[Kevin]

Who has a strong running 326 or 354? There are lots of threads out there with info on building 400+ cid Pontiacs for good street and street/strip performance. So, lets have a thread with just info on the smaller cid Pontiacs that everyone can reference in the future. I think were going to see more and more of these engines being built over the next few years.

If you have a 326 or 354 please post your combo here, what the goal of your combo is/was and how it performed. Whether you were going for good fuel economy, max streetable power or anything in between.

[Jagtec1]

My old 350 ran well. Best of 13.80.

Stock rods, Badger pistons, cam was a Crane 216/228 with .480 lift. Performer intake with a 600 cfm Holley Vacuum secondary carb. Heads were untouched 47's. 3.55 gear, 27" tire.

[Z Code 400]

My stock 58,000 mile 7.77:1 SCR 350 in my 1975 Formula is internally stock with the exception of recently added 1-3/4" Hedman 4 tube headers and 2.50" mandrel exhaust with a #42585 Flowmaster Crossflow. The Q-Jet and ignition curve was modified. I am experimenting with this engine will the 412 roller motor is completed.

When I bought the car in on July 11, 2005, it had just passed the California Smog Inspection and had only 44,000 actual miles. I had the car dyno'd in this condition to give a baseline for future modifications.

The test was conducted at 66°F ambient temperature and 77% relative humidity. The ambient barometric pressure was 29.98in/Hg and the elevation at the test site was 100' ASL. The operator estimated a 22% loss factor.

The results were 146.8 RWHP @ 4200 rpm and 204.1 lbs/ft RWTQ @ 2700 rpm.

The car is going to the chassis dyno again August 25, 2007 for some new baseline pulls to show what improvement was (or was not) made with the addition of the headers, exhaust system and tuning modifications. Following that, a set of 72cc #15 heads will be installed to bring the SCR up to 9.12:1 and a custom ground hydraulic flat tappet with .467"/.467" - 220°/226° @ .050" - 111.5° LSA will be fitted and the combo will be re-tuned and dyno'd again.

The results (and photos) will be posted to this thread for review...Robert

[b-man]

Here's a pretty long thread with a lot of 350 build-up info.

http://forums.maxperformanceinc.com/...&highlight=350

I'll be adding the 350 build I did to the 'Street Engine Combo' sticky thread, as all 326 and 350 engine builders are welcome to do as well.

[Donovan]

68 350HO 0.030" over

#18 heads, stock 9.8 -10 to 1
Summit 2800 cam
Stock intake and Cliff-tuned Qjet
1.65 stamped rockers
long branch manifolds
2.5" exhaust
TH350 and stock converter
3.23 open
3660 lbs with me in the car

14.1 in the quarter 99mph

Basically all stock parts, no porting and a small aftermarket cam

[Z Code 400]

Yesterday, I had my Formula dyno'd in preparation for the upcoming '092' cylinder head and .466"/.466" - 220°/226° @ .050" - 111.5° LSA camshaft swap. The previous baseline was 146.8 RWHP @ 4200 rpm and 204.1 lbs/ft RWTQ @ 2700 rpm. This was in totally stock condition with log manifolds and single exhaust. The car also passed it's last smog check in this state of tune.

Pretty sad performance!!!!

Since that test, I have recurved the HEI, installed the MSD Low Resistance Bushing, and installed AC plugs gapped at .080" with new AC Delco plug wires. I also built a Q-Jet from a 17058553 main body and a 7045568 air horn. I installed new bushings in the throttle body and secondary air valve shaft (upper) as both were badly worn.

Ignition timing is 20° BTDC @ idle with 36° BTDC total timing @ 3000 rpm and 8° of ported vacuum advance. Test was conducted on 87 octane fuel with no additives whatsoever.

I used .075" jets with a set of Cliff's new .045" metering rods, a 'Blue' power piston spring (from Cliff) and .070" upper and lower air bleeds. The idle tubes were enlarged to ..037" and the idle down channel restrictions are .047" in diameter. I used a 'G' hangar and .051" secondary metering rods.

I also installed a set of Heddman #28150 4-Tube Headers, 2.50" mandrel bent headpipes, an 'H' pipe and a #42585 Flowmaster Transverse Muffler with dual 2.50" mandrel bent tailpipes, exiting in the stock location.

The test was conducted at 88°F ambient temperature and 36% relative humidity. The ambient barometric pressure was 29.90in/Hg and the elevation at the test site was 100' ASL. The operator estimated a 22% loss factor. Coolant temperatures were in the 160° to 180° during testing.

The new figures were 247.6 RWTQ @ 3300 rpm and 201.3 RWHP @ 4200 rpm. I was unable to get an A/F ratio reading during this test as there was a problem with the sensor.

The tests will be conducted again once the '092' heads and new camshaft have been installed. I will post the results to this thread and track the performance gains.

I hope this information is helpful...Robert

P.S. The .080" plugs were used as they generated the lowest (cleanest) overall tailpipe emissions.

