Tech / General EngineIs your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
Welcome to ThirdGen.org!
Welcome to ThirdGen.org.
You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, at no cost, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, join the ThirdGen.org community today!
anyways I recently bought a 1985 trans am, with a 1969 chevy 350 in it. It has a lot of performance parts and I am trying to figure out how much horsepower I make just out of curiosity.
The engine is bored .060 over, I was told it was rebuilt 3 years ago, it has an edelbrock performer intake manifold, edelbrock 4 barrel carb 1405, headers, pro-race damper, upgraded to HEI, I recently replaced the radiator with a high flow aluminum racing radiator i got at a killer price, and thats about it.
Hard to guess at horsepower without knowing what heads you have, if they're stock, compression ratio, and camshaft specs.
this. Start by pulling a valve cover off and get the heads casting number. This will at least give you an idea of what the motor was stock. Of course who knows what the previous owner put in as far as new cam, pistons, etc. It may be a 200hp motor, or it may be a 400hp. However with the very limited info you have provided I have no clue from my computer.
well, i was told that it was recently rebuilt with keith black flat top pistons
i looked up the heads and this is what i got
354434.....75-79...262/267/305...60cc chambers
why would someone put 305 heads on a 350? especially a 350 that has been bored out?
well one, you might have a 305 not a 350.
flat top pistons and 60cc chambers? That's a formula for pretty stout compression. What octane fuel do you use? Also boring has nothing to do with performance or increasing airflow into the engine. It's just cleaning up the cylinder walls so you can reuse the block.
and the only other possibilities for the block is a 327 or a 302
so I am 99% positive it is a 350
and It hasnt really been driven much since I got it, because ive been working on the body and the interior, but when I did drive it i used 92 octane and a octane boaster i found at walmart
and I thought that boring the engine to a bigger displacement gave it more power?
and I thought that boring the engine to a bigger displacement gave it more power?
like a 350cu bored .060 over is like 360cu
No no no. Boring does make a motor bigger, which does increase power, but its minimal. A typical bore is .030 over, or another .030 over on the second rebuild which equals a total of .060 over. However this is not done for performance as that would be a waste of a potential rebuild.
Example: A 383. A 383 is a .030 over bored 350 and a new crank. The reason people bore their used 350 is because after many miles of use the cylinder walls become distorted and not perfectly round. So when you go to rebuild it you must bore out the cylinders to make them perfectly round and true again. However when you bore a block it decreases the cylinder wall thickness so you can only rebuild a motor once or twice, after that the block becomes useless. So yes when you bore the block it does pick up a few cu. but you'd be a fool to bore a brand new block just to pick up those few extra inches as that would be one less time you could rebuild that motor in the future.
So basically people bore their motors because its a lot cheaper than ordering a brand new block, the extra hp you pick up from the extra cubes is just a by product.
ok, and one more question, should i keep the 305 heads, or should i look for new heads?
and if new, any suggestions on what size chambers?
well I have no idea whats been done to those heads as far as port work, valves, springs, etc, or what kind of flow numbers they have. Perhaps someone else will chime in on that.
Personally with the motor being a flat tappet, already bored .060 over (cylinders walls are probly to thing to be rebuilt again), what I would do is just leave it alone and later done the road replace the whole motor with either a used L98 or even better a L31 out of any vortec truck. You can find used vortec motor for a couple hundred. Then just sell you current intake and get a vortec specific intake.
ok, if i ever had to replace the motor I would probably just get a block, rebuild it and keep the set up I have, because its pretty powerful and I like the simplicity of it, not having to deal with injectors or computers.
ok, if i ever had to replace the motor I would probably just get a block, rebuild it and keep the set up I have, because its pretty powerful and I like the simplicity of it, not having to deal with injectors or computers.
thats what i was referring to. l98 and l31 vortec heads both would make better hp than those heads in stock form. You could pick up a used vortec motor for $3-400, rip all the FI off and toss it aside. Rebuild it and toss in a new cam for another couple hundred, and bam have a new even stronger motor for less than a grand.
