have a bad feeling I need to do a compression for a cople reasons

1. low performance on a mustange dyno 220rwhp

2. when doing dyno run on decceleration car smokes likes crazy.

3. on cold start up smokes like crazy. even when warm smokes a little.

my question is do you guys think i should do a compression check and if so is there a cheap kit that i can use with my shorty headers.

Also builder says its normal that it smokes on deccel.

 

NEver hurts to check the compression; but I doubt it will tell you much useful in this situation.

Smoke at decel (extremely high vacuum) and startup is almost always valve guide seals. "Normal", maybe; "acceptable", no.

Not sure anything about "cheap kit"; ordinarily, I just use a compression gauge.

 

Had the same issue a few months back. Ended up pulling both heads. Valve guide seals were shot. The factory ones they install are sh*t. Also had them resurfaced while I was at it they were slightly warped, not unusual for our hot running engines. Machine shop said the shaving off of a little material would actually attribute a little more horse power. Not much though.

 

What color smoke? Blue-ish = Oil. Valve stem seals most likely. If the seals are on the older side, you can try an engine oil treatment that makes the seals swell a little and that might help. It worked on a rice burner I had. No more smoke at all.

I'm not sure what shorty headers have to do with a compression check? A hose and gauge just screws in the spark plug hole. Hose is flexible.

Poor performance on Dyno? What were you thinking and what did you get?

Engine specs please?

Don't forget that RWHP is about 30% lower than flywheel hp. (FWHP) I'm not sure of the exact percentage but that will get you in the ballpark. So you're 220 rwhp is like 300fwhp if that makes you feel any better.

I just had a cam and head installed and had poor performance that turned out to be valves were too tight. Loosened them up and adjusted while running the engine and gained bunches of power. Night and day difference.

HTH

 

yes i was just thinking i should have given that info sorry.

383 stroker flat tops -5cc. around 10.4compression
brand new RHS heads
cam is 500 lift cant remeber duration have 1.6 rockers
motor may have 1000 miles give or take a hundred or so

 

Man brand new heads. Brand new seals. Piston rings?

 

Whats the story on the motor. Crate engine. Shop built?

 

Just re-read original post. Builder says smoke is normal on decell? hmmmm. Blue smoke?

 

yes blue. i was recording a cold start up and battery died when i get home ill see how long it recorder and maybe upload


oh and yes new everything except for crand and carb.

 

i'm assuming you paid for this build? Sorry to break it to ya but engines shouldn't be built to consume oil and top off every couple hundred miles. Only upon break in but that's no more than 1/4 quart at most. Yeah man go with the compression check, simple in the spark plug hole guage and either rotate by hand or cutoff fuel to your carb and rotate with starter via key with a buddy or jumper starter by yourself. This is a slight chance though you may be extremely rich especially if its occuring on decel. But the color would be more blackish than a blue. Compression check and making sure those piston rings are sealing is your best bet to start.

 

Ok guys here is the vid of it smoking on start up sorry its only 1:08 long batteries in camera died. Hope the quality is good enough for use to see the smoke.

http://youtu.be/sYlUeNOWX5Q

 

Yeah thats definetely oil consumption man. When ya get a chance grab a compression guage. Record all compressions and post. If you are absolutely sure the heads were build in good quality then I would suspect either blown/leaky head gasket possibly not torqued properly down. Or the least favorable piston rings. somewhere in there your gettin oil in your cylinders.

 

I had a vehicle that had a oil ring that had skipped 1 bump (not collapsed) when installed and did not apply pressure to the cylinder walls. It smoked like that and worse under full throttle but still had great compression and ran great. The plus side was there were no mosquitos in my hood. Thats more than valve stem seals. I say oil ring on a piston. You can probably pull plugs and they'll tell you which cylinder(s) its happening in.
PS.. did seem like it took a lot to start the car in the video.

 

Yeah it did! You have some fuel adjustments/proper spark to look into as well.

 

not sure what u mean.

i always prime the oil before i start it. then i give it two pumps on the gas and it starts right up. i have to keep my foot on gas to keep it running. and it feels like its missing for a good 2 min.

Going to try and explain something eles.

when i was at the dyno the i asked the guy about a compression check. he has this big computer there that measures voltage or something on each cylinder said it was kinda like the same thing. was some kind of metal clip that went on top of dizzy he could cut off each cylinder with computer. any way when he did this ''voltage check'' only three cylinders read 9.5 steady others were all over the place not holding steady. does anybody no what i mean

 

Yeah he's reading timing differentials that are fed to the ECM for metering fuel and such. If you got a buddy that has that equipment by all means utilize it. I'm just not the type to fork over cash for something I can do with a plug in hose and a guage.
And come to find out I might have cursed myself for jumpin on this thread as I too need to do a compression check on the beast. Just re-installed both heads and intake manifold and I'll be darned if I was billowing white smoke (coolant) from left side of dual exhaust. Does anyone know if this would be a good indication of left side coolant intrusion? I'm gonna have to compression check to isolate cylinder/s. LOADS of fun I'll tell ya. I think I'll opt out of the coolant system pressure check as I am certain from the billowing white smoke its coolant related. Does anyone know of any tricks to isolate intake manifold from heads? Don't think there is but any short cuts would be much appreciated.

 

So you guys think I should start with a compression check?

