Lykins Motorsports 311ci SBF Piston To Valve Clearance Follow Up

[@tomrygmyr1382]

I've heard about this I've never seen this thing explain so precisely thank you very much for taking the time to do this video immaculate in what you're doing

[@jesslackey1003]

Hey Brent try this, take one of your exhaust valves and put it in the oven at 400° or 450 for 30 minutes measure the difference between the Cold valve and the hot valve. You can do this with the pistons also, it should give you the expansion rate of your parts now all you need is to determine your clearances after warm-up hopefully this helps but I love the video thanks

[@robertclymer6948]

Makes perfect sense Jess. We always retested specs at Borg Warner both Cold and hot.

[@tabor_experience]

"I'm gonna run it, and I'm gonna run it hard", lol that was exactly what I was thinking

[@anthonymacri8053]

You should fine with the Ptv clearance, your valvetrain is very stable, if it was a Hydraulic roller might be a little worried, love your videos, you do great work, look forward to the next

[@jesslackey1003]

Hey Brent try this take a measurement on the exhaust valve while it’s cold now put it in the oven at 450° preheat take it out measure it again this should give you the expansion rate of that material you can also do this with your piston this will give you a better idea of what’s going on in the cylinder

[@jeffdyer8541]

Run it! We built an 18 degree 300 ci super comp sbc with. 060 on plunge cut pistons at 9500. Not to say you could read the del west label in the carbon. You could. Never had any bent valves. Jeff

[@craigbowers4047]

I recently ran across your channel and I like the little 330 & 347 combinations. I don't need one and will probably never build one but they are cool. To my knowledge no one has tuned a 347 by cylinder pressure, and since the deck height is so short which makes the center 4 runners very short on a carb. manifold different cam timing & ignition timing for the 4 outer cylinders would help equalize the cylinder pressures. I can tell you from first hand experience that at 9300-9500 with a SBC using a steel rod, endurance skirted JE piston and a 2" rod journal the piston will touch at .038 or less. Doesn't hurt anything but it will touch. Some seem to think there's a little low lift flow to be gained by adding a radius to the edge of the intake valve pocket. I'm undecided about that and it may only help an engine with a lot of lift like a prostock or extreme prostock running 1.200" lift. Anyhow I think your piston to valve clearance is fine, good luck with your testing.

[@robertclymer6948]

Just an awesome video Brent!!! I did not know about the method you used being a weekend Hotrod wrencher. I think I will leave this type of build to the professionals like yourself. Great info. I learned a lot today and Thank you. Blessings & Cheers from Motown/Dearborn

[@wayneboyd2682]

Excellent follow up video, thanks. Look forward to seeing the next video's and the dyno results.

[@ldnwholesale8552]

When checking on the retainer you are slightly extenuating the lift being out further. Say 5 thou max. This engine is very close,, tha valve will be 10 thou longer when hot [at least] and any float wil halve that. And all race engine valves float, just depends how much!. Things get VERY busy at 7000 rpm. I use 080 on both and have still had valves kiss the head, enough to slightly bend them. Brand new Ferrea!

[@terrysibley9636]

Very nice, im putting together s small solid roller 311 sbf, my question is what lenght valve. Std , or .100 long?

[@terrysibley9636]

Very nice, are you running solid roller, what length valves, std or longer. Thanks

[@mikasantos3774]

You should be all right with your measurements like you said providing your valvetrain stability valve spring pressure is all in check Pro Stock engine builders would run the engine with less clearances than that can't wait to see the dyno mule pull the numbers also I'm waiting for the junkie junk return that was a pretty impressive little engine

[@nickwilson2475]

Great job explaining it

[@timrayburn2461]

Thanks

[@yarrdayarrdayarrda]

I'm shocked that a cam with such small duration numbers and low lift would have a valve to piston issue. I'm used to dealing with that in 408's and .700" lift. Are those heads milled a bunch? Here's another cool way to measure valve to piston when using a checker spring. Head on with gasket, rocker lashed. Pick a minimum clearance number you're comfortable with then grab your feeler gauges and swing a combination of gauges out that represent that clearance number. Slide the stack between the valve and rocker, then spin the crank over by hand, gently as you approach the tight spot. If you don't feel resistance, you're good to go. If you do, keep removing gauges until it will rotate past the tight spot, the difference being what you need to fly cut.

