Blown 84
 

New project using stock heads and block. SBC 6-71 Blower single carb an 800. Having the block splayed, rods reconditioned, forged 350 crank, bored to .030, forged dish pistons, comp cam kit, stainless valves, hardened pushrods,

Anyone who has went this way with a blown c4 I need help with choosing a setup. The considerable problem is the rack and pinion and blower pulley. Using V-belt pulleys.

I have run several roots type blowers and I am wondering a few things about your project. First, why are you using the stock heads? If it is because of a tight budget I would put the project on hold until you can acquire some better heads. Secondly if you are running a 671 blower you should consider 2 carbs even if you run smaller cfm carbs because dual carbs will offer a MUCH better fuel distribution with a roots type blower. I also recommend that you talk with Comp Cams about a blower specific camshaft kit which will favor a little more lift on the exhaust side and they will recommend a cam that has been ground on a 114. Hope this helps.

Sam Miller

Why are you getting forged pistons and crank but keeping stock rods?

I would look into a set of forged H beam rods at the very least. Rods to me are more important than a forged crankshaft

Don't forget to change your distributor. You'll need a little one to fit behind the blower!

I 2nd that.

But....I did build a 383 SBC with stock 400 rods, Scat crank, TRW slugs, Dart Iron Eagle 215cc heads and topped it off with a Hampton 6-71 blower and dual Holley 650 DP carbs...ran great!

A single Holley 800 will do fine if you're not looking to make any real power. As far as the cam, in my engine I used a NitrousHP cam from Comp, worked great. If your block is a 4-bolt, no point doing the splayed caps thing..waste of money on that stock block. Your heads are junk, look on Craigslist or Racingjunk or even here for a used set of aftermarket heads.

Stock crank will survive more than stock rods.

This is what happend after a while at 20 psi boost on stock shortblock.

Bent rods caused the crank counterweights to hit the pistons under the wrist pin.
The camshaft was broken into 6 pieces.
Several pieces missing from the engine block.

The crank could probably be reconditioned if I wanted to use it again.


Early that summer I went to a local race track.

60 foot - 1.827 s
1/8 mile - 7.245 s, 169.85 km/h ( 105 MPH )
1/4 mile - 10.862 s, 216.38 km/h (134 MPH )


Later the same summer, a few days before the engine exploded, I went to another temporary track with just unprepared tarmac. I had just built a more free flowing exhaust and power increase was substancial.

1/8 mile - 7.094 sek med 170.40 km/h ( 106 MPH )
This is a video of that run 1900 pound 1923 Ford with supercharger. ( Right click, save as )






( Click pictures )

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