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Earlier this month DEC 06 a thread turned to the lifter bore clearances, bushing lifter bores, etc. Someone said that .0015 was too tight and would make the lifters seize.

This website sometimes loses my little blue box by the threads I have replied, so I cannot find it now.

Here is a quote from someone who should know. I would call him a person of some noteworthy knowledge.


HOT ROD ENGINES magazine, Fall 2006, on the stands until end of February.

Page 72 article, "When Good Cams Go Bad",
quote on page 75, by Barry Robotnick, Engine Masters Challenge builder, Survival Motorsports, Walled Lake, MI.

The following quote is a response to camshaft failures and low oil pressure.

"Many daily-use or street/strip hot rod engines are built up from 35-40-year-old engine blocks. The average builder never checks the lifter-body-to-lifter-bore clearance. It may have doubled. Pro guys bush the lifter bores, but most homebuilders just dust the bore with a brakehone to make the bore smoother and remove varnish. If there's more than .001-.0015 clearance, you could be in trouble." Barry Robotnick

This concurs with what Smoky Yunick wrote many times..... You might also look up what Smoky had to say about SBC oil pressure.. 10 per 1,000 ? ....... and is regularly misquoted as saying.
 

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xntrik said:
Earlier this month DEC 06 a thread turned to the lifter bore clearances, bushing lifter bores, etc. Someone said that .0015 was too tight and would make the lifters seize.

This website sometimes loses my little blue box by the threads I have replied, so I cannot find it now.

Here is a quote from someone who should know. I would call him a person of some noteworthy knowledge.


HOT ROD ENGINES magazine, Fall 2006, on the stands until end of February.

Page 72 article, "When Good Cams Go Bad",
quote on page 75, by Barry Robotnick, Engine Masters Challenge builder, Survival Motorsports, Walled Lake, MI.

The following quote is a response to camshaft failures and low oil pressure.

"Many daily-use or street/strip hot rod engines are built up from 35-40-year-old engine blocks. The average builder never checks the lifter-body-to-lifter-bore clearance. It may have doubled. Pro guys bush the lifter bores, but most homebuilders just dust the bore with a brakehone to make the bore smoother and remove varnish. If there's more than .001-.0015 clearance, you could be in trouble." Barry Robotnick

This concurs with what Smoky Yunick wrote many times..... You might also look up what Smoky had to say about SBC oil pressure.. 10 per 1,000 ? ....... and is regularly misquoted as saying.
Well I hate to break this info to you as this hands on info and not from a book or magazine but I just measured a brand new GM lifter P/N 5232720 it measures .8422 in the middle of the lifter and we have measured the lifter bores on brand new block 10105123 and they seem to be right at .8443 which is too GM blue print and if you deduct .8422 form .8443 if my math is right it should come out to .0021 clearance which is perfect Now these are brand new peices right from GM and how do you explain this. HMMMMMMM

Take and measure lifters from different companies as you will find them to be different sizes and we have seen on many GM lifter bores that the lifter bores are not round and are not where they are suppose to be either unless it a new Bowtie block.

We have had to repaired some blocks for other machine shops that have machined lifter bores out to .875 on a SBC and have had them at .0012 clearance and the lifters have stuck in the bores on the dyno as we would have to bush them back and finish the bores at .8755 w and no more problems.

Call Precision Products in N.C. as they build lifters for a living and ask them what they prefer for clearance as Andy the owner has told me .0015 to .0025 is the prefered clearance.

We blue print machine a lot of blocks for engine builders and machine shops all over the country and I have never in 33 years of doing this type of work ever had anyone want a lifter bore with .001 clearance as I know this wont work.

We have seen engines come in the shop with worn bronze lifter bores and have around .005 clearance and seen low oil pressure at idle and with new bushings installed and CLEARANCED TO .0015 to .002 everything was fine.

Like I said measure a brand new block and then measure a brand new GM lifter your not going to find them to be .001

And as far as 10 PSI for every 1000 RPM what about the CUP engines that turn almost 10.000RPM and they are running around 42 pounds of oil pressure.

Another quote by the great Smokey that I and other engine builders have found not to be true is too much side clearance on rods will affect oil pressure, But we work on some piston guided rod egines that have almost .100 side clearance and we have seen zero problems with oil pressure as its not hard to figure out that it is bearing clearance that regulates the oil that is shed between the rods not side clearance unless there was under .007 side clearance then that may be the factor that wold restrict the oil flow.

Again I am sure if Smokey was still alive I am sure the book he wrote 40 years ago he woud revise some of his posts he wrote.

To compare apples to apples do you run or work in a performance machine shop and do the type of work we do on performace engines fi not can you tell me what kind of work you do??????????????????????

