post me some questions

[grumpyvette]

the first step is to do a compression test [n]on all cylinders and write down the results[/b] if you only did a few cylinders

and you need to verify the cam is lifting all the valves to the correct height and your getting spark at all the plugs, it sounds like your dealing with a worn cam or an ignition problem with the limited info

[bigbore468]

grumpyvette,

 

Can you share some insignt on what causes piston ring stacking; when the gaps in the 1st and 2nd piston rings line up in the bore.

We see this usually starts after 100-150 1/4 mile passes.

Believe the usual things that cause the ring gaps to stack is cylinder bore distortion, or detonation; however we still see this issue with SBC bow tie block using race gas; standard gap type piston rings; .043"

 

Any advice will be much appreciated.

 

Cheers

[grumpyvette]

first question, what makes you think the ring gaps are lining up, and is it occuring on one or all cylinders in YOUR application?

 

the only time IVE seen that was on exceptionally thin cylinder wall blocks (UNDER .200 on the THRUST SIDE) (.250 as a minimum is prefered and thicker is better)

keep in mind its not unheard of for rings to slowly rotate in the piston grouves and that means its normal for some rings on some pistons thru random chance to be aligned, at any given time, but detonation can and does cut a grouve thru the pistons ring lands/grouves , or partly melts and locks rings in place

Edited March 10, 2009 by grumpyvette

[bigbore468]

first question, what makes you think the ring gaps are lining up, and is it occuring on one or all cylinders in YOUR application?

 

the only time IVE seen that was on exceptionally thin cylinder wall blocks (UNDER .200 on the THRUST SIDE) (.250 as a minimum is prefered and thicker is better)

keep in mind its not unheard of for rings to slowly rotate in the piston grouves and that means its normal for some rings on some pistons thru random chance to be aligned, at any given time, but detonation can and does cut a grouve thru the pistons ring lands/grouves , or partly melts and locks rings in place

 

grumpyvette,

Thanks for the reply.

Here is what my buddy told me about the problem they are having:

 

He said that 7 out of 8 cylinders had their rings stacked, and he could

tell when that happened because the car would slow down. The engine has a .020 over bore. He is assuming that the power loss occurred slowly as each cylinder stacked one at a time.

[grumpyvette]

Are you seriously suggesting that your buddy says, he can tell when the ring gaps line on the pistons , by the way the car runs, and he has NOT pulled the short block down and carefully inspected each rod and piston and the condition of each cylibnder and piston and rod,too verify that that is indeed the case? HAS HE DONE A LEAK DOWN TEST ON THE BLOCK

whats to say the rings are not binding in thier grouves?

the end gaps are not butting under high heat?

the rings are warped, or not correctly clearanced?

the recess behind the rings is not carboned up?

the pistons not overheating and expanding due to detonation?

the side clearances are not correct?

the piston pins not binding in the piston or rods?

the bearing clearances on the rods is not consistant?

the blocks not align honed?

the cranks warped"

theres a valve train problem?

whats the surface of the cylinder hone pattern suggest is the cause?

was the block honed with a deck plate torqued in place?

were ALL the cylinder walls checked for thickness?

was the block deck verified as strait and level?

or a dozen other factors I can think of?

without careful inspection and verification, theres a strong tendency to relie on GUESSING and thats almost always related to spending a good deal of wasted time and money

Edited March 12, 2009 by grumpyvette

[bigbore468]

Are you seriously suggesting that your buddy says, he can tell when the ring gaps line on the pistons , by the way the car runs, and he has NOT pulled the short block down and carefully inspected each rod and piston and the condition of each cylibnder and piston and rod,too verify that that is indeed the case? HAS HE DONE A LEAK DOWN TEST ON THE BLOCK

whats to say the rings are not binding in thier grouves?

the end gaps are not butting under high heat?

the rings are warped, or not correctly clearanced?

the recess behind the rings is not carboned up?

the pistons not overheating and expanding due to detonation?

the side clearances are not correct?

the piston pins not binding in the piston or rods?

the bearing clearances on the rods is not consistant?

the blocks not align honed?

the cranks warped"

theres a valve train problem?

whats the surface of the cylinder hone pattern suggest is the cause?

was the block honed with a deck plate torqued in place?

were ALL the cylinder walls checked for thickness?

was the block deck verified as strait and level?

or a dozen other factors I can think of?

without careful inspection and verification, theres a strong tendency to relie on GUESSING and thats almost always related to spending a good deal of wasted time and money

 

Thanks grumpyvette for the advice.

