273 Mystery Motor

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brodphish

brodphish

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Just over 4 years ago I purchased a 1965 Barracuda that is a very clean Tucson car. It was advertised as having a Commando motor. I was suspicious of that, but the price was right and it's been a very fun 4 speed driver. Last fall I took it to a good Mopar shop here in Green Bay for a valve adjustment. They told me it had hydraulic lifters, of course raising questions. A few miles later the valve train became noisy, raising even more questions. They suspect the cam has a flat lobe and in a few weeks they are going to install a new cam. I'd like to have one in mind, but first:

1. I've recently read all 273's (including the 180hp 2BBL) had solid lifters. Is that true? If so, someone replaced them with hydraulic.
2. The motor has been modified in at least the following ways:
Offenhauser 360 single plane aluminum intake
Open element air cleaner
Quadrajet carb from 1989. I believe all q-jets from this era were 800 CFM which seems like a lot for the displacement
3. The block stamping on the pad below the head reads B273 11-19 which I think makes it a 66 motor.
4. The VIN tag decodes to a September 30 build date, which makes this a replacement motor, correct?
5. The VIN tag also decodes to the 180 hp 2BBL but if it a replacement, who knows?
6. The motor runs really really well but seems to run out of steam over 4,000 rpm, just when I thought it would be coming on cam.

My limited research indicates the Isky E-4 cam would be a good choice, or perhaps a stock 340 cam. Any thoughts on any of this? My primary goal is to select the right cam but any other thoughts are welcome. I know I should get a borescope and look at the pistons and I will do that.

IMG-0783.jpg


IMG-1406.jpg
 
Later 273s (68/69?) were hydraulic lifters.
The B273 11-19 make it a 66 model year engine assembled on 11/19/65
The scheduled build date September 30 is an approximation, final assembly was after 11/19.


Alan
 
If it has adjustable rockers, in all likelihood, it has solid lifters and the shop caused the flat cam by adjusting for a hydraulic.
 
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#1 pop a valve cover and see what's cooking under there. you'll know right away whether it's hyrdo or adjustable (are there adjustable rockers; if there are, a push test should tell you if the lifters are solid or not).

#2 scope the bore and check the pistons.

#3 why'd you take it in for a valve adjustment? was it running poorly or were you just getting ahead of it with some PM?

it's mighty coincidental that you just happen to have a cam go flat after a visit to a shop.
 
Yeah them saying hydraulic and then a flat cam? Get a known person(or yourself) to chk it out. Too big of a cam will kill that 273.
 
Keep in mind too, the pushrod length difference to go from the original solid to hydraulic. So that weighs even more that it probably has solid lifters.
 
It wasn't uncommon to replace the solid lifters with a hydraulic cam & lifters, retaining the adjustable rockers and using different pushrods. That's how my Commando is set up. But a flat lobe is questionable — a collapsed lifter would seem more likely.

But if you are choosing a new cam, the big question is do you really have Commando high compression pistons? The low compression 2bbl motor can't handle much cam.
 
The only sure way to know is a borescope. Look at the tops of the pistons. They should have 2 valve reliefs.
 
Junkyard the motor was running good, I took it in for PM. The same shop had my 67 earlier and went through it, got it back in a week and it was a much better car for it. They addressed a number of niggly issues. So I thought I'd have them at least look at the valve adjustments on my 65.
 
66fyssh said:
The only sure way to know is a borescope. Look at the tops of the pistons. They should have 2 valve reliefs.
Click to expand...
If they are the high compression pistons. 2 barrel low compression pistons have 4 valve reliefs.
 
brodphish said:
Junkyard the motor was running good, I took it in for PM. The same shop had my 67 earlier and went through it, got it back in a week and it was a much better car for it. They addressed a number of niggly issues. So I thought I'd have them at least look at the valve adjustments on my 65.
Click to expand...
Yep you have something wrong going on there. Solid cams and adjustable rockers were factory on the 2 and 4 barrel engines from 64 through 67. The cams between the 2 were a bit different. In 68 and 9 they went to a hydraulic cam and non adjustable rockers. The pushrods were also different on the hydraulic engines. You can use the adjustable rockers with a hydraulic cam as long as you use a special pushrod. Who knows what combination you have going on in there.
 
