Did a quick set of pulls on a mobile dyno on Saturday, so I've got some baseline data for future improvements. 215 rear wheel horsepower and 340 lb-ft on a mild 330. Not too bad, but lots of room for improvement.

Disclaimer: Run 1 was good, but Run 2 and 3 were bad because I punched it too early, and my torque converter skewed the data a bit, but if you look in the upper RPMs, it's pretty accurate even on runs 2 and 3.

 

Engine data:

- 330 bored .020 over, Egge high compression pistons, a little short on compression height, but block decked .010. Haven't measured actual compression or deck height, but builder calculated 10.4 to 1.
- Running 93 octane with 35 degrees total timing. Recurved HEI with 13 degrees initial and 35 degrees all-in at 2500 rpm. 10 degrees of vacuum advance.
- Stock #4 heads with stock valves, no porting but three angle valve job
- 1.75" full length headers, 3" collector with 18" extension, transitions into 2.5" dual exhaust, no h-pipe, exiting underneath before the rear end, cheap Thrush Turbo mufflers (replaced Flowmaster 40s after getting fix-it ticket from the police)
- Th400, 3.90 rear with 28.5" tires. 3333 rpm at 70 mph. Hit 115 MPH on this dyno run in 3rd gear (1 to 1). Should have seen 5,250 RPM, so converter must be slipping a little. Hughes 2,500 stall converter.
- and most importantly -> Comp Cams 265DEH cam with 211/221 duration at .050, 110 split

Aside from dropping in a 455 or turbo/supercharger, where should I focus my efforts? Any and all feedback would be much appreciated It's fun to drive, but I think there's more

 

- stock 330 cast iron 4-barrel intake
- 1977 Quadrajet running 12 to 1 AFR at WOT (per AEM wideband). Secondaries opening fully, no air cleaner during these dyno runs
- Fuel was at 12 to 1 throughout the RPM range, so not leaning out
- HEI seems to be struggling and will sometimes miss fire above 5,000 RPM, but ran okay during these pulls, no miss fires.

 

Upgrade to a 14005 Accel Super coil and the ignitor 3 HEI or MSD HEI module. A Performer RPM intake with the divider notched may help. The stock valve heads and small cam limit hp but very good torque numbers. That equals 270 hp, which isn't bad for what it is.

 

 

12.0:1 is too fat. 12.5-12.8 seems to be the sweet spot more often than not.
And get a better module for the HEI. That's most likely your problem there.

 

Where does that Hughes converter flash with that combo?

 

Thanks for all the comments guys!

Upgrading the HEI looks like the #1 priority. I see the torque declining as RPMs increase, so maybe that will help stretch the torque curve a little bit. It feels really weak above 5,000 rpm which might be the cam combo, but it would be good to eliminate any HEI weakness from the equation.

#2 -> Leaning up the secondaries to move the AFR higher. My primary jets are 68 with Cliff Ruggles' progressive rods, and I'm seeing 14.5 - 15.0 at cruise, so that's looking good. With higher compression, I'm keeping it a little on the rich side, but at WOT, I can definitely make that leaner than 12.0 (while keeping an eye on the spark plugs).

#3 -> I'm going to double-check my distributor timing. I don't trust my cheapo tach and want to be sure that I'm getting a good curve. A crappy timing curve could really hurt the torque, too, so that makes sense.

With regards to stall converter, I'm seeing it flash at about 2,200 RPM. It's a heavy car with me in it, which drags it higher, but I've got 3.90 gears in the rear that make it flash lower. More torque would move it into the 2,500 range. Anyway, lesson learned -> on the dyno, accelerate to 2.5k then punch it. Those torque numbers on runs 2 and 3 are bogus, so don't trust those.

 

What secondary rods and hanger?

 

CH secondary rods
K Hanger

 

The DR, EH or CL should be close and your K hanger isn't radical, it should work. Your secondaries are already on the lean side. Was the air door modified to open more as shown in Cliff's book? The late 70's carb like your's don't open much for the factory. I modified mine and when mine was giving me fits, I sent it to Everyday Performance and he opened it even more with the rebuild.

https://quadrajetparts.com/quadrajet...128_44_49.html

 

When I rebuilt the carb, I modified the secondary throttle plates to ensure a full 90 degree opening, and these are opening completely when I step on the throttle. On the other hand, the air valve seems to be too tight. I loosened in last night and took a test drive, and that improved things, but I still get a consistent misfire at 5,000 rpm, pointing to a weakness in my HEI.

