How would I even get started on diagnosing my motor?
 

I’ve got a 69 350 in my 69 Lemans, I’ve been told it’s an H.O. (Not sure if that matters). I have been wanting to start fixing up my engine but don’t know where to start.https://uploads.tapatalk-cdn.com/202...784a291e5f.jpg



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Try looking for the engine code on the passenger side front of engine block, just below the head.

Will be a stamped 7 digit number and a 2 letter code below it.

Look here for the 2 letter code:

Engine code Search

Post here also the data and we can decipher it also.

:)

There are lots of numbers so it can get confusing. You are looking for a 2-letter stamped code like the WW in this image:

https://forums.maxperformanceinc.com...1&d=1730313402

Outside of identifying the engine, what symptoms do you need to diagnose?

Squealing noise from the belts(been told there are two sizes of water pumps, appears I have the 400 on my 350 which is longer) weird sounds coming under floor which sounds to me like exhaust leak( squeaky sound when car is running) carburetor issues(too rich), sometimes there is white smoke that comes out of exhaust (I think it’s because the block has bad freeze plugs) transmission has shifting issues(TH350) just need this thing running right, money isn’t an issue because I have been saving. Please help me out


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A compression test and a leak down test will give a sense on the overall health of the engine.

White smoke would indicate coolant is making it's way into the combustion chamber. You'd also likely smell it in the exhaust. A bad freeze plug wouldn't allow coolant in the combustion chamber, but would cause an external leak. Usually a bad head gasket is the cause of coolant in the combustion chamber. What do your spark plugs look like?

There are two different water pump lengths in '69. Unless you have a mismatch in pulleys and they're not aligned, the water pump length wouldn't cause a squealing belt. Make sure you have the correct width belts and tension on them. There are a bunch of threads in the street section on belt sizes. I have a diagram somewhere that shows the correct width per application.

What are the shifting issues with the transmission? What's the trans fluid look and smell like?

For the sounds, I'd put it on a rack or some ramps while it's running to trace the source.

Trans fluid looks and smells like normal, the issue with the Trans is that it doesn’t shift half the time. Say I’m pulling out of my driveway, I have it backed out in Reverse but when I shift back into first it doesn’t move, just revs rpms, same with Drive into Reverse. This happens inconsistently so I’m really confused. Seems like it happens in the most inconvenient times LOL


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As for the spark plugs- I’d have to check when I get home, currently the head gasket seals looks all ratty and cracked so that might be the issue. I was told the freeze plugs can cause white smoke. But almost everything on this motor needs to be replaced. It’s in really bad condition but runs and drives. At the moment I just need someone to look at my car and tell me exactly what I need to buy, And what I can do to fix it.


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You can't see the head gasket condition from the outside of the engine. I'd start with the compression and leak down tests and get a look at the plugs while you're at it.

My advice is to figure out what's going on with it and check the basics (example: Is the trans low on fluid? Is the shifter linkage working correctly? ) before you start replacing parts or tearing into it.

Oh okay, I think I was remembering the valve cover gasket. I have no tools to do a compression test so I’ll pick some up from work. When looking at the spark plugs what should I be looking for? And what gap is the correct spacing for the arc? Trans isn’t low on fluid. How would one check to see if the linkage is working correctly? It might be straight forward but I have no idea what I’m doing. The car was recently given to me and I need all the assistance I can get


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Since you don't have any tools, are still getting up to speed on the car and have the funds, have you considered asking around and finding a local reputable shop that works on classic cars to give it a once over? It would ease the learning curve a bit.

You may also consider picking up a '69 service manual since it has all the diagnosis and repair procedures in it.

I think it matters if your Lemans is a real 350HO car. It would be one of only 2,687 Lemans 2-dr hardtops made in 1969 out of 4,238 total A-bodies (63.4% of total) equipped so. Not super rare, but not many exist any longer as many were destroyed not knowing what they were, became donor cars for GTO’s, or even became GTO’s…lol.

Tempest 2-door coupe: 85 (2.006%)
Tempest 4-door sedan: 10 (0.002%)

Custom S 2-door coupe: 87 (2.053%)
Custom S 2-door hardtop: 597 (13.851%)
Custom S 4-door hardtop: 30 (0.708%)
Custom S 2-door ragtop: 45 (1.062%)
Custom S 4-door sedan: 55 (1.298%)

LeMans 2-door coupe: 117 (2.761%)
LeMans 2-door hardtop: 2,687 (63.403%)
LeMans 4-door hardtop: 254 (5.993%)
LeMans 2-door ragtop: 271 (6.395%)
Total: 4,238 A-Bodies w/350HO (all transmissions)

The engine code for with an auto tranny (350HO’s could only get the TH400 automatic) is XU (under the passenger head on block), the tranny code is PS (on tag on driver side above pan), and the rear end should be a 3.55 gear (standard on 350HO’s with or without A/C) is XH with posi, or WH without posi (found on the backside of the driver axle tube). Other easy-to-see indicators are the #48 heads and the 4-bbl Q-jet & intake manifold. The exhaust manifolds are the standard logs.