brodphish said:
Just over 4 years ago I purchased a 1965 Barracuda that is a very clean Tucson car. It was advertised as having a Commando motor. I was suspicious of that, but the price was right and it's been a very fun 4 speed driver. Last fall I took it to a good Mopar shop here in Green Bay for a valve adjustment. They told me it had hydraulic lifters, of course raising questions. A few miles later the valve train became noisy, raising even more questions. They suspect the cam has a flat lobe and in a few weeks they are going to install a new cam. I'd like to have one in mind, but first:

1. I've recently read all 273's (including the 180hp 2BBL) had solid lifters. Is that true? If so, someone replaced them with hydraulic.
2. The motor has been modified in at least the following ways:
Offenhauser 360 single plane aluminum intake
Open element air cleaner
Quadrajet carb from 1989. I believe all q-jets from this era were 800 CFM which seems like a lot for the displacement
3. The block stamping on the pad below the head reads B273 11-19 which I think makes it a 66 motor.
4. The VIN tag decodes to a September 30 build date, which makes this a replacement motor, correct?
5. The VIN tag also decodes to the 180 hp 2BBL but if it a replacement, who knows?
6. The motor runs really really well but seems to run out of steam over 4,000 rpm, just when I thought it would be coming on cam.

My limited research indicates the Isky E-4 cam would be a good choice, or perhaps a stock 340 cam. Any thoughts on any of this? My primary goal is to select the right cam but any other thoughts are welcome. I know I should get a borescope and look at the pistons and I will do that.
Click to expand...

You need to verify the hydraulic cam. Most shops do not know what a solid cam is, let alone how to adjust the rockers hot and running. Did they adjust the rockers for .013 on intake and .021 on exhaust? Offy makes a nice intake and the Q-Jet carb is fine. It has an adjustable secondary air valve that lets it work with smaller engines. 2 barrel pistons are good in a 273, no need for the 10.5 Commando pistons. The E-4 Isky will also run very well with your combination. A friend had a 273 put together with 2 barrel pistons, E-4 cam, factory intake and AFB that dynoed 265 hp. Supposedly 10 hp less than a factory 340. You also have the advantage of a 4 speed. Low rpm is probably a function weak valve springs, ignition, and/or Cam?
 
So my strategy: It seems both the 2BBL and 4BBL pistons can handle the Isky E-4 cam. If I replace the current cam with E-4 and appropriate solid lifters, pushrods and adjustable rockers I should be good to go, correct?

I just have to be careful to use the 66 pushrods due to the block stamping of B273 11-19, correct?

Geez Ma Mopar didn't make it easy with this one.
 
brodphish said:
So my strategy: It seems both the 2BBL and 4BBL pistons can handle the Isky E-4 cam. If I replace the current cam with E-4 and appropriate solid lifters, pushrods and adjustable rockers I should be good to go, correct?

I just have to be careful to use the 66 pushrods due to the block stamping of B273 11-19, correct?

Geez Ma Mopar didn't make it easy with this one.
Click to expand...
They actually made it very easy. People make it difficult by not knowing what they have. You will save yourself a LOT of time, trouble and money if you buy a factory service manual and learn to do this yourself. That way, you'll know what you have.
 
the block doesn't have anything to do with the push rods. the type of cam and valve train gear are what determine your pushrod selection-- in this application.

pull a valve cover and verify what you have before making any choices.

there are several options to weigh here: is it a commando motor? do you care if it is? do you want or care if it's hydro or solid cammed whether it's a commando or not?
 
Pushrods were for all 273 engines from 1964 thru 1967. Then they went to the easier and cheaper hydraulic rockers and valvetrain. No big deal. Buy some valve cover gaskets, remove five 1/4 in bolts with a 7/16 socket, pull one cover, take some pictures. Easy to tell. Yes, the E-4 cam can be used with either piston configurations. Just be sure to check the timing chain and get 340 valve springs or equivalent, so that 273 can sing.
 
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