Switching from 305 to 350 with a hot cam and headers if I was to run the tbi what would need to be done to make the proper performance

 

From my experience with tbi which isn't much, and with tpi which is a lot, its mostly the tune and injectors and if you are using the 305 heads it may choke it and check the compression on it.

 

Yes, what heads? With most factory heads, it won't take much. With good heads, you'll want some good stuff.

Might be better to ask on the TBI forum, but I'd guess a good carb intake like a Peformer RPM or Victor Jr, 454 TBI, TBI to squarebore adapter (which will likely have to have the holes opened up). And a lot of tuning.

 

I have stock 350 heads been redone have diff springs for cam is all just was trying to wiegh the odds of using a carb or keeping what I have whatever is easeyer

 

You need a custom prom chip to use a 350 with TBI.

 

tbi if you arent going for performance all the way! Its cheaper to get a tune then buy a whole set up and if you ever want to change elivation you dont have to do anything! I would recommend putting different inj in it as a 350 will mmake more power but I know people on here have done it with the 305 ones.

 

Again, what heads? About 90% of stock factory 350 heads are performance junk.

The casting #'s would tell the story.

 

3888920 is the casting # they have been all redone ported valves screw in studs guides cut for big cam i have 1.6 roller rockers comp roller cam is 224 dur 502 int 510 exh lift

 

I'm not coming up with anything on that number. Could they be 3998920? Sometimes hard to tell the difference between 3, 8, 9 in those cast-in numbers.

For example:


From: https://www.thirdgen.org/forums/tech...251-heads.html

I'm afraid I would put them squarely in the 90% class. Especially if they are 76cc chambers.

They will have soft exhaust valves and seats unless they have been upgraded (expensive). Not good with today's unleaded gasoline.

You may get along okay with them, but I certainly wouldn't put any money in them (which is appears is too late in your case).

 

they are 3998920

 

I don't have specifics on those heads, but truck heads typically don't benefit from lift over .45". So, your valves will move through that last .05" of travel without any increase in flow.

What are you going to use for an intake manifold? Your stock TBI won't bolt on without modification to the center two bolt holes on each side. And, it wouldn't support a Hot Cam very well at all. An '86-earlier style carb intake will bolt up, though. You can use a TBI to carb adapter if you stick with TBI.

 

they came off a chevelle my buddy had them all redone and modified put 1000$ he said they are all set up for the cam im just gonnna run an air gap mainifold with holley carb i was just wondering about the tbi how much preformace they will actually support i plan on getting a set of dart heads in the near future but gotta run theese for now till i get more $$

 

That's a topic for the TBI forum. A should yield the answer.