Jump to content
HybridZ

631 (6 cylinders, 3 carbs, 1 turbo)


Recommended Posts

I'm using stock mikuni needle/seat set up but not sure about the webers. That jetting is almost identical to my setup so something else is going on, does the power cut out immediately/misfire when the AFR spikes? Or does it gradually go up with the powerband? What psi is that holley pump rated, flow/psi are two different issues.

If it's a sudden event make sure the carbs are sealed/holding the air pressure, I had a similar issue when the jet chamber cover wasn't sealing tight (due to a stripped bolt), you'd probably see gasoline around that though. 

Got mine dialed in today pretty much, the 145 mains landed me mid 11's as expected, 190 air still, 62.5 pilots. I also regapped my NGK 7's from .040 to .035 and it solved the transition lean/misfire I was having.

 

As far as I know I'm golden.. still have a slight gasoline leak on #1 carb though, not a lot but it glistens, looks like it's coming from the starter/rotating unit but not sure. 

 

Keep us posted.

Link to comment
Share on other sites

My issue was between 0-3psi. Cruise it would transiently go lean. Coughs and pops. More foot and it went to 3psi and it smoothed out and pulled fine.

 

It was chasing that lean at a specific rpm and different throttle positions....

 

"Shift Ctrl, arrow up"

"Shift Ctrl, arrow up"

 

Timing suspect?

 

Click, Shift Ctrl Arrow Up, Up, Up....

 

 

All I'm saying, besides "BWAhahaha!" Sorry...that's not helping but "those who say "carbs are easy" have never really tried tuning them!"

Link to comment
Share on other sites

  • 3 weeks later...

Alright guys, so the car is a beast. I have the waste gate set at 4 psi and she pulls like a mad man.  I drilled out my secondaries they were a 88f9 I snagged a .0468 reamer and opened them up a bit!  that brought my idle afrs down to 17.5-  19.7.  I also then opened up my mains to a whopping .240s   I can cruise around the city and hood nice and slow, but when I want to get the rpms up I need to boost.  which is an awesome experience.   I have been able to give it about half throttle and it goes just as quick as it did in the N.A form. boost comes on strong and is addictive on these straight sixes. I am used to boosting 4's.

Link to comment
Share on other sites

I also had the intake off and did a pressure check and it was good up to 20 psi, which is far beyond what I am shooting to run.  I also added a turbo blanket to keep some heat off the 3rd carb,  while the intake was off I went back over all the carbs and used the synchrometer  to readjust from last year.  

Link to comment
Share on other sites

  • 5 weeks later...

Poor TonyD more of us are coming out of the woodwork to bug you about blowthrough stuff lol.  I think I'm doing something wrong because my jetting is exact to kennymonster's specs aside from the mains i'm at 170. 145's and 150's didn't seem to work, if my dang afr gauge ever showed up I could finally see what was going on lol. 

Edited by mildsquare
Link to comment
Share on other sites

Poor TonyD more of us are coming out of the woodwork to bug you about blowthrough stuff lol.  I think I'm doing something wrong because my jetting is exact to kennymonster's specs aside from the mains i'm at 170. 145's and 150's didn't seem to work, if my dang afr gauge ever showed up I could finally see what was going on lol. 

 

He likes it ;p

 

Yeahh about my jetting, I'm still trying couple of different set ups and haven't kept up on here:

 

The 145 main / 190 air set up was ok for colder runs / low gears (1st to 3rd) shifting at redline, but I ran into issues under load with the transition leaning out.

 

I went to 150 / 180, transition was lot happier and low gear AFR was around 11.5. The real test is 4th gear pull from 2.5k and up in my opinion, on a flat surface, to simulate a dyno run in 1:1 ratio.

 

At 150 / 170, transition is just about right where it should be without any lean spikes, but 4th gear pull is right at 12 AFR (evening run)

 

I have 155 mains on the way, I think the 155 main  / 170 air will be right on the money at 11.5 ish in 4th with early main transition, with give or take little bit on either side.

 

 

*Mildsquare, I tried 160 mains for the hell of it and it kept me in 10's and sometimes 9's in offboost setting with 62.5 pilots, it ran ok but it's filthy rich. Def need some sort of wideband/measurement for this game, don't risk it!

Link to comment
Share on other sites

Block off your chokes if you have not yet.  Once I blocked mine off, it made a huge difference as they were bleeding out the pressure in the carbs. I drove the car from Minneapolis, to Cooperstown North dakota,  which was a five and a half hour drive.  The car did not miss a beat, I averaged about 120 miles per tank.  I also have a 4 speed and was going 95 mph, in a constant semi boost at 4k rpm.

Link to comment
Share on other sites

Poor TonyD more of us are coming out of the woodwork to bug you about blowthrough stuff lol.  I think I'm doing something wrong because my jetting is exact to kennymonster's specs aside from the mains i'm at 170. 145's and 150's didn't seem to work, if my dang afr gauge ever showed up I could finally see what was going on lol.

 

"Your experience may be different"! LOL

Link to comment
Share on other sites

Got the 155 main / 170 air combo in today, took care of the transition problem for high load @ 3rd / 4th gear

 

The smaller air corrector seems to have done the trick, mains kick in lot earlier and the 'lean spike' doesn't go past 12, at WOT it's at 11.2 to 11.3 under 4th gear pull to 6000.

Link to comment
Share on other sites

Got the 155 main / 170 air combo in today, took care of the transition problem for high load @ 3rd / 4th gear

 

The smaller air corrector seems to have done the trick, mains kick in lot earlier and the 'lean spike' doesn't go past 12, at WOT it's at 11.2 to 11.3 under 4th gear pull to 6000.

 

 

^^^ exactly my problem lol

Link to comment
Share on other sites

  • 2 months later...
  • 2 months later...

Funny weekend - Car sat over the holidays due to my schedule, finally got an aggressive Isky turbo cam to compliment the set up.

 

Went for a 20 min cruise to 'break in' the cam, was stoked to drive the thing again and looking forward to pounding that straight pipe sound, at the 25 min mark cylinder 1's ring decided to say 'enough!' (at cruise off boost)

 

The N42 bottom end was low compression/tired to begin with, I may have detonated a bit at the last autoX also, and probably just reached the limit finally. The easiest way to get back on the road would be throwing in a turbo block, but I've decided I like slow cars better and return to the snappy NA form for racing reasons.

 

The cartech kit is going up for sale to fund the new NA motor :(

Edited by Kennymonster
Link to comment
Share on other sites

 Being a Goonie means " Never Say Die!"  Imo keep the turbo setup look for an na motor to slap in and drive a round with. once you go boost its hard to go back, But I understand at times you got to do what you got to do. sorry to hear that man. I"m in Las vegas I know its a drive but i May know some one willing to part with an l28et or some other N/A blocks he has lying around.

Link to comment
Share on other sites

Yeah it's a tough choice having invested a lot of my time tuning and etc., but I figure that's all intellectual property now as far as what I've learned, not too bitter about it.

 

Turbo blocks are dime a dozen out here and I can probably be on the road quickly if I retain everything... but assessing what I use the car for, probably a smarter choice to not fight it. If I was into road racing / freeway trolling, this would still be the absolute choice, but for weekend cruising and autoX, the open trumpets are calling my name lol.

 

Thanks for the leads, have a couple of complete NA motors already tracked down and just waiting on the sale of this kit to fund it.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...