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BBC Roller no bottom end

4K views 24 replies 7 participants last post by  454C10 
#1 ·
I have a 396 Roller motor in my 67 nova. I bought the car with this motor with a fresh build. I know it's a roller cam but have no specs. This motor sounds so damn mean, it has a pretty loopy idle. Anyway when I get on it it just doesn't have any low end balls at all. It has a great top end but even brake torqueing it just don't respond like it should. It has cast heads and a TH350 trans with a 2400 stall. I know it has a lot more any ideas?
 
#3 ·
Short of tearing it apart I don't have cam specs. The heads are pretty stock besides springs and roller rockers after about 2500 rpms it goes. I can say that for some reason there are days this motor responds pretty good but most days it's just flat at start.
 
#5 ·
It really don't make sense to me to install a big roller cam with stock heads, heads are where the power is made. This is just a guess but I would almost bet that it has a Mother Thumpr cam in it. Those cams sound really wicked but they leave alot to be desired when it comes to performance. I have been told that with a proper tune, they perform fairly well but it takes a good tuner to get them there. There are retro fit kits available to install a roller cam into a standard block but a true roller cam will have roller cam bearings. Do you know what gear the rearend has? What intake and carb setup it has?
 
#21 ·
There are retro fit kits available to install a roller cam into a standard block but a true roller cam will have roller cam bearings.
S-10, all cam roller bearings I'm aware of are race only and aftermarket, you think GM ever put them in their OEM roller motors?
 
#7 ·
A vacuum secondary carb would be better in my opinion IF the cam will allow sufficient vacuum to operate it. This may be one reason it has a mechanical secondary carb on it. You would need to check how much vacuum the engine has with that cam before changing the carb.
 
#24 ·
To begin with, set the timing curve up correctly. Info here.

Once the timing curve is set up right, see if the carb problem has gone away or is much better.

Knowing the cam specs will help. Short of pulling the cam or timing cover to get the numbers off the cam, you can find the specs close enough for tuning by following the info here.

Good luck.
 
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