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Discussion Starter · #1 ·
The 393w that I've raced for several years finally had enough abuse. Apparently I over extended the cycle time of either the SR lifters or the roller rockers. At least I can say the motor served me well for many years.

A little background--this is a street/strip 393w using Scat crank and rods, Probe Pistons, Bullet custom 256/264 duration SR cam, Comp 944 springs (replaced last season), Comp 833 lifters, and Comp Gold 1.6 roller rockers. Both the lifters and rockers had several easy street miles and 600 track runs on them.

The motor was fresh last year, had been properly maintained during the racing season, and has seen nearly 200 runs in this configuration. Idle was always set for 1200RPM's with a 1 minute, 2K warm up before putting it in gear or letting it idle lower. Oil pressure was 35lbs at idle and 55lbs at speed.

Twelve passes before the catastrophic failure the valves were adjusted (all were close to begin with), a compression check was made, (all cylinders were withing 5lbs or less of the fresh build compression), the oil was changed. The oil filter changed and cut open with nothing out of the ordinary found. I was ecstatic that the motor had a such a clean bill of health and felt confident that it would make it to the end of this season.

Then after 25 easy street miles and 12 more runs down the track, the engine had what sounded like an exhaust leak at idle after a run. I had a loose ball and socket connection so I didn't think too much about it at the time. The next run the engine started missing at the top end and exhaust popping was heard as I headed for the trailer. I suspected the worse and thought that I had lost a solid lifter--which was confirmed when I found that the pushrod for #6 appeared to be 1/2" shorter-but it wasn't. Enough of the BS--here are the photos from the autopsy.

Hole in block:







Roller lifter tried to escape out the top of the lifter bore:





Nice Bullet cam lost 2 lobes:







Lifters were missing their rollers and the remaining stubs at the bottom were mushroomed. I ground off this metal from the underside of the block in attempt to salvage the lifter bores:



First lifter to go:



The lifter it helped to take out:



Other lifter parts:







The crank was not without issue as metal found its way to the mains:









Some piston skirts got their share too:





Opened the oil pump and had to drive out the rotor:







Cut open the oil filter:







The filter mag I had stuck on the filter had also gathered up a ton of shavings:



And what do I suspect was the originator of all this damage?









This C clip from the rocker was found in the head:



The other rocker show above also had a stiff trunnion bearing, but no further damage. Apparently it was timed to go next.

Luckily the pistons did not come into contact with the heads so it wasn't a complete loss.

Now I am having fun planning for my future motor--most probably a stock block 6.2" rod 408 with lighter weight internals.

Here is a nice photo of the car's last complete run:

 

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Damn. :( Bummer, dude. I'd agree with the marking on the rockers that it started there. That's why I won't sell my used sets - others may let go soon and I don't want that on my conscience. As you say, the up-side is the future. It's hard to avoid wondering if you should have shut it down with that odd noise. Don't look back. You probably will next time ;). I've wondered in similar situations, but honestly, I can't say I wouldn't do the same thing again in the same circumstances. That's racing. Look forward and enjoy the next step. Are you building the 408 similar?

David
 

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Sorry for your loss.
 

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Sorry to hear about the failure! But I'm looking forward to seeing the bigger, badder replacement!
 

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That's a bummer, I have seen these before, a lifter lets go and all hell breaks loose.

As late as early 2002, Comp was saying that after 300 passes they needed to be checked/rebuilt, but new oiled pins seem to make them last longer.

I'd replace them with an oiled bushing type and make sure you have a good billet cam core, not just a hardened lobe.

Not cheap
 

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Discussion Starter · #9 ·
Thanks for the sentiments. I questioned myself that race night and still ran it out to get into the finals-where I couldn't make the call. Next time I'll certainly consider the less manly option of loading up early and going home. (We need a "dumbass" icon. LOL)

I've moved beyond the carnage and the short end to my race year to look forward toward next year. Still looking to build a stock block street/strip machine, with the most emphasis on strip. Typical race schedule is nearly 250 runs a year, and street is usually around 500 miles now.