Next steps -
* confirming that mechanical timing is 'all-in' at 3,400 rpm and not drifting higher as rpms increase. I checked this a couple of years ago, but going to check again.
* checking for full voltage on the Batt wire at 5000 rpm
* replacing my engine block ground strap
* if that doesn't help, upgrade the module and coil

If I can cure that 5,000+ rpm misfire, I will look again at the secondary rods

Thanks!

 

Great info! Do you have any dragstrip times with this combo?

 

 

Thanks TripDeuces, good point. My air valve is opening, but just barely above 4,000 rpm, then the ignition begins to stutter, so I can't see it opening more than 20-30 degrees. I'm guessing a partial opening of the air valve is a good thing, I'll make sure it doesn't swing a full 90 either way

I cleaned up the engine ground strap and retested, and it was still stuttering above 4,500. I also wired the Batt connection directly to the battery, but that didn't help, so I ordered an HEI upgrade kit from Pertronix (coil, module, cap, rotor, etc...).

 

Regarding the high torque numbers on runs 2 & 3, my Hughes torque converter is loading up for those pulls, so they look artificially high (in terms of engine torque). However, that is a good illustration of how a converter can multiply torque. I can definitely feel the extra torque when I launch. I am sure that true engine torque is actually a bit lower at those RPMs.

 

I know its generally frowned upon to bring back years old threads but I am very sorry I missed this one. Unfortunately I was not yet a member when it was opened, and just came across it now.

pmathews nice car nice build but a bit of a sideways move when it comes to the cam I would think ? Assuming your 67 was already the high compression version to begin with.

Factory 320 HP cam, advertised duration 278/282 valve lift .430/.432

Comp Cams 265DEH, advertised duration 265/273 valve lift .472/.486

Guys correct me if I'm wrong but I'm assuming that slightly less duration and a bit more lift works out to somewhat of a wash ?

Done is done so please don't take this as an insult but I am thinking going with the 275DEH is the ideal move in retrospect.

275DEH
High performance street,
great power, works with stock converter,
best with 2000+ stall. Hyd. Hyd. 1500 to 5800 42-210-437 275DEH 275 282 219 233 .476 .508 110°

Yes of course hindsight is 20/20...

In any case your ride performed admirably. Just not sure that its much above stock.

HotRod 1968 tested a factory new 310 HP F85 ( 262/274 .440/.440 ) 350 CID and also saw 215 rear wheel horsepower. (To my understanding you have and had more cam ?) The 68 F85 was similarly set up with a 3.91 rear and headers. But it was stick and obviously plus 20 cubes.



Yes, and that would be lovely. Especially before and after.

For Comparison HotRods 215 RWHP F85 ran a 14.27 @ 96.15 with slicks back in 1968. The F85 was bare bones light but 2nd generations are considerably lighter than 3rd gen to begin with, so maybe close in weight...


P.S. sorry cam guys if I'm giving you a headache just trying to learn.

 

Cam lesson. Advertised duration means very little, especially from years ago. They used to take the adv duration at 0 lift, today some do it @.004, some at .006. There a couple that do it @.008, that will really skew the numbers. So always use the @.050 number as the comparison.

 

Mark, what are your thoughts on his cam choice? Those cams have a fairly big intake and exhaust duration split. Curious if he sorted out the misfire or rich at full throttle issues. Of course he could be running a LS now for all we know.

 

Question Christian, what’s different about the split of advertised vs @.050 duration on those Dual
energy cams as compared to what you’d normally see? Hmmmmm....

 

Thank you, unfortunately the @.050 number is not so easy to come by for factory cams from that era. No luck for the 330 (so far) but did find the 350 specs. Thanks to https://classicoldsmobile.com/ and its fellow members.

auto 350 cam 400084 36 250/264 .400/.400

auto cam @50 duration 186*/204* @.050" lift, 109* LSA


stick 350 cam 402486 48 262/274 .440/.440

stick cam @50 duration 196*/208* at .050


Thanks to your post you motivated me to bombard the internet for info and came up with some additional interesting and informative stuff.

 

HotRod March 1997 Comp Cams comparison (8.8:1 Chevy 350 with headers)

255DE = 303 HP @ 5000 RPM (203/212 duration at .050, .427/.458-lift and 110-degree lobe separation angle.)
265DE = 324 HP @ 5000 RPM (211/221 duration at .050, .442/.465-lift and 110-degree lobe separation angle.)
275DE = 338 HP @ 5500 RPM (219/229 duration at .050, .468/.488-lift and 110-degree lobe separation angle.)

