Maybe an LS series would be the way to go. The Edelbrock carb conversion kit is less than $700. Even the LM7 is a better starting point than old tech, low compression and flat tappet cams.
403 Olds or 400 sbc?
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joe_padavano said:
I know, why are you telling me?
I guess I didn't express it well, what my point is why not go for a big block? Especially if you want an Olds engine, if you're going to go Olds power in a car that's not already set up for an Olds engine you might as well go big block. Price wise, the benefits of an Olds SB are minimal over a Chevy SB. If you've already got say a 307 then go with whatever is available, but if you're converting from Chevy power to go Olds power why not go all out. And he said he wanted to keep weight down so he's not considering big blocks. But the Olds big blocks are not really that much heavier than the Olds small blocks. Unlike with a Chevy, where the big blocks are about 120 lbs heavier.
Even at that, I think the extra weight is totally justified.
Both engines have internal issues from the start. The 403 is windowed and the 400 has coolont issues with the block and they crack the cylinder walls. The 403 will give you the torque and pulling power but a 400 will always give you the HP power. I have a 350 Chevy in an 82 Cutlass and a 425 in a 73 Cutlass. The difference is there, the Chevy runs hard up top and the Olds runs hard on the bottom. Depends on how you want to go. I would go with a mild 403 build and have fun.
82cutty said:
Dont forget the inherent horrible rod length of the 400 chevy pretty much necessitating the need for an aftermarket rotating assembly from the very get go.
It seems completely backwards and counter intuitive to convert an LS based engine back to a carb. Why in the WORLD would you want to do that???
Most of the other cooling issues with the 400 are false. The 400 has steam holes where as the other SBC's don't and back in the day hot rodders would put double hump heads and all that stuff and never put the steam holes in the heads leading to the cracking issues and all the other things it brings. Thats how the rumors were started that the 400 would always run hot. I would do the 400 cause the mounts are there and you get the best of both worlds, amazing torque down low and high end HP. I read out of one of those big inch mouse motor books that with a pretty tame 230/236 cam and vortec heads they achieved something like 525 ft LBS of torque around 3500 rpm and I don't even remember the horsepower put it was around 430ish.
FE3X CLONE said:
Well I wouldnt say completely backwards but it does defeat part of the purpose. You still gain huge advancements in cylinder head design and weight savings.
The 403 with those #7 heads with a decent cam and headers with have decent horsepower and torque. My #8 headed 8.5 to 1 403 spins the tires hard hitting the fun peddle. It has spun them hard enough to break my no slip at it's weakest point.
SScamino said:
I couldn't agree more... Any machine shop worth their salt can easily drill the steam holes for you. I think my aftermarket heads were $35 drilled for the pair.
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