need some help. i have a 395 stroker that seems to not be living up to expectations. the best ive been able to run is a 12.9 at 104 mph. if i remember correctly, the 350 i had ran a 12.8 at around 107.

specs. 395 stroker
comp cams xtreme energy 288
1.5 rockers
ed performer rpm air gap (w/ spacer)
750 demon
around10.8. to 1 compression
2800 stall
AFR 195 (old style)
3.73 gears

i had a smaller cam(xtreme energy 276) same heads, and dart intake on the old 350 and it ran better.

question is, does the extra cubes rather have more cam(rocker ratio) or should i use a single plane(victor jr) type intake


i didn't know if this would be the right forum, if it isn't, mods please correct.

thanks in advance

 

Your setup looks good and very similar specs to my 350 that was running mid elevens (at sea level). This isn't an intake or rocker ratio problem.

Is it a 750 Mighty Demon?
Lift on the cam?
The stall is low for that combo. Another 1000RPM would do wonders for your 60'.
Post up the entire slip so we can see the incrementals.

 

Yea as you are thinking that engine should be probably around a second faster in the quarter.
Have you done any wot jetting and timing adjustments at the track or on a dyno?

And don't put a vic jr on. It may make a couple more horse up top, but you will loose way to much everywhere else.

Here's a dyno video where they test it.

 

thanks for the replies, here are the specs on the cam

Basic Operating RPM Range:2,500-6,000
Intake Duration at 050 inch Lift:236
Exhaust Duration at 050 inch Lift:242
Duration at 050 inch Lift:236 int./242 exh.
Advertised Intake Duration:288
Advertised Exhaust Duration:294
Advertised Duration:288 int./294 exh.
Intake Valve Lift with Factory Rocker Arm Ratio:0.520 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio:0.540 in.
Valve Lift with Factory Rocker Arm Ratio:0.520 int./0.540 exh.
Lobe Separation (degrees):110

ive been on the boards trying to figure this thing out. it seemed to have been fouling plugs, but i read on another board that racing plugs tend to foul easier if used at all on the street. considering i drive about 25 miles to the track, figured it was a good a place to start.
switched out to the ac delco recommended on AFR website, but the track was closed this weekend, so wasnt able to test. the last time i went to the track the top end seemed to go flat. that's the only reason i was considering going to the single plane.
the stall IS a bit low. i thought i had gotten a 3000, but i was going through receipts and it looks i had ordered the 2800. i think that going to be moving up on the wishlist. will a 3500 stall be ok on the street? 3800?

Thanks again!

 

you didn't answer my question
"Have you done any wot jetting and timing adjustments at the track or on a dyno?"

The plugs are fouling because the carb isn't set up right.
Read the holley tuning sticky

 

sorry, i havent done any WOT jetting, i increased the timing at the track and it seemed to lose top end. so i set it back to 32.
i read that in order to read the plugs you had to take them off at the track after. i have the old plugs i took off, i think they were in there for about 3 mo. i will try and post a pick

 

forget reading the plugs for now. Plus unless you put fresh plugs in before a run and then shut it off right after the finish line it won't be much help.
Just do the holley tuning sticky first for drive ability and main jetting.
Then using your mph from the track change secondary jets till you get the best mph.
Or buy a wideband gauge and tune wot to around 12.8 and then fine tune it using mph at the track.
Timing is basically the same way. Start at 30 and go up 2 degrees at a time until you don't really see an mph improvement, then go back 2 degrees for safety.

The carb being to lean or rich could be your whole problem.

 

Which model Demon carb and what jets are in it now?

 

copy of the slips



its a mighty demon. it has 85 in the secondaries, cant remember what was in the primaries. its what ever it came in it.
i do have a wideband.

 

what is the afr at wot?

 

at WOT im not sure. its a little rich at idle and part throttle. in the 13.8-14 range. where should the AFR at WOT be at?

 

That's not bad for cruise. maybe go down a couple jets in the front if you care about fuel economy.
Don't use the wideband for idle. Just set it the old fashioned way for max vacuum for now.
Max power at wot will be anywhere from 12.5 - 13.5. depends on the car. I usually just shoot for around 12.8 at wot in your 1 to 1 gear. (usually 3rd in and auto and 4th in a manual).

