Can't decide. stock 350 or 403! help

[olds307 and 403]

Stock replacement lifters would work. Clevite makes the 307 and 455 cam. DoubleV's idea is best but you need to find early heads. The headers fit best if you put them in before the motor, otherwise the oil filter adapter needs to be removed. The 204/214 cam roasted the tires with stock compression but I had a 2400 flash stall converter.

 

[brian_wms]

Thinking about buying the kb piston from someone on this forum. But it has to be bored to 0.39 is that over kill?

 

[DoubleV]

Thinking about buying the kb piston from someone on this forum. But it has to be bored to 0.39 is that over kill?

What are you trying to do with this engine? Are you getting a good running 403 that you want to do a few hop-ups to or are you doing a complete rebuild?

Be realistic with your goals, budget, and mechanical aptitude.

 

[brian_wms]

I really want a stock 403 that will burn rubber on a budget. That's why i want a mild cam, thought it would give me that extra little push. but guess not if i don't get my compression up.
looked a comp cam 252 i thinks it like 206/206

 

[Intragration]

455 is not stock. Dont care what anybody says big block does not look stock in a small block car.

Don't know if I agree with that. The headers and air cleaner are obviously aftermarket, but the motor itself looks an awful lot like a 307. If you're sharp you can tell them apart, but I believe you could easily pass the 455 off as a SBO to a casual looker.

 

[DoubleV]

I really want a stock 403 that will burn rubber on a budget.

Then how were you planning on installing oversized pistons in it? That requires new rings, complete dissassembly, overbore, and honing. At that stage you're practically rebuilding the whole thing.

That's why i want a mild cam, thought it would give me that extra little push. but guess not if i don't get my compression up.

A bigger cam will make a difference, it's just not going to knock your socks off they way you may be expecting it to.

looked a comp cam 252 i thinks it like 206/206

Many of the Olds builders/racers have said many times Comp cams don't work very well in an Olds engine so I say why argue with them. Get something better. Also, I don't think a single pattern camshaft would work very well with your heads that flow like crap on the exhaust side but you may wish to consult an Olds builder about that.

A cheap set of early 350 heads will solve all of your issues so why don't you just go that route? If you were prepared to drop the coin on oversized pistons/rings and all the required machine work then you should easily be able to afford a set of early 350 heads. You need to join an OLDS forum where things like early 350 heads could be had on a regular basis for cheap.

And again I'm going to stress to you the importance of gears. Just gears alone can make your car feel like it gained 50+ HP.

Also, you say you're on a budget but what IS your budget? Sometimes people have a very unrealistic goal in mind when they only have $500 to spend and want to go fast....

Do you already have this 403 already? Is it in good condition? Does it run fine the way it is now?

 

[CHRIS.O]

Just throw it in an run it. Aside from rebuilding it you can do heads, cam, while its in the car. You said you want more power than your 307. Believe me it will be a night and day difference. Not even in the same ball park. Throw it in and if anything I would look to getting a better rear end gear set like Doublev has mentioned. Don't get hung up on numbers. My 275hp formula runs 13's. The math doesn't really add up when you think that low of power but it does it so just throw it in maybe get a set of gears down the road. The 403 in the 72 Ritter and I mentioned earlier screamed and it was all stock. I dont know the rear end ratio but it was a one wheel peel and you could literally roll smoke off the tire at 40mph. We beat a lot of sh*t that was supposed to be faster stop light to stop light even with traction issues. You will enjoy it I promise.

 

[brian_wms]

how can i tell what gears i have? what options did the salon have?

 

[pontiacgp]

take the cover off and look, then you can change the oil cause it probably needed changing a long time ago

 

[565bbchevy]

This is the easy way we would get a close estimate of the rear gear.
First you would need 2 people then you would jack up the rear of the car and put it on jack stands and chock the front wheels, then put the trans in neutral and mark the drive wheel at the bottom and clearly mark the drive shaft on the bottom and have one person spin the tire slowly one full revolution while the other person carefully counts how many times the driveshaft spins, depending what factory gear you have the driveshaft should spin between 2-1/4 and 3-3/4 times which would equal your ratio most will be below 3 turns.