Believe me we have all Sunnen Bore gauges and the best mikes to measure lifters and bores with and this is factual info. and nothing from a book or magazine and the clearances I mentioned are standard in the industry and even new GM blocks are @ .0021 from what I have measured.

As its hard to argue with GM parts and someone who does this everyday for a living as we have seen what happens when lifters are run to tight.
 

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Discussion Starter · #3 ·
CNC
I am not "arguing" with you :nono: nor am I claiming anything.

I just passed on the direct quote. Call Barry Robotnick and tell him he is wrong. Survival Motorsports, 248-438-6900.

I have 40 years experience, more or less.
I got out of the full time engine business about 8 years ago. I love building, but it is a business that can be euphanistically catagorized as a pain-in-the-butt. You know what I mean? Taking it easy in the mountains.

True, Smoky might revise his old ideas... but the fact is that most of us are still dealing with the same old SBC from the 60-70-80s on a daily basis, and they haven't changed much except for better cam grinds and better flowing heads.

Oil pressure springs control the maximum pressure, not the minimum. If they're set at 42, then 42 is all the pressure you will get, hot or cold.

I feel that 10 at idle and 42 at 6000+ rpm is insufficient for the longevity of any street/performance engine.

93 truck SBC 5.7 has 150,000 miles on it and idles at 45 hot and hits 55+ on the spring at 2500 rpm.

Please, no red herring......... Cup cars cannot be compared to anything that we do here. period. They have $1000 camshafts, $1500 lifters, special crankshafts, and other gazillion dollar parts to make them last just one race.

Thanks for the dialog, :thumbup:
x
 

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Discussion Starter · #4 ·
Oh, by the way, Old Smoky said that oil pressure must be measured at the END of the gallery= the lowest pressure point in the system, not up by the pump.
 

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With all the GM blocks we machine I see the bores at ..8443 seems to very common in these blocks and lifter do vary from vender to vender and the gm lifter maybe on the small side compared to other lifters being built by other companys

We build alot of circle track engines in the Northeast and the tightest we have seen lifter bores on a small block and not stick is .0013 and under that we have seen them stick on the .875 and we have sone lifter bores that are on the high side and with the size of the lifters thay are up around .0025 on clearance and we have not seen any oil pressure problems as most of the 2 barrel engines we build we standard volume high pressure pumps in them and our engines run very good oil pressure.

On the engines we build with the 283 mains and Honda journal we actually have to machine another by pass in the pump cover to bleeed of the extra oil in the pan do to the small journals they don't shed much oil.

We had an engines come in the shop 2 years ago and this engine had SBC had .875 lifters and the bores were finished on the high side and the clearance was around .0032 and we saw no problems with oil pressure.

We have seen oil worn lifter bores that have been up around .005 and seen low oil pressure at idle and have replaced the bushings and it did pick the idle oil pressure up 12 to 15 pounds.

We finish lifter bores to blue print size which is .8443 on the small side as when we sell a blue printed block we have no idea what size the lifters that are going to be used .

When we hone lifter bores we don't use a brake hone as we use a Sunnen lifter bore hone and a Sunnen Bore gauge and when honing we can feel the out of round lifter bores and we have found them up to .0008 out of round and not cause a problem.
 

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Discussion Starter · #6 ·
I bet some of those old soft blocks with 150,000 miles have really egg shaped lilfter bores from the cam pushing sideways all the time. think? Most people just slap new stuff in the holes and go......

so 10 psi idle hot....... ??????? :sweat:
 

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xntrik said:
I bet some of those old soft blocks with 150,000 miles have really egg shaped lilfter bores from the cam pushing sideways all the time. think?
We had a 2.8 engine in the shop about 8 years ago and the lifters had worn about .030 do to the angle of the push rods on those engines but lifter bores were fine as I never figured that one out. HMMMMMMMM
 

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Discussion Starter · #8 ·
CNC BLOCKS N/E said:
We had a 2.8 engine in the shop about 8 years ago and the lifters had worn about .030 do to the angle of the push rods on those engines but lifter bores were fine as I never figured that one out. HMMMMMMMM

You mean the lifters were worn .030 and not the bores....??? yikes..... There's one for the "Automotive Ripley's" :thumbup:

Maybe it was some of those foreign lifters (?).

4 decades and still learning :D

Here's one.
Ford 302. Running fine, a little tail pipe smoke.

Found worn out cylinders measured .087 over with worn out .060 pistons.

Found 4 (four) flat tappet hydraulic lifters broken horizontally across the oil grooves and two of those the upper halves broken vertically in half also......

Ran fine, cam was fine........ ran like a screaming demon up to 6000 regularly..

Junked the block and installed a 5.0 HO fuelie T-5.

Hello, Ripley's ????????
 
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