push rod length

Jesse B.

Jesse B.

Member
I am in the process of rebuilding an ic 392 that was rebuilt several years ago and left in a garage. Since it had sat for so long I wanted to tear it down to double check everything and make sure nothing happened to it over the years.

While a variety of things did happen to it, which will be the subject of different threads, I am uncertain about the push rod length. The pushrods that I took out are 9.750 long (ball/ball type rods). My IH manual states they should be 9.362-9.388. When I checked online, rock auto states the pushrods are supposed to be 9.75. So, which is it?

The pushrods that I took out were used, although I don't know if they originally came out of the 392.

I believe the manual is correct, but since the manual does not cover all years the 392 was made, I was wondering if at some point IH used longer rods? Thanks,
 
Timely question Jesse!

Just this morning...I've completed sorting well over two hundred reconditioned IH app push rods into four boxes.

That would be the "welded" rocker push rods (cup and ball tips) for the 152/266/304 apps, and the "boat" rocker push rods (ball and ball tips) for the same.

Then the same two scenarios for the 196/345/392 apps.

I don't have any way of "precision" measuring push rod lengths here right now...but using a steel rule, I can tell ya that for the 196/345/392 items, the boat-type push rods measure 9.750" (1/64" resolution) overall. That is also the spec for "standard" replacement push rods from two of our sources, the third source uses a length of 9.775" overall.

The welded rocker push rods measure 9.562" overall, the "cup" on the rocker end appears to be a nominal 0.185">0.200" deep (an average measured on 20 samples). So that brings 'em real close to the book "spec" in the latest Scout II cts 2313 service manual (which should have reflected the change to the boat-type rocker assembly but does not). The service manual specs reflect the ball and socket push rod lengths, not the ball and ball lengths for the boat rockers.

However, the spec for replacement "long" ball and socket push rods shown in our engine kit component callouts appears to be "confused", I'll have to follow up on that. The engine kits can include push rods manufactured by three different sources but all show the same overall length as for the boat push rods so that cannot be correct!

correction...I've verified with our new replacement push rod source that while IH-pattern service part replacement push rods May be sourced under three different "brand names", in actuality, they all come from a single root manufacturer currently which is elgin. And the "extra-length" items will always have the "plus" (+) dimension permanently etched on the tube for identification.

You are correct regarding any IH service reference, the versions we use today do not reflect every possible change/evolution in design that was implemented over the years. That type info was imparted through the issuance of parts and service letters (what we today call "bulletins"), but type info is not currently available in the repop market. That is why we occasionally toss out some gems like that if one of us has it in our various personal collections.

The overall push rod length determines the "preload" on the hydraulic lifter (along with the base circle dimension on the camshaft being actually used).

If the cam was/is a "regrind", then over-length push rods could have been installed, the ones we have available new are in increments of 0.020". 0.040", and 0.060".

The lengths I've referred to are for 196/345/392 apps only, push rods for both styles for the 152/266/304 apps are nominally shorter.
 
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I don't know anything about the cam. The lobes have been parkerized, but other than that all I can see is the number 85r5, which is cast into the shaft. See pic. I tried measuring lobe lift and when multiplied by the rocker ratio its gets close to a stock lift, but I can't be sure about the duration.

Thank you very much for clearing up the push rod length question michael.
 

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Jesse,
do you see any numbers stamped on the rear end of the cam?

If you could post the minor lobe dimensions of a few lobes (base circle) we can see if it has been reduced when of if it was reground. This is important to maintain proper lifter preload. This is often overlooked and can cause a chronically noisy valve train.:(

Robert
 
What ya see on the cam is a "partial" IH part number for the cam Jesse. The actual number is "151985-r5". And for all Scout II 304/345, all year models, that is the oem cam part number, only a single cam p/n was used oem. I have acouplea those here too but the p/n is visible on only one of 'em, the other cam is in bad shape with several flat lobes. That also jives with the service parts list.

I'm trying to get a directv setup planted in the ground right now, when I get done I'll get a base circle dimension off the cam I know is a good runner I have, then I'll post what that one is for comparison.

Edit...tha dtv system is now functional for the first time inna year, so I win this round!

The base circle I have on an oem 345 pullout cam as described comes out to 1.500" on all lobes.

This info might also help with that other 345 engine project ya got goin' with tim Robert! I sent out some additional info on that this morning to him by email, I asked he share that with ya!
 
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Robert, the ends of the shaft are the first places I looked, so no, the only numbers (or letters) on the shaft are the ones cast into it and shown in the picture. (there are some random numbers and letters cast into the shaft in other locations, but it is usually just one or two marks, which does not seem helpful.)

Robert and michael, when I get back home I will re-measure the base circle, as well as the lobe lift, and post up tomorrow. Based on what michael says, it is very likely to be a stock shaft, but it could be reground. Thank you very much.
 