If results are low could that explain my (what I believe) low HP

 

transam: It won't hurt to do a comprssion check. It will actually be good info to know. And yes if compression is low that will steer you in a different direction. Who set you valves and valve lash. Just this week I had gripped about lower power than I thought it should be. Readjusted my valves and found out I had the too tight, about 1/2 to 3/4 turn too much. Adjusted them running, back off until the made noise plus a half turn, gave the lifter a chance to pump up if any, then tightened back down to the valve quited down and only gave a 1/2 turn more. The results= Much closer to the power I was thinking it should be. I still have more tuning to do, but what a lesson learned. I am much more pleased.
After reading your engine specs again, I think you should have closer to 275 rwhp. That would be like 350 fwhp. What kind of torque numbers did you have? List it in 500 rpm increments if you can.

 

Texas: Is you exhaust a dual exhaust that does not have a x pipe or h pipe? If they are totally seperate then the left side indication would be a fair analysis that its from the left bank.
The only trick I know might be to locate the cylinder its happening in. Pull the spark plug and see if it has a yellowish build up/tint on it. That would be the coolant crystalizing. I had this on a set of heads I pulled but did not have any white smoke appearing yet. But after removal that was the only cylinder that had a different color to it. So I took the spark plug to a friend with a lot more experience than me and he knew right off what it was. So I figured the head gasket failed fairly recently.
There is suppose to be a kit at autozone/oreily's that can tell you if there is exhaust gas in your coolant. If you know you have a leak and there is no exhaust gas in you coolant then I would think its in your intake as there is no pressure like in a cylinder. If it does have exhaust gas then I would think it would be in the head as the compression would push into the cooling system. Please update if you find a way to tell. As I recently installed .015 headgaskets and am a little nervous about them. The head was surfaced but the block was still in the truck. I've seen a hint of smoke, kind of a neutral color, not white but slightly. It may be condensation but you never know.

 

the builder adjusted valves before i got motor back. never been checked since.

all i can say is tq was around the same and it maxed at like 6200 rpm

 

Thats a pretty badass way of telling between intake manifold and cylinders. I pulled my valve covers and went 20 ft lbs above torque on my head bolts with Rockers arms still installed it is possible. Below the exhaust manifold a little more difficult. Fired her back up and got less smoke also went 10 ft lbs above torque on intake manifold. They felt like they could have used it anyhow. As I too got my heads resurfaced and not the block. But I went with Stock gaskets prob. should have gone slightly thicker. Gonna throw 10 more ft lbs at the heads what do ya think? Is going around 100 ft lbs asking for some warping? Original torque was 60 ft lbs. And yeah I have the H exhuast.

 

Success, retorqued to 100 ft lbs. No more coolant cleaning my spark plugs. Running a little like crap right now though I got the TBI so I'm gonna have to do some tinkerin round with vaccum and such. Also might try that trick with adjusting the rocker arms while in run. Sounds pretty badass as valve lash is such a sketchy process and I like the idea of listening to what the engine is telling me while I play with her.
Did you knock out the compression check yet dude? That smoke to be honest with you in the video looks to be a little bit more on the white side. Check to see if it feels somewhat steamy when you put your hand in the exhaust gases from the tailpipe. I know it sounds kinda weird but its a little less complicated troubleshooting. Mine felt kinda steamy when passing my hand through a few times. And it could be possible it's both coolant and oil making its way into the cylinders. Just some food for thought good luck.

 

compression test done. Had to take off my headers. Hooked up the Compression tester cranked motor over few times and this is what I got.

1. 200 2. 207
3. 205 4. 205
5. 205 6. 199
7. 200 8. 205

 

Actually, what the tech at the dyno shop was doing was a power balance test. The machine he had it connected to was most likely an engine analyzer. Pretty old school stuff. In the power balance test, the machine simply monitors rpm drop as each cylinder is cut. The metal piece he put on top of what Im betting is your HEI distributor is simply an inductive pick up to read KV. On an external coil ignition you would use an inductive pick up clamp like inductive timing lights have.

If your engine has a lopey cam, it's really hard to make sense of power balance test results. The lopey idle is basically a roving misfire and the engine analyzer will read it that way. Each test will show slightly different data for individual cylinders as the misfire moves around the engine. Your compression test results look pretty good. Did you perform a ring break in procedure? I'll bet you didn't. To break in rings, you need to find a steep hill where you can drive up and down at a slow pace. Put the car in a low gear like 2nd and slowly drive up the hill, keeping rpms around 2,000. Then turn around and drive down the hill allowing the engine to hold the car back. Don't let rpms go over 2,000 during the process. Repeat this about 20 times.

Now that you have put 1,000 miles plus on the engine and the rings are not seated, You will likely need to start over with new rings and a new cross hatch on the cylinders. Then, as soon as the engine is running again, do the ring seating procedure.

Texas, your steam sounds more like normal condensation in the exhaust. Most every car does this on cold start up. Especially cars with catalytic converters. As the exhaust cools after the car is shut down, moisture condenses in the exhaust. As the exhaust heats up on the next cold start, this moisture is boiled off and comes out as steam.

If you had a leak between a combustion chamber and a coolant passage, your coolant would be boiling anytime the engine is running. Combustion pressure is about 3,000psi, versus cooling system pressure of about 15psi. Coolant doesn't get into the combustion chambers, combustion gases flood into the cooling system, displacing coolant and causing severe overheating. The engine would be undriveable in this condition. Be careful with 100ft/lbs torque on those head bolts. That's a little excessive.