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Hello,
I own a 66 351W cpe. But I have a questions about my other car, which is a '71 chevy(!) vega dragracer. The Vega runs a 10.2 at the moment, which is not fast enough ( it should ru8n a 9.9). Its fitted with a holley 750 double pumper. I tried an 850 one, but 60ft times went bad (1.6)and endspeed was much higher with 135 mph (with the 750 it runs 1.49 and 130 mph). I decided to stay with the 750 and improve it. I will change the main jets (now 75 and 80). I also cutted off the choke house.

I need more power at high revs. According to advertisements a spacer with an open plenium givs more power at high revs. (I now have a 2 inch spacer with 4 holes).

Question: can anyone tell me if a spacer with an open plenium really gives more power at high revs (the engine makes a hefty 8.200 revs)? And what difference does a 2 inch spacer gives compared to a one inch ?

The engine is a 350 with alu heads and 2.02 valves,13.5 compression, and making some 600 hp and lots of revs (i set the rev limiter at 8.200).

I know its a chevy, but....

thanks,
willy reerink
holland
www.reerinkracing.com
 

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Looks like you're jetted way lean (IMO).
The taller spacer will help some with top end power (Not 3/10's), so will tightening the valve lash.... Retarding the cam (lower #intake center line) will help upper end but you will sacrafice a little lower end power.
You can also shorten the header tubes... Never tried this, but long tubes help bottom and mid-range, shorter tubes supposedly up top end power.
 

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IMHO, I would hook up an oxygen sensor to a PC to get a better reading on the air/fuel ratio at comparable rpm. While it is true, short tube headers are more appropriate for top end, I would hesitate re-degreeing the cam or tightening the lash until I know what the A/F ratio is first...I'm assuming the plugs are not giving any indications.
 
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