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ok, i have a comp cams big mutha thumper cam its hydraulic flat tappet. I need to know will this cam screw with my power brakes and is it wothy to be in a daily driver, i did not spend any money on this cam my brother in law was going to use it for his 406 sbc build but he decided to go a different way with his cam, the cam has never been used or out of the box it is a cam and lifter kit. Now when i go to do this cam swap i know to go with a 3000 stall converter my engine is a 350 jasper with 11000 miles on it but i have heard jasper engines are not that good so i am planning to run a complete rebuild new crank, rods, pistons, oil pump and every thing else i plan to use domed pistons but should i do forged pistons or should i use hypers i am useing this as a daily driver but i want to rebuild the engine to be stronger also would you prefer a cast crank or forged, rods no question will be forged i dont want to leave anything to chance :turn:
 

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I have this cam in my car. It's a hydraulic roller cam, didn't think they made a flat tappet version, but maybe? My car is a four speed, so I don't have a problem with the vacuum for the power brakes, but with an automatic, even with a 3000 stall converter, I doubt you're going to be happy with the idle quality and the available vacuum for the power brakes.
 

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ok, i have a comp cams big mutha thumper cam its hydraulic flat tappet. I need to know will this cam screw with my power brakes and is it wothy to be in a daily driver, i did not spend any money on this cam my brother in law was going to use it for his 406 sbc build but he decided to go a different way with his cam, the cam has never been used or out of the box it is a cam and lifter kit. :
The hydraulic flat tappet version of the cam has 90* of overlap and will be very difficult to get enough vacuum at idle to support power brakes even with a vacuum canister. I would not use this cam with a car needing power brakes. As a daily driver this cam would suck big time. If you want the big cam sound, pick a cam with a tight LSA but a lot less duration to keep the RPM HP peak below 5800 and overlap at or below 60*. Specs for Big Mutha Thumper:

Comp Cams 249-12-602-4
Exhaust Valve Lift (in.)0.486Intake Valve Lift (in.)0.500Int. Duration @ .050 in. (Deg)243Exh. Duration @ .050 in. (Deg)257Int. Duration Advertised (Deg)295Exh. Duration Advertised (Deg)313Engine Make/SizeChevy Small Block (262-400)Lifter Type Hydraulic Flat TappetUsageStreet/Strip RPM Range2000-9000 Jack
 

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You can't just put a cam in because it's free. The cam has to match the engine,heads,intake and so forth. Don't build you're motor to match the free cam.
 

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I have the same Cam on my 70 Nova. What I did was change everything including lifters, push rods, high compression valve springs, timing belt. I have drum brakes so it is not an issue as far as vacuum but what really sucks is the idle vibration. I am thinking of using adjustable rods to tie motor to chasis. It just have too much rumble. Other than that is fine
 

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I have the same Cam on my 70 Nova. What I did was change everything including lifters, push rods, high compression valve springs, timing belt. I have drum brakes so it is not an issue as far as vacuum but what really sucks is the idle vibration. I am thinking of using adjustable rods to tie motor to chasis. It just have too much rumble. Other than that is fine
That will give you more vibration I would think. Try some softer mounts, to absorb the vibe.
 

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Discussion Starter #8
i dont want to build an engine around the cam i want to build an engine that is able to hold together at what ever punishment i give it thats what i want but the cam is a deal breaker if it won't work for my app then i will have to get rid of it and go with the comp cam xe 268h k kit but i still plan on using forged rods and crank and also domed hyper pistonsbut thanks for the info on this
 

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my engine is a 350 jasper with 11000 miles on it but i have heard jasper engines are not that good so i am planning to run a complete rebuild new crank, rods, pistons, oil pump and every thing else i plan to use domed pistons but should i do forged pistons or should i use hypers i am useing this as a daily driver but i want to rebuild the engine to be stronger :
go with the comp cam xe 268h k kit but i still plan on using forged rods and crank and also domed hyper pistonsbut thanks for the info on this
Darrick, which "JASPER" engine do you have? If you decide to go with the 268XE then a cast crank will probably be just fine. They can support all the HP the 268 will deliver without using a boost of Juice. If the motor has been good for 11,000 miles, I would not waste my bucks and just do the cam swap with the engine in the car. Depending on what heads they used, the XE268 may not be the best choice of cam. A domed hyper may give too much compression (Static / Dynamic) depending on which Jasper you have. Do the swap and save the money for a "KILLER" 383 down the road after the car is no longer your daily driver...JMO Jack
 

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Can you guide me where to buy them? I looked and looked but they seem the same.
The only mounts that will probably be softer will factory rubber mounts. Try doing some basic tune up adjustments,check timing, set idle rpm to about 800 and adjust air idle mixture screws. See if that helps. Or possibly you have exhaust or something touching the body or frame. Also check you're subfrmae rubber mounts to see if they are good. RICK
 

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Discussion Starter #11
I have a stock reman jasper engine it has 250 hp what I want is to make sure it will handle abuse and I am not wanting a 383 unless it would be cheaper and able to work with ac
 

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The type of abuse would be highway driving, burn outs, and if I can find time go to a strip and test the time
Keep street tires and your good to go. I would use it until you break it. Just remember as you increase HP (And Abuse) in the engine, other parts of the car are now also weak links. So stuff like Axels, U-Joints, Tranny Parts, Differential Gears and such start to break. Speed costs money UP-FRONT and DOWN THE ROAD.....In your original post you stated that you wanted to re-build and you included the crank. If at some point you decide to go that route then do the 383. Same price, more HP and TQ...If you have "Deep Pockets" and money is no object, then spend away...By the way, if you do only a cam change in the old 250 HP Jasper, you will make better torque and about the same HP using the XE262 instead of the XE268. Either way you are now into premium gas country....Jack
 

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that cam is mainly for sound , if you like the sound , you can work around the vacume ,, find a vacume pump for a diesel truck , or similar , its out there ,, i've " heard " " read " some positive things about the power they can put out , but its the sound that sells them


they went big on the duration split , i think if i wanted enough sound and performance , i'd look at the Isky 292 or 280 cam , they're on a 108 , it will have a nice sound ,,

if ur car is making alot of vibrations , i'd go with a set of solid motor mounts ,, the stock ones fail sooner or later with abuse
 
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