On cams and engine rebuilds

"My bird IS the word" (mybirdistheword) 06/14/2018 at 15:42 • Filed to: None

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So finally having the scratch to do this, but not really, am I screwing myself?

For those less familiar: rebuilding my olds 403. No, its not the best engine. Yes, I’m keeping it. I have to ask though, this engine has a really poor smog cam in it. Low compression has little to do with the abysmal power curve. I’m not looking for peak performance here. The engine is basically stock. My thought is to put in something basic like this:

http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=1162&sb=2

Thats like the stock cam but... more. Nothing crazy, no magnum nonsense. A cam thats good enough and won’t cause problems. Im sure the machine shop can steer me straight on this. Except one thing. The extra $$

The cam? Not expensive. I should already replace lifters and such, but this is talking about adjustable valvetrain and all kinds of nonsense.

How much extra am I commiting to here? Should I just quit whining? The more I think about it the less I want to keep the stock cam, but I have no idea if I can afford it.

crowmolly > My bird IS the word 06/14/2018 at 15:48

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Few things, as I don’t remember what your combo is exactly.

1.) Static compression ratio?

2.) Carb & intake?

3.) Trans? If automatic- stock stall?

4.) Rear axle ratio?

5.) Upgrading valve springs?

Future next gen S2000 owner > My bird IS the word 06/14/2018 at 15:53

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Isn’t “adjustable” really just adding shims and getting the tolerances right?

lone_liberal > My bird IS the word 06/14/2018 at 15:53

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From what I see you only need valvetrain mods if you use lifter kit 863-16. If you use 852-16 you don’t. It looks like if you go down the list of components the second one listed is a high RPM/perfomance option that needs the extra stuff. I wouldn’t think twice about using a mild 260H cam. I would think you’d be fine.

My bird IS the word > crowmolly 06/14/2018 at 15:58

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8:1 compression, 2:41 rear axle (I do plan on upgrading to like 3:08) factory intake and quadrajet (think its supposed to flow 750cfm) and the trans is auto: stats aren’t listed but I’ve read 1400-1600 rpm

crowmolly > My bird IS the word 06/14/2018 at 16:01

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Cam should be good. See if you can run a thinner head gasket to boost compression a little. Are you having the engine bored at all? Or just a hone and re-ring?

Don’t worry about those extra components. You are doing basically a stock rebuild. Talk to your machine shop.

Party-vi > crowmolly 06/14/2018 at 16:05

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I will always suggest boring an engine vs a hone and re-ring. Plus, if you bore the engine new pistons that aren’t dished like soup bowls.

MoCamino > lone_liberal 06/14/2018 at 16:09

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That’s how I’m reading it, too. Using the high rev lifter kit requires an adjustable valvetrain, otherwise use the other lifter kit. Call/email Comp Cams to be sure, of course, but I think you’d be fine.

@Bird: Don’t let anyone talk you out of the Olds 403. There are a lot of valid arguments as to why an SBC would be the “better” solution. But the Olds motor has a certain “cool because it’s different” factor, especially if that’s what the car was originally built with. I also know from personal experience that an Olds Rocket motor topped with a well-tuned QuadraJet emits a unique howl when at WOT. I love that sound. :)

Dad had a 79 Delta 88 two-door with an Olds 350 when I was a kid. I learned to drive in that car. It was a boat by today’s standards, but I’d love to have that car back. 

crowmolly > Party-vi 06/14/2018 at 16:10

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Swapping to a set of less-dished pistons, even cast ones, will make a pretty big difference. And will change the cam selection too. 9.5:1, a dual plane intake, and a split pattern cam with a little more on the exhaust side would probably make a very nice street cruiser.

Edit:

Just dicking around, uising a 83cc head, 20cc piston, stock hg and hg volume, .025 in the hole, and 3.385 stroke I get 8.0:1 SCR

Change that to a 6cc piston instead and you get 9.0:1 SCR.

My bird IS the word > Future next gen S2000 owner 06/14/2018 at 16:10

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Hell if I know. Thats why I’m farming this out. Its just too much to risk me blowing it up.

My bird IS the word > MoCamino 06/14/2018 at 16:22

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It has a resale and sentimental value. If we are talking about smart decisions I wouldn’t have bought it in the first place. I will admit a blueprint 350 would have been a better plan but that ship has sadly sailed.

My bird IS the word > crowmolly 06/14/2018 at 16:23

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Just a hone and re ring. These can have cooling issues when you start to bore em out.

My bird IS the word > Party-vi 06/14/2018 at 16:24

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These have cooling problems when you start to bore them because its basically just a massively overbored 350.

My bird IS the word > crowmolly 06/14/2018 at 16:27

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But then I get into hood clearance issues, valve porting, stall converters and that would just kill the budget. A 350 or an ls would make more sense at that point.

crowmolly > My bird IS the word 06/14/2018 at 16:28

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What’s the stock head gasket thickness? Can you run a thinner one to bump compression?

Just trying to see if you can squeeze any more power out of this thing. Or get rid of more smog designs. You can run an Edelbrock 2711 under the stock TA hood. But I get your point- that’s $$ if you can’t find it used.

My bird IS the word > crowmolly 06/14/2018 at 16:33

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I have to look, the stock ones are supposed to be super thin but I don’t believe the replacements I got in the kit are that different. But I just bought a full kit from felpro

Party-vi > My bird IS the word 06/14/2018 at 16:42

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Orly? Dang.

My bird IS the word > Party-vi 06/14/2018 at 16:45

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Yeah same problem with the new focus rs. Siamesed cylinders and no cooling jackets.

MoCamino > My bird IS the word 06/14/2018 at 17:20

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Don’t be sad - especially considering the resale side of it, keeping the ‘correct’ motor in it is a good move. :)