Ok my first time ever really getting into an engine. It's a 1989 lb9. I know it's junk and a boat anchor and blah blah blah. I'm doing it anyway. Trying to figure out what parts to get and found a pretty good deal on a set of aluminum heads. But have no idea if they are really any good. Here is the link.

http://www.ebay.com/itm/SBC-CHEVY-21...-/330705371330

So the bottom end is staying as is. It's a 70000 mile stock 305 lb9 (when it throws a rod or spins a bearing or something i will go 350). I want to upgrade to a better set of heads that are affordable and flow better. I will change cam but no idea how to pick which one. Was thinking of trying to find a zz4 cam or similar. Not sure if these heads would allow for a zz4 cam with 1.6 rockers so I guess I would go 1.5 (suggestions?). Then I want to keep the tpi will I need to change any parts here. Gotten very mixed opinions on 305's with larger manifolds or bigger runners.

Opinions are welcomed and appreciated. I'm sure I would need a custom burned chip at this point, and I have already done all the other bolt ons and mods. I still need more power. I'm open to ideas because I really want to do something like this but don't want to buy junk or unnecessary parts. Will be a while (Christmas time or after) before I do this but trying to research and understand before I buy anything.

 

You can't put those heads on because the large intake valves would hit your small bores at any valve lift over about 0.450", less once you milled the heads to get some compression back. You don't want them anyway because 210 cc intake ports are for 406+ cubic inches. The only aluminum heads you can use are L98 / ZZ4, cast by Chevy, or the Trick Flow 175cc, or milled Edelbrock E-Tec 170 cc, which would be the best for the 350 you will someday try.

 

Those heads will not work on a 305, The valves are 2.02 intake and 1.60 exhaust They are to big unless you relieve the cylinders so the valves don't hit and that is the minimum you could do and that would need to be done by a quality machine shop.

 

Couldnt give me a set of those

Dont shop heads by price youll regret it.

Check into Summit Jegs etc for a quality head its always good money spent.

 

Thanks guys this is the kinda info I need. And I have looked all over for a set of l98 113 castings but never find a descent deal on them.

 

An IROC convertible may actually be collectible one day. Especialy if the car is well kept & in "original condition" .

I would leave the stock engine alone.

You are facing a daunting task with a convertible because the chassis is weaker than a t-top or coupe. which means sfcs and a roll bar to keep you safe.

these are things that will be hard to undo if you decide to part with the car.. and could turn off future buyers.

convertibles are not the best choice for a race car platform. especially ones that may hav value in the future.

but it's your car do as you wish.

 

IMHO I would find a model with a v6 or 305 TBI with the body in decent shape and a tired drivetrainm these cars are a dime a dozen.

scrap the whole drivetrain and build it to your taste (SBC 350+ , BBC, or LS )

 

I'll never sell it. It is my childhood dream car.

 

I bought my '88 Formula in 1993.

What are your long term expectations for performance and what do plan to do with your dream car for the next 20-30 years, if you keep it that long?

If you just want a nice convertible to cruise-in don't waste all the time and money hot rodding that engine because you will never get it back. (pennies on the dollar)

If you want a "race car" a convertible is simply the worst platform to begin with. you will spend alot of money just to make the car safe for track days to run in a slower ET bracket.

Convertibles require roll cage at a slower ET than a hardtop or t-top car.
They are also heavier (aka slower) since the OEM thru-in extra material to make the chassis "stiffer".

but an engine making more power means you will still need SFCs to make the chassis strong. then upgrade the rear end, the trans, the driveshaft. etc etc.


What do you want to do with this car.. that will help answer your question