AAR project

[marksmopars]

Interesting note on engine parts, this engine was prepped before and it appears that the crank and rods were shot peened and balanced. It includes 5 rods with stock 340 rod numbers and 3 rods with 318 stock numbers. Physically the rods look identical except for the number? They were balanced as a set including hand engraved numbers on the rods.
I’m hoping someone out there might know more about this as it’s my nature to want to know.

 

[Xcudame]

The factory 340 rods from 68-72 where 2899496 and the pin was bushed by the factory. In 71, the 360 used 3418645 rods that did not have pin bushings. The 318 used the 340 "496" rods, but didn't have pin bushings. In 73 the 318, 340 and 360 used the "645" rods. From what I can tell, there is no significant difference from the "496" rods and "645" rods other than the factory pin bushings in the 340 engines. The "645" rods have enough material to easily and safely install pin bushings.

 

[Challenger RTA]

As Xcudame posted. I knew the answers. But I had to look it up to be sure. Just busy. As far as the rods. If you old use rods They can be magnifluxed and reconditioned. I think that is the course of action to take. Thanks Xcudame!

 

[marksmopars]

The factory 340 rods from 68-72 where 2899496 and the pin was bushed by the factory. In 71, the 360 used 3418645 rods that did not have pin bushings. The 318 used the 340 "496" rods, but didn't have pin bushings. In 73 the 318, 340 and 360 used the "645" rods. From what I can tell, there is no significant difference from the "496" rods and "645" rods other than the factory pin bushings in the 340 engines. The "645" rods have enough material to easily and safely install pin bushings.

I should be specific that this engine has 5 rods numbered 2899496 and 3 numbered 3418645, should have said this earlier, fyi.

 

[Xcudame]

I figured that is what you meant because those are the two that look so much a like. The earlier 318 (and 273) connecting rods are slimmer and there would be no way to balance them the same as a 340 rod.

 

[fasjac]

Nice! Right original color too

 

[marksmopars]

Just received the rocker arm assemblies for the T/A motor, was not included with the car. Most everything else was and these look awesome! Just what we needed to finish the motor for this beast.

 

[Cuda Hunter]

Those look awesome! Can't wait to see a video of the car running!

 

[don selleck]

very nice

 

[marksmopars]

Word from my machinist is couple weeks to completion. I need to ask for thoughts on six pac carberator controls. The factory six pac runs the front and rear totally on vacuum. The set up I received is totally manual with the outboards set to hit full open when the primary is same.

I have the factory set up on my t/a and am very familiar with the vacuum set up. The manual set up for the Aar actually looks sound, but I’ve never run one so I’m hesitant to run as is. I have parts needed to return to factory set up.

Any thoughts on this? If it was yours what would you do? Note that I’ve just gotten the chassis onto a homemade frame jig and ordered needed frame rails and crossmember. I have an opportunity to take the engine frame the machine shop to an engine Dino, after which it will sit until I finish the body.

 

[don selleck]

I would try it mechanical, I usually run mechanical secondaries on four barrels, I like the instant response when there tuned right. Vacuum that I've ran seems to have that momentary hesitation. If you don't like how it responds you could always change it back later. would like to see the mechanical set up they did, I thought about making mine mechanical, doesn't seem to look to be much of an effort to change it, to that.

 

[fastmark]

It is not intended to run mechanical secondaries. They have no accelerator pumps so they will have a flat spot guaranteed. I restore and tune six packs and have owned and raced one since 1976. All you have to do is get the diaphragm spring kit and you can adjust them to where they come in faster and will not bog. Mopar made a setup that had mechanical secondaries but the outboards had accelerator pumps.

 

[marksmopars]

I would try it mechanical, I usually run mechanical secondaries on four barrels, I like the instant response when there tuned right. Vacuum that I've ran seems to have that momentary hesitation. If you don't like how it responds you could always change it back later. would like to see the mechanical set up they did, I thought about making mine mechanical, doesn't seem to look to be much of an effort to change it, to that.

 

[don selleck]

It is not intended to run mechanical secondaries. They have no accelerator pumps so they will have a flat spot guaranteed. I restore and tune six packs and have owned and raced one since 1976. All you have to do is get the diaphragm spring kit and you can adjust them to where they come in faster and will not bog. Mopar made a setup that had mechanical secondaries but the outboards had accelerator pumps.

makes sense, would starve for fuel upon kickdown, then catch up as venturi effects kick in. but would like to see how much.

 

[fastmark]

I’ve got several sets of those mechanical linkages in the parts stashes I’ve bought over the years. I tried it too. It had a big hesitation. The big 50 cc pumps helps some but then you are rich off idle in normal driving. The beauty of a six pack is the small 350 cfm to drive around for low end performance. Now mopar did make a setup with outboards that were made to be mechanical and they had accelerator pumps. I’ve tried a variation of that system with three center carbs of 350 and it worked good on the street but I did not like it racing. It was not as consistent as using the vacuum secondaries with light springs.

If you really want to know how if affects you fuel curve, get and AFR meter and install it. I’ve got the new FAST wireless that uses my phone as the display. It’s great. It has a 20 second graph display.

Funny story just happened the other day, since we are discussing accelerator pumps. I’m building a set of carbs to install on a customers restored six pack Superbird. He’s tried two sets of original carbs and even trailered the car to a Six Pack Performance guru that he found and still its no bueno. So he brought me a set of NOS Holleys from 1981 he’s been saving. I had to replace the rubber and gaskets because they were dried out and stiff. I put them on my car to test because of my AFR meter. Cranked them up fine and got the car warmed up and idle tuned in. Then I noticed that blipping the throttle caused a EXTREMELY lean spike in the fuel curve. What the heck. Looked in the center carb and zero pump shot? Push the accelerator pump and it would not move. It was stuck solid. Pulled the squirter off and it had gas and worked. The short story was the carb was defective. When Holley built the carburetor in 1981, the seat that is in the body was not driven in to the proper depth so when you installed the squirter nozzle and screw, it mechanically sealed the needle to the seat no it had zero pump shot. It would have had a terrible stumble off idle.

That’s the biggest reason I’ve found for off idle stumbles, even in Carters, is improper accelerator pump shots.

 

[don selleck]

very interesting, I always thought of a mechanical with the six pack never tried, was going with the stock set up anyways this time. I have a dual bank AFR gauge I will be installing on my cuda when I get to that stage, I always was a spark plug checker, did pretty well at it, but that's not gonna get you all the in between fuel burn ratio, thanks for the info.

 

[fastmark]

Here’s the information on the outboard springs. The springs kits are cheap. The chart is included in my old kit. I have used differ springs in the outboards sometimes to “tune” it more precisely. The white springs can be too quick and bog sometimes. I’ll pair it with a yellow in the rear and it stops the bog. The outboards are tied together and will open at the same time even if they don’t have the same spring. FYI, if you use the black spring, you only have a “ 2 pack”! Lol.

 

[fastmark]

Here’s the information on the outboard springs. The springs kits are cheap. The chart is included in my old kit. I have used differ springs in the outboards sometimes to “tune” it more precisely. The white springs can be too quick and bog sometimes. I’ll pair it with a yellow in the rear and it stops the bog. The outboards are tied together and will open at the same time even if they don’t have the same spring. FYI, if you use the black spring, you only have a “ 2 pack”! Lol.