[Stuckinda60s]

Robert:

Those are actually some pretty good numbers. You're making better hp and torque than a lot of the later 350 Chevy performance engines did with more compression. I realize the cam is really going to limit the hp but I wonder if you don't have weak valve springs as well, given the rpm peak you're seeing. I wouldn't be surprised to see you pick up 100 hp with the head change, if you've got good springs.

I've considered the 092-093 heads for a 350, myself. I like the quench of the bathtub heads and don't believe that, for a street 350, the sharp turn would hurt too much. And, you can always do some work on the short side radius to help it out.

Glad you're doing this, I'll be watching with some interest.

Donovan:

You're running pretty well, probably making over 350hp at the flywheel. Good job, I'm always pleased by guys running the "forgotten" Pontiac engines. Or maybe I should say the underestimated ones?

[Z Code 400]

Rich,

I have to say, I am really impressed with this Pontiac 350. I used to hate it, but now, we are making firends.

I didn't really expect it to make anything over the baseline, because the car disn't feel as strong after the headers went on, which makes sense, since it moved the torque band higher up in the rpm range.

What I concentrated on after the first baseline was taken, was all 'seat-of-the-pants' feel for tuning. I don't have any high-tech stuff, so I did it the way my Dad taught me to do.

I would use a stopwatch and time my 50 to 80 mph pulls in high gear with the kickdown cable unhooked. I would change the hanger and rods until performance peaked and then richen until the times fell off, then drop back to the parts that gave the best times.

On the primaries, I would richen the engine until it 'felt, sounded and smelled good,' then take an exhaust reading on my friend's smog machine. I would lean the primaries out as much as I could and still get smooth running, then I would fiddle with around with jets and metering rods until I had the lowest HC ppm emissions, trying to keep the APT in the 3.5 to 4.0 turn neighborhood.

I always like a lot of initial timing, so I played with weights and springs until I got 20° on the crank and 36° total. That just seemed like a good starting point to me and the engine 'felt good' at that setting, so I just left it there.

You can't say the 'seat-of-the-pants' dyno doesn't work, plus, its a helluva lot cheaper!!!

I agree with you on the 092 short turn. On mine, I am going to match the first .250" of the intake ports to the gasket, but that's it. I will smooth the rough edge from the short turns in both intake and exhaust, but I won't do any porting at all.

I'm using new stainless steel, swirl polished 1.600" exhaust valves in the stock 389 lengths. The intakes are good used OEM replacements (1.970") from a SBC, which just happens to have the same OAL as the stock 389 valves. I am using brand new, OEM replacement Pontiac dual valve springs set at 1.600" installed height.

It's really a very basic swap, nothing trick at all...Robert

[Stuckinda60s]

I had some Pontiac parts and Rhoads Lifters I was selling at Fall Carlisle, (For you Left-Coasters, that's a major East-Coast flea market.) and was talking to a guy who had a 326 '67 Le Mans. I told him that they could be made to run respectfully and had an instant friend. He asked for some tips and I gave them to him. Told him he should run an 068 cam, Rhoads Lifters(!) and do a little porting on the heads. He lived about 60 miles away and ended up ordering the cam and lifters from me. I made a trip and took them down to him as a favor so I could show him how to do the heads.

He must have done them right, as he said it would "light em up" from a dead punch, without power braking and said it pulled real well, starting to come alive about 3500. This was with a Turbo-400 and 3.08 posi. He was a very pleased individual.

I don't know if he ever ran it at the strip, but from what he said, I wouldn't be surprised to have seen real low 15's or better. Don't forget that the OHC 6's could run in the high 15's with just a little tuning.

Also don't forget that stock class '74 GTO that was the consistent class record-holder. NHRA kept factoring it and he kept going faster. Bill Rink if I remember correctly, he was running 11.60's at over 108. That's impressive for an engine with less than 8.5 to 1 compression. Try that with a 350 Chevy with that kind of compression. Due to factoring of the Pontiac, the Chevies ended up in a lower class.

[Ken -Ace- Brewer]

Just a update!! We dynoed the "Stock" 383. It made 371 hp at 5200 rpm and 439 ft lbs of torque. This is with a 212/218 duration at .050 cam. With regular old Performer manifold. And stock #17 heads.

Pretty excellent actualy. As most 400's with a 221/229 cam make about 370-385 hp at 4800 rpm and only 395-410 ft lbs of torque.

Overall I think it did very well! Right up there with the HP of a 400, but more torque! :-) And more rpm.

Be Cool,
Ace

[Z Code 400]

Sounds very respectable, Ace....

[Stuckinda60s]

A couple of more thoughts on 326/350 usage. I've always thought that a 326 or 350 would be an ideal engine to put in front of a T200-4R. You could run a lower gear than you would run with a 389 or bigger engine, still have a good high ratio for cruising and enjoy a trans which doesn't cost any more power to turn than a Powerglide. The T200 was designed with smaller engines in mind.

