Plans for a 478 build.

[bigblockv6]

For fuel injection on the 305 you can go with the Howell TBI most likely a 305 Chivy unit along with an HEI. I talked to Howell a few years ago and they said it would not be a problem with the 478. They do highly recommend running an HEI with it

[TJ's GMC]

Originally Posted by bigblockv6

For fuel injection on the 305 you can go with the Howell TBI most likely a 305 Chivy unit along with an HEI. I talked to Howell a few years ago and they said it would not be a problem with the 478. They do highly recommend running an HEI with it

Never hurts to have more spark. HEIs have been know to increase mileage and performance. It did on my 305. Cold starts and warm up are much smoother and the mileage is even better! I'm gonna be trying out that MSD box and see what it does.

[beerman]

bigblockv6
Re: Plans for a 478 build.
For fuel injection on the 305 you can go with the Howell TBI most likely a 305 Chivy unit along with an HEI. I talked to Howell a few years ago and they said it would not be a problem with the 478. They do highly recommend running an HEI with it

Did they say what ecu they would use to drive the injectors on the TB? Although aftermarket standalone controllers are nice, I like the idea of retro-fitting a GM system on it. I have an extra Procharger head unit sitting around and I thought about looking into the SY/TY 1227749 ecu (keeping it all GMC) which could handle boost. The problem with the SY/TY setup is that it would require an intake manifold and probably some sort of crank hub mounted reluctor. Maybe it's time to search the third gen.org site.

[TJ's GMC]

Be some fun fabricatin!

[beerman]

The wiring would be easy (you could probably even buy a standalone harness) and the sensors are readily available. They sell generic Prochager mounts, you'd only need to machine up some standoffs, maybe clock the head unit, run some tubing, add O2 bungs and make a mount for the reluctor. Plenty of room for an intercooler and bypass valve. LOL I even have tunerpro with romulator for tuning on the fly. I'd make a 329 ( put the bigger stroke in a 305) or a 379, because I'm still not totally sold on those extremely large bores. Of course I still need to put a floor in my cab but if your dreaming I'll dream with you.

[TJ's GMC]

Speaking of over stroke....can you put a 379 crank in a 305? Direct swap? The added stroke and a .060 overbore would be pretty cool. Bump in compression and bigger cam would be sweet to.

[beerman]

2 factory crank sizes 3.58 & 3.86
CID Bore Stroke
478 5.1250 3.86
443 5.1250 3.58
432 4.8750 3.86
401 4.8750 3.58
379 4.5625 3.86
351 4.5625 3.58
329 4.2500 3.86
305 4.2500 3.58

[beerman]

Old Bore 4.250
Over Bore 0.060
New Bore 4.310
Stroke 3.86
New CID 338

[TJ's GMC]

338 would be nice! I just wonder if the cranks will swap without issues on the 305. They are all different blocks from what I know.

[bigblockv6]

Here is a 4bbl manifold design by Andy Harman, I think it is a dual plane design rather than single plane as all our V6 engines have. He also has one for EFI if I can get it to upload