Maybe bunch of stupid questions, but I hope someone could answer these.

My previous engine (slightly built and LT1 cammed 305) got rod knock and as I got L05 350 lying around, I decided to swap the engine. I knew that it was TBI from newer Van, flat tappet cammed, but after disassembling upper side (manifold gaskets were leaking), I found out that it hasn't the roller lifter bosses cast, so I assume it's earlier TBI block.

As the engine was slightly sludged, sat in storage for about 10 years, of unknown state and the oil pressure after running with 10W40 is only about average, I think I would disassemble the engine in winter and maybe do some mods too. The goal would be totally streetable performer engine. I think around 350-375 hp, and 350-400 lbs torque. It would be fed with TBI, because I have some knowledge and experience how to tune it.

As I'm from Estonia, I have to order most parts, be happy with the block I already have and new 4 bolt crate engine to be foundation of build wouldn't be alternative because of shipping price too.

Now the questions:

1. As the block is for flat tappet cam, I guess the cheapest (not the best for performance) way to go would be new flat tappet cam? I know, it's possible to modify newer flat tappet L05 blocks to use factory roller assembly (the blocks got bosses that needs drilled and tapped, to hold lifters and cam in place), but I have no idea, how easy or expensive would be to convert the older non-roller block to roller one. Any reasonable suggestions are welcome.

2. Cam choice? What LSA and duration should I aim? Slightly lumpy idle wouldn't bother me and reasonably low idle vacuum too (until it could be compensated in tune), but the cam should be affordable, as it would be budget build. Some say that TBI needs cam with LSA 112-117, other say 108-112 would be fine?

3. Heads. I think I would go to ProComp route, buy bare castings, clean ports and assemble them myself. Just because porting stock 193 castings is not the way I want to go anymore (I ported my 305 heads and it took almost 2 weeks to get these almost perfect) and being tight budget the PC-s are the only ones I could afford. Aluminum is slight bonus too, considering weight. Any reasons that I should use something else?

4. Any concerns using 2 bolt mains with stock bolts? Should I use studs?

 

Flat tappet is ok, break in the lifters properly and use a zinc filled oil. Rotella will work if needed it has >1200ppm of zddp.

My only issue with the pro comp heads is they don't flow well for their port size. It is a bad combo for low end power. I would get a nice set of vortecs and rebuild them.

Not sure how crack prone the pro comps are I keep hearing mixed reviews.

I like my patriot vortecs I think I paid 720 assembled but I only have about 3k miles on them.

You can go roller with conversion lifters as well. But they are expensive.
To do the drill and tap method you need lifters from a 4.3L Vortec V6

I will let someone with more TBI knowledge say which cam.

Get a carb manifold and a TBI adapter.

 

I know that the PC-s don't flow too good, but I probably could not find here any Vortecs and being aluminum ProComps are way cheaper to ship. I guess they would benefit from slight porting anyway. Porting cast iron was PITA, but working on aluminum should be simpler job (I port matched Edelbrock intake to my old heads and it took only about an hour or so).

 

As long as you're running a 2-barrel TBI, the rest doesn't matter. Even modding the best TB, you're still limited to around 300 HP. So pick a small, torquey cam. LSA doesn't matter, what matters is how many degrees of non-overlap at 0.050". You can go zero-overlap with custom tuning and headers. I say leave those heads un-ported until you replace the TBI. I really can't spec a cam without knowing what tuning you can get, and 2 bolt mains with stock bolts are more than adequate for 400 HP, let alone 300. If you're likited to a mail-order chip, then the cam will have to be really mild anyway, and 300 HP will be about all you can hope for.

 

Yea what Atilla said. The tbi just doesn't have the fuel to really make any power. And it's not like a multiport where you can just get bigger injectors. You're going to need to either go to a carb or to an aftermarket fuel injection if you want to even come close to your goal.

As far as heads, I personally wouldn't waste my money on procomps. I have used them before, and yes you can make some power with them with a big cam like the guy on ebay did. But compared to any decent modern aftermarket head they are pretty crappy.
I would save up a little more an buy some profiler heads. They're around $1100 assembled and shipped. And they're made in the US, so you're money stays in this country!

 

Iron heads are fairly cheap to ship when you order through jegs or summit. Last time I shipped heads it was about $60. Hell I shipped a T5 trans from a member here for 75 and that was Texas to NY

Porting procomp would be a must but the ports would be still be to large for a low revs engine. The only time where procomps flow better than vortecs is over 500 lift.

You are going to need to run a mild cam for your 2bbl set up. You want down low power. Even if you run the 190cc heads you will have issues making decent tq. You will probably be in the low 400s for lift.


http://www.store.procompelectronics....oduct_id=37059



Something like this would work great. 871 the entire kit, free sipping

http://www.jegs.com/i/Chevrolet+Perf...060K1/10002/-1

 

Well, the shipping iron vs aluminum is issue if you don't live in US

Ok, maybe I overestimated the TBI air flow. I have seen a setup of 2 2-barrel TBIs on 383, so it couldn't be too mystical on 350 too? What about TBI unit from 454, some say it's good to about 400-450hp?

 

No, the 454 TB is still only 670 cfm. But you can't get injectors that flow enough for over 700 cfm. The aftermarket offers 4-barrel TBI assemblies but it still isn't port injection. Find some heads with intake ports no larger than 180 cc, or even any stock heads that aren't swirl-ports, and put most of your funds into the HSR, or a carburetor and matching intake. Then only way a 454 with stock TBI can do 400-450 HP is with a nitrous kit that includes its own extra fuel from the other side of the nitrous spacer plate.