Im doing my first engine rebuild. Cant really afford a 350 right now at the moment.
So anyways, at this point in time i have the normal dished pistons with reliefs and the 58cc heads. Im looking at a rebuild kit on summit that has flat top pistons with 4 reliefs. Would these work if i get my block board 0.30? What would the compression be on this setup? Could i still use pump gas?

Thanks

 

There's no such thing as "can't afford a 350". If you can afford to "rebuild" your 305, you can afford a 350. It will cost EXACTLY the same.

Think REAL CAREFULLY before you make that mistake. By the time you actually have a "rebuilt" motor (parts, machine wor, tools, fluids, incidentals, all the "might as well"s like a water pump and belts & hoses, and the list just goes on) you will have laid ot over $2000, GUARANTEED. There's no such thing as "can't afford" $50 for a junk core 350 to rebuild, instead of the junk core 305 you have now.

 

so, you propose to buy the junk $50 core and use the swirl port heads?

Also, when you price in the incidentals it's a wash so you can't add those to the cost of the 305 and not add it to the cost for the 350. Only politicians did that when they rammed through obamacare but i digress.

So, with that said, my 89 RS restoration had a running LO3. I had it rebuilt, parts included for $1300. I needed no new injectors, no computer program changes, nothing. I removed the engine, brought it to the shop and re-installed the engine.

Yes, for that same $1300 I could have shopped around for a junker 350 (definition- used 350 without any paperwork on the disposition) and dropped it into the car just to have it crap out in short order. I don't play those dice rolling games.

The 305 is a fine engine and can give you years of reliable service. No, it does not perform like a 454 or 427. If you want higher performance, then yes, replace the 305. But, don't do a junker swap.

 

No; incidentals are necessary, either way. There's no attempt being made to sugarcoat that. In fact that's part of the point: ALOT of money is going to be spent on an engine "rebuild", on ALOT of things besides hose big ticket items that are very visible; those little expenses ADD UP, and drive up the cost of the total project beyond a first-timer's ability to estimate them. The cost of THE CORE is a tiny drop in the bucket, in the big picture. The more "incidentals" end up being needed, the less difference THE CORE you're rebuilding makes. VERY FEW novice engine builders can get through a "first" rebuild for any $1300; they have no tools, have to pay somebody to do more of the work for them, and so on; that's NOT a realistic, REPEATABLE, DUPLICATABLE number, motor out to motor back in. The real number is going to more somewhere between $2000 and $2500. I know, that if I was about to spend THAT MUCH money doing something, if I could spend $50 up front and get 15% more results at the end, it would be a no-brainer.

The bad thing about rebuilding a 305 is, you spend ALL THAT MONEY, and then if you don't like what you get, there's basically NOTHING you can do about it, except go out and spend THE SAME MONEY ALL OVER AGAIN.

Heads, you can un-bolt and re-bolt later. Yes, you could even re-bolt the 305 swirlies to a 350, and while it would limit the 350's performance, it would be something you could go back and undo without, in effect, putting a bunch of already-spent money in the trash. Machine work to a block, not so much.

I'm also not advocating a "junker" swap. That's yet another attractive-looking, "cheeeep" path that leads straight to disappointment.

"Paperwork" also isn't an issue. The issue is, what CORE do you spend all that money on. The CORE. You know, the old dead one, that costs next to nothing, that you sink all the money into. The CORE limits what you can get for a finished product; so why let THE CHEEEEEPEST part of the whole "rebuild", ruin the ENTIRE THING?

Moral of the story, DON'T rebuild a 305. Go to the junkyard and get a 350 CORE to rebuild instead. You'll be glad you did, instead of regretting that you built a 305.

 

ok, add in the 350 injectors (over $100 if you buy outright), new fuel pump for more psi(over$100), the 350 prom....what
else
I also don't think it's as big of a deal as sofa is trying to get you to believe. you're not racing it or anything. save a few mpg that's all.

 

350 TBI and 305 TBI fuel pump and fuel pressure regulator is the same.

 

I have to concur with this.
I have had quotes on having my 305 rebuilt and it has been less than $1500 even with the added work I want done. The only added costs I will come across is antifreeze, hoses a oil change is really about it.
If I went to a 350, first a core is not going to cost $50, more like $300 if your lucky and $500 for a good solid motor that was running prior to pull.
If I put it together the same way as the plan for the 305, it would net me what 25-30 horses more and I'd have to make sure it can use the 305 parts like the intake etc because if it doesn't, oops there goes the cost skyrocketing.

 

you put incidentals aside because you are going to use them whether ypou drop in a 502 or the 305.

It comes down to what is best for you. I just so happen to have 2 pother performance vehicles and am restoring the 89 RS. If I wanted a performance vehicle then I would have purchased a crate engine. I won't touch junkers because you end up needing to rebuild them if you want it done right and sometimes the heads and blocks are just crap despite the assurances of the seller so you run up the costs real quickly.

My 305 was running with no knocks. So, a bore of .030 to clean up the 160k original miles and then a rebuild and it's now "young again" but I had a known commodity from where I was starting.

Yes, $1300 soup to nuts rebuild and I even reassembled the engine including the intake/tbi and flexplate and brought it to machine shop. They put the entire thing back together including installing the distributor.

So, for $1300 I have an engine that should give many more years of reliable service.

It all boils down to what are your needs. I didn't need a vehicle with 300RWHP or more, already have 2 of them.

 

I doubt his old fuel pump is going to keep up with what even a stock 350 wants. 55 lb/hr vs 61lb/hr
too risky if you ask me unless it's brand new.

 

Would not look at it that way, everything can/will fail at a certain point, no sense to replace everything.

How to fuel his rebuilt 305/350 tbi engine, brings up other important factors to take into account wenn rebuilding an engine, fueling and tuning.

To fuel a 350 tbi (stock specs) @ 11-13 psi, requires 61 lb/injectors and the 350 tbi prom, the stock tbi fuel pump will do the joob (if it is still working).

For the flow of 61 lb/hr injectors @ 12psi, the 55 lb/hr would need around 17psi.
Stock TBI fuel pump will not work for 17psi.
To fuel a 350 tbi with 55 lb/hr injectors @ 17 psi, requires high flow fuel pump (for exemple TPI fuel pump), AFPR and at least a coustom tune.

To fuel a modified 305/350 tbi that makes more power then stock, requires highflow fuel pump, adjustable VRFPR, injectors that resonably support the fuel demand and tuned EBL flash.

 

Here are some helpful calculators http://www.kb-silvolite.com/calc.php flat top pistons were used in later 350 with similar iron head combustion chambers and around 9.8 CR.