225 Push rod length.

I've made the decision on my choice of camshaft. STL3228-16-8, Duration: 232-228 @.050, Lift: Int. .536 Exh. .530, LSA: 108+4, Lash: Int. .004 Exh. .006. My head has been milled to 44cc chambers, (.100) with 1.700 and 1.440 valves. The block has been decked approximately .025 (engine ID# no longer visible.) .060 flat top pistons. Question: Will different push rods (length) be needed?
Norm
1965 Barracuda

circlepilot said:

I've made the decision on my choice of camshaft. STL3228-16-8, Duration: 232-228 @.050, Lift: Int. .536 Exh. .530, LSA: 108+4, Lash: Int. .004 Exh. .006. My head has been milled to 44cc chambers, (.100) with 1.700 and 1.440 valves. The block has been decked approximately .025 (engine ID# no longer visible.) .060 flat top pistons. Question: Will different push rods (length) be needed?
Norm
1965 Barracuda

Click to expand...

VERY likely no. There is a LOT of room on those adjusters, but the only way to know for sure will be to mock it up. My money is on you using stock pushrods.

Thanks Rusty for the assurance.
Norm

With those numbers you might be OK, but it will be close. Make sure to check. Also check valve to piston clearance.
PS: Whose cam is that? Looks like a Hughes number, but not listed on there website.

Charrlie_S said:

With those numbers you might be OK, but it will be close. Make sure to check. Also check valve to piston clearance.
PS: Whose cam is that? Looks like a Hughes number, but not listed on there website.

Click to expand...

You are right, Hughes cam. (not listed, must be a secret stash) I ran some numbers by them and Dave Hughes came up with several cams for my application. I'm looking at this one (and a similar one at Oregon) as it will fit the machine work that has been done and my projected use of the car. I already have his valves and springs. I'll be doing a "mock-up" as Rusty had said, and checking in with you for some other things. I going to concentrate on building the engine vs the car itself, as the weather (cold) conditions control my work space. Maybe one day I'll enclose the entrance to my carport.
Norm

Thats .125, If you want to preserve the 'geometry' of the adjusters and the thread stickout, you can actually cut these down. You chuck them in a lathe and cut the last 1/8" of the thinwall tubing at the round end. You can tell when the thinwall is cut as it will change color to brown right before its through, then you just tap the round tips back up into the shorter tube. The tips are hardened, the tube is not. I cut down 16 225 pushrods for a 273 I built.

pishta said:

Thats .125, If you want to preserve the 'geometry' of the adjusters and the thread stickout, you can actually cut these down. You chuck them in a lathe and cut the last 1/8" of the thinwall tubing at the round end. You can tell when the thinwall is cut as it will change color to brown right before its through, then you just tap the round tips back up into the shorter tube. The tips are hardened, the tube is not. I cut down 16 225 pushrods for a 273 I built.
View attachment 1715642508

Click to expand...

You need to look at the pushrods. Some you can do that, and some not. I do that on most 170 engines I build. Cheaper then custom push rods. It seems like the 170 is more likely to need a shorter pushrod, then the 225. I used to use the old TRW 3/8 pushrod for the 225 and shorten them.

Pishta: It is really not .125. shorter that would be required. With a higher lift cam, the base circle is smaller, so the lifter/pushrod would sit lower.
Lift of the new cam .536 minus stock lift (approx .390)= .146 divided by rocker ratio 1.5 =.097
This is theoretical as there are manufacturing variations.

Charrlie_S said:

I used to use the old TRW 3/8 pushrod for the 225 and shorten them.

Click to expand...

Hey Charlie, what did the 3/8 pushrods fit originally? I considered doing that also, but I wasn't certain what application to get them from.

Badvert65 said:

Hey Charlie, what did the 3/8 pushrods fit originally? I considered doing that also, but I wasn't certain what application to get them from.

Click to expand...

