Questions about measuring pushrod length

[TexasRoadRunner68]

I am getting close to needing to measure pushrods and check PTV clearance and had a few questions.

For a bit of background, I am building a 400-512 stroker with tfs270 heads, t&d 1.6 rockers, and a lunati voodoo hydraulic roller cam with comp cams evolution lifters.

Any ideas on what length range of adjustable pushrod tool I should buy? I would assume somewhere between 8-9” with the factory 400 pushrod being an 8.575” one?

I do not have head gaskets yet, since I don’t have pushrods installed and haven’t checked PTV. But I know they sell 0.040 and 0.060 thickness gaskets, I figured I’d go for the smaller of the two if possible. Is just snugly bolting the head to the block without the head gasket going to make a big change in pushrod length measurement? I know for PtV clearance you add the compressed head gasket.

 

[69Bee]

The instructions for the heads should tell you what length pushrods are needed, so that should be you starting point on length to determine which adjustable PR length checker to get.

 

[steve340]

I always use a test head gasket - then you know everything you measure is correct and the heads are were they would be when the engine is assembled.
A few thousands here and there will not be a problem but not 40 thou IMO.

 

[Bella804]

an adjustable pushrod tool in the range of 8.5" to 9" should work well, considering the factory pushrod length of 8.575". It’s advisable to measure with the approximate thickness of the head gasket you intend to use, so if you’re leaning toward the 0.040" option, this can help refine your pushrod length.

Just snugging the heads without a gasket will not significantly affect the pushrod length measurement, but it’s better to use a compressed gasket thickness to ensure accuracy for PTV clearance. Also, when checking PTV, remember to account for the compressed gasket thickness to get a true representation of clearance. It’s crucial to double-check these measurements to avoid clearance issues once the engine is assembled

 

[TexasRoadRunner68]

an adjustable pushrod tool in the range of 8.5" to 9" should work well, considering the factory pushrod length of 8.575". It’s advisable to measure with the approximate thickness of the head gasket you intend to use, so if you’re leaning toward the 0.040" option, this can help refine your pushrod length.

Just snugging the heads without a gasket will not significantly affect the pushrod length measurement, but it’s better to use a compressed gasket thickness to ensure accuracy for PTV clearance. Also, when checking PTV, remember to account for the compressed gasket thickness to get a true representation of clearance. It’s crucial to double-check these measurements to avoid clearance issues once the engine is assembled

So maybe I’m better off buying a single new “test” head gasket?

 

[RemCharger]

So maybe I’m better off buying a single new “test” head gasket?

What's the piston deck height?

 

[TexasRoadRunner68]

-.000" below deck

 

[451Mopar]

If cam duration is under 260@ 0.050" you should have good piston to valve clearance if using the ICON pistons.
I don't think the Trick flow heads use a large offset intake rocker like the Victor MW (0.725") or INDY (0.800"), but you still might want to check both intake and exhaust pushrod lengths. On my Victor MW heads the Intake pushrods are 0.025" longer than the exhaust pushrods.

 

[TexasRoadRunner68]

If cam duration is under 260@ 0.050" you should have good piston to valve clearance if using the ICON pistons.
I don't think the Trick flow heads use a large offset intake rocker like the Victor MW (0.725") or INDY (0.800"), but you still might want to check both intake and exhaust pushrod lengths. On my Victor MW heads the Intake pushrods are 0.025" longer than the exhaust pushrods.

It’s their -24cc dish piston…from what I gather their kits have icon pistons.

Cam has duration of 243/251 at 0.050” and an “advertised” duration of 295/303.

 

[451Mopar]

It’s their -24cc dish piston…from what I gather their kits have icon pistons.

Cam has duration of 243/251 at 0.050” and an “advertised” duration of 295/303.

That cam should have plenty of piston to valve clearance.
I don't recall the pushrod lengths I used, just knew the rocker offset slightly affected them if I wanted to have about the same rocker adjuster lengths.
My T&D rockers use pushrods that are ball end on both sides. If your rockers use the cup end pushrod, make sure the adjustable checking pushrod has the cup.

 

[TexasRoadRunner68]

That cam should have plenty of piston to valve clearance.
I don't recall the pushrod lengths I used, just knew the rocker offset slightly affected them if I wanted to have about the same rocker adjuster lengths.
My T&D rockers use pushrods that are ball end on both sides. If your rockers use the cup end pushrod, make sure the adjustable checking pushrod has the cup.

They are ball on both ends. Of course I have the wrong adjustable pushrod tool.

You think it’s fine just assuming PTV is good with those specs? I know it’s best to actually measure, but how risky is just throwing the heads on and measuring pushrods?

 

[steve340]

They look like nice rockers on the engine.

 

[33 IMP]

I always use a test head gasket - then you know everything you measure is correct and the heads are were they would be when the engine is assembled.
A few thousands here and there will not be a problem but not 40 thou IMO.

Agree. I always mock the assembly up with an old hg or two, cause I can measure it in as-crushed condition. A safer way to check p/v in my opinion.

 

[33 IMP]

an adjustable pushrod tool in the range of 8.5" to 9" should work well, considering the factory pushrod length of 8.575". It’s advisable to measure with the approximate thickness of the head gasket you intend to use, so if you’re leaning toward the 0.040" option, this can help refine your pushrod length.

Just snugging the heads without a gasket will not significantly affect the pushrod length measurement, but it’s better to use a compressed gasket thickness to ensure accuracy for PTV clearance. Also, when checking PTV, remember to account for the compressed gasket thickness to get a true representation of clearance. It’s crucial to double-check these measurements to avoid clearance issues once the engine is assembled

It all depends how much taller and higher the roller lifters are than the the stock hydraulics. But I agree, an 8 to 9" range should be correct.
A taller roller lifter would mean a shorter pushrod. Then the rocker geometry enters the equation too.

 

[33 IMP]

They are ball on both ends. Of course I have the wrong adjustable pushrod tool.

You think it’s fine just assuming PTV is good with those specs? I know it’s best to actually measure, but how risky is just throwing the heads on and measuring pushrods?

View attachment 1736735

View attachment 1736736

View attachment 1736737

Kinda hard to check p/v without the pushrod/rods.
Do you remember how much valve notch was below the dish? If it had notches, I would be shocked if you have p/v problems. I would check it, anyway.
I've got a set,of stroker pistons (for a set of,B1's) that have a dish, and HUGE valve notches. I'd bet they will clear a 280 at .050/.900 cam.

 

[451Mopar]

I would still check piston to valve clearance just to have the data.
you might want to also check how far the valve drops to the head/block surface as different heads may have the valve seats deeper in the head (just another data point for future reference.)
The only Trick flow heads I have used are the 240s, so I don't have any data on the 270s. Do they use the same size valves would be the big question.
My 500" 400 stroker with the flat top ICON pistons has a 272/278 @ 0.050" 110 lsa solid roller (0.726" lift) it is installed at split overlap because piston to valve clearance was getting fairly close.
When I built the 505" 440 with the TF240 heads and a mild solid roller in the 240's @ 0.050" range there was plenty of PV clearance. and that has the 7.1" rods so more TDC piston dwell than the low deck 6.535" rods.
I have gathered the parts for another 512 RB440, but just bought the 4.25" low deck B stroker crank and 6.535" rods (no pistons yet.)
I thought it might be interesting to build them the exact same to see what difference rod ratio makes between a 512 RB and 512 B engine.
Just need a bunch more money