Pinto compression?

[cunn5]

I have an 89 Van Diemen with a pinto 2 liter, what should the compression be? what should the acceptable difference be across the cylinders?

[Purple Frog]

Race engines are usually measured by doing a "leak down test". It requires a set of leak down gauges to do it. Do a search on Apex (FC general discussion) and you'll get lots of instructions.

Depending on how serious you are... most don't like to see any cylinder losing more than 5%. Maybe even less at the pointy end of the grid.

[rickb99]

Race engines are usually measured by doing a "leak down test". It requires a set of leak down gauges to do it.

A touch on the pricey side. But with the amount of info you can get about your engine, worth the price....

http://www.pegasusautoracing.com/productdetails.asp?RecID=5380

[jdp526]

has an inexpensive test kit for apprx $35: http://www.harborfreight.com/catalog...ry=&q=leakdown

I dont like buying Chinese but for home mechanic that doesnt use tools very often they do offer a savings.

[DanW]

has an inexpensive test kit for apprx $35: http://www.harborfreight.com/catalog...ry=&q=leakdown

I dont like buying Chinese but for home mechanic that doesnt use tools very often they do offer a savings.

I bought the HF one. Used it once.

Then bought a good calibrated one from AC Spruce. It works but could use a smaller orifice.

[rickb99]

....I dont like buying Chinese but for home mechanic that doesnt use tools very often they do offer a savings.

MOST Harborfreight/Chinese products are designed to be used 2 to 3 times then discarded before they self distruct. The orignial Mission Impossible keeping a Harborfreight product working.

[DaveW]

I bought the HF one. Used it once.

Then bought a good calibrated one from AC Spruce. It works but could use a smaller orifice.

I made my own a long time ago with a smaller orifice so that the readings were in the middle of the measurement gauge. I used 50 psig gauges so that getting sufficient pressure to max out the reference gauge was never a problem. It cost only the price of the two gauges + fittings. You can make any orifice size you need and substitute it for the original.

[Buc01]

I agree with the leak down test as being the best.

However, as a comparison, my engine read 160 to 165 psi across all cylinders with the engine cold and the carb closed. Cranked the engine over 5 times on each cylinder. I have no idea how much time is on the engine as I just purchased the car last July. I would say the temperature was about 85 F.

Upon purchasing the car and hearing the engine run, I wanted a quick and dirty way to see what kind of condition the engine was in so I did a compression check.

I have no doubt that a very fresh engine would give better numbers I am guessing 180 - 200?

Not trying to start a controversy, just sharing information.

Aaron

[cunn5]

I guess that is what I was asking. You think 180-200 is good? what about % of difference between cylinders?

[Pop Chevy]

I 'd be very surprised to see 180#. I think 160/165 is real good. These are not high compression engines after all. All cylinders within 5 # is excellent! Pops

[cunn5]

Thanks. I bought the car used about a year ago and ran some laps at a track I ran last January, last weekend and the times were down, on a 2 mile course, 3 seconds. I am running the same tires from a year ago, they probably have 350 miles on them for the entire year and still have pretty deep wear indicators. The weather was 15 degrees cooler and it was a night event compared to the warmer daytime event a year ago. I was thinking I should start checking for possible problems.

[Pop Chevy]

Possible problem is : Your tires are junk !!!

[rorym]

165 is a heathy engine...^^ Agree with Pop.
R

[cunn5]

Is this John Berget tires a good economical place to buy tires?

[Bob Coury]

I was going to purchase gages, orifices, and the like from McMAster and make my own. The price to do all that was right up there with purchasing one from Pegasus or Saferacer, or possibly an OTC Brand unit.

As others have stated, I would stay away from the Chinese junk. I woould have zero confidence in the results. Sometimes you get lucky with the Chinese stuff, like the manual tire machines or perhaps a grinder or press, but most of the time, most of it from toys to electronics, it ends up in the landfills.