Passed this along to my buddy and told him to do more research on his own; as you noted, there are too many factors that could have caused his piston ring problems...

[Bowtiez]

I have dumped the Supercharger idea for now. I found a 700CFM Holley Double Pumper which just so happened to be sitting on Blue Oval Z's unwanted Manta kit car Chevy drive train so I bought the whole thing for a future project. Throttle response is better the 650 dirt track I borrowed. No flat spots and it idles smoothly at 950 CFM with an Edelbrock 2204 roller cam. No more switching back and forth to an Edelbrock for a street carb!

[280Zone]

My question relates to a 60's era 327 SBC and reasonably priced option heads.

 

Based on the block number it appears I might have a 60's era corvette 327 small block with stock heads (Motec says the engine came with 60cc chambered heads). The question is would a set of 70's era 64cc camel hump heads (1.94 1.5 valves) be a good choice to have rebuilt for a combination to create around 260HP? Any suggestions for cam specs and carb size with that target in mind?

[grumpyvette]

first id want to know the application, IE manual or auto trans, and your intended purpose for the engine, getting 300hp from a decent 327 is fairly easy and those camel hump heads are fine at that hp level, but they are also 40-50 years old and may not be rebuildable are a reasonable cost to value ratio, IE you might pay more to rebuild them than the heads are worth.

Id be glad to work out a decent combo if I get more valid info

[BelgianZ]

There are many Chevy V8 engine builders in America, but is it possible to have an engine-transmission combo built in America (by one shop) so that I can have the entire package shipped to Europe?

 

Great thread BTW:icon14:

[Careless]

There are many Chevy V8 engine builders in America, but is it possible to have an engine-transmission combo built in America (by one shop) so that I can have the entire package shipped to Europe?

 

Great thread BTW:icon14:

 

you can ship anything that will fit in a shipping container. even a car.

[Michael]

I guess that I'll take my turn at asking what's hopefully a serious, practical question.... It has to do with oil leaks.

 

As Grumpy already knows, I have a Mark IV 454-based big block, originally from a 1978 Suburban. The block is 0.030-over, decked, but otherwise stock. The crank is ground 0.020" on the mains and balanced, but otherwise stock. The rods are resized and fitted with ARP bolts, but otherwise stock. The oil pump is Moroso something-or-other high volume (sorry, can't recall the PN) with a pickup welded out-of-the-box. The oil pan is a Hamburger 8-quart, and uses a single-piece gasket from Napa. I have a stock 8" damper.

 

Now the question... whenever I spin the oil pump with a drill, there is a significant leak of oil from the back end of the oil pan. It is not profuse, but enough to make a foot-wide puddle after 15 minutes of vigorous spinning of the pump and turning of the crank with a wrench. I can not, however, find an obvious area of the oil pan where oil would be dripping. The flywheel and the surrounding area, to the extent that it is visible, is however moist with oil.

 

Do I have a leak through the rear main seal? Or can another cause be impugned? The engine has a total of 43 miles on it, and has not been run in 2-3 years. And would the leak go away if the engine is actually running, instead of being hand-cranked, because of net suction inside the oil pan? I most definitely do NOT want to do another rebuild, as it will have been the 4th rebuild so far (so, that averages 10 miles per rebuild!!!). BTW the oil windage screen is 3/8" above the sump floor - I verified with clay. And the oil pressure rises to 60 psi about 3-4 seconds after I start spinning the pump with the drill motor.

