Does anyone have the piston depth spec on 1984 L69 305 HO engine? Iam trying to run desktop dyno and getting some very high HP and Torque readings using the program. Thanx......

 

Are you asking about what is commonly referred to as "deck height?" That varies slightly from engine to engine, but it seems that most stock SBCs are consistently in the range of 0.015-0.025".

 

Using the desktop dyno with air flow characteristics from carcraft cyl head chart for the L98 aluminum heads,660 cfm dual plane and other parts from sig I'm getting 343 flywheel HP @ 6500 RPM and 307 TQ@5000 RPM and 101.3 VE @ 5500RPM. Also using small tube headers with open exhaust. This seems unreal How far off is this? Engine seems real strong but not that strong.......also my combustion chambers are 55.00 cc

 

Try changing you exhaust profile to small primaries with mufflers and see if it makes a difference.

 

Quick question though. What are you using for camshaft specs?

 

Using the small tube/mufflers combo it did come down to about 306 HP. For cam specs I am using my cam card for comp cams # CS XE256H-12 which is the cam in the car now. Ialso used deck heighth of .025 in the hole. bach to exhaust the reason I used open headers was the 3" dump where the converter used to be.

 

According to what you've listed, I'd say that's about right. The L-98 heads were actually pretty decent flow-wise. That's why a lot of aftermarket companies like T.P.I.S. and Lingenfelter Performance used them in their combos. Some of the combos received ported heads, others didn't. I'd say you found a cheap way to make good power, so pat yourself on the back for all the money you just saved. For comparison sake, the 350 H.O. makes 330 H.P. and the ZZ4 makes 355. Your motor should be good for high 13's or really low 14's in the 1/4 and you'll get better gas mileage too. The stock 350 made around 230 H.P. in the camaro and 240 in the vette. For the limited mods you've made, you got some pretty decent power.

 

Yeah now al I have to do is learn to work the tree at the dragstrip. I will try to break something this coming friday night. Maybe brackets on saturday. Thanx for all the replies........Bill

 

...Tony