Hello all. I am pondering the question of whether shorter pushrods are really needed for my 250. My thinking is that since the block was decked 0.090 and the head 0.030 (I have the CI aluminum head), and that total being 0.120, I should get pushrods 1/8" shorter. The problem is CI doesn't have any ball/cup pushrods 1/8" shorter, and custom pushrods are very expensive. I have the roller tip shaft 1.6 rocker arms. I have all that good stuff from my last car that was sold recently, and this build-up has to be low buck. My stuff will be back from the machine shop soon, and I can put together enough to measure what the pushrods should be, and I will do that. I was just wondering who has had experience with this before?????
Custom pushrods really needed???
- Thread starter dmsmith63
- Start date
Howdy DMSmith:
What head gasket are you going to use? That will add back possibly. I'm assuming hydraulic lifters? Typically Hydraulic lifters can compensate for approximately .125". At that your dimensions will be very close to the limit. My guess is, Yes, on the pushrods, but I'd sure do a mock assembly and measure to be certain.
Just for curiosity, what is your goal CR?
Adios, David
What head gasket are you going to use? That will add back possibly. I'm assuming hydraulic lifters? Typically Hydraulic lifters can compensate for approximately .125". At that your dimensions will be very close to the limit. My guess is, Yes, on the pushrods, but I'd sure do a mock assembly and measure to be certain.
Just for curiosity, what is your goal CR?
Adios, David
If this concerns you then do a mock up like David suggests. You can get adjustable pushrods from Mike and then order the proper length if needed. I recently went though a minor hassle because my pushrods were a bit too long in my 250 engine. Adjusted all the way out with hydraulic lifters the valves weren't closing; the problem wasn't immediately apparent because the lifters pumped up after the run-in period. You only have a few choices, 1/8 or 1/4 inch shorter than OEM. Mike may have a set 1/2 inch.
Good luck,
John
Good luck,
John
Hey David: I am going to use a Cortego head gasket, figuring on 0.050 compressed. Charlotte, NC area is about 700 ft. elevation. I have not decided on a cam yet, but I was thinking the 274/274 110LS Clay Smith (IVC 67) OR I already have a Comp Cams 260H (IVC 57) that I am considering, mostly because it is paid for. I did do a mock-up today, as soon as I got my stuff home from the machinist, just to see if stock pushrods would work, and I believe they will. Shorter by 1/8" would be ideal, but I think the hyd lifters and adjustable rockers will take up the extra. I have not measured the actual deck height yet; I will do that tomorrow before making any rash decisions.
As was mentioned before, do a mockup & use an adjustable pushrod.
The ideal length is at midlift the rocker arm footprint should be in the center of the valve stem.
The correct length is the one that has the least footprint on the top of the valve stem.
Do the checking with either a solid lifter if the head is already assembled otherwise use a weak spring which is made for checking for correct pushrod length.
Mike, can order special length pushrods from clay smith cams. Their pushrods are of top quality & the cost is reasonable. I know from a previous ordered set. Bill
The ideal length is at midlift the rocker arm footprint should be in the center of the valve stem.
The correct length is the one that has the least footprint on the top of the valve stem.
Do the checking with either a solid lifter if the head is already assembled otherwise use a weak spring which is made for checking for correct pushrod length.
Mike, can order special length pushrods from clay smith cams. Their pushrods are of top quality & the cost is reasonable. I know from a previous ordered set. Bill
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