I don't remember. I used the progressive size chart in the back of the catalog to find one longer then what I needed.

pishta said:

Thats .125, If you want to preserve the 'geometry' of the adjusters and the thread stickout, you can actually cut these down. You chuck them in a lathe and cut the last 1/8" of the thinwall tubing at the round end. You can tell when the thinwall is cut as it will change color to brown right before its through, then you just tap the round tips back up into the shorter tube. The tips are hardened, the tube is not. I cut down 16 225 pushrods for a 273 I built.
View attachment 1715642508

Click to expand...

Last year we talked about this...hoping that my push rods would be ok...well the are too long and best I can tell, as much as 3/16th or more. The cupped end is actually touching the barrel of the adjuster. (Ball nut backed out almost all the way.) you say that you cut the tube at the ball end? My push rods appear to have the ball end spot welded? If you cut through the tube wall, how about the piece that will still be on the ball insert?
Norm

circlepilot said:

Last year we talked about this...hoping that my push rods would be ok...well the are too long and best I can tell, as much as 3/16th or more. The cupped end is actually touching the barrel of the adjuster. (Ball nut backed out almost all the way.) you say that you cut the tube at the ball end? My push rods appear to have the ball end spot welded? If you cut through the tube wall, how about the piece that will still be on the ball insert?
Norm

Click to expand...

Dammit man. I had close to .160" cut off my head I'm running right now and the pushrods still fit with room to spare.

RustyRatRod said:

Dammit man. I had close to .160" cut off my head I'm running right now and the pushrods still fit with room to spare.

Click to expand...

I finally got my head installed (after the machine / speed shop got my cam degree straighten out) this evening. I got my rocker arms all set up on the shaft with the adjusters backed way off. As I was tightening the shaft bolts, I noticed that #5 intake valve was compressed and the push rod "cone" was touching the barrel. at first I thought the push rod had jumped out of the lifter. With 1:5 rockers the total lift on the intake valve is .536. It was getting late and I've had a long day. I may be reading more into it and there may not be a problem. I'm going to take the shaft back off and just install two rockers on that cylinder and set the lash. As best I remember, when I was trying to use the Dutra method to degree my cam, using two rockers, (and valves) installed in the #2 chamber and bolting that chamber over #1 cylinder. I didn't see any problem with the push rods then and with the lash set. I'll look at it again tomorrow.
Norm

circlepilot said:

I finally got my head installed (after the machine / speed shop got my cam degree straighten out) this evening. I got my rocker arms all set up on the shaft with the adjusters backed way off. As I was tightening the shaft bolts, I noticed that #5 intake valve was compressed and the push rod "cone" was touching the barrel. at first I thought the push rod had jumped out of the lifter. With 1:5 rockers the total lift on the intake valve is .536. It was getting late and I've had a long day. I may be reading more into it and there may not be a problem. I'm going to take the shaft back off and just install two rockers on that cylinder and set the lash. As best I remember, when I was trying to use the Dutra method to degree my cam, using two rockers, (and valves) installed in the #2 chamber and bolting that chamber over #1 cylinder. I didn't see any problem with the push rods then and with the lash set. I'll look at it again tomorrow.
Norm

Click to expand...

Now hang on now. That sounds like a FIGURED valve lift and not MEASURED. Is that right? I ask because slant 6 rockers are never ever 1.5. Some are even as low as 1.4. They're pretty inconsistent. I'm terrible with descriptions. I need pictures. If you can maybe post a couple of good ones when you can that would help.

When you cut the tips off, I ground the tube right under the hardened tip until it started changing color. I chucked them in a drill press and just held a flap wheel on a grinder to that rotating area, quick work like <10 seconds each. Then I grabbed the tip with a pair of pliers and just pulled them out. Youre left with a mangled tube end but your trimming that part down anyway. For a .125 adjustment, you have very little to work with. I cut them down about an inch from a 225 to a 273 size so I had lots of wiggle room. Maybe if you took a hack saw blade and cut the rod at <.125 and then removed the tip from that 1/8 inch stub, it would be more precise. Finish grind the rod to .125 spec (or whatever you find you need) and them push tip back into rod (heat rod to expand and push in)
Dont know what the lift on the stocker is but your .125 shorter already. Add the dropped base circle, and your max lift is still .125 higher on the rocker as the lobe crowns dont usually change from the cam bearing datum. If you factor in the smaller base circle of the performance cam I think its gonna be -.125 plus the lift difference to give you a <.125 shorter pushrod. If That sounds right, I'd not try to use any formula, I'd get some adjustable pushrods or some 3/8 allthread with a coupler and mock up a pushrod length that will give you the same amount of threads showing with the new lift and go with that if that makes sense. Watch coil bind.