Jesse b. said:
Robert, the ends of the shaft are the first places I looked, so no, the only numbers (or letters) on the shaft are the ones cast into it and shown in the picture. (there are some random numbers and letters cast into the shaft in other locations, but it is usually just one or two marks, which does not seem helpful.)
Click to expand...

Jesse,
you could have a new oem cam!! A rare find if it is. Some regrinders only put od markings for id.

Jesse b. said:
Robert and michael, when I get back home I will re-measure the base circle, as well as the lobe lift, and post up tomorrow. Based on what michael says, it is very likely to be a stock shaft, but it could be reground. Thank you very much.
Click to expand...

Would be very helpfull to have the dimensions and compare them with mm's cam.

Robert
 
And...since we are onna roll here to get some definitive info locked in, I need to send this oem sv cam down to Robert for analysis.

So the list of stuff I need to gather and pack for that effort...

1) used oem sv cam

2) used "r2" cam drive gear set

3) a new g3336s epw or sealed power 221-3336s cam drive gear set

4) a cam gear woodruff key, retainer bolt and fuel pump cam

what else would ya need Robert...any other valve train components? As I understand it, you already have a used "r1" cam gear set to use for comparison. If not, surely that very early 152 I have on the stand now has an r1 set, the cam needs to come out and be shipped to the grinder as a core for ihon anyway so I'll get on that asap.

Since we "think" the currently available new cam gears are of the "r2" configuration (I've yet to confirm that the mythical "r3" gear set actually exists), then our interest here is understanding any cam timing "difference" the use of the r2 gear induces. New r1 gears are not available except maybe nos stuff somewhere which is not a constant. So we need to come up with the best methodology using currently available parts for accurate cam timing inna performance engine build.

And whatever solution we come up with will also impact the installation of any one particular aftermarket replacement cam.

That's a long list of stuff for an old fart to try and remember. Just yesterday I shipped a guy a box that was supposed to contain two carbs...got to the po and the pochick sed the box sure seemed "light" as compared to what I usually dropped off. She was right, I'd forgot to put the carbs in the box! I appreciate everyone lookin' out for me!
 
Michael,
that should about cover it...
I do have the r1 timing set.

I was going to incorporate a degree wheel into the test fixture. I have one but need it regular like for engine builds so can't leave it on. You have an extra one?:winky:

you mention the cam you are sending me needs to go out for a regrind?? If so maybe a to far gone for rework cam is better

that mean I can't cut the nose off of it?:(
I was thinking it would help on the build of the setup to not have to machine the cam representative mounting.

If so maybe a to far gone for rework cam is better.

I will leave the tool as is for later timing set data gathering.

Even better, I can send you the test fixture so you can play with it.

Robert
 
I'll send ya a new el cheepo mr. Gasket degree wheel I just took out of the package for another project.

The sv cam I'm sending is in perfect condition and I plan to re-use in the "sonja" motor project, just discussed this with her two days (surprise!) ago as we're gonna try and keep cash outlay minimal.

So ya need an sv cam that can be butchered?? I don't have any others here that are what I call "scrap"! But I bet Jeff does. The 152 cam I have for a core is "owed" to the cam grinder for a core replacement so we can keep the core bank alive for ihon.

For an oem-spec sv cam core...do ya need one that has all lobes in useable condition...or one that has only a pair of lobes useable so ya can section it?

I'd think that any cam that is simply "flat" is a core for reweld/grind, but one with a toasted journal would be scrap and thus useable for a sectioning. New sv cam blanks are available and used by all the aftermarket cam grinders that offer an IH product, new I-4 cam blanks are not available any longer so we must have a "weldable" core for exchange to keep the pipeline moving.

Sorry for the hijack Jesse...but we need to get this resolved as it could impact your project as well and it is a timely concern!
 
Michael,
I think two separate issues are on the table here.:gringrin:
1) to measure lobe minor diameter for Jesse's push rod length and the archiving of data.
Need to measure this but you can do it with a micrometer.
2) a cam for a degreeing setup.
Only need the nose of the cam with 1 bearing journal for the fixture. Can be any sv or IH cam that will accept the timing set.

Can you send me the cam retainer plate also???

Robert
 
Well, it looks like this cam has been reground. The base circle of each cam lobe is 1.493 - 1.492. The exhaust lobes have a lift of 0.223 and the intake lobes have a lift of 0.247. If we multiply by the rocker ratio (1.7 x 0.223 = 0.379 exhaust valve lift) (1.6 x 0.247 = 0.395 intake valve lift), we get something that is quite a bit less than stock (0.395 exhaust, 0.440 intake). Who knows what they did to the duration profile.

Based only upon valve lift, it is possible that this cam is aftermarket, since several of the aftermarket cams have intake valve lift that is less than stock. However, none of the aftermarket cams I am aware of (and I have looked at comp, isky, and schneider) are less than 0.400, and those cams should not have the IH part number cast into the blank. So I think this is a reground stock cam. Thoughts?

