Continued 383 headaches

I guess I was mislead by their advertizing. I was under the impression the Thumper cams have moderate duration but still give you a mean sounding idle. There are only 3 cams available for a SB, the mildest one is still pretty hot and I doubt it would be much different from what you have: major difference I see from the little data they provide is the lobe center on 107 degrees versus 112 on the RPM cam.

I think this would work:

http://store.summitracing.com/partdetail.asp?part=CCA-CL12-211-2&autoview=sku

or a little more:
http://store.summitracing.com/partdetail.asp?part=CCA-CL12-212-2&autoview=sku

This is the hottest I would choose, might still be a little rough at 1600 rpm....

http://store.summitracing.com/partdetail.asp?part=CCA-CL12-246-3&autoview=sku

and don't forget: you need new lifters with a new flat tappet cam.
 
MYBAD79 said:
Do you still have the 1.6 ratio rockers ? They would help the lift a little, .501" vs .470"
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Not on this motor it came with aluminum 1.5 rockers. My corvette still has the 350 with the 1.6 rockers. I am hoping the new cam will have some low end power with the 10.1 compression with a little lumpy idle. Plus some city manners, maybe even be as good as my Corvettes 350 but with some decent performance. I still will be putting some 3.73s in the rear of the car.
 
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MYBAD79 said:
I thought this was your new 383 for the Vette :confused:
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This motor is for a Chevy Nova that I bought from my friend last week. He gave up on it due to the assorted problems, so I am trying to sort out the motor.I was helping him take out his decent running 350 and install the new 383.As you have seen it has not been easy. The Nova has a Toyota 5 speed the same as my Vette that I helped get installed after i did the install in the vette last year.

If I get it running as it should I will probably sell it back to him after be sees it running good. He just gave up and was going to sell it to someone else for cheep.
 
If you're using non-roller lifters, you MUST replace them too. Used lifters on a new cam will eat them all. Goes the other way too- New lifters on a used cam will eat everything too. No experience with rollers, but I'm chicken- I'd replace them too.
 
TimAT said:
If you're using non-roller lifters, you MUST replace them too. Used lifters on a new cam will eat them all. Goes the other way too- New lifters on a used cam will eat everything too. No experience with rollers, but I'm chicken- I'd replace them too.
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Tim, FACTORY rollers are fine, new cam used rollers been in my engine for some 12 years and over 100k miles now....

obviously they were smooth and kosher....NO comment on aftermarket stuffs...

:gurney:
 
TimAT said:
If you're using non-roller lifters, you MUST replace them too. Used lifters on a new cam will eat them all. Goes the other way too- New lifters on a used cam will eat everything too. No experience with rollers, but I'm chicken- I'd replace them too.
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Thanks Tim I did order the cam and lifter kit as MB79 suggested.:drink:

With the 110 lobe separation it should have a decent idle sound.
 
TimAT said:
If you're using non-roller lifters, you MUST replace them too. Used lifters on a new cam will eat them all. Goes the other way too- New lifters on a used cam will eat everything too. No experience with rollers, but I'm chicken- I'd replace them too.
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Used rollers are fine as long as you match correct cam to lifter--that would be the lobe shape itself. Interesting thread here. :quote:
 
TimAT said:
I have this GM cam in a 350. Runs great-- above 3000 RPM. Idles like crap and stays rough and nasty until you hit 3k. If you let it idle below 1000 RPM it'll eat spark plugs like candy. Solid lifter and way before anyone was running roller anything except for the big buck race guys.

3927140 Mechanical - 257/269 - .493/.512 - 112 - Off Road
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I actually found the 140 cam to be a good street cam. It'll idle at 900 to 950 all day and has a good torque curve to 6500 rpm. I've used this cam in a number of engines - even with automatics with 3000 stalls.


I don't know what "140" cam you have. :search:
 
Well the new cam, lifters and gaskets arrived yesterday by UPS. So next week it's tear down time...............again.........:push:
 
I hope it works for you. Did you install the cam yet ? I can't wait to read how much it improved your engine.
 
Arthur Brown said:
I hope it works for you. Did you install the cam yet ? I can't wait to read how much it improved your engine.
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Well finally finished getting the car back on the road. I changed the cam & lifters plus put 3:73 gears in the rear. The car is running great plus the idle is around 800-850 rpm. What a difference driving in the Bangkok traffic. It lost a little HP but it is more street friendly.:smash:
 
Good news. So you got the Comp cam with 224/224 duration and .470" lift ? If you use 1.6 ratio rockers you'll increase the lift, .470" is a little low.... there's still room for improvement without spending big bux.... :smash::thumbs:
 
MYBAD79 said:
Good news. So you got the Comp cam with 224/224 duration and .470" lift ? If you use 1.6 ratio rockers you'll increase the lift, .470" is a little low.... there's still room for improvement without spending big bux.... :smash::thumbs:
Click to expand...

Let him enjoy it a while....:surrender::thumbs:

we gonna get him into a GENE syndrome, fix it till it broke again....

:smash:
 
mrvette said:
MYBAD79 said:
Good news. So you got the Comp cam with 224/224 duration and .470" lift ? If you use 1.6 ratio rockers you'll increase the lift, .470" is a little low.... there's still room for improvement without spending big bux.... :smash::thumbs:
Click to expand...

Let him enjoy it a while....:surrender::thumbs:

we gonna get him into a GENE syndrome, fix it till it broke again....

:smash:
Click to expand...

Boy that sound like a great idea....................:chinese:
 
Hey Bangkok Dean, how is that cam working out? I'm about to do something similar. I'm going from a hydraulic tappet cam, Summit 1105, 224/234 duration, to a hydraulic roller, LT4 Hot Cam, 218/228 duration. I have 1.65 ration rockers so my lift will go up, while the duration will go down. The 1105 has been a great cam, but it too was worthless in high gear below 1500 rpm, but reves strong to 7000rpm with my new AFR 195s and fuel injection. I'm detuning the car just a bit for better idle, driveability, and gas mileage. I hope I'm not giving up too much horsepower. I don't race anymore, but I hope to stroke this motor to a 396 someday. I love, love, love, torque. The C4 guys act like the LT4 Hot Cam is pretty radical. I'm going to the Pomona Swap meet tomorow to start buying pieces. Once I start, I'll start my own thread. I just wanted to know how the cam worked out?
Bee Jay
 
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