RustyRatRod said:

Now hang on now. That sounds like a FIGURED valve lift and not MEASURED. Is that right? I ask because slant 6 rockers are never ever 1.5. Some are even as low as 1.4. They're pretty inconsistent. I'm terrible with descriptions. I need pictures. If you can maybe post a couple of good ones when you can that would help.

Click to expand...

Will do this evening when I get home home and set it up again. I don't know if you remember my cam card. BTW...according to my dial indicator...I did achieve + or - a few degrees the lobe lift indicated on the card. .357
Norm

That's a slant cam? Look at those lash numbers...I guess that is a 'tight lash' cam..?

pishta said:

That's a slant cam? Look at those lash numbers...I guess that is a 'tight lash' cam..?

Click to expand...

Yep!

RustyRatRod said:

Now hang on now. That sounds like a FIGURED valve lift and not MEASURED. Is that right? I ask because slant 6 rockers are never ever 1.5. Some are even as low as 1.4. They're pretty inconsistent. I'm terrible with descriptions. I need pictures. If you can maybe post a couple of good ones when you can that would help.

Click to expand...

Rocker ratio 1.5

Discussion Starter · #1 · 8 mo ago (Edited by Moderator)

An Insane Number of Mopar Slant Six Engine Specifications



Journal Number



1980 3.7-Liter
(225 CID) Slant Six

1 2.75' x 0.877"
2 2.75" x 0.877"
3 2.75" x 1.107"
4 2.75" x 0.877"

The engine had four replaceable steel-backed (aluminum alloy on steel) babbitt crankshaft main bearings. Oil grooves were in the upper half of the bearings, and in the lower half of the #1 bearing. The connecting rod bearings were aluminum on steel.

In most years, closed-circuit crankcase ventilation was used; crankcase vapors were routed to the combustion chambers through a PCV valve located in the valve cover. Vapors were burned before being expelled into the air through the exhaust system.

Oil pressure ranged from 35-65 p.s.i. @ 2.000 rp.m. Crankcase oil capacity was four quarts (one more when changing the filter).

