hmm
so
all right here's this uh this is a cra pro late model this is a class that it runs
it's a template body deal it's just got a gm 604 crate engine in it uh obviously carbureted
kind of thing i don't really know much about the rules for the engine itself
um i know that being a crate engine though they do that just to try to um you know get the class
close power wise and this particular engine as of last year was required to run a uh inch 200
restrictor under the carburetor so they're trying to balance the class power wise very well um so
any advantages you can get are going to come from stuff you can change like running different oils
uh air cleaner design stuff as far as like air pan where you're pulling the air source from
the carburetor itself um that kind of that kind of thing so this is just a pump gas engine i
believe it's uh like a nine and a half ten to one deal which would make sense for the compression
ratio but i believe that's just what the class requires so this will be something interesting
i'm going to this is actually here to get broken in it is a fresh engine we're going to do some
braking procedure stuff which is just a lot of moderate load uh you know slow rpm sweeps to
into basically trying to vary manifold vacuum to set the ring so we're going to go through that
process first and then start tuning it i have two carburetors set up for this i'll be curious to see
if there's an advantage one over the other uh sometimes there is sometimes there's not
it depends so one of them is a brand new car the one that's on it was on their last engine
so i'm gonna get this thing strapped down uh run through the brake in process and then we'll start
uh going to the tuning process i know right now he's got this thing set at 35 degrees of timing
i think once i get through the break-in process get it up to temperature
i'm going to drop that down to uh to 30 and start this we'll start at 30 get the
feeling close and start bumping a couple degrees into it until we see the torque peak level off
so yeah i'm gonna drive it into this thing and get the engine broken and we'll go from there
so
okay so that was the first hit the wideband reading was so rich that
it actually didn't even get a good reading so it was mid tens all the way
i'm gonna go ahead and move some jet sizes i don't know what's in this yet um but we're gonna
probably pull four sizes out of it to start and then go from there so right well i'm gonna keep
working all right here's the power curve the all the dots are because we didn't make it through the
uh recording window so it recorded on the way up and on the way down um you see the little
torque hit here in the center this thing's got a lot of gear and it's got like a 567
gear in it currently uh i was starting to pull at 3 000. i'm probably going to start it at try
it at 2500 and see if that'll smooth that that value out there but you can see these dips here
and here that's actually where it was breaking up because of how much fuel was in it
um so now that we've got the 70 jets in it or the well that's not true because we've got 70s in the
front and 72s in the back so we've gone down uh two sizes in the front three sizes in the back
and we'll see if that uh fixes our overly rich issue uh it made right there 326 horsepower 364
foot-pounds of torque it made peak power at 5800 again this thing is a little it's got 30 degrees
of timing in it they typically from what i've what the customer told me they usually run around 35
so that power peak will move as we increase timing and i will show you that as well um but for
now we're ready to uh get some fuel back in the carburetor and make another hit with a jet change
okay you definitely tell it rain smoother that time time all the way to the limiter this
class runs a 6400 ship it's it's still in it i've left it there
um so it didn't make a big peak number difference
um i'll show you it made 327 peak rather than 325 it actually lost a little bit of torque but again
because of that hit in the beginning uh it still has that spike in the initial throttle pickup
it's kind of the dilemma with the dyno with light rollers like this thing has and the gear ratio the
car has if this thing had a 410 in it rather than the 567 gear that's in it that would be much more
controllable it's just kind of violent the way it sits but check out the average number difference
oops sorry was on the top there 250 231 uh so 19 foot pounds of torque and like eight horsepower
look at the difference in the curve move that out of your way a second
so yeah check out the difference in the curve uh the top line obviously being the one with the fuel
pulled out of it the bottom line being without it so see how much of a difference it made up here
that where it was breaking up before it didn't run clean obviously it ran clean through that
time looks much better so now that the jetting is in the ballpark uh ignition timing will have
an effect on the afr so i'm going to start putting a couple degrees of timing in it and uh see if we
see if see how it likes it see how it likes the timing change see what it does to the fuel curve
uh it is mid-11s now which is still pretty rich i'm gonna leave the thing a touch safe um
i want to leave it around probably like low 12s because these things travel all over the country
different elevations different humidity way different weather conditions excuse me so i tend
to tune them a little conservative on the fuel so they've got some it'll move around a little
bit and still be okay uh timing wise it's pretty much the humidity will have an effect on it but
again margin for error on something like this is pretty pretty decent so we'll leave the timing a
little bit conservative say two degrees shy of mbt and run it there um so i'm gonna put
two degrees in this thing leave the jetting alone and we'll make another hit and see what
happens
okay we put two degrees in it so it's got 32 total on it uh it saw some pretty good gains um looking
like went from well here's the before and after so 358 to 363 327 to 336. so decent on the peaks
but uh the average is really where it's at check out the horsepower average difference 184 203 you
can see the graphs here how much it just improved it uh pretty much everywhere so we're gonna put
two more degrees in it not the thing up to 34. um make another hit and see where that gets us
okay 34 degrees in it uh afr is now into the 12 12 0 area and we picked up another
9 foot pounds of torque and 11 horsepower so that's at 34 so we're gonna put two more in it
and uh keep on keep see how it likes it i'm gonna guess we're gonna end up around 36 38 maybe even
but you can see how much of a difference that made uh everywhere from about yeah about 4 000 on
um so which is really where these things are gonna operate anyway
but uh but yeah looking good i'm gonna put two more in it and give her another go
okay so here's the graph with 36 degrees in it afr is now uh 11 9 in the beginning 12 2 at the
end of the hit so it's right right about where we want a little conservative which is what i'm
shooting for with this thing right uh so you can see with the 36 in it there's some deviations
where it made more a little bit here a little bit there same here same there uh so on 34 degrees it
made peak power out here and on 36 it moved the power peak back 200 rpm uh that and the slight
deviations through the curve tell me that we're pretty much at mbt or very close to it i'm gonna
leave the thing at 36 degrees and call it good it does need to be again a little bit conservative
it also is geared really short um so it'd be cool to put like a 410 gear ratio in this thing and see
what we want for timing then i would expect it to be in the 34 32 range with the gear change um but
without doing it we don't really know so i'm gonna call this one good i do have another carburetor to
put on here and dial in so we'll see if that makes any difference and i'm gonna get moving on that
all right after the carburetor change uh we lost a little bit of power the afr was uh
like twelve twelve one five twelve one oh instead of the twelve two five uh so you know
close enough to be you know whether that makes a difference or not i would argue that it doesn't uh
and the other carburetor made a little bit more horsepower for whichever reason i ran them
at the same oil temp same coolant temp uh that whole thing so the give you an idea here
for peak numbers so the original carburetor made feet 353 or 352.9 and the new one made 345.6 and
then torque was was pretty close uh so that's a wrap for this thing so as it turns out i was lying
that wasn't the last hit i got a text from this customer in the morning they asked you to pull the
restrictors out because as i said previously this is a and this engine runs a restrictor
so the restrictor was worth uh the difference there's like 23 horsepower
um but here's the curve difference pretty big change average over the duration so
yeah ended up making 368 the tire with the restrictor pulled out of it um so yeah i thought
that was interesting again it's a it's a cra pro late model so it is a sealed uh gm 604 crate
engine class um and this engine is required to run a restrictor because they were outperforming
the rest of them previously so to try to keep the field even they put that restrictor in there and
that's what it killed about 23 horsepower so kind of interesting but so again that's it for
this one for sure this time because they're on the way to come pick it up thanks for watching