Thread: ideas for 350 spec anyone???

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Hi every one. Just introduced myself on the New Member section, but Hi to those who havent seen my post.

At the moment im throwing round ideas for the spec of a planned 350 rebuild. Its gona be for my series III landy, with which ill be taking part in anything from trials, to rallies to the odd car park drag race (thats as good as it gets in england im afraid).

As you've probably guessed im not chasing high hps, but im after axle snapping torque (extra hp is always good though). I'm on quite a small bugget (so new heads etc are prob out the question), but id rather spend a bit more and do a job propperly. and to contradict the last statement: ill be doing most of the work myself (that i have the facilities for)
at the moment i was thinking along the lines of:

750cfm q-jet or 700 cfm vac secondaries (holley or edelbrock)
performer air gap or performer EPS manifold
electronic ignition
stock heads (with some home porting and bowl work)
1 5/8 headers
rebuilt, honed, and balanced block and crank
hypereutetic pistons
roller valvetrain

for the cam i was think along the lines of....

around 112 lobe separation
215 degress duration at 0.050
270 duration
0.5 lift

what do you guys think? any ideas would be good as everyone on this forum is bound to know more on chevys than me!
also, whats everyones views on the carbs designed specially for trucks (ok i know this is a hotrod forum!) such as the Edelbrock Thunder Series AVS, and the Holley Truck Avenger? are they worth the extra $100?

cheers for your patience guys
Lobster

Geez, you need to get the group started on cam selection, that usually gets some good discussion. I am probably wrong and I won't know until I get the engine running (Summer 2006?) but I have tried to ignore the high rpm H.P. numbers and so far here is what I have selected based partly on financial limitations and partly on a desire to get low rpm torque to run an OD 0.7 4th geat with a 3.55 rear at about 1800 rpm. Most of the dyno sheets don't even show any results until 2500 rpm but in the OD 4th gear the rpms are going to be below 2000. I probably should have installed a 3.7 rear but the money is spent now on a 3.55 so I am pretty much stuck with it unless it really bogs in high gear. My silly idea has been to calibrate on my memories of my old '47 Ford which had a 3.78 ratio rear but an engine that was only about 100 H.P. maxing out at around 4000 rpm. So with a mild SBC 350, 3.55 rear, light weight of about 2500 pounds and about 275 H.P. at 4000 rpm I chose a Crane street cam supposed to be very good for torque (194/204 @0.050", about 270 degrees duration total). Look at the list of stock cams before you go wild with a long duration cam:

http://www.kendrick-auto.com/chevrol...y_cam_spec.htm

There are even shorter duration cams emphasizing low rpm torque, but I ended up with a little more duration than the factory cam for the 300 H.P. SBC (at the flywheel). So I have kept the engine build to about $1800 U.S. using a '76 Corvette two-bolt block with 882 heads, Z28 springs, roller-tip rockers and an Edelbrock EPS manifold and only a 600 CFM carb from Edelbrock. Using a stock converter I hope to be able to cruise at 65 mph at around 1900 rpm but a Model A is about as streamlined as a brick so I hope I have enough torque to run the car in 4th gear without down shifting to third a lot. So you see I have avoided the popular Comp Cam 268 and something more like the Comp Cam High Energy 252 to try to get low rpm torque in 4th gear to be able to push that brick through the air at 65 mph. For some reason the guy (old circle-track racer) who built my short block would not install a Comp Cam and said he had bad luck with them but many others like them; anyway I ended up with the Crane "Street Cam". One further point is that a lot of folks don't like the 882 heads but I already had a set so I just went with a three-angle valve job and smoothing out the exhaust ports with port matching the aluminum gaskets to 1 5/8" tubular headers. Probably it is risky to mess with the intake ports on the 882 heads since the walls are supposed to be very thin and prone to cracking but a rough surface in the intake ports is supposed to help maintain atomization of the gas while smoothing the exhaust ports helps a lot. I am only answering this to help you since no one else replied. I am a novice in builing a SBC for the street but I have tried to emphasize torque rather than high rpm H.P. Check out Ryan's dyno builds but remember once again the low rpm part of the torque/H.P. curve is usually ignored.

http://www.ryanscarpage.50megs.com/combos1.html

As far a heads go the early 327 double hump heads are very good but may not have accessory holes in the ends and may have combustion chambers which are too small and lead to impractical compression ratios. I used flat top pistos 0.030" oversize and estimate a 9:1 C.R. A recent thread on this Forum discussed a relatively new design for Dart heads if you can afford them but the factory Vortec heads are supposed to be very good too and cheaper although they require a different intake manifold. Well if you really want torque you need to ignore the drag racers who have high stall converters and cams set up to max out around 6500 rpm OR maybe set up a 4.11 rear gear. Hey that is my limited list of mistakes and I won't know if my selection for low rpm torque really works until next summer at the earliest. Take a look at this head-flow site also:

http://chevyhiperformance.com/techarticles/41598/

Next time start a thread entitled "SBC Cam?", that should get a lively discussion started. Good Luck.

Don Shillady
Retired Scientist/teen rodder