[north]

The 69 350 HO was a strong engine, at 330 horse, it was substantially upgraded from 68 and 1969 was its last year. By comparison other 4bbl high compression 350ish engines were lower:
the 4bbl 350 Buick GS engine was only 285 horse, the Chevy 350 L48 was 300, even the Oldsmobile 350 was only 310 horse and even the W version was 325 horse.

A big difference with the Pontiac 350 was it had a lot of stroke compared to the other divisions 350’s. This gave it more grunt and the 69 version switching to the Cam and heads of the Ram air 400 gave it better top end power too. The downside of the long stroke (3.75”, same as the 400’s) was a reputation for being not great on gas, especially the 2bbl 350 when compared to other 350’s.

[SD455DJ]

Originally Posted by Verdoro 68

Ah, I missed your comment about the tach reading high and did a double take on the pic of the tach. 5400 is still a bit higher than your typical 400. Stout little engine!

It was quite surprising being the first time doing full throttle blasts since we bought the Custom S. Figuring it weighed around 4100 lbs. with a full tank of 93, us two, and tools on the rear seat floor. It's amazing what working secondaries can do...lol! The 350 factory cast pistons are only an ounce lighter than the 400's, so not really any more 'revability' than the larger bore brother.

North mentioned the 350 2-bbl's not being good on gas mileage compared to the other makes 350's, but the HO engine got almost 16 mpg on the highway at 70-75 mph, buzzing happily along at 3200 rpm with it's 3.55 rear gear.

Dennis

[north]

My comment about mileage is not really my own, I've seen it mentioned in several 1968-72 period magazine articles (all with 350 2bbl LeMans cars) that the Pontiac's got the worst mileage of their 350ish cid peers. Perhaps related to the rather heavy engine and long stroke. What I can say is that my two 2bbl 350's (both with AC, Th400 and 2.73-2.56 axles) get mileage that is no better than my GTO's with 400/TH400/3.55 no AC or 400-366/TH400/3.23 AC cars get. That being said the 350 2bbl with th400 and 2.78 gears is lovely to drive, very smooth and responsive thanks to the venturis on the 2bbl being much bigger than the Qjet primaries and the torque biased 2bbl cam. Similarly my 69 Catalina with a 2bbl 400 and 2.78 gears is much more responsive in normal daily driving than my other cat with the 428-360 and 3.08 gears (up to engaging the secondaries on the Qjet of course). They knew what they were doing with the different standard axle ratios on different engine-trans combos.

[AG]

My '68 FB with a 350 2 bbl and manual 3 speed with 3.23 gears is very peppy. It actually surprised me. It's not as peppy as my '72 LeMans vert with 455 4 bbl and 3.55 gears though.

[SD455DJ]

I recall reading about bad gas mileage in the Car Life magazine where they tested '69 intermediates (from memory...Lemans 4-dr hdtp loaded, Chevelle 4-dr hdtp 350/300 hp loaded, Ford Fairlane 4-dr 351, and a Belvedere 2-dr (?) 318 not so loaded). The Lemans did get the worst gas mileage of the bunch as well as being the slowest in all the performance tests I recall.

Dennis

[johnta1]

I think with the Qjet, it would actually be using smaller venturis than the 2 bbl. So if one drove miserly (not my way of pedal to metal) it would be a lot better gas mileage. Then on full throttle the extra size would be wonderful.

[HWYSTR455]

I had a '67 Dodge Cornet convertible with a 318 2bbl. I rebuilt it, .030, and a dual plane intake with a Holley 725cfm vacuum 2ndary. (Think it was a 725cfm?). That car with a 3.23 rear and 927 auto got @ 32mpg at 60 on the highway, used to have to prove it to people because they didn't believe me.

When I got my '71 LeMans Sport, it was a 350/2bbl 350 auto AC car with 3.08s. It was all original with @ 68k miles on it. It was certainly 'peppy' and surprised me as well. Not sure what mileage was but it was certainly less than my 455 bird and convertible.

With no other changes, I put an Edelbrock Performer on it with a small sized Holley vac 2nd, and it lost a lot of that peppy-ness. Granted, it wasn't properly tuned right off the bat but it was still very noticeable.

I was building a 400 for it, so I didn't really bother too much getting optimized.



.

[SD455DJ]

That's amazing with a 318 Mopar. They are good little engines and fairly efficient. Our dad bought a '70 Olds Cutlass S new (2-dr hardtop) with a 350 2-bbl, AC, TH350, std. rear gear (2.78?) and it got 20 mpg easily on the highway, not to mention, it could lay rubber for a good city block by just flooring it, no power braking. (We tried to talk him into getting the W-31 package instead of AC, but he wasn't buying it...lol.)

Dennis

[HWYSTR455]

Someone gave me a 68 Buick Skylark with a B350 2bbl, 2 speed, and like 2.76 gears, and that thing would fry a tire. Wouldn't pass inspection, so I swapped plates on it for almost 2 years and drove it until I was recognized no matter where I went, then gave it away. Total rust bucket but ran great. Know it had decent mpg, but never checked it.

The Coronet was actually pretty light for what it was, lighter than I would have imagined, think it was around 3300-3400 lbs? But with just a simple suspension rebuild, it handled amazingly well. It was surprisingly quick too, not like large displacement quick, but it surprised a lot of people, and would take on camaros/firebirds of the 80s easily.

