Pushrod Problems?

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Gramps1

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Hello
We are working on a 79 225.
We are putting a Comp Cam in it when it goes together.
When we mocked things together the adjusters for the rockers won't reach the pushrods with the nuts on the adjusters.
We noticed the same was true before doing anything.
I guess I'm trying to find out if there are different length stock pushrods?
Is there another reason for this?
Thanks
 
I have heard that sometimes,with high performance cams, the base circle is smaller and this could account for the push rod adjuster issue.
 
Low deck 170 vs tall deck 225. Not a slant 6 guy so guessing.
 
Low deck 170 vs tall deck 225. Not a slant 6 guy so guessing.
This us the 1st slant we have done anything to so I'm not familiar with them either.
Is it possible to put a 170 head on a 225 if you know?
Thanks
 
This us the 1st slant we have done anything to so I'm not familiar with them either.
Is it possible to put a 170 head on a 225 if you know?
Thanks

Yup, you can. None of the 170s ever came with the "revised" chamber head that I know. I think that head came out in 68. Same size chamber, just made supposedly "better"....kinda stupid, really, IMO. They should have redesigned the whole head FOR the 225, but performance was not in the the ballpark. Just remember to use the 225 pushrods as they are longer than the 170 pushrods.
 
So question @RustyRatRod, how many stock /6 sized pushrods are there? Solid and hydraulic, tall and short deck? So 4?
 
I have heard that sometimes,with high performance cams, the base circle is smaller and this could account for the push rod adjuster issue.
That is correct most of the time, the floor has to be lowered instead of the lobes raise as the lobes barely fit through the cam bearings as it is. Just mill down the head to gain some length! :D
 
Yes a 170 head can be used on a 225. Question, did your push rods come out of that engine?
Yes same push rods different rockers.
We got the rockers from Rocker Arms Unlimited, they look the same as the original.
This was a running engine when we started..The adjusters on the original were adjusted about the same as far as no lock nuts and the adjuster deep in the rocker.
Like I said it was running,but if its a deal where we need different pushrods now is the time.
I'm just not sure they are the problem.
Thanks
 
Yup, you can. None of the 170s ever came with the "revised" chamber head that I know. I think that head came out in 68. Same size chamber, just made supposedly "better"....kinda stupid, really, IMO. They should have redesigned the whole head FOR the 225, but performance was not in the the ballpark. Just remember to use the 225 pushrods as they are longer than the 170 pushrods.
Are the pushrods visibility different lengths?
We are looking at a goog 1/2 in of length.
Thanks
 
No. Just three. Solid 170 (never was hydraulic) solid 198 and 225 (both same length) and hydraulic 225
No. Just three. Solid 170 (never was hydraulic) solid 198 and 225 (both same length) and hydraulic 225
Are the hydraulic pushrods longer?
I dont know anything about this engine other than we drove it home.
Is it possible someone put a solid lifter cam and lifters in a hydraulic cam engine and didnt change the pushrods?
Thanks again
 
That is correct most of the time, the floor has to be lowered instead of the lobes raise as the lobes barely fit through the cam bearings as it is. Just mill down the head to gain some length! :D
I didnt explain it well in my original post.
We are short by maybe 1/2 inch.
We CAN get the adjusters to reach the pushrods but not with the lock nuts on the adjusters.

Maybe thats the way its supposed to be and I just don't know it but it sure doesn't look right to me.
Thanks for your reply.
 
Something is not right. The OEM rockers/adjusters, did not have nuts on the them.
You may be on to something here.
All we know about the engine is we drove it home so it ran.
When we took it apart the original rockers had NO lock nuts on them.There was visible wear on the rockers and shift so we got replacements from Rocker Arms Unlimited and they have lock nuts on them.
You say they arent supposed to have the lock nuts?
We took the lock nuts off and xan get the adjuster to touch the pushrods but the adjuster is threaded WAY in the rocker .Shouldn't the adjuster be like halfway in?

Sorry about the book here and thanks
 
Do you have a stock rocker you can compare to the replacement rockers?
Or a picture of the replacement rocker? It sounds like the problem is not the push rods, but the rockers. The 170 push rods are much shorter then the 198/225 push rods. More then an inch. The hydraulic pushrods have a ball on both ends, not a ball and cup.
Where are you located?
 
Do you have a stock rocker you can compare to the replacement rockers?
Or a picture of the replacement rocker? It sounds like the problem is not the push rods, but the rockers. The 170 push rods are much shorter then the 198/225 push rods. More then an inch. The hydraulic pushrods have a ball on both ends, not a ball and cup.
Where are you located?
I still have the original rockers they look the same.
I can post a picture when I get home.
These pushrods have a ball and cup.
Did the 170 pushrods have a ball and cup?
We are in Indiana,explains a lot I know.
Thanks
 
FYI, stock length OE 225 pushrods (mechanical cam) measure 9.954" (over-all length).
Jus sayin............
 
I still have the original rockers they look the same.
I can post a picture when I get home.
These pushrods have a ball and cup.
Did the 170 pushrods have a ball and cup?
We are in Indiana,explains a lot I know.
Thanks
Just wanted to know if you were anywhere near someone (maybe me) versed in slant sixes.
170 pushrods are ball and cup, but there is no way they could work on a 198/225 engine.
You said the original rocker setup, had the same issue (adjusters way down in)?
Do you know if any valve work has been done to the head?
There are only a few things that could cause the problem you have.
1) wrong push rods (possible, but not the 170 units)
2) Cam base circle too small (again possible, but not likely to cause that big an error)
3) Incorrect valve stem heights, due to incorrect valve job. (very possible)
4) Rocker shaft/arms not in the correct height in relation to the cam (usually problem is in the other direction, due to head milling)
5) since the rockers were rebuilt possible problem there (in your case not likely, as you stated problem also with original rockers.
I'm leaning toward number 1, or 3
 
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