Does anyone know how hard it is going to be to get some respectable HP, say around 300, out of a late 70's Pontiac 400 without changing heads?

It's possible, but the heads you most likely have would require some porting, and some work...

The main problem with the late 70's 400's was they dropped the compression ratio's and the power went right along with that drop. So for the most part, the heads are the key ingredient, to making the power. (the best way to do it)

Think of the engine as a big air pump. The more air you can get into the engine, and the more air you can get out, will produce more torque and HP.

So, depending on what motor it is (code?) and what heads you do have... you can do all the basic bolt on things (Headers/Intake/Carb/Ignition etc... and gain some power, enough to feel... but with out doing some upgrades or even changing the heads, it may not be enough... but will be a change in the right direction.

You may need to tell us more about the engine before you get some more specific answers?

Engine year and code. Any mods now like headers, carb, intake etc.. What car is it in, what tranny, what gears in the rear etc... All variables that will effect the final outcome.

Good luck, keep us posted -
Brett - 67 Drop Top 455!

I just read an interseting article on the National Firebird and Trans Am club web site. A guy took a late 70s Olds 403 and invested $1600 and was pushing about 350HP. I guess there are some real Pontiac die hards that shiver at the fact that an Olds small block 403 was ever used in a Firebird. However, it is an economical way to get some ponies under the hood.

Vince

$1600 bucks into the Olds only made 350 hp? I've got less than that in my 455 making well over 500 hp. Now that's economical HP!

Drew... what's your combo consist of? Just curious...

I was estimating my 455 set up pretty stock (73 engine with 6X4 heads stock came etc... right about 300-350 hp tops) Until I do some work to her...

But always like to hear what others do to squeeze some juice out of their ponchos!

Thanks - Brett - 67 Drop Top 455!

Mine's stock - really!

Without touching the heads, swapping the intake, cam and adding headers or RA III mainfolds will get you the most bang for the buck. Make torque at low RPM instead of HP at high RPM. Adding a few degrees advance to most stock cams will really wake up a low compression motor, too.

Q

70 4 bolt 455 bored .060, Holley Street Dominator intake, heat cross over completly milled off the intake, Holley 780 vac secondary, 1 inch spacer, gasket matched intake and heads, milled 6X-8s milled to 96cc, 1.77 exhaust valves, home ported and polished, Lunati Bracket Master II cam, 1.65 Roller Rockers, double roller chain, crank scraper, headers, and HEI conversion.

Sweet, thanks for the info! All that fit under the hood ok? Even with the spacer?

Some day I'll port my heads, and swap cams... but for now, it's just a cruiser!

Thanks again Drew.

Brett - 67 Drop Top 455!

Hey Drew, When you put on the 1.65 rockers did you have to go with taller valve covers or di they fit under the stock covers?

Robert

Robert, my 455 has Harland Sharp 1.65's and they fit under the stock chrome covers no problem.

H.S's are about $209 form Jeg's etc... cheaper and from what I hear better than most on the market.

Talk at ya - Brett!

Thanks Brett, I was a little worried that my covers were going to get beat up when I fired the motor up.

Robert