Wish I could find another one reasonably priced, maybe one day I will, miss that car. Easy to work on, inexpensive parts, and reliable with an upgraded mopar electronic dizzy setup. It started cold any time of year with a 1-pump pedal & key-turn, was almost instant. I had like $6500 in it, including rust repair and paint. That was in the mid-80s. Had to have put an easy 75k miles on it with just about nothing more than gas, tires, and brakes.



.


.

[north]

Years ago I swapped out the factory 2 bbl carb and intake on a 69 Cat (400-290, 2bbl carb, th400, 2.73) with a stock 69 Qjet and intake. Everything else was untouched and bone stock. The switchover resulted in three noticeable changes: responsiveness and tip on was much worse, city mileage improved a bit but highway mileage improved over 10%. All make sense given the small primaries on the Qjet. More throttle opening angle improves efficiency at the price of response.

This is why you typically saw (until the mid 70’s when economy trumped everything) that 4bbl engines had steeper gears than the 2bbl version. Case in point the 400-290 2bbl had 2.73, but the 428-360 4bbl had 3.08.

[SD455DJ]

The tip-in on the new Q-jet is amazing and so much better than the previous Q-jet. It is very 'peppy' just off idle. Makes me wonder how it would feel with a 2-bbl set-up. I will say that it doesn't feel nearly as quick as Dan's '69 350HO Firebird with the M20 and 3.55 gear. He's run as quick as 14.20's at 100 mph granny shifting at 5000 rpm, but is a good 350 lbs lighter.

Dennis

[SD455DJ]

I took the Custom S to the Pure Stock Drags this past weekend hoping to get a few passes down the quarter mile after the flurry of teching cars for the race wound down to a trickle. The idea was to get a couple of base runs then swap in a recurved distributor and dial I the jetting (secondaries and secondary air valve tension). We double checked the engine oil and trans fluid levels and headed for the staging lanes. Leaving the trans in Drive the first pass revealed a bad accelerator pump causing a stumble off the line and then a surprising slip on the 1-2 shift (revved an additional 500 rpm over the 4800 rpm factory programmed shift point). It ran a respectable 15.561 at 90.47 mph…better than I was expecting with the tiny exhaust system it has and scaling in at a whopping 4080 lbs (with me inside)! Just to make sure I wasn’t imaging the slipping 1-2 shift I went back up for base line run #2. I power braked it to 1200 rpm to help offset the bad accelerator pump bog and the 1-2 shift revved almost to 6000 rpm before sliding into 2nd gear. I stayed in it and the 2-3 shift was firm at 4800 rpm. It actually ran a better time at 15.424 at 91.25 mph despite the poor 1-2 shift. I was in the left lane for both passes car TT1.

After that pass I decided that was enough punishment on the trans because I still had to drive back home in the evening. I know what I’ll be doing this winter. I did grudge race Steve Courter’s gorgeous ’73 400 4-bbl Lemans GT in the second round. With a good shifting trans, better exhaust system and the recurved distributor it will easily run in the high 14’s at 95 mph without getting into the engine.

Dennis

[north]

Nifty, do you think that’s the first ever runs for the car? Those are about the times I’d expect bone stock from the factory. I never ran my LeMans HO at the track but it (3990 without me but a full tank and TH400 and 3.23 I believe) feels like a 90 mph car.

. Qjet woes, part of the Pontiac life. My 428 (360) Catalina was finally running nice this year after sorting out persistent accel pump issues over the winter hiatus but now I’m noticing hard starting when engine is at operating temp. Accel pump is fine, cold start is good with two pumps and even after a week it fires in less than ten seconds. But when it’s warm it now takes about ten seconds to fire. Probably a bad leak down so it wets the intake after sitting for 10-30 minutes. Usually my Qjet (and all my 2bbl cars) fire instantly without touching the gas when they are at operating temp. Did the plugs and points etc over the winter and maybe 400 miles since then. Tomorrow night we hit her with a timing light, dwell meter and then a car opening.

This Cat pulls nice also, 428-360, AC, TH400 and 3.23 STT (3.23 was the optional “performance” ratio, standard was 3.08). Can you really feel the 4.8% extra gear multiplication, why did someone bother to order it, mind you it was all of $2.11!

[SD455DJ]

North - Yes, I believe that is the first time on a drag strip and it was ‘bone stock’ as well. I didn't even pump up the tires to 45 psi front/ 40 psi rear to decrease rolling resistance and left them at 28 psi all around. We scoped the cylinder bores and the pistons were std. bore and the factory cast pistons. When the OO removed the engine to replace the timing chain & gears, he installed new factory rings, bearings with new factory head gaskets. It was obvious that he didn’t remove the exhaust manifolds from the heads as they still have the head bolt locks on them. He didn’t even touch the valves or springs. We are going to order a bunch of accelerator pumps from Cliff and replace them on at least a dozen cars.

The plan this fall/winter/spring is to pull the engine & trans to 1) rebuild the TH400; 2) remove the stuck exhaust headpipes flange bolts from the manifolds (after cutting the head-pipes with a Sawzall as close to the manifolds as possible; and 3) install the new 2.5” exhaust system.

Dennis