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I Need Engine Experts! 340 Roller Lifter and Pushrod Issue

HawkRod

Formerly hsorman
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I need some help from the brain trust here please! First some specs:
* Small block LA 340, bored .030" over
* Stroker crank, so now displaces 416 CI
* HAD a hydraulic flat tappet cam (more on that below)
* Aluminum Renegade brand heads
* 1.5 ratio roller rockers
* New hydraulic lifter cam specs: cam lobe lift .340", so lift is .510" with 1.5 ratio rockers

The engine has run over 18,000 miles with the hydraulic lifter flat tappet cam. We are now replacing the flat tappet cam with a hydraulic roller cam. The issue I am having is that the roller lifters are significantly taller than a flat tappet lifter. The roller lifter is .770" taller than the flat tappet lifter (as measured from the bottom of the lifter where it contacts the cam to the "cup" in the lifter where the pushrod contacts the lifter).


So the lifters are taller - who cares? Well, the angle between the lifters and pushrod is excessive. In general, it is poor on a LA block, but it is made even worse with the tall lifters. See picture below where I am pointing:
20240504_201302.jpg


So I set up and measured the actual lift (or more specifically, valve opening) that the cam was making. See mock up below:
20240505_084703.jpg


In an ideal world, it would measure .510" (and I realize you never have ideal world). Well, it measured .370". Wow - so it is losing .140" lift!!! The picture below shows the valve train geometry and it looks terrible to me.
20240505_084739.jpg


Are there better (less tall) lifters? Other ways to address this? Lots of people have put roller cams into small blocks, so what am I missing?

Any help from those who have experienced this would be greatly appreciated - thanks!
 
Did you try blocking the hydraulic plunger so it remains topped out while testing? I've never tried it on a hydraulic roller but do it when testing FT hydraulics....
 
With “Most” link bar style HR lifters, you can’t get the plunger out past the tie bar rivet.

As for the lifter height itself……..
HR lifters are typically way taller than their HFT counterparts.
Both physically and with regards to pushrod seat height.
The difference in PR seat height for a SBM on a Howard’s SFT vs HR is .829”(1.832 vs 2.661).

Also, Opening up the bottom of the pushrod tunnel on non-factory HR heads is often necessary.
 
Did you try blocking the hydraulic plunger so it remains topped out while testing? I've never tried it on a hydraulic roller but do it when testing FT hydraulics....
I didn't have a very weak temporary spring, so we actually used a friend's fingers as our "spring". The valve spring was removed and he just gently pushed against the spring retainer to keep it seated. So no, we didn't block the plunger but we did make sure we did not collapse the lifter.

With “Most” link bar style HR lifters, you can’t get the plunger out past the tie bar rivet.

As for the lifter height itself……..
HR lifters are typically way taller than their HFT counterparts.
Both physically and with regards to pushrod seat height.
The difference in PR seat height for a SBM on a Howard’s SFT vs HR is .829”(1.832 vs 2.661).

Also, Opening up the bottom of the pushrod tunnel on non-factory HR heads is often necessary.
The adjustable lifter I was using to test everything was contacting the pushrod tunnel in the heads, so I did need to clearance the heads a little bit.
Also, as a FYI: it looks like this application needs 6.600" push rods.
We looked for shorter roller lifters, and were unable to source a set that made a difference. I get it that roller lifters need to be taller - they have a big 'ol wheel on the bottom! But then the problem still remains...
 
Here’s my .02……

Measure the lobe lift of the cam to verify its correct.

If that’s good, mock everything up to confirm there is no contact between the pushrods & heads, and pushrods & lifter bodies.
Correct any issues as necessary.
Order up proper length pushrods.
Put it together.
 
Here’s my .02……

Measure the lobe lift of the cam to verify its correct.

If that’s good, mock everything up to confirm there is no contact between the pushrods & heads, and pushrods & lifter bodies.
Correct any issues as necessary.
Order up proper length pushrods.
Put it together.

Cam spec was .340" lobe lift, and I measured .331". The .009" might be my measuring error or it could be the way the cam was cut. Either way, I'll call that pretty close and verified.

But I'd really like to get better than .370" valve opening!
 
Cam spec was .340" lobe lift, and I measured .331". The .009" might be my measuring error or it could be the way the cam was cut. Either way, I'll call that pretty close and verified.

But I'd really like to get better than .370" valve opening!
If you had a solid flat lifter you could measure lift..
 
