I have a 91 formula with a 305 t-5 combo. It has headers a full exhaust and a cai. I plan on replacing the 305 within a year or so. I have been looking at the 290hp gm 350 crate motors do you think it would be worth it to dish out the $1600? or should I just look around for an old 350 block and attempt to build it? This is my daily driver 8 out of 12 months and while performance is obviously important a smooth running efficent motor is probably more important which is why id like to keep the tuned port.

id like to use as much stuff from the 305 as possible is there anything differnt id need to buy/make to get it all to work efficently? also how will the t-5 hold up

sorry for all the questions i know some are already on here i just couldent get a good answer to these 3 thanks alot

 

It's been discussed several times, a few people have used them in one configuration or another.

The Goodwrench crate motor is '85-earlier configuration, meaning the crankshaft has a two-piece rear main seal (uses a different flywheel than your engine); the intake manifold mount bolts have a 90 degree angle rather than 72 degree angle like the center two bolts of your intake have; and the valve covers are of the perimeter bolt style rather than center bolt (there have been some reports of accessory interference when using later accessory mounts on that type of engine).

All of these can be overcome - buy a flywheel for a '83-'85 3rd gen 305; modify the center two intake base mount holes on each side of your base; modify the valve covers until your accessories fit.

The engine also has rather poor heads compression- and flow-wise, although they would meet your criteria, they wouldn't respond well to modification.

Your TPI is the speed density version, so you would need to re-do the PROM to account for the different engine characteristics based on the displacement increase. You would also want to get 350 knock sensor stuff.

Your T5 will be fine as long as you don't do clutch dumps or speed shifts.

 

thanks alot for the info, wow it would of took me forever to figure all that out.. I was hoping for more of a compatable motor. Would i be better off finding a 90-92 l98 350 block? then all i would need is the prom right?

thank you very much for the responce

 

There is a similar engine often called a Caprice replacement that will bolt right in (with the 350 knock sensor and PROM changes still being required).

 

http://www.sdpc2000.com/catalog/123/...B-D-L0557K.htm

 

thanks for the link, I may save up for that but is there any place l98 blocks can be bought?

 

None that I know of. My brother got a rebuilt L98 engine from an outfit in Washington, about the same price as that new Caprice crate, he's quite happy with the results.