Nice Lemans btw! (I hope it's an HO too!)

Dennis

Haven’t checked the codes but. It is posi and once ran its original intake with original 4bbl carb(now changed to a ported dual plane p4b intake and 600cfm E-choke Edelbrock Carb) I’m also looking to revamp this setup for more power. Any tips? I’m currently making around 320hp


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A few resources on belts and pulleys as you diagnose your squealing problem.

https://forums.maxperformanceinc.com...1&d=1730480206

https://forums.maxperformanceinc.com...1&d=1730480221

https://forums.maxperformanceinc.com...1&d=1730480244

Sounds like it could be a 350HO if it had a factory 4-bbl intake and Q-jet carb, plus having a Safe-T-Track (posi in Pontiac-speak) are good signs. If your car is an HO car (and has the original rear end) it should have 3.55 gears, more than good enough to support more performance goals in the future. Confirm you have #48 heads, then it’s just a matter of choosing the right cam. In most applications with an automatic trans and stock style (low stall) convertor, you want to keep the cam timing conservative like the factory 067 cam (197/213/113 @ .407”/.407” lift) or the Summit 2800 (204/214/112 @ .422”/.444” lift) and equivalents. With a looser convertor (higher stall), you could use the factory 068 (212/226/116 @ .407/.407” lift) or the Summit 2801 (214/224/112 @ .444”/.466” lift). New valve springs to support the lift/rpm range of the cam you choose needs to be selected. With lifts higher than .450”, you need to check for valve to block interference (at the cylinder bore) between the intake valve head and cylinder bore (which should have scallops/chamfers at the deck surface). Don’t go crazy with big cam timing.

If you are rebuilding the short block, go with a lighter reciprocating assembly with Eagle H-beam rods and lighter forged pistons with the 1/16” - 1/16” - 3/16” ring packs. Have the block decked to zero and use the Felpro 1016 head gaskets for .040” quench. Use Ram Air exhaust manifolds or 4-tube headers (1 ¾” tubes) with a good 2 1/2” mandrel bent exhaust system (Pypes) with DynoMax UltraFlo’s or MagnaFlo mufflers. This should get you in the 340 – 350 hp range and keep your Lemans very drivable.

Dennis

Masaki,

I see you are asking about engine upgrades to your 350 in the Street forums. If your Lemans is or isn’t an 350HO car, I, myself, would pull the 350, stick it under the workbench (if it’s numbers matching to the car) and go the stroker 400 route. Get a Butler 4.25” stroker forged balanced rotating assembly that will get you a 461 at .030 over, or 467 at .060 over. They make brutal torque off idle with any heads, stock 6x-8’s for 9.5 compression to ported aluminums. Get a good roller cam (many on this board cam help better than I, like Paul K…) and valvetrain, aluminum intake (your P4B), Cliff Q-jet, and good headers (Dougs, etc.), and you’ll be in the 450 hp/550 lbft torque with stock iron heads to low 500 hp/600 lbft torque with any out-of-the-box aluminum heads before you know. Porting will get you more! Make sure you get the block machined at a competent shop that knows Pontiacs.

You can get the same forged rotating assembly for the 350 for the same costs as the 400/455 blocks, but your giving up 100 hp/100 lbft torque at least. I'm guessing you aren't concerned about originality, so may as well go big. Anyway, something to stew on. If you want to continue with a 350 stroker, that is fine too. There is a really nice '70 Firebird that has a stroker 350 engine that's been in the forum's recently (SRMMM?), so maybe you could contact him for advice.

Don’t forget that making more power is going to expose the cars next weakest link…trans, rearend, suspension, brakes, etc. Build the Lemans so it can handle the power and be safe to drive.

Dennis

That’s the thing. I’m not looking for crazy power numbers. It’s going to be a daily I still want to have fun with. I will be taking thorough time and care of the vehicle if it gets the 383 installed. I’m not looking for a 500+ horsepower street freak. I’m looking for reasonable power with keeping the original block. Plus it would be a great unique build. I understand the pros and cons of not swapping for bigger displacement. But EVERYONE does that. I’m looking for more of a low-key unique restomod that will start conversation.


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I totally get what you are saying. It will be a great build to follow.

Dennis