Cman7713

My 69 Cutlass is headed to the shop for an engine rebuild this week. Not looking for anything wild, stock intake/headers /new edelbrock 1405/ #5 heads.
Anyone have a recommendation on a cam to wake up a mostly stock rebuild? Trans is a th350 that will be rebuilt at the end of summer. rear end is 12bolt O type I believe non posi 2.73?

captjim

Are you replacing the pistons? If so, what are you using. Compression ratio will determine cam choice to some degree.

Cman7713

Piston replacement is to be determined once it's torn down and we see the condition of the pistons and cylinder walls. I'm aiming at 10:1

cutlassefi

If you do end up with 10:0:1 then I'd do an Erson Hi flow 1. However don't expect too much out of this rebuild no matter what. That 2.73 gear and stock converter is your ball and chain.

captjim

10 to 1 is actually pretty high for a street engine with iron heads on pump gas. You will need new pistons unless you have the small dish stock units and if they are re-usable (unlikely). You might be better shooting for 9 to 1 if you want to keep the stock gear and converter. That, with a cam in the 210-215 and .480-.490 lift would make a nice peppy combo.

alacran

I recommend Comp cam XE268H or XE262H. For the 403 build we are working on, those were the two we looked at...we installed XE262.

We are not done with the build but the intent was similar, stock drive train and rear end...while boosting the CR on anemic 403 from 7.7:1 to 9.4:1.

Cman7713

Thank you for the input guys, as always it's appreciated. I'm jumping into the rebuild first to get the car on the street sooner then later. My dad has fallen ill and i'm not sure how much time we have left. We bought the car together and i'd never forgive myself if I dragged my feet any longer and never got the chance to drive in it together. The rear gears, torque converter and trans are all on the to do list but for the meantime being able to at least have a reliable driver is my priority.

1BOSS83

-New pistons are a must. They aren't that expensive and open up a whole new world. In order to get an accurate measurement of your CR you gotta pull it all apart and have your heads cc'd,mine came in at 66 cc (which is an obvious variance to the factory listings and I've heard of people ranging up to 68-69cc) and if you've played with a CR calculator that can mean the difference in a motor that pings or pulls. Once the heads are off the presumably factory 0.17 gaskets are toast which would mean a drop in CR by default which limits your cam options if you decided to stay firm on the stock pistons. Just my opinion.

-If you decide to go with an aftermarket piston I can tell you that Probe pistons are back ordered and the date they give you is bullshit. I went with a -5.8 cc speed pro for my application and the results are still pending as the build is finalizing now.

-To answer the first question about the cam, one thing my build has taught me is cam before compression ratio= carriage before horse in terms of a build that produces your best $/HP ratio. Can I assume that is the goal?

oldcutlass

I hope you and your dad get to drive in the car together, good luck.

Cman7713

$/HP ratio is a good way to put it yes. I talked with my builder yesterday. The engine is out and on his stand, teardown should be the next day or so. While on the phone with him we talked CR and he said the current goal should be between 9.5:1 - 10.0:1 depending on how much I want to spend. Once I confirm the final number with him i'll get a better idea of what direction to take.

HWYSTR455

Exactly. This combo forces you to make power down lower in the RPM range, and kills any potential power improvements overall. 350s like gear and stall.

If you plan on changing those two things in the near future, you can plan your build on it.

Forged pistons are a no-brainer. Don't even bother with cast replacements. The cost difference is what a piece of mind costs, and considering what you will spend for everything else, pointless to take the chance with cast.

I've never had any luck with the Comp XE grinds, I avoid them like the plague.

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Cman7713

Both are on the to do list as soon as I have the funds. Ideally finding a whole new rear drum to drum would be awesome, I heard the 12 bolt O type are hard to find parts for. Thinking a 3.42 gear would work, as for stall i'm clueless. Somewhere in the 2000-2500 range or is that undersized for a mild street build ? These are all things i'm discussing with my builder when i'm there next week. I'd like the engine to be "ready" for these other changes.

HWYSTR455

I have 342, and a 3000 stall, and it works well. With small blocks, converters usually don't stall as advertised, it always is on the low end. So if it says 2500-3000, it's going to be 2500.

