RHS head 416 at the track...part 'tree

-
dusterdoug

dusterdoug

FABO Gold Member
FABO Gold Member
Joined
Sep 26, 2007
Messages
1,092
Reaction score
309
Location
Tracy, CA
In the last episode, (SIX months ago!) we got the low dollar hauler RHS-headed 416 to go a 10.33 @ 131, throught the muffs. Here's a quick combo recap:

4.07 340 block
SCAT 4.00" crank
SCAT I-beam rods
KB 745 flat top slugs (.020 out of the hole)
RHS LA heads (2.02 intake)
Custom Bullet flat tappet cam (268/276 - .585 after lash)
Eddy Victor
Holley 800
904 (2.45 low gear)
8" Contnential converter (freshened by Len Schneider)
4.56 8 3/4 with a 29.5 Phoenix slick

Car weights right at 3,100 race ready.

Turns out our 131 MPH was BOGUS. The Sac clocks then were 3 MPH faster compared to other tracks. They are now fixed, but I really was liking that we had a 130 MPH small block. Oh well...

We have rebuilt the front end, and added Wilwood's up front and done a little carb work. Added 50 cfm to the ol 800 Holley and thought we'd go out look like we knew what we doing as the air was real good compared to the July evening air that produced the 10.33. Well, I spent 6 runs chasing a carb problem that I THOUGHT was present, all the while ignoring the one that was obvious. Results:

12.88 @ 91 (Don't ask)

10.34 @ 126 (Leaned it...black smoke says it's rich)

10.14 @ 129/6.38 @ 107 in the 1/8 (Leaned it some more, still rich)

I now have less fuel in it when it ran the 10.33 last summer, but it's still fat. IN BETTER AIR???!!!??? I don't get it. More wasted gas and runs the next day but were 1/8 mile -

6.68 @ 105 - Leaned it some more. WHAT?? Where's the 6.38 from the 10.14 run the day before?? Same air, but still very rich... #*&@%%!

6.50 @ 106 - (Leaned it some more...but plugs are UGLY)

6.50 @ 106 - (Fresh plugs. Guess the old ones that I just tossed in the trash weren't so bad, huh? Lost first round with a .012 light and a 6.48 dail. I just wanna go home now...)

I figured out where I had my head up my a** and the carb's getting fixed tomorrow night when I have the time. Turns out it WAS NOT rich, but the tuner (me) was LEAN IN THE BRAIN CELLS. Back up next Saturday, weather permitting.

Interesting to note that on the 10.33 run last summer it went 1.40 flat in 60'. This weekend it only could go 1.41 (on the 10.14 run) leaving at the same RPM. Well, the front end does seem kind of stiff since it was rebuilt...but is that it or the carb issues?? I would have THOUGHT a very high 1.38 was doable...but what do I know? Obviously not much...

At least it drives easier and stops MUCH better!
 
What did you find that you thought was making it rich? Please explain.
 
Another question, You said your pistons are 0.020 out of the hole. How are you doing that with closed chamber heads??
 
My car here in Texas would run a mid 6.60 @ 101 MPH on several different tracks, I think one time it ran 102 (tire spin due to bad burn out), thats the only way I can see your running 4-5 MPH faster unless my tune was way off.
 
jefflock said:
What did you find that you thought was making it rich? Please explain.
Click to expand...

Each time it was started it left a PILE of soot under the turndowns. Black smoke the first part of the burnout, black some duing the hit and early in the run, black plugs...

But see, that's what happens when it idles on the main jet rather then the idle circuit. What I didn't realize was two things:

1) Without drilling holes in the primary throtle blades, they were open far enough to expose the transition slot.

2) With our carb tweaking the signal is so much stronger it was pulling alot of fuel past the boosters at idle.

Just basic Holley stuff...along with me being a dumbass like I said.

We had made other mods to the carb THINKING it wouldn't need the primary plates drilled, and I was so stuck on that I couldn't see the forrest for the trees.
 
the67fish said:
My car here in Texas would run a mid 6.60 @ 101 MPH on several different tracks, I think one time it ran 102 (tire spin due to bad burn out), thats the only way I can see your running 4-5 MPH faster unless my tune was way off.
Click to expand...

I can't speak to your tune, but I can speak to mine and I'm so lost it isn't funny. I can't even say the jet combo was right on the 6.38/10.14 run as I was making BIG jet changes and getting more lost each time.

That said, I wasn't surprised at the 107 best 1/8 mile speed per say. It went darn near 105 last July.

Motor still only has 30* of timing...LOVE these 4" crank small blocks!!
 
It's running really well for an engine with some iron doorstops for heads. :)

Get that idle/jetting situation straightened out and I bet the 60' starts to pick back up.
 
70aarcuda said:
how big are the squirter's?
Click to expand...

37's. Why 37's? Cuz that was all I had and I wanted an a bigger squirt due the increased plenum with a 2" spacer. Don't know if it's the right theory or not, but I thought it'd be a good place to start.
 
Mr Hemi said:
What are the exhaust temps ?
Click to expand...

We don't have a clue. Not that far advanced to be watching EGT's. But man, in hindsight that would have forced me to go another route.

I think we were close on the 10.14 run and the soot and smoking early was just the motor cleaning up all the raw fuel. Lucky I was taking jet OUT...had I kept going the other way might have washed the rings out of it.
 
crackedback said:
It's running really well for an engine with some iron doorstops for heads. :)

Get that idle/jetting situation straightened out and I bet the 60' starts to pick back up.
Click to expand...

Yea cracked, those OEM replacement heads are for RAM pick ups not race cars! :toothy10:
 
Dusterdoug, now what are you running for jetting. What did you start with and whats does it(did) run best with.

Every time iv'e been to the track the car smokes out the exhaust. I still have not been able to get a proper tune out of this car beacuse of lousy track prep and suspension tire adjustments thrown in. Anyway it seems to run best with 75 primaries with a PV and 81 in the rear without thru 3" flowmasters at the diff. It seems these heads don't respond well to overjetting?.
 
w2360Duster said:
Dusterdoug, now what are you running for jetting. What did you start with and whats does it(did) run best with.

Every time iv'e been to the track the car smokes out the exhaust. I still have not been able to get a proper tune out of this car beacuse of lousy track prep and suspension tire adjustments thrown in. Anyway it seems to run best with 75 primaries with a PV and 81 in the rear without thru 3" flowmasters at the diff. It seems these heads don't respond well to overjetting?.
Click to expand...

We had 83/90's (PV in the primary/no PV in secondary) when it went 10.33 last July. We then "tuned up" the 800 and one result was gaining 50 cfm. Being the smart guy that I am, I decided that required a jet increase, as well as the better air we were going to run in. THEN just to show more brillance, I decide I'm going to make a "race" carb out of it and eliminate the primary PV thus adding even MORE jet to the primary side.

On the last two runs Saturday it had (and still has) 78/80's, but that is .12 at the 1/8 mile slower than the 84/86 jets that were in on the 6.38/10.14 run an TnT the day before. So, that tells me the 84/86 jets were close. ???????????
 
You must log in or register to reply here.
-

Back
Top