I've been studying a better solid roller and shaft rockers, but really haven't ruled out a Hydraulic roller either. In many ways it makes sense due to less over all maintenance and less chance of a "surprise." :rolleyes:

What I am having difficulties in is finding a decent piston that will give me 10.5:1 to 11:1 compression with a 58cc head, zero deck, 6.200" rods, 9.5cc gasket and 4.030 bore. I can get 10.2 or so but would rather go up a half point more for racing. I can also find what I need "competition" series, but fear its usage on the street.

Currently looking at using a lightweight I beam-around 620g. Cast crank seems to be the way to go for the weight savings. Probably external balance.

Would moving up to a 6.250" rod be a bad thing? I can get what I want compression-wise with that combo. Shifting at 6400-6500 max is desired with it being able to free rev up to the 7K chip. I don't want a piston that isn't streetable either.

David (or anyone) do you have a recipe for a good rotating assembly running stocked-block 408 for maybe 600hp or so? Planning on staying NA and would like to continue to use pump gas (93.)
 

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Well, there are many ways to go, but I'd start with saying your old combo was serving well. So, how would you feel re-packaging you previous setup into a 408? What would you change (especially that now you would have a bit more lung)?

My 2 cents on pistons is to stay with 6.200 rods (still a hair better than the 393 was) and keep the piston stability, land height and ring pack height over the increased R/S ratio. An example forged piston would be the Icon IC750. Summit has full piston/ring kits here. Run your anticipated build numbers and tell me what you think.

David

 

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Here is a link to the pistons I am running Dennis...I think they are the same pistons that David posted above..
United Engine & Machine Co. Incorporated

I am not sure how they compare for wieght to what you were running but my 408 definetely revs quick in my opinion..I was a little leary of them because of all the negative feedback that KB pistons seem to get(although I think that is all because of the ring gap issues with the KB hyper pistons).These are forged units..Anyway Joe Sherman says he runs them all the time and likes them due to their generous sized valve reliefs..Makes it easy to do cam swaps on the dyno I guess...I am running the 6.2 inch chevy I beam cap screw rods that came in the Scat rotating kit that I bought..Here is a link to those.
http://www.cnc-motorsports.com/conn...premium-pro-comp-i-beam-connecting-rods.html/
 

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Discussion Starter · #13 · (Edited)
Thank You David and Willy. I found the Icon pistons on the KB website last night, but had never heard of them before. After a little research, I found that they are made of a decent material and have a decent reputation. To hear that Joe likes them is a plus. Definitely something I will consider.

Compression would be about 11.1 when everything is considered, assuming zero deck. Hopefully the right cam will help keep it streetable on 93 octane. If I calculated correctly, dynamic compression could be held to about 8.88 with a similar cam like I destroyed.

Generally how accurate are AFR's claim of 58cc's, assuming the head was not decked?

So, how would you feel re-packaging you previous setup into a 408? What would you change (especially that now you would have a bit more lung)?

My 2 cents on pistons is to stay with 6.200 rods (still a hair better than the 393 was) and keep the piston stability, land height and ring pack height over the increased R/S ratio.
David
David, you have read my mind about wanting to repackage what I had before. Vic Jr intake (I have a Senior on the shelf, but would have hood interference issues and is being saved for future expansion.) 1 3/4" headers, 3" exhaust for the track. Reusing my AFR 205's for this year, but like to make the change to TEA 205's in the future. Holley 950HP should work, but I could be open to going the 850 route too.

My goal, of course, is to go faster (like Duh.) :) Due to my desire to maintain some streetability (which is easier with a stick car), I am limited on what I want to do suspension-wise. I've mini-tubbed it, and I have all the trick Calvert racing stuff. My original thought was to build a Dart big bore 428, but then reality sat in. With the 393w and a stick being borderline in traction, I would never get the 428 to hook at our greasy local track. To help this situation, I am planning on a jump to 28x10.5 drag slicks from the 26.5x10's I've been running so that should help.

Anyways, my desire is a light-weight rotating assembly and the yet strength to handle 600-650 HP should I up the ante in the future. I like Scat products and see that the basic cast crank is 8lbs lighter than the forged units at 52lbs. That's an 8lb savings from my 393. I have also considered Scat lightweight I beams, but am open to other options in crank and especially rods. I agree that the 6.200 rod length makes the most sense.

