Lateral-g Forums - Hyd to Solid cam conversion

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ive been working on the girlfriends neon all day! its been a long one! but yeah i understand your intent..

Quote:

Originally Posted by GregWeld (Post 223292)

Just to expand on what Eric advised... The valve train is CRITICAL in any engine - especially in one you plan to spin to 7000 rpm's. We used to launch our 277 ci 55 Nomad at about 7200 -- and wind it up from there! LOL

You have several things to check - buy - etc before you just stick a new stick in there.... You need to be concerned with whether or not the springs you have will work with the new cam (spring rate AND size) -- You'll need a push rod length checking tool -- Screw in studs - guide plates if you don't already have them and on and on. Let's not even get into the match up of whether or not your HEADS are capable of delivering the air you need at the lift your cam makes (which might already be an issue...)

I have to ask though -- if your cam is already capable of spinning to 6800 -- what do you think the new cam is going to do for you when it's range is only 7000... What don't you like about your current set up? Why the change?

Have you considered the entire car as a whole? The weight of the car - the size of the motor - the gear ratios - the tire size - the convertor stall (if you have an automatic). The cam you're talking about is what I'd consider a full out DRAG race piece... Driving on the street with that beast would be a horrible experience in my opinion. It would have zero bottom end torque...

Tell us about your car... what you're plans are for it... gears - tires - heads - use etc and maybe some of the 'boys' here can help you get to where you want to go with it.

Just my .02 worth.. LOL

Thanks for the answers!!, I´m constantly reading and learning about cars and engines and this kind of experiences are very helpful.

Well, I´ll try to answer the questions. First of all, the cam change is oriented and hopefully "matched" to the new heads we´re going to use, a set of 64cc camel hump fully ported with big valves. Actually our cam is capable to spin 6500 rpm with a set of 72cc heads, ported by my brother and myself.

Valve springs will be changed for a set recommended for the chosen cam, and so with the others parts that we´ll have to buy.

"What don't you like about your current set up?"
Just tryin to upgrade according to the budget. The current set up for our 350ci is very basic: flat top hyp pistons overboared to 4.040, stock rods and crank, 2800-6400 crane cam and heads a little bit worked.
Gear ratio is 3.42, 4 speed transmission, 265/50/15 tires.

"Why the change?"
Because it would be the next "cheap" upgrade. Forged internal, and full roller set are my wet dream right now, but my pockets are pretty empty haha, so I thought that a cam change should help me.

Hope you can help to make my decision. The car is used to keep my inner balance and my head clean, don´t use it everyday so daily driving is not a big issue, besides, I love agressive idle sound.

Muchas gracias guys,
Cristián Urrutia.

https://www.youtube.com/watch?v=qITAw_LIx2g

Quote:

Originally Posted by Cristián (Post 223665)

Cristian --

Change your gear ratio -- the cam you're talking about should have fairly decent gears - and that's a cheap fix. That and spinning a stock bottom end 350 beyond 6500 is already asking for a windowed pan/block. A decent rear end gear change would wake the car right up - it might kill your cruising speeds but if you want good seat of the pants feel/change on a budget - gears would do it.

Right now @ 6500 your top speed (calculated) is 143 mph -- you could go to a 4.11 gear and change nothing else and you're top speed (calculated) would be 119.5... that's still 120 mph but buddy would you get there a whole lot quicker!! 3.70's would give you top speed of 132...

7000 rpm in a 350 is almost 4100 ft/minute mean piston speed. I'd be looking at forged pistons, steel crank, and balancing if I was planning on really going up there very often. A two-bolt block would probably be adequate for dragstrip duty, but I'd want four for any sustained high-rpm use (such as open-tracking, open road competition a la the Silver State Classic event, and possibly Maxton Mile).

Norm