 

thanks, wont be able to go the track this weekend, but ill try and make a safe WOT run in the backroads later this week.
i have the car up on rims right know. it seems to like the new plugs and timing. it starts right up. havent had that happen in a long while.
if the WOT is around 12.5-13.5, then what then.....

 

No incrementals on the slip...I guess that track only times at the 1/4 mile. The 1.85 60' isn't bad. Is the trans shifting hard? What was the weather like? Any idea what your car weighs? Just trying to figure out if your car is making the power I think it should be making.

 

the car weights around 3k. I've removed rear seats and all the extra stuff in the engine compartment. other than that, it's a stock rs. I can't remember when that was. but Laredo, tx is HOT most of the year. this was some time back. the last couple of times I went out there they were having issues printing out slips. so it's been hard to try one thing or the other and verify. they are supposedly fixing all that stuff

 

I also have a MIghty Demon on my car. I didn't change the jets too far from stock. I did, however, open up the PVCR significantly to get enough fuel at WOT. It was running pretty lean (out of the box) at WOT and way too rich at idle.

 

I think mine had 75 in the primary. it actually had one 83 Jet and one 85 jet in the secondary. we went ahead and left it with 85s. need to record what the afr is at wot

 

Demon carbs are infamous for having these quality control issues.

 

You are heading in the right direction with checking if you are running lean or rich but there are a few other things to consider as well.

Are you using a 700R4? At what rpm are you shifting? I would expect a better 60' time than 1.85 60' time as well. With a higher stall, good traction and launch RPM I would expect the 60' to be in the 1.7's to 1.6's to get into the 11's. I know that motor is capable of doing that.

 

well, to tell you the truth, i really thought i would be hitting the low 12's, high elevens without messing with the carb. like i said, this exact carb and intake combo ran 12.80's before on the old 350.
after a bit more research, the intake swap wont be a good idea.
if i remember correctly i had a 3000 stall with the old combo....
hoping to make that WOT run tmrw or friday. hoping it in that 12.5-13 range that JOBOT suggested. that way at least i can eliminate the carb as a culprit.

i hate chasing down gremlins.......

 

I hear you but going from a 350 to the 395 is a big change ans would require to make a lot of other changes to get the best performance from your engine. You will definitely need to make some changes to that carb

I have to agree with this as well.

 

ok, i was able to take it out tonight. i was first planning on writing the afr's as i drove, stopped, drove, stopped.... but then i figured i can take a video....
i actually thought i had taken 3 different videos, but apparently i had just paused it.

at idle its at 12.5-12.8 depending if its in gear or in park

the first part (0-09 sec) is cruising around 45-50 mph AFR is in the low 13's
second part (11-24 sec) is accelerating to around 35-40 and getting to a stop sign. AFR seems rich
the third part (25 sec) is in second to third at WOT. AFR seems to be around 13.

to me it seems to be rich in the primary but ok in the secondary. maybe go up a jet in the secondary? that would put it at 86.

heres the vid

 

The Victor Jr lost no noticeable low-end torque on the 305 in the Corvette. Trapped 106 mph with an Edelbrock 500 on top. With a 3,000 stalled TH400 and 3.07 gears it will lay down a pair of 10" wide rubber stripes all the way through first gear.

 

so.... what do u guys think about the AFR?

 

You can also just follow the holley tuning sticky and just use afr for wot.

What distributor due you have? What is the total iming set at?

It doesn't seam like the carb afr is out enough to make the car run that slow. While you should do the carb tuning I think there is something else that is the issue.
I agree that a higher stall convert will help but I don't think it's the issue. You should be trapping a much higher mph. 104 mph matches your 12.9 pretty well. So it's a power issue not a converter issue or a slipping trans or something.
Although once you get it sorted out a higher stall converter would work better if you don't mind driving it on the street with the higher stall.

 

yeah, i noticed the MPH matched up with the et's. and i like u said, i dont think the carb is that much off to hurt it that much. especially at WOT. from what i have gathered here , the WOT afr seems good
i have a mallory unilite dist, mallory promaster coil, MSD 6AL box.
timing is now at 32
thats why i was leaning towards maybe the intake or go to 1.6 lifters.
it does have an AFR hydra-rev kit on it. anyone have bad experience with these?