67 440 915 heads. what do i do now to use the big cam i already paid for?

[tony1977]

I bought a thumper cam and have shaft mounted rockers. This is my first street rod. What do I do now , buy an adjustable shaft mount set upfor stock 915's or go get some aftermarket stud mount heads. Im nottrying to stay stock. I Should have thought about it before buying the cam but what can I do now that I did innstead of returning it?

 

[rdrunning]

Why do you think you need all that? It shouldn't be close to the pistons, 440s are down on the hole a good bit. I would be worried about vacume at idle, stall converter, gears, and loss of low end. But it should sound good!

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When buying a cam it's best to make your decision based on the car as a whole and take into consideration the items above. The different cam manufacturers and jegs/summit racing have tech tip phone lines to help out.

 

[67 B-body]

Big Mopar only uses shaft mount rockers....... You could upgrade to roller tip adjustable rockers though......

"Why do you think you need all that? It shouldn't be close to the pistons, 440s are down on the hole a good bit. I would be worried about vacume at idle, stall converter, gears, and loss of low end. But it should sound good"

Did I miss something??? I see nothing about his camshaft specs being BIG enough to concern himself about piston clearance... The "Thumper" camshaft isn't a whole lot different than the MP 284 / 484 camshaft.... 440's suck those cams up with any decent compression and something other than Junk heads...

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Tony,,,
I have .590 lift and 1.6:1 ratio rockers making about .630 lift at the valve... I have shaft mount adjustable rockers!

 

[Rocketman]

I recently upgraded my 440 and went the adjustable roller rockers from Memphis Comp Cams (Cam is from there also). My racing buddies that saw the rockers said they would be buying them for their race cars from now on. I lover them.

 

[Meep-Meep]

You already have the good heads so now need to know how big the cam is. There is a limit on factory heads before you need to cut spring seats or reach the point where they don't work well with too much cam.

 

[Cranky]

Need to know what engine we're dealing with. You say 67 440 915 heads so do you have a 440 for them to go on? The 915 casting was also used on other engines besides the 440 and not all 440 engines had pistons that were way down in the hole. Also, some 383's had pistons that were pretty close to deck height and the 440 6 pack engines were around .020 down. Shaft mount rockers are actually more stable than stud mount systems too plus I don't get what this love affair is with roller tipped rockers which are expensive and dyno tests show pretty much no gain in horsepower with medium lift cams. They do help with guide wear with the bigger cams. The higher the lift, the greater the guide wear becomes but this isn't usually a problem with the lower lift high performance cams and there are many different brands of non roller rockers that are adjustable without having to spend money needlessly.

 

[HT413]

Also, there are a bunch of different thumpr cams, which one do you have?

 

[Meep-Meep]

I will add that just because you already paid for a cam that doesn't mean you must use it, especially if it's wrong for your application. Cheaper in the long run to just get the right components.

 

[Jim Bob The Dancing Bear]

If you ordered it from someone like Summit and have not installed it you can always return it.

 

[pistol_grip_polara]

I posted an article about what cam to buy when buying parts for my motor.. boy was I taken to school.. Best to do research, figure out what you want, taking everything into consideration, including car, transmission/torque converter, what the car will be used for etc.

Probably best that if the cam doesn't suit your needs, save it for a future project maybe?? and get the one that will..

 

[Sixer]

Less is always more in my experience. Too many guys go for too much, thinking that the "rump rump" idle is king only to learn the the fun car has gone away-I am also a victim of this (long, long ago). Few motorheads can resist the attraction of a car that has that seductive idle quality that gets the oohs and awwhs, only to discover that the car is now difficult to start, won't tune, and is generally a pain in the ***. Many end up going to a basic light cam, headers and smaller carb and discover that a hot rod doesn't have to be a pain in the ***-and usually find that the car is a whole lot more enjoyable as a result. Sell the cam, do some research, and and forget racing specs-it's a street car, and a whole different set of parameters come into play-unless you are willing to pay the price.

 

[Meep-Meep]

Less is always more in my experience. Too many guys go for too much, thinking that the "rump rump" idle is king only to learn the the fun car has gone away-I am also a victim of this (long, long ago). Few motorheads can resist the attraction of a car that has that seductive idle quality that gets the oohs and awwhs, only to discover that the car is now difficult to start, won't tune, and is generally a pain in the ***. Many end up going to a basic light cam, headers and smaller carb and discover that a hot rod doesn't have to be a pain in the ***-and usually find that the car is a whole lot more enjoyable as a result. Sell the cam, do some research, and and forget racing specs-it's a street car, and a whole different set of parameters come into play-unless you are willing to pay the price.

This is absolutely true!!! I beat everyone over the head with this who wants to build a STREET car that will be driven regularly.

 

[Propwash]

Less is always more in my experience. Too many guys go for too much, thinking that the "rump rump" idle is king only to learn the the fun car has gone away-I am also a victim of this (long, long ago). Few motorheads can resist the attraction of a car that has that seductive idle quality that gets the oohs and awwhs, only to discover that the car is now difficult to start, won't tune, and is generally a pain in the ***. Many end up going to a basic light cam, headers and smaller carb and discover that a hot rod doesn't have to be a pain in the ***-and usually find that the car is a whole lot more enjoyable as a result. Sell the cam, do some research, and and forget racing specs-it's a street car, and a whole different set of parameters come into play-unless you are willing to pay the price.

This is absolutely true!!! I beat everyone over the head with this who wants to build a STREET car that will be driven regularly.

X2! I'd sell or return the cam as well. If not, you're gonna need to build all the car's parameters around it to make it work worth a pinch, and you don't know what you got to begin with. Even before you pick your cam, you need to think about your heads, how they're gonna flow, valve train requirments, compression, carburation, vacuum requirements (Ex. power brakes), tranny stall speed (if auto), rear gear ratio, exhaust, driving environment ect..ect.. Big power, now you're looking at chassis reinforcements, upgraded fuel system, rear and driveline upgrades...and the list goes on.

The biggies would be; what's your power goal in the end, where/how will the car be driven, and how much do you want to spend. Listen to sixer, Meep and the others, they're dead on. Too many folks slap a big part in and automatically expect big results, but usually end up with a car that's unreliable, doesn't perform or turns into maintenance nightmare. You need to balance the whole package and it starts with the cam & heads and how they're gonna work with everything else.

Good luck

 

[Rocketman]

I only drive my car on weekends and some afternoons. Of course I have a 4 speed making the larger cam easier to use. It has a great idle and gets lots of looks. A comment today was "that car has no manners". Of course I will probably never drive it over 300 miles in one day, most days less that 100 miles. I would highly recommend Memphis Comp Cams and their rockers/pushrods. They are easy folks to work with.