If you had a solid flat lifter you could measure lift..
I don't have one handy here at the house, so my .331" number will need to stand - but that's close enough to verify that the cam was ground at least pretty close to spec. I'm not worried about a few thousandths, but losing .140" has me concerned.
 
I’m sure the true net lift in the running engine will be closer to .500”.

(Because I doubt the effective rocker ratio is actually 1.11)
 
Would a solid roller lifter be an option? They are shorter than hydraulic rollers.
 
I want to update folks on the status of this:

Regarding the significant angle between the lifter and pushrod:
This is what it is, and there is nothing really that can be done about this given the parts that I have. The angle is made worse by a taller lifter, so a solid lifter is a possibility to reduce the angle (and lift losses), but for this engine, the hydraulic lifter is the right way to go, especially given that this is a street driven car.
My measurement of the losses for this was likely in error. By calculation for this application, it looks like (all other things perfect) that the angle means you only get 94.6% of the cam lobe lift transmitted to the top of the pushrod. Not ideal by any means, but still workable. (Knowing this, I would definitely use 1.6 rockers in the future.)

Regarding rocker geometry:
I called and spoke with Mike at B3 Racing engines this morning. What a super guy and based on our conversation, I highly recommend him.
The rocker arms for this engine are contacting the valve stem in a decent spot, but the shaft is no doubt lower than ideal. His kits (custom made for each application) improve this geometry. The biggest gain, from my perspective, is that the improvement in rocker geometry means the valve will spend more time when it is near fully open. Ultimately, this means better flow, and we all know our engines improve with better flow.
The gentleman that now owns this engine needs to make decision if he wants the kit from B3 Racing. The biggest issue we have now is time so he may go with the geometry as it is and upgrade later in the year. If he does this, the downside will be that he will need to buy another set of pushrods. Either way, I will do some extra clearancing of the heads to hopefully cover any future relocation needs, be it in 3 weeks or 3 months.
(P.S. I will almost certainly order one of these kits for my 400 based stroker motor as I think they will improve my geometry on that.)

Now time to make progress with getting this thing running!

Again, I want to offer a humble and sincere Thank You to everyone that contributed ideas! :thumbsup:
 
Gotta throw in my thoughts on hydraulic vs solid lifters whether flat tappet or roller... The reason for hydraulics is no maintenance... But honestly replacing valve cover gaskets once in a while since we all know they are gonna leak isn't a big deal... Why is running the valves while replacing the gaskets a big deal... Besides even with a hydraulic cam you should be looking over the valvetrain occasionally on any high performance type build....
 
Gotta throw in my thoughts on hydraulic vs solid lifters whether flat tappet or roller... The reason for hydraulics is no maintenance... But honestly replacing valve cover gaskets once in a while since we all know they are gonna leak isn't a big deal... Why is running the valves while replacing the gaskets a big deal... Besides even with a hydraulic cam you should be looking over the valvetrain occasionally on any high performance type build....
I agree from a maintenance perspective: It is absolutely NOT a "frequent valve adjustment" issue. Done (and tightened properly), they last for years with minimal work required. I have a high lift solid lifter car I haven't had to touch for 5 years so far. In this case with the 340 we've been talking about, there is an adjustment nut anyway, so it could come loose for a hydraulic lifter as easily as it could for a solid lifter.

From my understanding of cams, a hydraulic lifter actually has an advantage off the seat, and you also don't lose the lift from the required lash setting. Finally, although it is not that hard to address, lash gets a bit more variable with aluminum heads since they grow more with temperature.

I am NOT saying a hydraulic cam is better than a solid lifter cam. Solid lifter cams absolutely have their advantages, especially in high RPM applications.

In this case this car used to be owned by me but is now owned by a super nice young guy who is in to hot rods and old Mopars. He street drives the car and is still learning much about engines and these old cars. In this application I felt a hydraulic cam was the better choice.
 
The 59* blocks all have that crappy lifter angle that's why 48* blocks are better.

Petty used to cut out the lifter valley and furnace braze it back in after correcting that angle.

Call around to see who can supply you with a shorter lifter...I can't remember who makes them but they are out there.

The .903 lifter diameter provides near roller lifter performance. Maybe you should bore the lifters bores to use .937 or 1.0 flat tappets. Then you would have that extra HP but you need to find a core that is made for those big lifters. Callies?
 