[grumpyvette]

the first step in fixing any oil leak is finding the source, of that leak, theres several suspects on the rear of the block. youll want to verify whats leaking, potential sources

a rear main seal installed facing the wrong dirrection , the wrong oil pan, the wrong oil pan, gasket ,the wrong oil filter, the wrong oil filter adapter, or improper installation, or forgetting to connect or plug a passage jumps to mind

one old trick is to clean the area with carb cleaner , that tends to leave a dry surface and then dust it with talcum powder , use a strong light and have a buddy spin the oil pump, tracks in the talc dust make it easier to find the source

look at

rear intake manifold seal

rear cam freeze plug

oil passage plugs

oil temp sensor

oil pressure sensor

pressure sensor threads

oil pan gasket

rear main seal

oil filter adapter

oil filter

 

this might help locate the source

 

http://forums.hybridz.org/showthread.php?t=126081

 

http://forum.grumpysperformance.com/viewtopic.php?f=54&t=206&p=242#p242

Edited March 25, 2009 by grumpyvette

[gvincent]

I have an Hamburger oil pan on an LT1 and used the 4 piece Transdapt/Hamburger gasket kit, I had the same leak from the rear, I dropped the pan again and re-applied more sealant and it still leaked but a lot less. I called Transdapt and they sent me another gasket kit free of charge, I haven't installed it yet as the motor deveelped a knock and is being swapped out right now, I know you are not supposed to use the one piece GM pan gasket with the pan, Maybe you need to use the Hamburger Gasket? and not use the "single-piece gasket from Napa"???

Greg

[belizeN714]

I'm curious, will a type r throttle body(62mm from what I hear) work on my l28et or should I stick to getting the 5.0 mustang throttle body(60mm)?

Edited March 25, 2009 by belizeN714
this is for a l28et not a chevy motor plz forgive me

[scubamark3995]

I noticed bad vibration when I accelerate from a stop. I checked the rear u-joint. It has a little slop in one direction. Will that cause the vibration? It does stop after I build a little speed. I have a new bottom mount on the diff and I am getting ready to install a top R/T mount. What is the diference in measurement for the v8 flange vs the stock. So I know which one I have. Someone else built the car.

Test.... Do you know where the oil pressure sending unit is located on an `03 3/4 ton GMC?

[jay260z]

Same basic location as a sbc but in the middle of the block instead of to the side, you may need to take the manifold off to get to it.

 

 

http://econtent.autozone.com:24991/znetrgs/repair_guide_content/en_us/images//0900c152/80/1c/b1/cc//medium/0900c152801cb1cc.gif

[scubamark3995]

:(Thanks, but not what I wanted to hear.

[waterjetguy]

HI ,

I`m new to the Z ownership but have a lot of great memories with one as a friend owned a `78 that was a vette killer in stock form.My comment to the LS coming on strong is the Hp you recieve [400+] for only 30lbs of weight gain, and the way it sits it gives a lower more even center of gravity for handling. No suspension changes needed maybe bumping up to the R200 diff. so bang for the buck is very good and the computerized injection is pretty fuel effecient for the power and has great street manners. if you change altitude allot where you live careberetors can be a pain and not very efficient

My 2 cents,Chris

[jay260z]

The motor ive got is a sbc 327 with 9.5-1 comp, forged pistons, I beam rods, forged crank, double hump heads, performer rpm manifold, holley 4160 ~600cfm carb, full msd ign. The cam is unknown because he lost the build specs and dosnt recall whats in the engine. It came out of a frieds chevelle after about a year of very light use then he converted the car to a ls1/4l60e to be faster and more reliable on the street.

 

My z is going to be a street/strip car and i am hoping to run in the low-mid 12's if not faster on just the motor. The engine is backed to a tremec t56 out of a lt1 camaro and the rear end ratio is gonig to be a 3.7 or 3.9 ratio once i find one. The engine right now will not run that fast i konw for sure because the 3800lb chevelle ran a 14.48 at 97mph with a th350, 2300 stall, 3.73 posi and no tire spin but ran out of gear before the 1000 foot mark.

 

What cam would you suggest to use to run the lower end of a 12sec pass or faster?