1968 detailed specifications

Engines 170 cubic inch 225 cubic inch
Carburetor Single barrel Single barrel
Bore and Stroke (nominal) 3.4 x 3.125 3.4 x 4.125
Bore spacing (CL to CL) 3.98 (1-2, 3-4, 5-6);
4.0 (2-3, 4-5) 3.98 (1-2, 3-4, 5-6);
4.0 (2-3, 4-5)
Firing Order 1-5-3-6-2-4 1-5-3-6-2-4
Compres. Ratio (nominal) 8.5 8.4
Cylinder Head Material Cast iron Cast iron
Cylinder Block Material Cast iron Cast iron
Cylinder Sleeve None None
Number of mtg. points (Front) Two Two
Number of mtg. points (Rear) One One
Engine Installation Angle Lateral 0°, Up 3° Lateral 0°, Up 3°
Taxable Horsepower 27.7 27.7
Publishing max. bhp* @eng. RPM [email protected] [email protected]
Publishing max. torque * (lb. ft. @RPM) [email protected] [email protected]
Weight (piston only ) oz. 16.4 16.4
Clearance (limits) Top land .024 min. .024 min.
Clearance (limits) Skirt Top .0005 - .0015 .0005 - .0015
Clearance (limits) Skirt Bottom -.0005 - +.0005 -.0005 - +.0005
Ring groove depth No. 1 and No. 2 ring .179 .179
Ring groove depth No. 3 ring .181 .181
Compression Rings Twist and taper, tin-plated Twist and taper, tin-plated
Oil Rings Cast iron, steel expanders 3-piece abutment-type, stainless steel spacer-expander with chrome-plated segments
Piston Pins 170 cubic inches 225 cubic inches
Length 2.965 2.965
Diameter .9008 .9008
Type (Locked in rod, in piston, floating, etc.) Press-fit in rod Press-fit in rod
Type (Bushing, in rod or piston) None None
Type (Bushing, material) - -
Clearance (In piston) .00045 to .00075 .00045 to .00075
Clearance (In rod) .0007 to .00014 interference .0007 to .00014 interference
Direction & amount offset in piston Right .06 Right .06
Connecting Rods 170 cubic inches 225 cubic inches
Weight (oz.) 25.7 26.8
Length (center to center) 5.707 6.699
Bearing (material & type) Lead-based babbitt on steel Lead-based babbitt on steel
Bearing (overall length) .985 .985
Bearing (clearance [limits]) .0002 to .0022 .0002 to .0022
Bearing (end play) .006 - .012 .006 - .012
Carburetors (Valiant) 170 225
Idle speed - Manual* 750 650
Idle speed- Automatic* 750 650
Idle air-fuel mixture* 14.0 - 14.4 14.0 - 14.4
Transmission Manual, Automatic Manual, Automatic
Carburetors (Make) Ball and Ball** Holley
Carburetors (Model) BBS-4414 S (Manual), BBS-4415 S (Automatic) R-3919 A (Manual), R-3920 A (Automatic)
No. used and type 1, 1-bbl 1, 1-bbl
Barrel Size 1.56 (Manual), 1.69 (Automatic) 1.69
Suspension details (Valiant) 170 225
Front spring height by diameter 35.8 x 0.83 35.8 x 0.83
Spring - Rate at wheel (lb. per in.) 85 85
Number of leaves in rear springs 4 5
1968 Slant Six crankshafts

Material Drop-forged steel
Vibration Damper Type Non-adhesive, rubber, dynamic
End thrust taken by bearing (No.) Three
Crankshaft end play .002 - .007
Main bearing (material & type) Lead-base babbitt on steel, removable, precision
Main bearing (clearance) .0002 - .0022 specified,
.0005 - .0015 desired
Main bearing (Journal dia. and bearing overall length) No. 1 2.75 x 1.034
Main bearing (Journal dia. and bearing overall length) No. 2 2.75 x 1.034
Main bearing (Journal dia. and bearing overall length) No. 3 2.75 x 1.254
Main bearing (Journal dia. and bearing overall length) No. 4 2.75 x 1.034
Crankpin journal diameter 2.187

1968 slant six camshafts were hardened cast iron, with the oil pump and distributor drive gears cast integrally; bearings were lead-based babbitts on steel. There were four bearings. The crank sprocket was made of malleable cast iron or sintered iron (Super Oilite). The cam sprocket was cast iron.

1968 slant six valves

Model Slant Six
Lifters Mechanical
Valve Rotator, type (intake, exhaust) Low-friction lock on exhaust
Rocker ratio 1.5
Operating tappet clearance (Intake) .010 hot
Operating tappet clearance (Exhaust) .020 hot
Timing (Intake - opens [°BTC]) 10
Timing (Intake - closes [°ABC]) 50
Timing (Intake - duration -deg.) 240
Timing (Exhaust - opens [°BBC]) 50
Timing (Exhaust - closes [°ATC]) 6
Timing (Exhaust - duration -deg.) 236
Timing (Valve opening overlap) 16
Intake (Overall length) 4.77
Intake (Actual overall head dia.) 1.62
Intake (Angle of seat & face, deg)

circlepilot said:

Discussion Starter · #1 · 8 mo ago (Edited by Moderator)

An Insane Number of Mopar Slant Six Engine Specifications



Journal Number



1980 3.7-Liter
(225 CID) Slant Six

1 2.75' x 0.877"
2 2.75" x 0.877"
3 2.75" x 1.107"
4 2.75" x 0.877"

The engine had four replaceable steel-backed (aluminum alloy on steel) babbitt crankshaft main bearings. Oil grooves were in the upper half of the bearings, and in the lower half of the #1 bearing. The connecting rod bearings were aluminum on steel.