70 on the highway for more than an hour starts to get to be a bit of a drag, but I did do power tour with it, wasn't too bad. MPG was the biggest drawback. At 60 I get like 18+, at 70-75, I get like 10-12. Think it starts dipping into the secondaries is why.

You could probably pick up an 8.5 rear pretty cheap and rebuild it. For a small block it's plenty. If you find a BOP one even better, bolt in axles. I did mine, posi, gears, install kit, and moser axles, had a shop do it, think I have like $1200-1400 max in it. Can look at it in my build thread.

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Fun71

I have a Hughes Performance 2500 converter (part number GM25BPO) and I like it. Behind my engine, it stalls around 2400 coming off the line at WOT but feels a lot like the factory converter all other times.

HWYSTR455

Perfect example of not reaching advertised stall with a small block. You got lucky with it too, lucky it doesn't flash as low as 2000.

Hughes are pretty good, fairly tight, and not much slippage.

I had a TCI Break-away, which is rated at 2400-2600, and it was stalling at 1800/1900 (flash). I stepped up to a Street Fighter, which is rated at 3000-3500, and I'm seeing roughly 2800/3000. It was a day/night difference. I always run the anti-balloon plates too.

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RocketV8

I would call 2400 on a rated 2500 pretty accurate... For what it's worth, I have that same converter and it flashes at 2500 behind my 352. It makes sense since I have a slightly smaller cam than Fun71 (211 vs 217).

HWYSTR455 - what engine stalled so low in your cases?

70cutty

I have the hughes 2500 HD(gmbpo25hd) behind my 455, and it flashes around 2800-2900. Just to give you an idea how the converter with same advertised stall works with different engines.

HWYSTR455

Actually, true, point I was trying to make was that you can't expect a converter to flash at exactly what it's rated. 70cutty is another example. That converter is probably rated more accurately with a small block is my guess.

Mine's a .030 over 350, #5 heads, and with that converter was running a 220/226 112 Crower, which requires a steeper gear, which is probably why it didn't flash as high. The Crane HR I have now is better on the bottom, and less sensitive to the gear.

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olds 307 and 403

I must be lucky then. My 2000-2600 pos that eventually imploded stalled at 2400 behind my 403. My current converter stalls at 2300 behind my mild 350, rated at 2200-2500.

HWYSTR455

Have to understand, a torque converter is just that, and is based off how much torque a config makes. Factors like vehicle weight, rear gear, displacement, and cam all play a part. There's no way a converter manufacturer can state a stall of X with all those factors, just no way.

Same car, if you only change the cam, it can have a dramatic effect on stall. If you have a cam that makes power in the upper RPM range, it will most likely suffer in the lower RPM range, so the converter will stall lower.

So if it's stalling close to the rated stall, it's because they took many of the factors that match your config to rate it. 'Average' factors are used, like 200-400 ft lbs, vehicle weight of 3500, rear gear of like 323, averages like that.

So yeah, if you have a converter that is stalling close to the rated stall, you are lucky.

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olds 307 and 403

So if I installed the cam my 350 needs, around a 217/223 vs my 204/214, it would stall lower? I am planning a converter swap when I get my 425 stroker done, using the Dr Dan 10" 2800? stall from PTC. I just assumed more torque meant higher stall, never thought of the higher power band affecting it.

HWYSTR455

Yes, more torque is higher stall, so when you change a cam to something that's more 'drag race' the torque down lower is less, hence the lower stall. So you generally look at what the 'power range' or 'cruise RPM' of a cam is to choose the converter stall.

So if it says power band 2500-6500, with a cruise of 3000, you would choose something in the 2500-3000 range. Still a little of a crap shoot, since most converter manufacturers don't stipulate between a small block and big block. But gets you close.

People who are dialing in their' combo usually go custom stall, and send their' converters back several times to get the desired stall. Once you know what you flash at, you can give your converter guy that info, and tell him that you want it 500 more, or less, and because of the way it's setup, they know how to mod it.

If you have desktop dyno, plug in your combo, and look at the torque curve. You will see where it starts picking up, and that's roughly where you want to choose a stall. Will also give you an idea of where it will stall too.

Also keep in mind flash can be higher than what you cruise at, and as long as you aren't under a heavy load, and it's an efficient converter, you won't have any issues.

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