Chip for 85 305 TPI on carb 350

[Michael Davis]

I have been using the HLH-3200 (updated 85 vette 350TPI) as the
basis for my motor (stock 305 TPI w/ transplated ZZ4 under it) 
and has been working out ok thus far..

The base image is on my site (http://www.eecis.udel.edu/~davis/z28/)

The 305 should have smaller 58cc chambers and would have a raised
compression on the 350 if they were used...

The 305 used 19lb injectors and the 350 vette used 22lbs. (some early
'85 models were reported to have shipped with 24s ??)  The 305 chip
had the same flow rate as the 350, though the other fueling parameters
softened the differences in the injector rates.

Terry has most of the data for the '870 in GMEPro which I'm using.

(I was able to advance the timing about 12 deg in my stock 305TPI
 chip and it ran much better..  I imagine the lower CR 350 would 
 benefit from alot more...)

mike

In message <37A16A76.BC828599 at cruzers.com>,Ludis Langens writes:
>A neighbor has a 66 El Camino with a 305 TPI.  It came from an 85
>meaning it uses the 1226870 ECM.  The 305 blew up and was replaced with
>an early/mid 80's 350 carbureted long block.  A table in Chilton's
>implies that it must be an 85 or 86.  The original 305 TPI equipment was
>transferred over.  Right now it runs OK, but I'm trying to figure out
>what would be a correct/better chip for this configuration.
>
>Supposedly, the old 305 and new 350 both had heads with the same size
>chambers.  I don't know which heads ended up in the car.  If Chilton's
>is to be believed, this engine now has a CR of 8.2:1, compared to 9.0
>for a 350 TPI and 9.5 for a 305 TPI.  Could someone who has a head for
>Chevy heads confirm this?
>
>Presumably, this 350 block has a wimpier cam than a TPI would normally
>have.
>
>Are 305 and 350 TPI injectors the same, or does the 350 use a higher
>flow rate?
>
>What should be changed to deal with the lower CR?  Advance the timing?
>
>I'm sure that some of this is answered in the list archive, which is my
>next stop.
>
>-- 
>Ludis Langens                               ludis (at) cruzers (dot) com
>Mac, Fiero, & engine controller goodies:  http://www.cruzers.com/~ludis/
>