School me on guideplates

[Caveman Tony]

Yes, they are pretty much inanimate objects. Whatevah.

I found out the hard way what happens when you don't take them seriously.

Who uses 'em?

Re-uses 'em?

Recondition?

Rework?

Repair?

Replace? When? Why?

What kind? Plate style? Adjustable?

[jcharliem]

Nothing mysterious about 'em. Been around since I've been toying with mills. Standard fare on hi-po motors since the 60s...heck, maybe even earlier. They help stabalize the valve train. Just make sure you use hardened pushrods...if not, it's gonna get ugly.

Why recondition or repair them? They're dirt cheap compared to the alternative (if you even need 'em to begin with). Nothing fancy about them.

[squirrel]

If you're talking big block....they are important, you need to check them for cracks. If they are on the head while it's being machined or otherwise handled, and the head tips over the guide plate can be cracked and ready to break off. They're case hardened, so they're kind of brittle.

Also there are different size plates for different pushrod sizes.

I've always used good used ones on my engines, only had one fail, and that was right after getting the engine running...within a week, no serious damage, but it did loose the pushrod into the pan if I recall correctly. that was 33 years ago.

[Caveman Tony]

I've seen SBC's with/without 'em... what makes them required items? Style of rocker arm?

Are they mandatory for BBC's with stock-style rockers?

When would you need to use adjustable ones?

[squirrel]

On older big blocks, they're required. Small blocks came with cast in pushrod guides, only the high perf engines had bolt on guides. And later small blocks have rockers with notches in the ends so the guides are not required.

I"ve had to cut and adjust and reweld big block guideplates on a race engine with a high lift cam and roller rockers...to get the rocker to align properly with the valve stem tip. Not my engine.

[Caveman Tony]

If you're talking big block....they are important, you need to check them for cracks. If they are on the head while it's being machined or otherwise handled, and the head tips over the guide plate can be cracked and ready to break off. They're case hardened, so they're kind of brittle.

That is a distinctly possible explanation for my troubles with the Red Ball truck. The looked okay when they came off the engine prior to rebuild, but I didn't look THAT close. Coulda been cracked.

I DID notice one had been brazed, as if it had cracked... didn't remember that being like that when I dropped them off with the heads at the machine shop. The brazed one was one of the ones still in its proper place though.

Figures. Cheapest pieces on the engine, and I didn't replace 'em. Didn't know, didn't understand. Expensive lesson.

[oldsman71]

could be easy to overlook I re-used some on a buddy 454 a while back, they seem to work ok but theres always that chance

[Scott Liggett]

Reusing the stock ones on the Caprice's 454. I put them on my old iron heads that were on the Impala. The push rod holes were not big enough and had casting flash causing the push rods to drag, slow down, and toss the rockers off; very much like valve float. Four push rods got the snot beat out of them on road trips where the engine was spinning at 3000+ rpm for long periods of time. I had the push rods opened up, but that required guideplates to keep them aligned correctly.

[squirrel]

Reusing the stock ones on the Caprice's 454. I put them on my old iron heads that were on the Impala.

these are two completely different engines, right? The impala has a small block in it, doesn't it?

[Scott Liggett]

these are two completely different engines, right? The impala has a small block in it, doesn't it?

Yes. The 383 sbc is in the impala.

[Caveman Tony]

Yes. The 383 sbc is in the impala.

ok, yo soy mucho confuso.

So, I thought BBC & SBC guideplates were two different parts, two different sizes?

[BKBridges]

[QUOTE=jcharliem;677708] They help stabalize the valve train. Just make sure you use hardened pushrods...if not, it's gonna get ugly.

QUOTE]
Doubling down on using hardened pushrods when running guide plates... Nasty results if you dont. Im a Mopar guy, wht did I know about guide plates and SBCs at the time...

[squirrel]

So, I thought BBC & SBC guideplates were two different parts, two different sizes?

Yup, completely different animals. Older small blocks have pushrod guides machined in the heads, big blocks all used guide plates.

[Beagle]

^^ by necessity, valve spacing on BBC is different and if I'm not mistaken, canted.

[anotheridiot]

I would bet the guide plate was brazed at the head shop. They do more brazing on cast iron than welding on steel.

And yeah, small blocks are right next to eachother, where big blocks are staggered high intake to low exhaust valve positions.