Author Topic: Quick question I'm probably overthinking  (Read 90 times)

Offline Ksp3cialK

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Quick question I'm probably overthinking
« on: March 17, 2020, 06:47:46 PM »
So my first post here a few years ago before life happened, https://cliffshighperformance.com/simplemachinesforum/index.php/topic,3146.0.html

I'm back to working on this truck, got the trans working properly now and recurved the distributor. Now the truck is much more alive than before.

My carb #17080213 is still set to stock with the 72/50M combo. I also figured out it's an 800CFM that was originally on a 454CI truck.

With the primaries larger on this carb, will that affect part throttle at all on this stock 350?

Currently while cruising if I floor it, it goes pretty lean on the WB then gets pretty rich and takes off on the downshift. I'm guessing maybe a pump shot issue but I have trimmed the shaft some and moved the rod to the inner hole.

I'm probably overthinking this. I might start with a fresh rebuild with parts from this store. When I take it apart, should I mess with air bleeds or idle tubes since it was for a big block originally?


Offline tayto

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Re: Quick question I'm probably overthinking
« Reply #1 on: March 17, 2020, 06:56:23 PM »
cliff already answered you're question in your original post. reman'd qjets are garbage. find a virgin core and order a rebuild kit. i'm pretty sure after the mid 70s all Qjets were of the 800 cfm variety.

Offline Frank400

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Re: Quick question I'm probably overthinking
« Reply #2 on: March 17, 2020, 07:36:47 PM »
the 800 cfm (large primary venturi) will NOT affect anything in your case.  Even lazy Pontiac 301s had a 800 cfm Quadrajet. 

Offline Ksp3cialK

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Re: Quick question I'm probably overthinking
« Reply #3 on: March 17, 2020, 07:51:48 PM »
the 800 cfm (large primary venturi) will NOT affect anything in your case.  Even lazy Pontiac 301s had a 800 cfm Quadrajet.

That's good to know. Thank you for your reply.

Offline Ksp3cialK

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Re: Quick question I'm probably overthinking
« Reply #4 on: March 17, 2020, 07:59:03 PM »
cliff already answered you're question in your original post. reman'd qjets are garbage. find a virgin core and order a rebuild kit. i'm pretty sure after the mid 70s all Qjets were of the 800 cfm variety.

Suggestions on the best way to find those and know 100% that it's unmolested? Only one salvage yard around me and they don't keep much of the older stuff around and the stuff they do have is not cheap. No way to trust anything online like ebay.

Offline tayto

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Re: Quick question I'm probably overthinking
« Reply #5 on: March 17, 2020, 09:48:45 PM »
reman'd carbs have a metal tag screwed to them or a sticker.

Offline Ksp3cialK

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Re: Quick question I'm probably overthinking
« Reply #6 on: March 18, 2020, 07:21:17 AM »
reman'd carbs have a metal tag screwed to them or a sticker.

Nothing to stop a person from removing a sticker or taking a tag off.

With the carbs now 40-50 years old, finding a virgin at that age seems pretty hard.

Offline tayto

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Re: Quick question I'm probably overthinking
« Reply #7 on: March 18, 2020, 11:45:39 AM »
i guess you can try playing around with it if you haven't already. you'll probably just have to live with the drivability issues if no effort is put into locating a non-reman'd core. search the forums, you'll find the same answers and solutions to using reman'd carbs from cliff and others. good luck.

Offline tayto

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Re: Quick question I'm probably overthinking
« Reply #8 on: March 18, 2020, 11:51:05 AM »
your best course of action may be to take the carb apart and blueprint it and then post your findings here. it can then be determined if it has been "butchered" or not.

Offline Ksp3cialK

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Re: Quick question I'm probably overthinking
« Reply #9 on: March 18, 2020, 04:29:16 PM »
I decided to pull it apart and the gasket came off in one piece thankfully.

Turns out I actually have 48M rods in it instead of the 50M as I thought. Anyway, I decided to put the strongest power piston spring I have in and fired it up. It was fully seated at idle so I took it for a drive. When I stomp it, I only see green on the wideband and it just goes, no hesitation whatsoever. The tires even started spinning for a few seconds after shifting into second.

Idle numbers on the WB are pretty good and the exhaust is not rich smelling, also pulling around 20 on the vac gauge in park.
Cruise is also looking pretty good on the WB and not too lean or rich.1

I can finally try swapping some secondary rods around now that the transition to them isn't lean.