I'm thinking of swapping out the 305 and going for the 350. I have TPI so I will stay with that. So far as I know, I need to change the knock sensor, get an 87+ non LT1 or LS1 block, and the 24lb injectors (maybe). Will my 305 heads work on a 350 TPI? Is there any power and performance in doing that? I would of course have bigger valves put in, definitely 1.94" intake. Can the 305 heads be machined for 2.02" intake valves? My last question is what is the difference between a short block and a long block? Thanks in advance for any information you can lend!
Brandon

 

Also,.. What's the difference or differences in a flat tappet and roller tappet cam? What the heck is a tappet?

 

Stick with a 1987-1992 L98 350 Block. Use your induction system but the heads are 56cc and will make your compression ratio too high for 92 octane. Stick with about 9 to 1 for cast iron heads. Aluminum heads can go about 10 to 1. I believe that the 350 heads are 64cc. The head/piston/head gasket/block deck height etc. should be chosen to get to the 9 to 1 target. Roller hydraulic lifters have a roller that rides on the cam lobe that reduces friction at that point. Flat hydraulic lifters have a flat face that rides on the cam lobe. All 1987 and later blocks are set up for the roller cam/lifters. From what I understand, the TPI setup was designed to give the 305 the much needed torque curve improvement. GM used the identical system on the 350. Just remember to design your entire system for primarily torque. Our engines are horsepower limited at above around 5000 RPM. But, there is a mountain in the middle of the torque curve due to the great design of the TPI setup. Don't forget your new cal-pack prom for your computer. GM will need to know your transmission type, rear-end ratio, and engine size. Well, I've typed enough for now. Good luck with your project. I'm just about to finish mine after almost a year of interruptions.

------------------
'85 Sport Coupe V6 T5(bought new)Putting in 88 350 TPI/AOD and a bunch of 88 IROC and aftermarket performance parts now.
86 IROC 305 TPI AOD
(selling after Sport Coupe rebuild is done)

 

Two more things.
1. I have no clue about the origin of the word tappet but if I had to guess I would guess it is the sound of mechanical lifters when they are out of adjustment i.e. too much clearance in the valve train.

2. A short block does not include the heads or intake setup. A long block does.

------------------
'85 Sport Coupe V6 T5(bought new)Putting in 88 350 TPI/AOD and a bunch of 88 IROC and aftermarket performance parts now.
86 IROC 305 TPI AOD
(selling after Sport Coupe rebuild is done)