[@jesslackey1003]

Also remember there’s always a thicker head gasket lol good luck

[@robertclymer6948]

I forgot what compression ratio Brent was shooting for, but for a Dyno mule, a little loss in compression might not matter. ?

[@davidfawcett7861]

Thanks for the reply Brent. Do you think there is any disadvantage to having a large piston to valve clearance - say 200 to 300 thou?

[@donaldhill2775]

Hi, I’m in France building a sb Ford, 289 block with 302 eagle crank & rods, seem to have assembled a bit of an eclectic mix of components here and wondered if you have time to for a quick look and your professional opinion, AFR 185 heads 58cc chambers 2.20in 1.60ex valves, flat top pistons 0.014 in the hole & 8cc valve reliefs, Comp 31-333-4 270s grind 270-270 adv 224-224 @.50 110* lob flat tappet solid lifter Weiand dual intake & 500cfm Edelbrock, timed it straight up and checked piston / valve, is fine, street motor for 65 mustang with T5 and stock rear, my 1st American engine and clueless, thank you ! Don Hill,

[@alvinwilliamson2461]

You will be fine with those numbers on PTV

[@tomhamilton9140]

Can you cut .010 of the face of the valve. What static compression are you shooting for? The piston domes are very small just curious. Thank you.

[@JohnThomas-vb9se]

.90 and .94 isn’t including lash is it? It should be fine.

[@wysetech2000]

You still have the head gasket thickness to consider, but then you also have longer aluminum rods when hot.

[@lykinsmotorsports]

Covered that in the two videos.

[@wysetech2000]

@@lykinsmotorsports Sorry, Brent, I missed the previous video. I watched it after and realized my thoughts were answered.

[@robertbruneau112]

What about the aluminum rod growth?

[@davidfawcett7861]

Hi Brent, very informative video as always - this is the only KZbin channel I have subscribed to! I have a similar spec engine (slightly higher compression with small dome), in my GT40 replica here in France and have a couple of questions. You show a difference in valve clearance of .050" (.090"-.040"), between using checking springs and the actual springs, but earlier on a difference of .017" ((.559"-(.556"-.014")) between net lift with checking springs and the cam card. These to differences seem to be at odds with each other - I could see around 20 thou with deflection but 50 thou seems a lot. Also if 50 thou is correct then surely you will have less lift than shown on the cam card? Thanks, Dave

[@lykinsmotorsports]

.050" deflection is pretty typical. It can be upward of .070" with higher spring pressures.

[@lykinsmotorsports]

One other reply....I changed cam timing quite a bit through the video, which gave the biggest change.

[@danonoveh8114]

It's a little tight for hyd roller,solid roller will be good👍

[@Jkush463]

dumb question, i had a shop build my bottom end a nd put the cam in, he left the cam dowel long and smashed it down with the cam bolt is that going to be a problem? most peoples seem to sit nice and flat.

[@lykinsmotorsports]

I certainly wouldn’t run it like that. If the washer yields, you will lose preload on your bolt.

[@Jkush463]

@@lykinsmotorsports i was afraid of that, ill try to pull the dowel and cut it down and fix it.

[@craig8187]

Ally rod growth with heat ~.020" on a 6" rod at running temp(is this an ally rod motor?) Belt drive cam? - although preferable for stability with rpm the belt will get that exhaust valve closer than a good chain will. You wont be accumulating carbon between that ex valve and piston thats for sure! Can you sink the valve seats even .020" for some extra safety margin. Going to be a cool little motor👍

[@anthonymacri8053]

Hey Brent..where's the Pontiac?

[@yarrdayarrdayarrda]

I don't see a head gasket, are you not measuring with the gasket installed?

[@lykinsmotorsports]

Using head gasket and lash. Heads have been cut a lot, but cam is very high in .200" duration as well.

[@yarrdayarrdayarrda]

@@lykinsmotorsports Well the heads being milled a bunch makes a bit more sense.

[@clevo351]

I would advance it another degree so your ex has a bit more clearance.

[@ldnwholesale8552]

Piston to valve thi close you will have to check all 8. Or an accident may well happen. I have been in a similar situation with a GM engine and for some reason,,GM Machining! it was only bad on no 1.

[@jackwells1452]

Seems awfully close