Hey Robert, if you still need a cam for your experiment, let me know if you think this one will work. I am not going to roll the dice and use a cam with an unknown profile.
 
Jesse b. said:
well, it looks like this cam has been reground. The base circle of each cam lobe is 1.493 - 1.492. The exhaust lobes have a lift of 0.223 and the intake lobes have a lift of 0.247. If we multiply by the rocker ratio (1.7 x 0.223 = 0.379 exhaust valve lift) (1.6 x 0.247 = 0.395 intake valve lift), we get something that is quite a bit less than stock (0.395 exhaust, 0.440 intake). Who knows what they did to the duration profile.
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Jesse, I do think you have a regrind. But you are right with wanting to put one of a known quantity in. The rocker are ratios are ofter mis stated by cam suppliers. Even people who seem to know error their. My measurements show more along the lines of 1.76 and 1.7. This will be another data collection test we need to do so we will know for sure. Rig a head with light dummy valve springs, rocker assembly dial indicator @ valve tip and induce known tappet lift scenarios. The valve lift will quantify for sure the rocker arm ration real time.

Jesse b. said:
Based only upon valve lift, it is possible that this cam is aftermarket, since several of the aftermarket cams have intake valve lift that is less than stock. However, none of the aftermarket cams I am aware of (and I have looked at comp, isky, and schneider) are less than 0.400, and those cams should not have the IH part number cast into the blank. So I think this is a reground stock cam. Thoughts?
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Just look at lobe lift numbers. Stock iirc is .224 intake and .254 exhaust. Example below in red high light shows considerably more lobe lift but using 1.6 rr. Good cam!!

Performance camshaft. Great low end torque. Decent vacuum at idle. Iho north's personal favorite. Fits all 266,304, 345, and 392 v-8 engines.
Rpm range: 1800-5000
valve lift is calculated with zero lash and rocker ratio of 1.6
Intake timing duration: 256 deg.
Open: 18 before tdc
close: 58 after bdc
cam lift: .281"
valve lift: .450"
Exhaust timing duration: 262 deg.
Open: 61 before bdc
close: 21 after tdc
cam lift: .290"
valve lift: .465"
Lobe center: 110 deg.
Overlap: 39 deg.
Cam advance: 0 deg.
The above timing is checked at .020 (open) lifter rise .020 (close)
the following timing is taken at .050" lifter rise and gives a more accurate determination of camshaft position.
Intake duration: 202 deg.
Open: -9 before tdc
close: 31 after bdc
exhaust duration: 208 deg.
Open: 34 before bdc
close: -6 after tdc
recommended isky cam kit parts and setup information
lifters: 1902-hy
lifter type: hydraulic


Jesse b. said:
Hey Robert, if you still need a cam for your experiment, let me know if you think this one will work. I am not going to roll the dice and use a cam with an unknown profile.
Click to expand...

Thanks for the offer!!! I have a buddy down here is so cal who has one for me.. Your old cam is a new regrind cam. Put it in the classifieds and maybe some one will buy it

Robert
 
Robert,

see if this picture helps any in regards to rocker arm ratio.
 

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Jeff,
thanks, that does help with the "boat" type of rocker as I have not had the opportunity to measure them. Good to do a setup with those to map ratio as a function of lift.

The stamped type I have roughly measured the same way and could also do a test of those also.

Typically the off of the seat lift ( calculated like your picture) is different than the overall lift as installed so I would like to test some time.

Robert
 
Ok...based on Jeff's shot of a boat rocker, I'm gonna send off to Robert a test setup he can cut up if needed, consisting of an assortment of both boat and welded rocker arms, spacers, spacer springs, and push rods for all apps. Along with some rocker stands that have not been butched! And appropriate hardware for mounting.

Not knowing exactly how he's gonna set this up (onna sectioned head I suppose now??), a single "style" rocker shaft will work since it ain't gonna haveta run, just needs to mount the rockers in proper position.

A cam retainer plate and hardware will be included. That way he can use whatever he wants/needs to prove out this stuff!

We still have time before I send the stuff down, I'm outta pocket this weekend, the timing gear set won't be here until prolly next Tuesday. So it looks like Robert needs a junk head to section also?? Does tim also have a cracked head he can donate? I have a spare usable 152/304 head but shipping costs would be a bitch!

See whatcha started Jesse???
 
Michael,
I have a complete 9 stand assembly so I really only need 1 intake boat and 1 exhaust boat ra and any special hardware you think I May need for 1 cylinder.

The head will be another thing and you are right damn expensive to ship!!

I think tim has 2 heads in his garage that he May let me use..:gringrin:

with my schedule I won't be able to get to it right away so lets put it on the " ihon to do" list for now.

See mm if I was retired I could keep my self busy also. But I'm not sooooo..... :dita: :gringrin:

Robert
 
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