I have a new 383 stroker with less than 1000 miles and it is starting to have some engine blow by. I don't have a PCV set up just a filtered breather in each valve cover. At idle it starts to smoke out of the breather's. I did a compression test and found 233lbs at each cylinder which sounds like a lot. Please give me your opinions.

hope it's on at least 100 octane. pressure's sound good though. good for racing.. not well for pump gas like 93 octane.

maybe gets some semi hard pulls on it from second gear through half of third gear,, to load the rings against the cylinder walls and see if it seals up.

was it torque plate honed?? what type rings and what type bore finish were used for them to seat to???

WOW!!! As said "Race Gas"

74RAT:

I can use 93 Octane with no problem. It does have a nice lopy idle. I bought the engine from (Arracracingunl) Ebay seller who is an engine builder. The build sheet states the machine work, which includes "Bore Torque Hone" The rings are listed as "Childs & Alberts-zz gapdura Moly file fit rings"
I have heard that higher cylinder pressure will cause some blow-by. I have thought about adding a PCV set up but I am hesitant about the effect it might have on my Carb performance taking away that much Vacuum?

Thanks for your comments!

I have 205 and run air breathers only no pcv.

IMO all engines needs some type of PCV with a vac pull on it.. The stock PCV idea is one of the best for street/strip engines. Use a 69 camaro z28 302 replacement PCV valve.. Also heard the 4th gen F body 6 cyl valves works good in high performance engines.

Evac is next for race engines. This uses the exhaust to pull a vac on the engine rather than useing the carb.. Only prob is with alot of street use they are known to blow oil out the exhaust pipes.

Then for all out hardcore racers.. The vac pump set up

74RAT:

I can use 93 Octane with no problem. It does have a nice lopy idle. I bought the engine from (Arracracingunl) Ebay seller who is an engine builder. The build sheet states the machine work, which includes "Bore Torque Hone" The rings are listed as "Childs & Alberts-zz gapdura Moly file fit rings"
I have heard that higher cylinder pressure will cause some blow-by. I have thought about adding a PCV set up but I am hesitant about the effect it might have on my Carb performance taking away that much Vacuum?

Thanks for your comments!

i'd figure that if you did a leakdown test to get a current idea of where you are with it,, you'd always have a comparative tool in your head to know where you are with it,, and be able to tell if it's getting sealed or loosing seal from this point on with it.

i'd also think that if you had 5% leakage at 233lbs of cranking pressure,, that it would be more leakage than 5% of say 150lbs of cranking pressure. but most are checked/leakdown tested at arround 100lbs of pressure for the most part. but it's a comparative tool at best. some leakage/blowby is not unusual in the first miles of running an engine. if it's just a little smoke,, and not puuuking oil on the covers,, i wouldn't sweat it just yet. a pcv should take care of it and re-burn what's left-over as it finishes sealing up.

i agree with night rider on the pcv setup for the street. someone else mentioned also a 90 or 91 camaro 3.1-Liter v-6 pcv valve works well also. something about it having a smaller restriction orrifice and spring tension for lower vacuum engines.

i also think it's both of those 2 guys here above running over 200lbs. cranking pressure on pump fuel. i'd cater to them first for timing advance rate querry's before you ping that puppy out of commission. be careful with it on timing settings. that's alot of cylinder pressure. maybe start with arround 28*-29* total and get some plug readings as you sneak up on the total. i realize you say you're having "no problems" with it on pump fuel,, is that with "no traction"???? traction makes a difference.

i'm sure they'll have some good input. just not much of a safety margin at that level with that fuel rating. a stall converter that slips through to the torque peak and deeper gearing will help unload the engine below peak torque to ease the pinging problems getting it moving,, and sometimes not using or limiting the amount of vacuum advance available sometimes helps. jmho. good luck with it. sounds like it's gonna be potent as all get out. keep us posted.

Like 74rat said detonation will be a prob with that cyl pressure and pump fuel.. No question to it.. You hearing it or not.. It is there unless you got the tune spot on.

I'm running 212 to 218 psi cyl pressure and just to get it to run on pump fuel with total timing that didnt kill power was a nightmare really.

I'm iron headed, with .040" quench height, polished piston crowns, and head chambers.

pump 93 octane.

34* total timing, full at 3100 rpm. Limit vac advance to 9* To keep from pinging to death I had to jet the carb pig rich, add a sealed to hood scoop cold air intake setup. No Tstat just a plate with a 3/4" hole in it. Keep water temp in the 180's to 190* max.

2800 rpm stall 11" converter, 3.42 gears to take the load off engine. Along with a few other things here and there to keep detonation at bay.

Guys:

I really apperciate your comments. I learn something each time and just love this site. I will try the PCV set up. Hey 74rat: At about 700 miles I had to see what this set up would do and did 3 runs for a best of 12.7 with a 60' of 1.741 at 105MPH. I did have MT 275/55/15 Drag radials on at the time.
I was impressed since it was basically out of the box not really set up.
I also have a 2800 stall 3:73 rear with a 3.06 first in the 700R4.

The build sheet states it has 10.3.1 compression. I have heard that Aluminum heads help with higher compression and detonation problems.

Again Thanks!

cool deal!!!! yes,, aluminum gives up the effects of about approximately a 1/2 point of compression ratio,, maybe a little more in some cases. so that could be your saving grace, if that's what you have. can't wait to hear the times with the final tune up!! good luck with it. sounds strong as it is.