MORE VALVE TRAIN QUESTIONS................

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I guess I should be more specific. The PR's that I have are brand new and shorter than the OEM's. I got them from the seller and they were supposed to match the rocker gear that I got from him. The pic shows those rods to be a tad taller than they need to be. Was hoping the masses would tell me that I am good to go LOL. So, I made a set of adjustable pushrods to figure out exactly where I at.

The thing that threw me off, was the fittament of the OEM 340 non adjustable rocker gear. Once I bolted THEM down, I had .125 of preload.

So, I tried both set ups...........With the adjustable stuff, I need PRs 7.069 inches plus the preload. And with OEM non adjustable I need 7.4 inches plus the pre load.

Question about pre-load on adjustable gear: So a local engine guy suggested that I go .010 of pre load. Everything I have read suggests .030, or even slightly more. What are the ramifications of changing the preload from say .010 to .040?

Question about pre-load on non-adjustable gear: Comp Cams literature gives a really broad range for this type of set up. They recommend .020-.080. Why would that be different than the the specs for the adjustable gear. What should I shoot for if I go this non adjustable route?

Thanks
 
The reason for such a short pre-load of say 010 is in case the hyd lifters pump up at high rpm. If the preload was, say, 080, that would mean the valve can theoretically increase max lift by 0.120" with 1.5 rockers.....& the valve could hit the piston.
If you have adequate valve spring tension, you will not get get lifter pump up. Internal lifter travel is typically at least 0.150" & you set the pre load anywhere within that range. If not sure of the available preload, compress a lifter in the vise [ slowly if it has oil in it ].
 
Bewy said:
The reason for such a short pre-load of say 010 is in case the hyd lifters pump up at high rpm. If the preload was, say, 080, that would mean the valve can theoretically increase max lift by 0.120" with 1.5 rockers.....& the valve could hit the piston.
If you have adequate valve spring tension, you will not get get lifter pump up. Internal lifter travel is typically at least 0.150" & you set the pre load anywhere within that range. If not sure of the available preload, compress a lifter in the vise [ slowly if it has oil in it ].
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Thanks for that.....Helps me to understand. The springs I am using have an installed height of 1.7, seat pressure of 115, and an SR of 339. My cam has a .471 lift and is a mild XE262.

Based on this info, would you have a range recommendation for pre load on both adjustable and non-adjustable rocker gear? Trying to determine my pushrod length.

Thanks
 
The non-adj rockers will be fine with whatever prods you have that position the prod cup within the range of the lifter travel. The XE 262 is going to be rpm limited so the springs should be ok.

Same deal with the adj rockers. Adjust the rocker so that prod cup is depressed about 0.020", not critical.
You will now get arguments about how many threads of the adjuster are showing & how it affects lift, but with this mild cam I doubt you could measure any difference on a dyno.
 
Bewy said:
The non-adj rockers will be fine with whatever prods you have that position the prod cup within the range of the lifter travel. The XE 262 is going to be rpm limited so the springs should be ok.

Same deal with the adj rockers. Adjust the rocker so that prod cup is depressed about 0.020", not critical.
You will now get arguments about how many threads of the adjuster are showing & how it affects lift, but with this mild cam I doubt you could measure any difference on a dyno.
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Does more preload increase cam/lifter wear?
 
Does anyone have any info on pushrod sourcing? Not looking for bulletproof race products, but rather something in the realm of OEM.......Middle of the line stuff.
 
CFD244 said:
Does anyone have any info on pushrod sourcing? Not looking for bulletproof race products, but rather something in the realm of OEM.......Middle of the line stuff.
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I made the rounds last summer looking for a set, all the made to fit joints like Smith were 3 weeks plus. I ended up hitting the counter at Summitracing for a set of Comp's that fit perfect.. sometimes you get lucky.
 
Believe it or not Troy, if I get the part # I need Ive had pretty good luck with Amazon. 2 local guys were going to price **** for me WEEKS ago, still crickets from them. Amazon had parts to my door in 2 days. Ordered Friday and arrived Sunday lol
 
I would not run a preload as light as .010". Only with the right lifter. That is one with the heavy duty snap ring retaining the plunger, instead of the small, inadequate wire clip. With only .010" preload, the plungers can and will escape the wire retainers and the plunger itself can then escape and you will lose oil pressure or worse if the plunger makes it past the lifter valley.
 
Are those adjusters 3/8 × 24? If so would .010 be a 1/4 turn preload?
 
RustyRatRod said:
I would not run a preload as light as .010". Only with the right lifter. That is one with the heavy duty snap ring retaining the plunger, instead of the small, inadequate wire clip. With only .010" preload, the plungers can and will escape the wire retainers and the plunger itself can then escape and you will lose oil pressure or worse if the plunger makes it past the lifter valley.
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Shooting for .030 +/- Where should I be shopping for pushrods. I got 7.069 @ 0 preload measured from the tip to the flat top of the cup. Subtract .156 to get the length from the tip, to the bottom of the cup. I would think that 7.1 would be a good length to buy.