So far it looks like I'll be mimicking Frdnut's shortblock combo. Would love to have access to your CI cam Willy! ;)
 

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I've moved beyond the carnage and the short end to my race year to look forward toward next year. Still looking to build a stock block street/strip machine, with the most emphasis on strip. Typical race schedule is nearly 250 runs a year, and street is usually around 500 miles now.
Boy that sucks. Sorry to hear about your engine and short season. Thought I would get to meet you at prp this year.

I'm sure you will build it better and faster.

Lou
 

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I haven't looked at this website in a while. The day I decide to check it out.....I log on and see this. That is an interesting way to lose an engine. If it were me I would strongly consider a Dart block based larger stroker. Probably not really needed at 650hp. It is very easy to run pretty hard on a 408 cubic inch Windsor. Let me put it this way....9 second power is easily attainable for a street strip car that is pretty heavy. At that speed the safety **** makes it pretty easy to tell the car means business and probably isn't driven around on the street very much. I've been using those same lifters...lol Good luck with the rebuild. I like the TEA Highports if you are considering Trick Flow Total Engine Airflow | Custom Cylinder Head Assemblies Tallmadge | Airflow Development | Custom Cylinder Head Ohio | TEA Total Engine | CNC Porting | Cylinder Heads | Cylinder Head CNC Porting | Ohio | :: Total Engine Airflow ::
 

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Dennis, Sorry your track time has been shortened this year. My 2 cents. A light weight neutral balance rotating assembly is a good thing. I don't think a 6.25 rod when married with a forged piston will have a shorten life. The stroke choice depends on you power curve goals. CHP has nice lightweight I beam rods, I have them in my 418w. Good luck with your build, can't wait to see your choices and outcome! Alan


Thank You David and Willy. I found the Icon pistons on the KB website last night, but had never heard of them before. After a little research, I found that they are made of a decent material and have a decent reputation. To hear that Joe likes them is a plus. Definitely something I will consider.

Compression would be about 11.1 when everything is considered, assuming zero deck. Hopefully the right cam will help keep it streetable on 93 octane. If I calculated correctly, dynamic compression could be held to about 8.88 with a similar cam like I destroyed.

Generally how accurate are AFR's claim of 58cc's, assuming the head was not decked?



David, you have read my mind about wanting to repackage what I had before. Vic Jr intake (I have a Senior on the shelf, but would have hood interference issues and is being saved for future expansion.) 1 3/4" headers, 3" exhaust for the track. Reusing my AFR 205's for this year, but like to make the change to TEA 205's in the future. Holley 950HP should work, but I could be open to going the 850 route too.

My goal, of course, is to go faster (like Duh.) :) Due to my desire to maintain some streetability (which is easier with a stick car), I am limited on what I want to do suspension-wise. I've mini-tubbed it, and I have all the trick Calvert racing stuff. My original thought was to build a Dart big bore 428, but then reality sat in. With the 393w and a stick being borderline in traction, I would never get the 428 to hook at our greasy local track. To help this situation, I am planning on a jump to 28x10.5 drag slicks from the 26.5x10's I've been running so that should help.

Anyways, my desire is a light-weight rotating assembly and the yet strength to handle 600-650 HP should I up the ante in the future. I like Scat products and see that the basic cast crank is 8lbs lighter than the forged units at 52lbs. That's an 8lb savings from my 393. I have also considered Scat lightweight I beams, but am open to other options in crank and especially rods. I agree that the 6.200 rod length makes the most sense.

So far it looks like I'll be mimicking Frdnut's shortblock combo. Would love to have access to your CI cam Willy! ;)
 

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... CHP has nice lightweight I beam rods, I have them in my 418w. ...
+1, I have the original Llemmon rods (that the CHPs are copies of) in my street 427W, though that one is limited to 6300 by my cam choice. I really like everything as light as possible, and would have recommended those, but I have not tried CHPs version, so I can't say if they are capable with the heavier pistons listed. Probable so, but a call to CHP would be in order. H-beams are very strong, but very heavy, and are unnecessary for any reasonable RPM if the pistons are also light. Light weight = less recip mass = less stress at RPM = more equivalent strength than massive parts that cause stress by their own mass. So, I always choose light/ultralight I-beams and pistons for NA below 7500 or 8000. H-beams I reserve for their compressive strength in N2O or boosted applications where RPMs are lower but column stress is higher, such as a pump-gas 408W with 8.5:1 compression and 12 psig boost at just over 750hp. ;)

David
 
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