My street Challeger runs a 360. It has a Crane 669621 hyd roller (222/[email protected]"). Crane 1.6 rockers. What ever length pushrod it took to get the adjuster in the correct location. I wasn't thrilled with the length of the Crane rocker. So lash caps were used as an extra measure for more tip contact. I know a lot more now than I did when this engine was built in 2003. That being said its mild 9.0-1, LD340, 650 Holley, ported 360 2 brl heads with 2.02 Int, TTI headers, 2 1/2 TTI system. 4 speed with a 2.47 1st gear running a 3.55. Using drag radials it's been 12.70's@109, with a 4.30 and slicks 12.52@110. Other than the tires it was run in full street trim. With the air filter, full exhaust, factory leaf springs, and generic shocks. It pulls fine to 6500, even smooth to 7000. Never adjusted the valves since it's been built. Runs on 87 octane to boot. It'll be fine.
Doug
 
The 59* blocks all have that crappy lifter angle that's why 48* blocks are better.

Petty used to cut out the lifter valley and furnace braze it back in after correcting that angle.

Call around to see who can supply you with a shorter lifter...I can't remember who makes them but they are out there.

The .903 lifter diameter provides near roller lifter performance. Maybe you should bore the lifters bores to use .937 or 1.0 flat tappets. Then you would have that extra HP but you need to find a core that is made for those big lifters. Callies?
Yeah, I think I'm going to leave the lifter bores alone - I'm leaving the short block alone since there is nothing wrong with that. The non-ideal angle will need to stay.

My street Challeger runs a 360. It has a Crane 669621 hyd roller (222/[email protected]"). Crane 1.6 rockers. What ever length pushrod it took to get the adjuster in the correct location. I wasn't thrilled with the length of the Crane rocker. So lash caps were used as an extra measure for more tip contact. I know a lot more now than I did when this engine was built in 2003. That being said its mild 9.0-1, LD340, 650 Holley, ported 360 2 brl heads with 2.02 Int, TTI headers, 2 1/2 TTI system. 4 speed with a 2.47 1st gear running a 3.55. Using drag radials it's been 12.70's@109, with a 4.30 and slicks 12.52@110. Other than the tires it was run in full street trim. With the air filter, full exhaust, factory leaf springs, and generic shocks. It pulls fine to 6500, even smooth to 7000. Never adjusted the valves since it's been built. Runs on 87 octane to boot. It'll be fine.
Doug
Thanks for the specs and details there seem to be a fair amount of similarities between the two engines. I assume yours is a 408?
This engine was 9.4:1 compression, but I'm putting thinner head gaskets on it so it should move closer to 9.8 or so to 1. The roller cam is a 226/234 @ .050 with .510 lift and a 110 centerline. With the stroke it displaces 416 cubic inches.
The PRW rockers seem to fit pretty decent as far as where the rollers contact the tip of the valve, but I'm sure an adjustment with shims would make them better. But, they are only 1.5:1 rockers. The aluminum heads are not ported but should flow pretty decent out of the box.

The down side it is in a heavy 73 Road Runner, but it has a 3.55 and Torqueflight.

From a push rod perspective, I messed around with a few lengths. Basically, the longer the rod, the better the geometry is at the rocker. I tried 6.5, 6.550 and 6.6 length rods. I also had to be sure the oiling holes lined up inside the rocker as well.

In the pictures below I was looking at how many adjuster threads were exposed and making sure the adjuster oil hole was still in the correct spot within the rocker.
20240506_194145.jpg


20240506_193519.jpg


20240506_194906.jpg


Here is the oil hole in the adjuster (I have no picture of the corresponding hole in the lifter, but it is actually pretty high up)
20240506_200604.jpg


Funny enough, it turns out the with the oil hole drilled high up, the 6.6" push rods actually work really well. However, I need to have adjustment, so I can't go beyond 6.6" - I'm already pushing the issue with 6.6" push rods!

Now it is hard to see in these pictures, but as the push rod length goes up, the angle between the push rod and the rocker arm adjuster go down. So longer is better.
20240506_195959.jpg


20240506_200445.jpg


Anyway, that is a @Budnicks wall of text to say I ended up with 6.6" pushrods!!! :lol:
 
With that style of rocker, I try to have the adjuster screw set up as follows:
Thread the adjuster all the way up into the rocker as far as it will go.
Go back down one turn……snug lock nut.
Adjust checking pushrod to just fit between lifter and rocker…….then add the desired lifter preload to that length.

That will give you an adjustment range of +/- one turn and still keep the oil holes in the correct position.
 
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