In most years, closed-circuit crankcase ventilation was used; crankcase vapors were routed to the combustion chambers through a PCV valve located in the valve cover. Vapors were burned before being expelled into the air through the exhaust system.

Oil pressure ranged from 35-65 p.s.i. @ 2.000 rp.m. Crankcase oil capacity was four quarts (one more when changing the filter).

1968 detailed specifications

Engines 170 cubic inch 225 cubic inch
Carburetor Single barrel Single barrel
Bore and Stroke (nominal) 3.4 x 3.125 3.4 x 4.125
Bore spacing (CL to CL) 3.98 (1-2, 3-4, 5-6);
4.0 (2-3, 4-5) 3.98 (1-2, 3-4, 5-6);
4.0 (2-3, 4-5)
Firing Order 1-5-3-6-2-4 1-5-3-6-2-4
Compres. Ratio (nominal) 8.5 8.4
Cylinder Head Material Cast iron Cast iron
Cylinder Block Material Cast iron Cast iron
Cylinder Sleeve None None
Number of mtg. points (Front) Two Two
Number of mtg. points (Rear) One One
Engine Installation Angle Lateral 0°, Up 3° Lateral 0°, Up 3°
Taxable Horsepower 27.7 27.7
Publishing max. bhp* @eng. RPM [email protected] [email protected]
Publishing max. torque * (lb. ft. @RPM) [email protected] [email protected]
Weight (piston only ) oz. 16.4 16.4
Clearance (limits) Top land .024 min. .024 min.
Clearance (limits) Skirt Top .0005 - .0015 .0005 - .0015
Clearance (limits) Skirt Bottom -.0005 - +.0005 -.0005 - +.0005
Ring groove depth No. 1 and No. 2 ring .179 .179
Ring groove depth No. 3 ring .181 .181
Compression Rings Twist and taper, tin-plated Twist and taper, tin-plated
Oil Rings Cast iron, steel expanders 3-piece abutment-type, stainless steel spacer-expander with chrome-plated segments
Piston Pins 170 cubic inches 225 cubic inches
Length 2.965 2.965
Diameter .9008 .9008
Type (Locked in rod, in piston, floating, etc.) Press-fit in rod Press-fit in rod
Type (Bushing, in rod or piston) None None
Type (Bushing, material) - -
Clearance (In piston) .00045 to .00075 .00045 to .00075
Clearance (In rod) .0007 to .00014 interference .0007 to .00014 interference
Direction & amount offset in piston Right .06 Right .06
Connecting Rods 170 cubic inches 225 cubic inches
Weight (oz.) 25.7 26.8
Length (center to center) 5.707 6.699
Bearing (material & type) Lead-based babbitt on steel Lead-based babbitt on steel
Bearing (overall length) .985 .985
Bearing (clearance [limits]) .0002 to .0022 .0002 to .0022
Bearing (end play) .006 - .012 .006 - .012
Carburetors (Valiant) 170 225
Idle speed - Manual* 750 650
Idle speed- Automatic* 750 650
Idle air-fuel mixture* 14.0 - 14.4 14.0 - 14.4
Transmission Manual, Automatic Manual, Automatic
Carburetors (Make) Ball and Ball** Holley
Carburetors (Model) BBS-4414 S (Manual), BBS-4415 S (Automatic) R-3919 A (Manual), R-3920 A (Automatic)
No. used and type 1, 1-bbl 1, 1-bbl
Barrel Size 1.56 (Manual), 1.69 (Automatic) 1.69
Suspension details (Valiant) 170 225
Front spring height by diameter 35.8 x 0.83 35.8 x 0.83
Spring - Rate at wheel (lb. per in.) 85 85
Number of leaves in rear springs 4 5
1968 Slant Six crankshafts