I can make a case were these are roughly the equivalent of, in order, auto cam, stick cam, rallye stick cam. For Oldsmobile 350.

olds 307 and 403 I stand by my observation that the 265 which is more aggressive now than in 1997 (slightly different specs) is still somewhat of a sideways move with a 320 HP 330. (Factory 320 HP cam, advertised duration 278/282 valve lift .430/.432) If you minus the average 60 give or take variance from the advertised duration on factory spec the 320 HP 330 has an approximate estimated 218/222 duration @.050.

What do you think ?

 

Actually I believe the factory 1970 350 stick cam is more aggressive, I believe it is the 400/455 442 auto cam on some years. Supercars Unlimited has that stick 350 cam at 216/217 .472/.472 on a 113 LSA.

 

Hey Guys, no worries, thanks for all the comments, I appreciate the help! I agree that my cam choice isn't the best, but here's what I discovered:

1.) My static compression was lower than I realized -> 9.3 (vs. 10.4)
a.) I cc'd my combustion chambers at 64 cc which is higher than the purported 58 cc on #4 heads. Maybe my 3-angle valve job dropped the valves deeper? Probably not enough to add 6 cc, so just shows that all #4 heads are not 58 cc.
b.) The compression height with the Egge pistons was deeper in the hole than I realized. I took off the heads and measured it myself, it was 15 thou deeper (measured 30 thou in the hole), with a 40 thou gasket that makes a 70 thou quench height, not sure that matters with open chamber and dished pistons, but it does impact compression. I had heard that Egge lowers the compression height as a safety measure for blocks that have been decked during a rebuild -> well I can confirm that this rumor is true.
c.) The Egge High Compression piston has a 4.9 cc dish (measured it with clay and a graduated cylinder), so that was good to go.

2.) My valve springs were installed a little on the loose side in terms of seat pressure and needed a valve shim to increase the seat pressure. This had a pretty significant impact on my max RPM. I am guessing that my engine builder was doing me a favor during break-in, but either he forgot to mention it or I forgot to remember it. Either way, there were no shims under the Comp Cam springs. It was stuttering at 4700 rpm with the loose setup, but after adding a 60 thou shim, it increased to 5300 rpm before stuttering (valve float). I didn't measure seat pressure with a valve spring compression gauge, but I imagine that I could add another shim and get some higher RPMs, but it may be a while before I pull the heads again.

The 265DEH drives pretty good, it's been fun around town with the increased valve seat pressure, but open to suggestions (thanks!)

 

Ahhh, I hear you. What I call the rallye stick cam is the same one. I thought it was a one model thing. Motor Trend mentions the cam February of 1970. But only mentions that "it may be used on all manual versions of the L74 engine for rest of 1970" http://wildaboutcarsonline.com/membe...ye_350_1-3.pdf With the 262/274 .440/.440 cam still in play I figured it didn't happen....

That's what really matters, enjoy your ride. And thank you very much for chiming in.

 

Thanks for that info. There was a discussion about this years ago and no one had an engine/pistons to measure and confirm or deny the height was correct.

 

[QUOTE=pmathews;1080242]Engine data:

- 330 bored .020 over, Egge high compression pistons,
- Stock #4 heads with stock valves, no porting but three angle valve job
- 1.75" full length headers, 3" collector with 18" extension, transitions into 2.5" dual exhaust, no h-pipe, exiting underneath before the rear end, cheap Thrush Turbo mufflers (replaced Flowmaster 40s after getting fix-it ticket from the police)
Hi from New Zealand, I know your post is a few years old now but hoping you can give me some info. I am interested in headers fitted to 330 V8s in Cutlass models. What year and model is your Oldsmobile? What brand and model headers are installed in your car? Here's hoping!
A bit more digging and it looks like you have a 1967 Cutlass (or had) which is great news as it's the 1964-1967 Cutlass models that have the skinny frame rails (about 1.5") when compared to later Cutlass models. This is why trying to fit headers is a bit of a nightmare on the early Cutlass models like my 1965 Sports Coupe. Really would love to hear from you soon. Cheers.

 

Regarding my long tube headers, I got an old, rusty pair from a friend, so I don't know the brand. They are definitely big block headers because they hang a little low, but they fit without any issues. I removed the rust in a vinegar bath and coated them with high temp ceramic paint, and they work great. I guess that I must have gotten an early set of headers because I hear that newer versions don't fit 67 Cutlass models (big or small block). Regardless, I would ask others on this board since someone else may have found a good alternative. Good luck!