I am currently getting my engine rebuilt and it is a 305 with tpi and i was wondering whether i should go 40 or 30 boarded out and what else could could i do to give my self more horse power, should i also get a tach since im going to be going to the race strip even if it is an automatic, since ill be shifting anyways

 

Well dude, that not a bad idea due to the fact that you already have the block. i even thought of doing that myself. If it was up to me, id bring the motor to an machine shop or speed shop and have them hot/high pressure wash it (bare block) and talk to them to see wether it would benefit you to bore 40 or 60 over. Id def talk to them, cause if the cyl.'s are bored too much, then the walls between the cyl.'s could possibly bee too thin and cause a hole to form between cyl.'s. Oh, and having an automatic for the strip isnt a bad thing, cause you get better launches opossed to a slightly slower launch but more horses to the wheels in a stick. Ive got a 88' IROZ/Z28. its got the 305 HO tpi in it, which moves pretty good for a 305. Well whatever, ill relpy back if i find out anything else, and update myself if you find anything else out. Lata!

OnFiRe705

 

I read something in GMHTP magazine that was written by a tranny guru and he said you should not manually shift an auto b/c the transmission doesn;t build up enough pressure or something to that tune.


Nov 2002 vol8 num6 pg58
"Q: In a 700R4 or 4L60E is it better to shift manually in a drag race or let the tranny automatically shift?
A: In a street/strip application, the tranny should be set up to shift automatically in overdrive or drive. When you manually shift it, theres a delay in pressure rise. You push the lever and it wont respond right away b/c theres not enough line rise. You can burn the trans out shifting manually b/c there isnt enough pressure to hold the clutches."

Just looking out for you bud - I'd leave it in overdrive

Direct from Eric Schertz guru at Countyline Transmissions.

 

i think you kinda missed the point with the trasmission part. With a stick (manuel trans) you have a slight slower start, but theres less friction in the trans, than an automatic. unless the automatic was rebuilt really good. Automatics have better launches, but lose a little bit of hp due to the friction in the trans. unless like i said before....you have it rebuilt strong with needle roller bearings. Im just curious......have you ever been out to a drag strip, cause anybody i know that drags with an automatic manually shifts it. They also make Co2 actuated solenoids for big drag racers (automatic trans). You will lose 1/4 to 1/2 of a second off 1/4 mile time if you leave it in D (drive). This manual shifting technique is also used on the street drags. Well whatever, im just letting you know what goes on at a race. Trust me, i know cause i work for a tranny shop, going on 2 years now.

OnFiRe705

 

Okay Completely Disregard everything these people have said...

When rebuilding an Engine, You do not go .030 or .040 out To Increase Horsepower. You Do so to clean up the bore to ensure a good ring seal.

As such, You should only go out the minimum amount nessicary to assure the surface is true, and your machine shop will be able to assertain that.

As far as Items to increase horsepower, Thats the Open Ended question of the century. You sound like you don't have alot of experiance, So you might do well to do some research.

These boards on this webpage are a wealth of information, and truth be told, we could probrably shut them down now and only offer them as a Searchable archive, and few questions would go unasnwerd.

As such, decide what your budget is, Decide how you want to use the car, and decide How fast you want to go.

Then search read and search, Find a combination that falls within your budget, and satisfy's your needs.

Then come back and ask us more specific questions, and we can help you get dialed in on exactly what you want to do.

As far as the Tach, IMO its money better spent elswhere. The Factory Tach is more than sufficent for all but the fastest Cars.

The Automatic/Manual Arguement Is a pretty Moot one, Too. If you want to be a quick quarter Miler, Then a Solid Automatic With High Quality Torque Converter will give you the quickest ET's.

But Manuals are More Fun to Drive, Better on the Autox and Road Race Circuts, Will get you better Gas milage, ect, And with a skilled driver arent That Bad in the 1/4.

So Its up to you, and again... What you Want from the Car.

If I offended anyone, Its okay... Im An *******.

 

No, you're never an Asxxole when the truth is spoken, enlightening the "less-enlightened" crowd is what this forum is about.

Only the most extreme racer will bore as much as possible to gain the extra few HP, but as mentioned in the above post, less is better...AFAIK .030 is all that is recommended on a 305 anyways...but (as when mentioned before) never bore for HP, only for need.

Tach is always a good idea, even when using an automatic, could let you know it's time to back off if the upshift doesn't occur...could be the difference of grenading the engine or being able to drive home after posting a higher ET than expected.

 

No thanks, I'll leave it in overdrive if it's all the same.
I tend to believe what I read in GM Mags.

 

Well Actually, Leaving it in overdrive Will Kill the tranny faster. Thats a Fact.

Leave it In drive except for when your cruising. The tranny shifting in and out of OD all the time is what stuffs it.

 

Thats what I would like to think, But Some on here don't feel that way.

Truth Hurts, lol.