So I bought a 68-71 olds 350 from a fellow enthusiast here in MO. I honed it, put new pistons and rings, rod and main bearings, etc. Crank turned without any binding when installing and tested with rear main seals removed to eliminate friction from them, and it was smooth. Everything went well except maybe the head should have been rebuilt. I suspect sticking of valves, and or the lifters had stuck open and found 5 or more bent pushrods (stock Melling mpr-307 pushrods).

I replaced the rods, primed the engine to pump oil into the lifters and the rockers and pushrods feel nice and snug like they should be. But, she still just wont start
I have ensured the cam and crank marks are aligned at the marks to 12 and 12 o'clock postition for the correct stroke.
I have tried two different HEI distributors, and will probably try to replace the plug wires next(new spark plugs properly gapped at .032" i think..)

I need some more idea with things to try to get this bass-terd started. It is all stock except a crappy 4 barrel aluminum intake i found from the 80s or something, and a cheap edelbrock 1407 with manual choke I found on ebay. Maybe the carb isn't getting fuel in there? I tried pouring fuel directly in the primary and secondary areas. When I received the carb, I wasn't sure if it was rebuilt, it was definitely clean and had new seals, but was VERY squeaky when operating the throttle and choke like they had soaked it in carb cleaner for a year. Let me know what you guys think. Thanks in advance.

 

You need to check basics, Fuel, Spark and Compression and then there is timing. With spark and fuel of any kind there should be a pop, a backfire or something.... You could try moving the distributor a bit right and left while cranking...

 

make sure you have spark, make sure you stabbed the distributor in correctly. and not 180 degrees off make sure you #1 terminal and the rotor on the distributor are correct , make sure your plug wires are correct. Make sure there is fuel coming out of the carb if you pump the throttle and fuel does not spray in then there is no fuel getting there yet. The 1407 may be a tad big for for your 350 I ran a 1405 in a mild 350 and it was more than enough ( that's just an observation) I know the qjets are 750's but I believe engine vacuum and air velocity determine the overall CFM on q jets as where on aftermarket carbs there is no metered restriction. I didn't need a 750 in my 350's until I started running in the 12's about 375hp 380 ish.

 

All vacuum secondary carbs, Qjet or otherwise, rely on demand to open the butterflies.
And I put 750’s on mild 350’s all the time. They work fine when jetted correctly.
Op- as stated check the basics first then go from there.

 

@cutlassefi I tried a 750 on a mild 350 and.it did.not work very well that's just from my personal experience. The car went well into the low 13's in the 1/4 mile with a 600 cfm carb feeding it and worked well straight out the box all around. Compared other cars the e/t mph reflected and confirmed it was running well. Im under the impression the q jet for some reason had a few circuits that could dictate the overall opening rate . on the edelbrocks and Holley once you go WOT and vacuum drops the secondary Just go full bore open and the only restriction is the rate of secondary actuation not the over all opening? During normal driving conditions I know its based of load where the secondaries are in relation but during WOT it never changes or shouldnt., I think or thought on the q jet it could meter that since its secondaries at the base are mechanical and the air valve dictates the amount and rate based of velocity so technically if you.go to WOT the top plate can still restrict it at WOT.

 

sounds interesting, would it be ok two tune the 1407 down or is the whole air flow/vacuum that will pull air and fuel through just too much? I have one of those edelbrock tuning kits with the diff size/tension jets and springs.

 

The jets control the fuel flow and the engine demand controls the air flow, so yes, you should be able to tune it correctly.

 

You will need to re jet and change the step up springs . do not forget that you also have 3 adjustments at the throttle lever at the accelerator pump or whatever edelbrock calls it.

 

Copper
I didn’t read through your whole post but here’s the skinny, you can regulate the secondaries opening on any vacuum secondary carburetor and they meter fuel accordingly. However the Quadrajet has two sets of secondary plates with the top needing to open slower. They have to, because why?

 

Motor has to run before he should mess with tuning the carb.

 

Just to clarify, the Qjet is not a vacuum secondary carb. The Holley 4160 is a vacuum secondary carb - the large vacuum diaphragm that opens the secondary throttle plates is directly connected to manifold vacuum. The Qjet has secondary throttle plates that are mechanically opened. Turn the carb over and operate the throttle arm - the secondaries open (assuming the choke lockout is not holding them closed). The only thing that controls how much they open is your right foot.The air valves above the secondary throttle plates are opened by mass air flow through the carb, not vacuum. There is no vacuum diaphragm and no connection between manifold vacuum and the air valves (yes, there is a dashpot that controls how quickly they open, but it certainly does not open them - the carb will still work if you disconnect that dashpot). As the secondary throttle plates open, air moves past the loosely fitted air valves. The mass of this air pushes down more on the larger side of the air valves, overcoming the spring force holding them closed. More mass air flow, more opening - and as they open, they also control fuel flow by raising the metering rods. Note that this is essentially how EFI with a MAF works. Some early MAF sensors were very similar to the Qjet secondary air valves - a vane with a torsion spring. Instead of directly controlling fuel flow, these systems operated a potentiometer that let the ECU control fuel flow. Think of it another way - the Qjet is a mechanical analog computer.

 

The air doors on a Qjet are the restriction as described. Why? Simple, there are no venturis in the secondaries so the only way it’ll pull fuel out of the bowl and thru the jets is to have restriction/pressure drop to simulate a conventional carb throat with venturis.
Thats why they’re so prone to bog if the air doors are allowed to open too quickly. No restriction, no fuel.

 

To the OP
Do you have spark?
Have you checked cranking compression?
Besides the fuel you poured into the carb, is the carb adding fuel when you operate the throttle?

 

Im still hung up on the fact the op suspected sticky valves and had to replace bent pushrods .Did you do any checks on these heads before just changing the push rods?maybe i missed something .I would also double check the firing order Olds distributors spin counterclockwise(this sounds easy ,but has tripped up many )when you get the engine running i agree on the use of a quadrajet.

 

Was this the factory non adjustable valve train? If so there can be no over adjustment like an aftermarket adjustable valve train and the heads should be gone through by a machine shop. Pushrods bend for a reason. Was the nylon cam gear in pieces? As far as the bog on the Qjet, nearly everyone I have touched had the secondary air doors set too loose. I assume the spring lost tension over time. Also a leaking pulloff will cause this. A higher stall converter and deeper than most factory gearing is needed for a loose setting like I found. I would bet the W30 and W31 with 3.91 gears and a factory high stall didn't have bog issues especially with no primary metering rods. You could just about have 0 spring tension on them, I would bet. Your 750 carb will no doubt be rich as is and no choke is problematic unless tuned right on. Prime the carb with carb cleaner or gas. It will attempt to fire or run. That tells if the timing is right and spark is present. If a bunch of valves are holding part way open, good luck getting it running.