Thread: Chevy 350 rebuilding tips

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Did 5 runs on the Dyno yesterday and our peak horsepower was 193! We where just excited the engine ran! I got 193 with stock everything and the timing at 18 deg. adv., when I went to 20 deg. adv. it fell to 188 Oh well 193 is good enuff for me. Today we are putting on the mods. Just a performance intake and some big tube headers. We'll see if we can get on that Dyno again today....update tomorrow!

PS- Any advice on spark plugs? Would it make a difference at all to do anything to them or buy better ones than autolites?

Don't know never had a car on a dyno. My volvo is intercooled it sucks it's air through a radiator like housing. I heard somewhere that for every 10 degrees cooling you gain like 5% or 10% maybe I'm wrong I don't know for sure. I've even seen devices where they spray mist on the intercooler to help it cool the air charge even more.

After putting on the RPM Edelbrock Intake Manifold and small tube headers with magnaflow mufflers we squeezed 215 HP outta the engine on the dyno. Friday we put in a Cam so we'll see what happens today with a new high lift cam in it!

Can you clarify the dyno setup? You say installing the engine in the T so that means you are measuring H.P. at the rear wheels on a Chassis Dyno?

Don Shillady
Retired SCientist/teen rodder

Originally posted by Don Shillady
Can you clarify the dyno setup? You say installing the engine in the T so that means you are measuring H.P. at the rear wheels on a Chassis Dyno?

Don Shillady
Retired SCientist/teen rodder

Yeah we have a chasis dyno at school we usein my hotrodding class. Goal is to make over 335 hp at the rear wheels by next wednesday. today we dyno'd at 244hp with the 490 cam we put in yesterday. Tomorrow we put on a set of Bowtie heads with a solid cam and lifters. Just need to find the right CFM carb to go with it. Rumor is that one group is using dry ice in the intake manifold to cool incomming air temp for more horesepower. if I had that kind of money I would do it but instead and I am just trying to build horsepower with a little bit of blood sweat and tears.

Any one have any ideas on how to get more ponies outta this thing?

two words... NITROUS FRIGGIN OXIDE!

can you use any fuel additives?

Originally posted by devil wrench
two words... NITROUS FRIGGIN OXIDE!

can you use any fuel additives?

Yeah we can use fuel additives but we can't use NOS till we hit 335 or over on the dyno.
So everyone is racing to do that at the moment. we are getting a solid lifter cam and I hear people have problems adjusting those so I need to find a good way to do that with the car off and just bump the engine.

Any fuel additive that works? I mean other than race fuel
Any adice on which spark plug to use with the Bowtie heads I am putting on today?

Plugs are a science unto it's self.

Ever notice when NASCAR guys test or qualify, (until this year), they would run past the finish a bit and then shut the eingine off. They coast back to the pits and a mechanic removes each plug and hands it over to an employee of Champion. That gentelman puts the plug in a little holder thingy and looks deep down inside the plug. He is looking for burn marks on the insulator and burn marks on the electrode. If you go on the web there are many sites on how to read a plug for optimum burn.

One little trick some of the racers did was to index the plugs. It doesn't work on a Hemi but most all other heads it will. You won't get a whole lot out of it but every little bit helps.

Take the plug and mark on the ioutside insulator the direction of the electrode gap. The object here is to get every plug gap facing down into the cylinder. It's a bit tough to do but taking each plug and trying it in a hole until it lines up. At one time they made indexing washers for plugs but I haven't found them in years. So if you have a big pile of plugs gaped to the correct setting just keep trying different ones until the gap faces down.

Plug gapping is another black majic trick that you may want to read up on.

Oh... Hot plug vs Cold plug... more stuff for you to read!

It never ends does it?


I love this stuff

So our highest HP on the Dyno today was 297. We need to make over 335 by tuesday of next week with what we have. Might have to resort into putting dry ice on the manifiold to up the power but wanted to do it mechanically instead. Anyone have any ideas. here is my current set up.

Chevy small block 350 with stock internals (pistons, crank, rods.)

cast iron Bow Tie heads (2.02/1.60)

Hydraulic .515/.520 lift Cam 310 duration

Single Plane Vic. Jr. manifold

750cfm Street Demon Carb

1.6 roller rockers

I pretty much can change out the carb, manifold, and mufflers at this point.
We have every carb cfm known to man available and 2 inch spacers.

Any help is appreciated!!

Thanks sooooooo much!!!

Okay I've got some ideas :

1 Block off the exhaust heat risers with a solid type inlet manifold gasket, this will insulate the manifold from the exhaust hear and help a bit to increase the intake air density, not much but every little bit helps

2 Make up a steel splash shield to stop hot engine oil splashing up onto the bottom of the alloy manifold, this also keeps the manifold cool for same reasons as stated above.

3 Bottom end install a windage tray and crank scraper, when the engine is doing high revs at least a good quart of oil is wrapped around the crankshaft this can eat as much as 15 hp as shown on some dyno results.

4 Use a stock oil pump that pumps 60 psi at 6000 rpm and is a standard volume pump, high pressure high volume pumps eat HP and contribute to the problem above as well.

5 Check your valve train geometry, when it's operating correctly you pick up more horsepower.


NB : what is the staic compression ratio with those heads on the block, because with a cam with that type of duration is going to need a high compression ratio to get the dynamic compression ratio up, There is a definite relationship between high duration cams and high compression ratios.

if you have a fan on the water pump take it off..... oil the hell out of the u joints and axles check your gear case oil you dont want alot just enough to touch the ring..easy stuff we do in qualifing....you shoulda got some vortec heads they work great and there pretty cheap.