Do you have any suggestios as to where I can get these?
 
CFD244 said:
Shooting for .030 +/- Where should I be shopping for pushrods. I got 7.069 @ 0 preload measured from the tip to the flat top of the cup. Subtract .156 to get the length from the tip, to the bottom of the cup. I would think that 7.1 would be a good length to buy.

Do you have any suggestios as to where I can get these?
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Smith Brothers.
 
Post #30. No increase in wear by setting the p'rod cup down into the lifter to max travel. With a new lifter hat has no oil in it, you can push the plunger down easily by hand, just a soft spring inside.
 
Bewy said:
Post #30. No increase in wear by setting the p'rod cup down into the lifter to max travel. With a new lifter hat has no oil in it, you can push the plunger down easily by hand, just a soft spring inside.
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Thanks. I always figured that when they got oil pressure, it put more pressure on the components while the engine was running.......Still learning.
 
Plymouth 65 said:
You should have about 1.5 threads out of the adjusters. If not, your pushrod cups may contact the rockers. 65'
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David Vizard did a video recommending to bottom the plungers in the hydraulic lifter and then back off 1/4 to 1/2 turn on the adjuster. The lifter still functions as a hydraulic but can not collapse. Proper valve springs control pumpup.
 
You can try calling this company for pushrods. I have not used them but saved the link after some positive recommendations on this site. Apparently they make pushrods for some of the other companies. May be worth a call of looking for a custom length.

Home - OE Push Rods - Manufacturer & Distributor
 
5/16" ball in a 5/16" cup, not 3/8" cup, correct? Sounds dumb, but I have seen dumber...
Why buy new rods when you could just remove cups and trim the rod if needed?
 
DON BURKHOLDER said:
5/16" ball in a 5/16" cup, not 3/8" cup, correct? Sounds dumb, but I have seen dumber...
Why buy new rods when you could just remove cups and trim the rod if needed?
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Not sure if the cups are crimped in, pressed in, glued in etc. I'd hate like hell to have them com apart in a running engine. I believe the threads are 3/8, but the ball and cup are 5/16.
 
CFD244 said:
Not sure if the cups are crimped in, pressed in, glued in etc. I'd hate like hell to have them com apart in a running engine. I believe the threads are 3/8, but the ball and cup are 5/16.
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Direct Connection (I'm aged), had sold a pushrod kit that had the cups separate, allowing you to trim the tubes to size then drill for a light interference fit of the cup stem. I have taken them apart before, trimmed to size and reinserted the cups with a drop of blue Loctite. The cup stem still required a light press to slide in but I used Loctite for insurance. The picture you provided looked like the adjuster's 5/16" ball was sunk into the rod cup and is why I questioned it for verification. The difference in radius between .3125" and .375" is small but could be enough to ruin your day.
 
I know this isn’t the length you are after but if my notes are correct, these pushrods are made for running 273 rocker’s with factory hydraulic lifters. Sum-G6420. They are 7.389
 
Bodyperson said:
I know this isn’t the length you are after but if my notes are correct, these pushrods are made for running 273 rocker’s with factory hydraulic lifters. Sum-G6420. They are 7.389
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Thanks. The new pushrods that came with the package are comp cams. They have the same advertised length as the one that you have mentioned. When they are installed with .040 pre load, I get no threads showing on the adjuster. Consensus seems to suggest that I need shorter pushrods. 7.1 will give me .030 preload, and 2 threads showing.
 
DON BURKHOLDER said:
Direct Connection (I'm aged), had sold a pushrod kit that had the cups separate, allowing you to trim the tubes to size then drill for a light interference fit of the cup stem. I have taken them apart before, trimmed to size and reinserted the cups with a drop of blue Loctite. The cup stem still required a light press to slide in but I used Loctite for insurance. The picture you provided looked like the adjuster's 5/16" ball was sunk into the rod cup and is why I questioned it for verification. The difference in radius between .3125" and .375" is small but could be enough to ruin your day.
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I hear you. In order to get my new comp cams apart, I suspect the I would have to lightly heat the cup end of the pushrod to overcome the "press fit". By applying heat, I would then question the integrity of the pushrod metallurgy. The damn problem is, if it fails........Big bucks! LOL
 
No heat required. I slid a 3/8" box wrench over the ball end of the rod - down to the back side of the cup, then tighten the ball end into a drill press chuck to hold it. Then tap the wrench with a small hammer and the cup will come off the the rod tube. You can use the drill press to reassemble the cup stem into the rod tube after trimming to size.
 
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