Thread: How big is too big?

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Hey everyone, I'm new to the forums and am currently building a 468 to go in my 1970 Chevelle. This vehicle will be used street (40%) and strip (60%). I want to run a solid roller cam and it has been suggested by several cam companies that I run a cam in the area of low to mid .700" lift. My engine builder says that he believes that high lift roller cams like that don't fare to well on the street. He says that with the fast ramp rates, it may stretch valves over time. I have told every person at the big cam companies what the car will be used for. Do you guys think this might be a problem? Have you heard of this? I am just worried about durability. I don't want to have to tear this motor down every month to check valve length's....

Advice please!

Brent

I'll have to agree with your builder. if you have .700 lift, theres No Way your going to be able to drive that thing on the street. I havent heard of anyone complaining about valve stretch due to cam lift, but i imagine it may lead to some valve issues. If it was me personally, i would consider .600 the limit. I would reccomend about .550 lift. Unless you plan for this car to be your absolute race-and-only-race car.

I agree with the builder, my concern is the valve springs to support that kind of lift. youll be eating up valvesprings regularly.
You can have an 11 sec streetable Chevelle that will survive with good components & combination. I agree with Tech, The Chevelle is a farley heavy car...but a reliable mid 11 sec performer is achievable...but the valve sprins that youll need will take away its reliability

Very good info here! I am dead set on a roller cam. I don't think I mentioned my combo so here goes. I have 12.5:1 Ross pistons, forged h-beams, forged crank, Merlin heads port matched to a Dart single plane, Holley 4150 series1000 cfm carb, Coan built Turbo 400 w/ full manual reverse valve body, 4500 stall, with 4:10 or 4:56's out back. I really do not want to scrap any of these parts. Would a hydraulic roller be better? What cam or cams would offer more longevity and reliability? This car will see no more than 1000 miles per year......ever. Never be driven on any type of highway either. Oh, by the way, so far I am really impressed with this site and its members. I am not used to members being truthful and most important knowledgable!!

Thanks Brent

Interesting proposal, but it's not the 60/40 race/street motor you described in your first post. This is basically a race motor, and if you put that type of cam in it, your power band is going to be in the 4000 - 7000 RPM range. You can probably rump-rump around the drive-in, but "streetable?" Nope.

For your compression ratio and other parts, something like a comp cams 306BR10 fits what you asked for. Mechanical roller, bracket race, 12:1 in a heavy car. 270/280 @ .050 lift, .710/.714 lift, 110 lobe centers. Note that I said "what you asked for." What you asked for ain't a street motor.

Originally posted by techinspector1
O.K. Brent, now I'm a little confused. In your first post, you said the car would be used 40% on the street. In your last post, you said the car would never be driven on any type of highway. Which is it so I can formulate an intelligent reply?

Well my idea of "street" is obviously different than yours. I took it for granted that you would understand exactly what I meant. When I said 40% street , here is what I intended. It will be taken out of my garage and driven to the local cruise-in. This will not involve any out of town driving, i.e. highway use. The 40% number is based on me driving it only on a weekend (Sat. or Sun.) to visit with the other car guys at the hangout. The rest of the use, will be at any of my local dragstrips. To get to the track each time, it will be hauled in an enclosed trailer. When I say streetable, I am asking for something that will be able to putt around town on occasion. I live just on the edge of my town, therefore it will not actually require any sustained high speeds. This may or may not clear up what I am hoping to accomplish?

so...its a drag race motor....that might get driven to the local cruise every now & than.
Oh OK...well, thats totally differant in my opinion, I was thinking you ment streetable. Sorry

Yes, that sums it up pretty accurately. I guess when I said streetable, I was intending just this...... to be able to take it on a Saturday evening to a cruise in. Once again, sorry for the confusion.

Brent

Brent, from my experience on this board I will have to tell you to listen to them not the cam companies. When I first came here I listened to others not on this board, and guess what a year later and a lot of money later I wound up doing exactly what these guys here told me. And one those is tech, he knows what he is talking about, Do the chevelle as a street/show car, and find another body for the strip, Maybe another chevelle if you love them so much, but keep them seperate, for the strip car, you can strip it down to the bare minimun needed for the rules at your strip to make it lighter, maybe even change some steel out for aluminum or fiberglass for weight, but as far as that going on the street the tickets and tows will cost you too much in the long run, make a street legal and a strip legal car, may seem to cost you more now, but in the long run will be cheaper, I wish I did that when I was in the military, my camaro was used for both and the money and time I spent making the car for both, I could have easily built 2 cars.
Think about what everyone has said and use all the knowledge to help you. Good luck on the car
also the cam tech linked, does look like a nice one, bigger is not always better

Originally posted by Streets
You could ALWAYS trailer it to the cruise-in!!

I wouldn't be the only one to do this, but what's the fun in trailering it

Originally posted by joker51
Brent, from my experience on this board I will have to tell you to listen to them not the cam companies. When I first came here I listened to others not on this board, and guess what a year later and a lot of money later I wound up doing exactly what these guys here told me. And one those is tech, he knows what he is talking about, Do the chevelle as a street/show car, and find another body for the strip, Maybe another chevelle if you love them so much, but keep them seperate, for the strip car, you can strip it down to the bare minimun needed for the rules at your strip to make it lighter, maybe even change some steel out for aluminum or fiberglass for weight, but as far as that going on the street the tickets and tows will cost you too much in the long run, make a street legal and a strip legal car, may seem to cost you more now, but in the long run will be cheaper, I wish I did that when I was in the military, my camaro was used for both and the money and time I spent making the car for both, I could have easily built 2 cars.
Think about what everyone has said and use all the knowledge to help you. Good luck on the car
also the cam tech linked, does look like a nice one, bigger is not always better

Thanks Tim, I am taking all of this in. Due to the fact that I have been in the blue oval small block crowd until just recently, I am looking for all of the advice I can get.