probably be worth it to find another block. that minimizes the down time and negative price impact of not having a numbers matching car. Brian

 

[Stallion]

Yes, about the matching numbers when I'm looking for a Vette. Would you suggest that the Vettes I look at and think of buying should match numbers? Is that a pretty standard and necessary thing?

Thanks!

TR

 

[sscam69]

Not standard and necessary but if you looking to sell the car down the road you can sell it for more if its a numbers matching car.

My vette has been tampered with and there is no point in restoring it back to original condition so I am modding the heck out of it!

If you haven't seen Chris's (69myway) check it out. It was a numbers matching car for the most part but the car was at a point beyond return because it was in such bad shape. Most people would do an about face before taking on a project like that. BUT dat boy haz skillz! Just check out his webpage.

:BOWKiller

The point is its up to you, it'll be YOUR vette.

Frank

 

[Stallion]

With my budget (6-7k) I wouldn't mind getting a Vette that's in decent condition (can drive and operate well) and then I could mod it and restore it as necessary. Due to my age and lack of a shop, I don't think that I would be able to do any major mods to it, but I could learn and fix up some things that would cause the Vette to sell lower.

That's how I see it. Reasonable? Hopefully...

TR

 

[AKRAY4PLAY]

i bought mine for $3700. it was a good runner, but not very sporty. so i went for the mods, but keeping all the old parts and not doing any mods that were not reversible. now i have a stock interior and body lines car with new suspension and drivetrain. including the price of purchase, i have about $20,000 wrapped up in it so far. don't let your age stop you from living a dream, that is what building a sweet car is all about!! if you put your mind to it and invest wisely, having the coolest car out of all your friends is easy to achieve. GO FOR IT!! and have fun with it, Brian

 

[Stallion]

Wow, that's a good price you purchased at and it seems like you've put a lot of time and money and love into your Vette. You wouldn't happen to have a picture lying around that you could post here, do you? I'm kinda curious as to how she looks.

Yes, I do hope that I will live out the dream of like what you did. Buy it and it runs, and then work on it constantly to make it better and more beautiful. Ah, that's my dream!

TR

 

[hotrodd]

In my opinoin yhe best question you can ask yourself is How will I be driving the car,when it come's to highperformance part's.I told the speed shop finally that I wanted some power under my foot and to be able to drive it a 500 mile cruise also.Came up with AFR Heads lunati hydraulic roller cam Demon carb and so forth,oh don't forget you have to get all that to the ground so a hughes trans. was ordered.I haven't broke anything yet and I have taken 500 mile cruses and got 21 mile to the gallon.I am real happy and finally built what I consider my dream! Turned a best et of 13.538 in 1/4 mile,not to bad for my fourth time down the drag strip and drive it home when your done.Take your time and ask lot's of questions.

 

[Stallion]

Hey, that sounds nice how you rigged up your Vette. Let's see, how I would drive it. It would be a "daily driver" and it would be my main car, as Vettes should be, IMO. I would also like to have power like you. I think drag-racing would be interesting, and I might try it, but I wouldn't sacrafice a "daily" driving Vette for racing. You know?

Thanks!

TR

 

[AKRAY4PLAY]

TR,
i can do one better than a picture! here is a link to a video clip of my car. it is a little commercialized because it was shot for my friend's snowmachine riding movie. but at least you get to see the car in action. i hope the link works. http://www.c3sharktank.com/sound/burnout.mov
enjoy, Brian

 

[sscam69]

Hey Akray

what did you trap on that run? Did you have traction issues?

Frank

 

[AKRAY4PLAY]

Frank,
you might say i had a little problem with traction, but the fun factor is way high along with the tire bill. i have yet to run at the track, but the good old boy system of co-pilot timing the 1/4 mile is around 11.5 seconds. the car actually gets very good hook up. it only wants to smoke the tires if i am low on fuel and nobody else is in the car. that and i only drive like an idiot when i'm alone and the road is clear of traffic. but putting 2200 rpm of brake stall into the equation, she'll rip'em loose anytime. Brian

 

[Stallion]

AKRAY4PLAY, how would you fix that traction problem? That's a pretty good time! Thanks for the video, I'm going to look at it now. Can't wait!

TR

 

[AKRAY4PLAY]

the biggest help in the traction department was the Vette Brakes suspension plus kit. more exactly the rear camber rod kit. it allows the tires to stay verticle through the suspension travel. C3's are bad for having massive camber swings with the rear tires through the movement of the rear suspension. the kit lowers the rod mounting location and gives a parallel camber/rear driveline relationship. this in turn keeps the camber constant through the swing. the other added bonus is the tie-rod style camber adjusting rods. they don't loose their setting when you apply massive amounts of torque. i think the camber rod kit alone is around $250, a very good investment. Brian

 

[sscam69]

TR

Tires make a BIG difference next to the suspension setup. The best tires right now on the market are the Nitto 555R's and the BFgoodrich Drag Radials. These are street legal tires.

These are basically street legal slicks. When you look at the Nittos it looks like a racing slick and someone to a razor and cut thin lines so that they could use it on the street.

If it rains these tires are far from optimal but for racing on dry pavement their awesome!

Frank

 

[Stallion]

So, the problem with traction comes when the wheels don't stay verticle? I guess because there's not enough contact from wheels on the road, resulting in bad distribution on the tires, which is lack of traction. Correct? That's what I logically think. I don't know for sure. Thanks!

TR

 

[AKRAY4PLAY]

TR,
your logic is as good as Spock's. your right, when the suspension is extended the rear tire leans out at the top. and conversely when the suspension is compressed the top of the tire leans inward. changing your camber rods to the new stuff is always a good idea. then your street tires bite like slicks on a stock suspension. if you run slicks with the new set-up, breaking traction becomes almost impossible. this is where you get into breaking rear-end components, traction + torque = broken stock stuff. but don't worry about breaking anything until you start going over the 450 ft/lb mark. Brian