Material Drop-forged steel
Vibration Damper Type Non-adhesive, rubber, dynamic
End thrust taken by bearing (No.) Three
Crankshaft end play .002 - .007
Main bearing (material & type) Lead-base babbitt on steel, removable, precision
Main bearing (clearance) .0002 - .0022 specified,
.0005 - .0015 desired
Main bearing (Journal dia. and bearing overall length) No. 1 2.75 x 1.034
Main bearing (Journal dia. and bearing overall length) No. 2 2.75 x 1.034
Main bearing (Journal dia. and bearing overall length) No. 3 2.75 x 1.254
Main bearing (Journal dia. and bearing overall length) No. 4 2.75 x 1.034
Crankpin journal diameter 2.187

1968 slant six camshafts were hardened cast iron, with the oil pump and distributor drive gears cast integrally; bearings were lead-based babbitts on steel. There were four bearings. The crank sprocket was made of malleable cast iron or sintered iron (Super Oilite). The cam sprocket was cast iron.

1968 slant six valves

Model Slant Six
Lifters Mechanical
Valve Rotator, type (intake, exhaust) Low-friction lock on exhaust
Rocker ratio 1.5
Operating tappet clearance (Intake) .010 hot
Operating tappet clearance (Exhaust) .020 hot
Timing (Intake - opens [°BTC]) 10
Timing (Intake - closes [°ABC]) 50
Timing (Intake - duration -deg.) 240
Timing (Exhaust - opens [°BBC]) 50
Timing (Exhaust - closes [°ATC]) 6
Timing (Exhaust - duration -deg.) 236
Timing (Valve opening overlap) 16
Intake (Overall length) 4.77
Intake (Actual overall head dia.) 1.62
Intake (Angle of seat & face, deg)

Click to expand...

Ok....and what was the point of "all that"?

RustyRatRod said:

Ok....and what was the point of "all that"?

Click to expand...

Nothing...I was going back and checking the specifications I have been working with (just one set...example) to follow up on the rocker arm specs. You said they were 1:4 not 1:5???? My specs. and Hughes said they are 1:5. Anyway I think I was jumping the gun on the push rod length. Installed everything again and this time, everything seem just fine. I'm still finishing up a few things. Came upstairs to see if I could find a reference to what type of sealant to use on the two 3/4 pipe plugs in the cylinder head. I'll post some pictures of the valve train later.
Norm

They are not precision rockers, just stamped steel so the ratio may be off. Even the 273 rockers were subject to production tolerances.

RustyRatRod said:

Ok....and what was the point of "all that"?

Click to expand...

Here is what I finished up with. Intake fully compressed, Exhaust compressed. what I'm not looking forward to is having to break down the springs after the break in run and install the secondary springs, without removing the head.

There's no way I wouldn't have run it in with both sprAngs. Keep us posted and good luck with it!

circlepilot said:

Will do this evening when I get home home and set it up again. I don't know if you remember my cam card. BTW...according to my dial indicator...I did achieve + or - a few degrees the lobe lift indicated on the card. .357
Norm

View attachment 1715775677

Click to expand...

Right. The point I was making is that the rockers are not accurate at all. Several people, including yours truly, have tested and verified that they are mostly not 1.5. More like down in the 1.4s. So the only way to get a true measurement of lift will be at the valve sprAng retainer with zero lash.

See.....here's the thing. ....and this is why I think you're ok with the pushrods.....and people always somehow forget this. ...and this is also why I think I ended up ok.

When you regrind a camshaft, what did you just do to the base circle? Made it smaller. Normally what would that require of the pushrod? To be 100% correct, it would need to be lengthened. Of course the slant 6 has a lot of leeway there.

Ok, conversely, when you mill the head, what do you need now? Since the head and rocker gear is getting closer to the camshaft, shorter pushrods.

A camshaft regrind plus a head mill need opposite direction for pushrods for correction, so they cancel each other out some.

That's my story and I'm stickin to it. LOL

Just a FYI. I would have used hardened washers under the head bolts. When you mill the head the bolt threads go deeper into the block. By using washers, the threads are closer to the original depth. Also the washers help to get more consistant head clamping.