I have a 1970 LT1 that made 360hp stock. I took it to the machine shop to get hot tanked and a valve job. The engine has not been bored. The only only things that I am changing is the cam and intake. I even have the organal carb that just got rebuilt. Here are the stock specs . Casting # GM P/N Description Block 3970010 4 bolt main, suffix codes: CTB, CTC Crankshaft 330550 Forged steel Heads 3927186 63.995 cc, 2.02/1.6 valves, screw in studs & guide plates Cam 3972182 3972178 symbol: (1) square Solid lifter - 0.458(I)/0.484(E) lift, 317I/346E duration Pistons Domed type - yields 11.0:1 compression Intake 3972110 Carb (A/T) 3972120 Holley List 4490, 780cfm , 4150 series - 4BBL The cam I am using is a Comp cam XE294H- 0.519 I/ 0.523 E Hyd flat lifters. I am also using there recommend spring kit -986-16. I am using a RPM Performer Air Gap intake. What do you think my horsepower gain is going to be? My other info is in my sig under 83 TA When I take it to the track it will havee 26in. slicks. Thank for any help you can give.

well your RPM intake will be alot better than the stocker. and if you jump up with the cam, i would say 400hp more than likely. i would recommend a new carb, as 70's technology and reliability cant compare to todays. you could see a big gain just from the carb itself. since thats a decent sized bumpstick, you could be up to 450hp. those heads could used some work to really benefit you. better flow will greatly increase your potential with that intake, and cam combo you got there.

450 NA hp is a lot to make with 350cid, unported 186 heads and the rpm limits of a dual plane intake and 161cc intake ports.

You had a solid cam before, why not keep it solid? You'll make more power. Also, you're converter and 3.42 gears may be on the low end of the acceptable range for an XE294 and 350cid.

Cool.. I was hopeing over 450 but wont be sure till I get it in the car and go to the chissi dyno. Any thought on what it might run in the 1/4 mile. I am hoping mid 12s atlest.

I'm gonna be honest here - those heads don't flow enough unported to get to 400hp, let alone 450.

If you were to upgrade the heads, 450hp should be no problem as long as the can is correct and the engine is assembled correctly.

ok, after looking at some flow numbers i see they say 385hp is about all those heads will support at .500 inch of lift

flow about 188/135 which is worse than L98 heads LOL

i would say with that cam, i would expect 375hp or so