beerfish89

got the 305 apart and found a spunt rod bearing, cranks gone! Three piston skirts were broke and smashed. I think the block looks ok other wise.

Anyway, I wanted to rebuild the 305 becuse its a manual, G92, 3.45 car, but I think it is going to be more cost effective to build a 355. I just need to know how much of my exsiting tpi can I still use. Injectors ect. Do I have to get a l98 block or will and roller moter block be ok? I assume I can't use my 305 heads? It just seems so much simpler to rebuild the 305! Just looking for a little advice so I can get started in the right direction.

THanx

Damon

Given that you already own the 305 and it's basically worthless in resale, it may be your least-cost option to simply rebuild.

If you go 350 the whole TPI will bolt right on, but you'll have to upgrade to the larger injectors used on a 350 TPI at least and get a custom chip to run it all (they never made a 350 TPI with a manual trans, so no factory chips available that will truly plug-n-play.)

Starting from a factory 350 roller block (L-98) would be a true bolt-in, but earlier non-roller blocks can be made to work with little effort. For your TPI to bolt onto a 350 you'll have to use heads that are designed for the later 87-up bolt pattern (again, old cast iron L-98 heads are available cheap and will truly work with no changes). Yes, you can bolt your 305 heads onto a 350 if you watch your compression ratio (dished pistons) and realize they don't flow as well as a set of 350 heads due to the smaller valves and ports.
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If you want to upgrade with perhaps aftermarket heads, larger cam, etc., it's all possible. For money and if you get a chip to make it all work together. Question really becomes.... what do you want to do and how much money do you have?

dream02transam

I dont know too much about all the rest but I know the 305 head will physcially bolt on the new motor but its chanbers a considerably smaller somewhere in the 50 cc range while 350 heads are usually 64 cc which depending on pistions can give you a 10:1 compression range (flat top pistons) and they come in 74cc (stock heads) and will give you th 9:1 range. The 305 head will give you around 11:1 or more which you will need 100 something octane and wont be able to run on pump gas.

F-BIRD'88

The 305TPI heads u have now are very usable on a new 350.
If you were to rebuild them and upgrade them with larger 350 sized valves you would have the equivelent of a 350 L-98 TPI head.

When you cut the new seats for the new larger 1.94x 1.60 valves you will have to relieve the combustion chamber wall around the valves a little to physically fit the new larger valve. (unshrouding) This will naturally enlargen the chamber a little from the stock 58cc . when you're done the chambers will be more like 61-62cc's not much different from the 350's 64cc's.

So your actual compression ratio with your 305 heads on a new 350 will not be exessive.

The ports are basicly the same. Once you install larger 350 valves, your 305 heads will be a functional = to a 350tpi head.
With some porting they will make more power.
So you actually have a good set of heads to work with.

The only real difference between the two heads is the chamber size and valve size.

beerfish89

I am definately looking for a low cost solution. Not worried to much about power just enough to bust a few stangs every once in a while.

F-BIRD'88

Then reworking your 305 heads with some porting, chamber deshrouding and larger valves along with a trip to the machine shop for a valve job will get you what you're looking for.
There is lots of performance locked in those heads Wether you end up going with a 305 or 350 bottom end.

On a 305 upgrade your heads to 1.94"x1.50" valves.
On a 350 upgrade to 1.94" x 1.60" valves.

Cost is the same.

Sitting Bull

F-Bird'88 speaks the gospel, brother beerfish :hail:

Follow the link at the end of my sig for the lowdown

ME Leigh

Thats not entirely true the 3rd gen 305 heads have 1.84" valves which is bigger then most most 350 heads. Also the 416 ports are about the biggest the General made at 165cc, pretty much the only thing bigger are the 461X "HO camel hump" at 172 cc the regular "camel hump" 461 heads only have 160cc ports. So...... there is a ton of potential in 416 heads!!!

five7kid

iTrader: (14)

Rebuilding a 305 shortblock is rarely the "low-cost" option. If the crank is indeed "wiped out", and you need new pistons, those things cost the same as 350 parts. But, for the cost of another 305 crank (by the time it's ready to install), you can probably buy a builder 350 shortblock.

However, I happen to have an '87 LB9 shortblock sitting in my garage. It was rebuilt with .040-over pistons and .010-under crank. It has cracks in the lifter valley, which is probably why it required rebuilding in the first place, but I pulled the bearing caps and the crank/bearings are in great shape. The pistons are probably reuseable, too. If you want it, it's yours for coming to get it. Otherwise, go look for a rebuildable 350 shortblock.

I'm assuming this engine is an '89, from your username. Those would be 081 heads. Very similar to the vaunted 416's, and very useable on a 350 if modified as suggested above.

I don't know if I'd go so far as to say "most" 350 heads have smaller valves than 1.84". But, you do need to be aware of what you've got before spending any money on 350 heads.

beerfish89

appreciate the offer but I am over here in ky, shipping would be the only option.