The other thought was that the 670 heads would probably be perfect for a 350. They have the improved valve angle of the later heads with more quench. I'm not sure if open chamber heads would be a help for the smaller engines or not, but I do think that the improved flame travel wouldn't give the results that they do on the larger bores. The 670's also yield a streetable compression ratio with the benefits of screw in studs. Of course there are the 140 or 141 heads which came on '67 326's, also, but I don't know anything about them. They would have the later valve angles, though, and the 140's would probably be capable of running street gas without any issues.

Anyone got any comments, thoughts or proven results?

[Z Code 400]

Aside from having them laying around, I felt the 'narrow' valve spacing of the '092's would be a good choice on a 350. The engine doesn't require a lot of port flow, so I don't think the heads would need anything to make them work well in that application...Robert

[rolling money pits]

was about ready to ask, what in the world happened to that engine with respect to it's torque output?!

then i re-read your post and saw you reversed the HP and TQ figures from the first paragraph.

good show, with what appears to be pretty low cost mods.

[Rack776]

This thread is good it means the 72 350 heads I have laying arround are not
just junk anymore, only problem is guys dont want to throw away 350s anymore
like they used to. I could of had a free stock 75 350 for my 75 bird to make it closer
to original but I passed on it and I went with a 400, I could kick myself for not
taking it when I had the chance.

Good post!

[just501]

Thought I'd add my 350 to the thread. The engine is in a '68 firebird, m-21, 3.36 blown posi. I plan to go to long branch manifolds and 2.5" exhaust as this car will eventually go back to a 400. (I have not tuned either carb.)

Baseline:
Stock '73 350 (2v rated 150hp)
'73 #46 heads 96cc (after pulling these, I found 2 burned valves)
Stock 555 Cam
Performer intake and Edelbrock 850 cfm
2" dual exhaust through a set of glasspacks, stock log manifolds.

Swapped cam:
performer cam 204/214 .420/.440 110 LSA.
Timing @ 12* ini and 38* total

Swapped heads and carb:
'70 #16 small valve heads, shaved to 68cc.
SCR appx 9.9:1
Compression test appx 190 psi on all cylinders.
Timing @ 6* ini and 32*total to prevent detonation.
Change the carb to Edelbrock 650 cfm (appx 14.1:1 afr @ WOT)

Dyno results baseline, after cam, and after heads and carb swaps:

274 RWTQ @ 3100 rpm; 196 RWHP @ 4200 rpm -- baseline
274 RWTQ @ 3450 rpm; 205 RWHP @ 4600 rpm -- cam swap
293 RWTQ @ 3300 rpm; 228 RWHP @ 4750 rpm -- head/carb swap

Torque curve was nearly flat with 280+ from 2000 to 4200 rpm after the head/carb change.

Hope this information is useful to someone!

[Formulafr]

i'm thinking about my stock 75' 350 4bbl. 555cam, 5C head....

interesting thread, continu guys!

[just501]

Thought I'd add latest change and dyno results to this thread. Sorry couldn't edit my previous post.


Baseline:
Stock '73 350 (2v factory rated @ 150hp)
'73 #46 heads 96cc (after pulling these, I found 2 burned exhaust valves)
Stock 555 Cam
Performer intake and Edelbrock 850 cfm
2" dual exhaust through a set of glasspacks, stock log manifolds.

Swapped cam:
performer cam 204/214 .420/.440 110 LSA.
Timing @ 12* ini and 38* total

Swapped heads and carb:
'70 #16 small valve heads, shaved to 68cc.
SCR appx 9.9:1
Compression test appx 190 psi on all cylinders.
Timing @ 6* ini and 32*total to prevent detonation.
Change the carb to Edelbrock 650 cfm (lean ~14.1:1 afr @ WOT)

Swapped carb:
Back to Edelbrock 850 (Rich ~12.0:1 afr @ WOT)

Dyno results baseline, after cam, and after heads and carb swaps:

274 RWTQ @ 3100 rpm; 196 RWHP @ 4200 rpm -- baseline
274 RWTQ @ 3450 rpm; 205 RWHP @ 4600 rpm -- cam swap 850 carb
293 RWTQ @ 3300 rpm; 228 RWHP @ 4750 rpm -- head/carb swap to 650
308 RWTQ @ 3400 rpm; 247 RWHP @ 4800 rpm -- carb swap back to 850

Torque curve was nearly flat with 295+ from 2000 to 4300 rpm after swapping back to 850 carb. Next change will be exhaust, then perhaps go to Q-Jet or another cam swap.

[Stuckinda60s]

Nice numbers, they're comparable with a lot of late model performance machines. Thanks for the update, I'm sure there are some interested people on here. I'm also sure you'd be surprised at the way it would respond to timing. The Edelbrock 850, is that the Q-jet clone? If so, I'd keep it and work with it. As an experiment, after the exhaust work and subsequent tuning, try mixing some racing fuel and optimizing the timing for it. As I said, I think you'd be surprised.

Keep up the good work.

[just501]

Thanks Rich,
The last dyno session, I worked on the timing. Swapped weights and springs in the dist. prior to dyno and timing for max power and torque was @ 36* total.

I posted the carb as 850 cfm, it is actually the 800 cfm #1413.

Justin