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380 ci sbc bending exhaust valve

General engine tech -- Drag Racing to Circle Track

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GRTfast
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Re: 380 ci sbc bending exhaust valve

Post by GRTfast » Sat Jun 08, 2019 7:56 am

Krooser wrote:
Sat Jun 08, 2019 7:32 am
Ditch the exhaust valve seals... Old Indian trick.

Seriously... I read that years ago. My engines (351C) never seemed to miss them. I was running a dirt sportsman car... 6500 rpm...

The 388 SBM I'm working on won't get exhaust valve seals either.
You have any oil consumption issues when you do that?

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Re: 380 ci sbc bending exhaust valve

Post by gsbrown83 » Sat Jun 08, 2019 10:30 am

As far as intake it is a Victor Jr single plain. The cooling system we have tried everything. Have jacked the front of the car as high as we can to try to make sure it gets to there rear. We have also used a vacuum system that sucked the cooling system into a vacuum then fills using the vacuum to prevent air pockets. He has it apart right now does not see anything mechanical wrong. I was wondering about the oil galley plug in the back of the block he's certain that it has the right restrictors. So we r still at a loss.

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Re: 380 ci sbc bending exhaust valve

Post by modok » Sun Jun 09, 2019 5:09 am

So what's the clearance?

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Re: 380 ci sbc bending exhaust valve

Post by novafornow » Sun Jun 09, 2019 10:55 am

I have not run exhaust valve seals in a very long time. I stuck a valve back around 1980 and have not run them since.

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Re: 380 ci sbc bending exhaust valve

Post by Kirk600 » Sun Jun 09, 2019 7:16 pm

modok wrote:
Sun Jun 09, 2019 5:09 am
So what's the clearance?
I seriously doubt the engine builder will share that info, he may loosen up the valve/guide clearances and/or change seals. he has plenty of motors out there he built that are not having same problems. He does quality work and lots of customers have won championships over the years

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Re: 380 ci sbc bending exhaust valve

Post by modok » Sun Jun 09, 2019 8:19 pm

Trouble shoot from the basics outward.
Examining the cooling system? he's lost

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Re: 380 ci sbc bending exhaust valve

Post by Jim Hanig » Sun Jun 09, 2019 8:43 pm

I would ck the lifters ,had a engine do the same thing . moved the lifter from 7 to 1 and bent 1. the lifter was .002 out of round.

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Re: 380 ci sbc bending exhaust valve

Post by gmrocket » Sun Jun 09, 2019 8:53 pm

gsbrown83 wrote:
Mon Jun 03, 2019 9:57 pm
Pictures are hard for me to get as i drop it off to him and he calls with updates. He is old school so probably not big on pictures. Let me ask you guys this what is acceptable seal clearance and or type of seals and valve to guide clearance
If it's sticking in the guide, that's easy to see by the stem condition.

This problems needs pics for sure.

Are you running four corner cooling?

I would want to know the ex valve to piston clearance before Anything...any reputable builder should include that in the build spec sheet he supplies you with...right? Just look it up 😉

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Re: 380 ci sbc bending exhaust valve

Post by gsbrown83 » Mon Jun 10, 2019 7:09 am

We have changed valve train parts from 7 to 2 still 7. Now it's 1.3.7. the next time I personally talk to him I will ask about clearance. If it is a clearance issue why doesn't it do it on the passenger side. Never once has it. Always odd cylinders that's why I'm looking for what would effect just that side.

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Re: 380 ci sbc bending exhaust valve

Post by modok » Tue Jun 11, 2019 8:37 pm

A moving part becoming a NON moving part IS a clearance issue, it's not moving because it ran out of clearance.

WHY? is what you need to know. Scoring? The guide shrunk? The guide is bent? Valve stem is bent? What does the stem look like...is there a sticky film on it?
The guide ID is either going to be bigger, smaller, or the same size as it was before, and that's a big clue.

Crazy things can happen. Maybe even when the head is bolted on the block the guide might be in a bind....tho i really doubt it, could happen. More likely would be basic things like.... you had no valve lash and the valve overheated. valve hit piston. Retainer hit the top of the guide and pinched it. Don't rule it out off the bat.

In order to find out if a valve guide is straight, one great way to do that if you have live pilots, is see what the largest size pilot will fit through it.
You can use a bore gauge to see what size the Id actually is.
if your guy has the tools to do it, then Ok let him do it, but let us know what is found and it would be far more helpful.

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Re: 380 ci sbc bending exhaust valve

Post by Keith Morganstein » Tue Jun 11, 2019 9:05 pm

gsbrown83 wrote:
Mon Jun 10, 2019 7:09 am
We have changed valve train parts from 7 to 2 still 7. Now it's 1.3.7. the next time I personally talk to him I will ask about clearance. If it is a clearance issue why doesn't it do it on the passenger side. Never once has it. Always odd cylinders that's why I'm looking for what would effect just that side.
It may be an oiling issue. How does everything else look on the side (rockers, pushrod tips, valve tips, etc... ?

Warm the engine up and then run it with the valve covers off of both sides and observe the oiling. (Cut the tops off of old tin valve covers if you want less of a mess)

If oiling looks good and even on both banks, go ahead and remove the exhaust valve seals on that side. Whatever it takes to make it survive...
Automotive Machining, cylinder head rebuilding, engine building. Can't seem to quit #-o

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Re: 380 ci sbc bending exhaust valve

Post by PRH » Tue Jun 11, 2019 9:27 pm

I don’t know if this was mentioned already, but are you using the same rocker arms?

Are they rockers that provide oil to the valve tips, or do the valves rely on splash oiling mist in the valve cover?

If it’s splash oiling, the fact that it’s the inboard head, raises the possibility that the g forces in the turns would be pulling the oil away from the valves.
Somewhat handy with a die grinder.

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Re: 380 ci sbc bending exhaust valve

Post by gsbrown83 » Tue Jun 18, 2019 10:43 pm

Little update. Builder put the engine back together again and we we're lucky enough to have a fellow performance engine shop with a Dyno squeeze us in to put it on and run it. Tonight we fired it on the Dyno set the timing and shut it off to pull the covers and see what was there for oil and kinda like we were guessing there is barely any to either head. Fired the motor back up with the left valve cover off and oil just barely trickled out the pushrods not nearly enough. So we r sure now that we are on a oiling problem. I will let you all know once it gets figured out

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Re: 380 ci sbc bending exhaust valve

Post by F-BIRD'88 » Wed Jun 19, 2019 1:09 am

Wrong rear cam bearing.
Oil gallery plug in too deep.

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Re: 380 ci sbc bending exhaust valve

Post by PRH » Wed Jun 19, 2019 11:07 am

Flat tappet or roller cam?
Somewhat handy with a die grinder.

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