[steve25]

Your talking in very broad terms!
Sure these Carbs ran and functioned on a good number of different cid motors , but in many cases only to some 85% of being optimal, especially at the top of there metered fuel flow range.

Just look at how with the Q-jet carbs there is quite a response difference between the short and long taper metering rods!

[dataway]

Here's a pic of my valley when I pulled it apart after a cam break-in. Numerous puddles of oil.
Yours looks kind of dry ... might be a different issue than the pushrod issue though.

[steve25]

What's troubling to me in going back to the OPs picture of his lifter valley and comparing it to yours dataway is that the main core / non lobe portion of your Cam looks as it should with a oil coating on it, his does not!

I am starting to wonder what some of his rod bearings and mains might look like?

[dataway]

Yes, I see what you mean, didn't notice that. Yikes.
Hopefully an illusion of the photo process.

[jamaca85]

arnt the pushrods for a 389 shorter than for a 69 400? with the 62 heads need 9.17 pushrods not the 8.71 that are for a 389. make sure you have the correct pushrods

[steve25]

Yes, if you run 326,389, early 1967 400 or 421 type heads you need the shorter push Rods .

[1965gp]

Just a quick update. I’ve been back to work full speed so that means traveling 4+ days a week and did not have time to get to the shop.

I forwarded this write up to the guy working on it and he said that the valve train is adjustable so he doesn’t think the pushrod length is an issue. He checked if it is getting oil to the top of the push rods and it is so I think we need to look at other options.

They put larger jets in the center carb and the car loved it. He said he went from 63’s to 72’s in the center carb. He said normally that would be a huge difference but the car loved it, didn’t run rich and ran better.

Here is my next question- the car seems to be liking extra fuel. The center carb is small, much smaller than the end carbs. Is this correct for a 65 Tri Power? I bought it used so it’s possible it is the wrong carb?

[PontiacJim1959]

Originally Posted by 1965gp

Just a quick update. I’ve been back to work full speed so that means traveling 4+ days a week and did not have time to get to the shop.

I forwarded this write up to the guy working on it and he said that the valve train is adjustable so he doesn’t think the pushrod length is an issue. He checked if it is getting oil to the top of the push rods and it is so I think we need to look at other options.

They put larger jets in the center carb and the car loved it. He said he went from 63’s to 72’s in the center carb. He said normally that would be a huge difference but the car loved it, didn’t run rich and ran better.

Here is my next question- the car seems to be liking extra fuel. The center carb is small, much smaller than the end carbs. Is this correct for a 65 Tri Power? I bought it used so it’s possible it is the wrong carb?

Yes, smaller center carb on 1965, all the same size on 1966. No, the larger center carb will not just bolt on.

[Half-Inch Stud]

Originally Posted by 1965gp

Just a quick update........

They put larger jets in the center carb and the car loved it. He said he went from 63’s to 72’s in the center carb. He said normally that would be a huge difference but the car loved it, didn’t run rich and ran better.

Here is my next question- the car seems to be liking extra fuel. The center carb is small, much smaller than the end carbs. Is this correct for a 65 Tri Power? .............

Pontiacs love big jets for big HP. My 1050 has to JET-up alot and i never leaned it back. My best Q-JET work was setting them to run rich, but hey the plugs show clean. Must have an common airleak in all my builds.

only TriPower i had was a 1966 Intake for the big center carb. never ran it. Just knew it could perform. I got too much of a Spreadbore or Dual-Quad mindset.

[Tom Vaught]

Richard Holdener in one of his Engine videos did a series of dyno tests on increasing the jet size on the Primary side of the carb and saw maybe a 5 hp loss in power with a jet that was about 15 jet sizes larger than stock. Engine still ran fine, just the top end power was down a few hp. The idle circuit and the transfer slot circuit set most of the normal drive manners on the typical carb, That with the booster design on Rochester 2 BBL carbs.

If it drives good and you are happy, leave it at the richer jetting. F.E. might be a bit less, but if you are into the
TRI-POWER very much it will make little difference.

Tom V.

[1965gp]

The shop has concern that there is a vacuum leak that we are trying to compensate for. Putting hands over the end carbs richened up the mixture immediately so we may need to have the end carbs gone through again to see if they are leaking.

It’s very frustrating- the car drove so good when I got it back I didn’t see this coming.

[TCSGTO]

Since there is no idle system on the end carbs of a tripower their throttle plates need to be 100% closed. There is actually a sealer some builders one on the carb base that makes sure no air leaks past the throttle plate at idle.
As far as he pushrod issue I’d still vote for wrong length and bad geometry. I’d ask what length they put in or if they don’t know for sure ask if they are stock389 length. If they’re 389 pushrods they are way too short. Just because the valvetrain is adjustable and you can run an adjusting nut down and tighten everything up doesn’t mean that pushrod length will work.

[1965gp]

Quick update- after talking to the Tri Power guys at Norwalk they said they had never seen a lean condition cause this so that was good enough for me. I told the shop and the next day they had the heads off and at the machine shop.

The machine shop said they had to beat the valves out and said there was obviously a problem and they were going to take care of it.

They asked if the motor got hot because you could see where the head got really hot where the valves got stuck and you can also see it on the head gasket.

My thinking is the tight / incorrect tolerance caused the heat otherwise it would be at other points as well.

They should have the heads done this week- I will verify the length of the pushrods- I needs the 9.17 on a 77 400 block with 62 heads correct?

[steve25]

The stock length for a 400 with a factory cam is 9.130 with a 1967 and up D port head of any casting number.
There are many things that can make for the need of a push rod not of 9.130” in length, so it’s best that you get a adjustable push rod to check your geometry to find out what length it is you do need,