Chev 350 gurus (help required)

[Ross Myers]

> Guys,
> 
> In an earlier post I wrote my TPI chev 530 pinged on pump leaded with 4deg
> static advance.  Now I thought it was due to too high a compression, and so
> I've finally done a compression test.  The engine is standard flat top
> pistons and 520 iron headswith 1.5 ratio roller rockers, 305 TPI using
> aftermarket speed density ECU. 

Well I'm sorry but I missed your earlier posting, however I am a bit 
confused why you're TPI system doesn't have a fully electronic dizzy. 
I can only assume your aftermarket ECU has no ignition 
capabilities so you had to ditch it. As another post said, you are 
much better off switching back to a GM fully electronic dizzy and 
their ECU and get a PROM custom done for you (Would have been cheaper 
than your aftermarket ECU I bet).

> The cam specs are:
> 
> inlet opens 23btdc, closes 61 abdc, duration 264deg, cam lift 0.269"
> exhaust opens 68bbdc, closes 26atdc, duration 274deg, cam lift 0.285"

Well I'm no cam expert but the cam you have is a low end performer, 
and those lift figures seem lowish!!!. I learnt the hard way about 
big cams, the cam I previously had in mine (a 350, injected chev)-

 Int 34/78, dur 292, lift .453
 Ext 80/32. dur 292, lift .453

This made the car run so bad (stalling etc) that I had to ditch it 
for a much midler cam which was basically a bit more beefy than yours
however it was suited to the engine and the style of driving (city).
Unless you build your motor to rev higher you are wasting your time 
getting the experts bigger cam installed, which I dont know if it 
would help your pining problem, it would sure kill performance 
though. Call Comp Cams or Edelbrock etc, they make cams suited for 
TPI motors (with the GM ECU), that will perform heaps better without 
any compromise.

> 1.  Is this cam an economy cam ?  The guy that ground it said it would be
> perfectly suited for a TPI speed density system (I think so too, got lots of
> power up to 5300rpm, then it runs out of power quite noticeably).

Sounds right, but isn't that enough RPM, or have you modified the 
motor for more?. 

> 2.  Can you calculate the compression ration from the psi reading ?  If so
> what is the equation ?

 I'd like to know that too.
 
> 3.  If I need a bigger cam, any suggestions ?  Don't forget a standard TPI
> is only good for around 5500rpm.

Call the cam companys, they have been there before.

> P.S. next thing to try is a tank full of BP100 racing fuel.

Or some Nitromethane!!!.