(rings) leak down. What's to much and how much does it matter?

[yellowfever]

I have a 2.4 bridge port block (1993) it's now a carb motor. How much does ring leak mater? How much is to much leak down? The motor used to run 7800rpm with a 28 et prop. Over about a year of running ever weekend it will now only do about 7200rpm. Is leak down my problem? How can I test it? When the motor is cooled it will run 7800 7700rpm but after the first pass it will only run 7200rpm. It has 120 pounds on all 6. I put 2.0 heads on it and it's still at 120. Is it time to re ring it. HELP!!!!

[yellowfever]

I got a new cdi stator,new cdi trigger and it still runs the same. Even with a 26 et cut copper it still runs 7200 rpm

[wanagofass]

Sounds like it's tired to me, do a leak down and post your results, JSRE on here sells a really good leak down tester look in the stickys at the top of the technical section. Id do the leak down cold first then warm the motor up and see if it changes since you say it runs fine for the first pass, may not be any real damage just ring wear, could be loosing ring tention with heat.

[HStream1]

I've seen good compression and a poor leakdown. To answer your questions. A rering is possibly the solution. But you need to do a Leakdown or have one done. IMO as well as others 10% is the breaking point for a rering if you see 8% I'd do one anyway. To accompolish a leakdown you need a leakdown tester. IMO there is no substitute for a quality leakdown tester just like any other tool. There are plenty el-cheepo's on the market (harbor freight, northern tool etc) and they are just that. They may work OK for awhile but it's crap shoot.

Balzy sells one of the best leakdown testers going. While Jay at JSRE sells alot or really highend products I never knew of him selling leakdown testers as he personally uses a Balz.

Here is a link,e-mail etc to Michael Balz. looks like he still might have a couple left from the last batch he built.
http://www.screamandfly.com/showthread.php?235307-Get-your-Leakdown-Testers-NOW-!!!!!&highlight=leakdown+tester

[Lockjaw]

I got one from Summit Racing, it works well. The harbor frieght one sucks.

[sixpac]

10 % is what most look for a little over is no big deal for a rec motor, does sound tired but may have other issues at 120 psi comp.

[rev.ronnie]

I got one from Summit Racing, it works well. The harbor frieght one sucks.

The harbor freight one is a complete POS. Had to replace both gauges on the one I bought for the car trailer..all their stuff pretty much sucks rocks.

[Jay Smith]

I like 8% or less on a known broke in motor... If a nik coated bore motor is more that 10% its fixing to cost you a plating job IF you don't make a move and re ring and QUICK !

Jay

[yellowfever]

Isn't a bp block crome plated? And from the factory they had 125 psi. Right? And shouldn't the comp. Of gone up with 2.0 heads?

[Jay Smith]

I don't guess at anything, the ONLY way to tell is a fluid burett and CC both of the sets..

Jay

[yellowfever]

So r bp blocks nik or crome? And on a regular 2.4 when u bolt on 2.0 heads the comp gos from about 125 psi to around 145 psi. So u might gess a bp motor would do the same?

[Lockjaw]

The harbor freight one is a complete POS. Had to replace both gauges on the one I bought for the car trailer..all their stuff pretty much sucks rocks.

It's awful. I could only get mine to go to 10 psi on the first gauge before the second one maxed out. None of the o-rings were any good either. I had to work way to hard to get it to seal up just to put air pressure to it.

[yellowfever]

I did a leak down test with a good Mac tester and I got 6persent when the motor was cooled. Then I let the motor run and warm up, but it don't get very warm on the hose. Anyways warmed up it was 11persent.

[rvaha]

I've got one from Balzy. Works great. Had one from Harbor Freight and took it back. This is just a shot, but any chance that things might be carboned up and a heavy dose of Seefoam might help? Best of luck!!

[yellowfever]

I tried that but no change. I will rering it or build a new one next week. This one runs great it just will not pull the rpms it used to. And yes a bp block is Crome NOT nik. I was thinking of building same motor but a 5 peddle insted of a 7 peddle. I think it will pull harder and still make the same 7800 rpms.

[Steve Pope]

1988 and later BP 2.4 were Nicasil,1987 and earlier were Chrome. Steve

[yellowfever]

I have a 87 and two 92s and they r chrome

[Balzy]

Sorry I missed this thread. I would rering at 8% on any nic motor or it's just going to cost you more. (like Jay said) If you are just a fishing boat guy you can get away with 12% on a steel bore motor if they are all even and you don't care about performance. I have a bunch of LD testers built up and ready to ship again. Click on the website link below for details.