Pormance on my 408
#2107534
07/10/16 10:09 PM
07/10/16 10:09 PM
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Joined: May 2004
Posts: 1,522 Ste-Sophie, Quebec, Canada
Wedgeman
OP
pro stock
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OP
pro stock
Joined: May 2004
Posts: 1,522
Ste-Sophie, Quebec, Canada
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Hello everyone !
I would need your comments on the performance of my Indy headed 408.
I've been quite happy with the pleasure and fun my 67 Barracuda for the past 2 years. But some questions are left unanswered concerning performance. First, here is the set up:
67 Barracuda 3000lbs with me in ti ladder bar with Dana 60 , 4.56 gear 5000 stall conv 904 trans, low gear set 408 cid 10.8 cr -1 heads 343 cfm int 275 exh Mopar W2 tunnel ram with a pair of Proform main body (750cfm) and billet metering block around
My 60ft are pretty good, yesterday I made a 1.29sec 60ft with the dual quad
Last year average 60ft was 1.32sec...
Here is the problem: I run on an 1/8 mile track, and I feel et's are not what they are supposed to be....
If I had a 60ft of 1.32, et was 6.42 If I had a 60ft of 1.30, et was 6.30 If I had a 60ft of 1.34, et was 6.34 and so on....
I scratch my head and say to myself: heck with that 60 ft, I'm supposed to run faster et's !!! right ????
I feel something is wrong here......but what ???????
Yesterday, with a 60ft of 1.29, I ran 6.50 sec no power valve and 75 jets....Ok it is a new set up, needs fine tuning etc.......But still !!
What is going on here ?? I'm supposed to be faster than that !!
Need any idea you can throw....
Dan
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Re: Pormance on my 408
[Re: Wedgeman]
#2107548
07/10/16 10:24 PM
07/10/16 10:24 PM
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Joined: Jul 2004
Posts: 19,317 State of confusion
Thumperdart
I Live Here
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I Live Here
Joined: Jul 2004
Posts: 19,317
State of confusion
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You can only go as fast as the power available and those 60`s indicate a good working suspension........Not to say the carbs don`t need attention though..............
Last edited by Thumperdart; 07/10/16 10:25 PM.
72 Dart 470 n/a BB stroker street car `THUMPER`...Check me out on FB Dominic Thumper for videos and lots of carb pics......760-900-3895.....
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Re: Pormance on my 408
[Re: Wedgeman]
#2107567
07/10/16 11:05 PM
07/10/16 11:05 PM
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Joined: Jan 2003
Posts: 17,918 Akron, Ohio
ProSport
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 17,918
Akron, Ohio
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MPH is definitely some needed info, did the time slip not print out correctly? Have you had time to jet the carbs up or down or move the timing up and down? Your 60 foot is pretty awesome.
1970 Challenger, all aluminum 528 Hemi, HDK suspension, Tremec 5 speed manual
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Re: Pormance on my 408
[Re: ProSport]
#2107574
07/10/16 11:19 PM
07/10/16 11:19 PM
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Joined: Jan 2003
Posts: 5,485 SoCal
Brian Hafliger
master
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master
Joined: Jan 2003
Posts: 5,485
SoCal
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I would never run an engine with a tunnel ram without first dyno tuning it! That said, you should be closer to 80 jets with no power valves...OOTB around 72-80 jetting with PV in front, so more like 80's square but I would try 78 jets square in both carbs first. If it's really lean it will pick up a ton with jet...if 78's work, try 80's square and so on... Brian
Brian Hafliger
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Re: Pormance on my 408
[Re: Wedgeman]
#2107588
07/10/16 11:37 PM
07/10/16 11:37 PM
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Joined: Jan 2003
Posts: 17,918 Akron, Ohio
ProSport
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 17,918
Akron, Ohio
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No mph at this track.....
No I didn't have time to play with jet or timing...
I'll try to lower my jets to 72 next week end I agree with Ou812, I never dyno my engines buy I definitely think you should try the 78 jets and then 80.
1970 Challenger, all aluminum 528 Hemi, HDK suspension, Tremec 5 speed manual
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Re: Pormance on my 408
[Re: Wedgeman]
#2107691
07/11/16 02:04 AM
07/11/16 02:04 AM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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You start out great then it losses power... check your fuel supply... are you looking at the plugs right after you shut down or driving back to your pit.. sounds like your fat at low rpm(when you get back to your pit and pulling the plugs then)... on a 1/8 track its hard to pull them right after you turn off.. if you have to drive a bit
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Re: Pormance on my 408
[Re: Wedgeman]
#2107693
07/11/16 02:06 AM
07/11/16 02:06 AM
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Joined: Feb 2005
Posts: 20,174 PA.
pittsburghracer
"Little"John
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"Little"John
Joined: Feb 2005
Posts: 20,174
PA.
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408 cid 10.8 cr -1 heads 343 cfm int 275 exh
I personally would like more compression and what are your cam specs? With that 60 foot your car SHOULD be flying.
1970 Duster Edelbrock headed 408 5.984@112.52 422 Indy headed small block 5.982@112.56 mph 9.42@138.27
Livin and lovin life one day at a time
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Re: Pormance on my 408
[Re: Wedgeman]
#2107789
07/11/16 11:05 AM
07/11/16 11:05 AM
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Joined: Feb 2005
Posts: 20,174 PA.
pittsburghracer
"Little"John
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"Little"John
Joined: Feb 2005
Posts: 20,174
PA.
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Cam specs are 255*/285* int 263*/293* exh ?????
1970 Duster Edelbrock headed 408 5.984@112.52 422 Indy headed small block 5.982@112.56 mph 9.42@138.27
Livin and lovin life one day at a time
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Re: Pormance on my 408
[Re: pittsburghracer]
#2107826
07/11/16 12:06 PM
07/11/16 12:06 PM
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Joined: Jul 2004
Posts: 19,317 State of confusion
Thumperdart
I Live Here
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I Live Here
Joined: Jul 2004
Posts: 19,317
State of confusion
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Cam specs are 255*/285* int 263*/293* exh ????? I second that?????????????
72 Dart 470 n/a BB stroker street car `THUMPER`...Check me out on FB Dominic Thumper for videos and lots of carb pics......760-900-3895.....
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Re: Pormance on my 408
[Re: Wedgeman]
#2108002
07/11/16 05:03 PM
07/11/16 05:03 PM
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Joined: Jan 2003
Posts: 5,485 SoCal
Brian Hafliger
master
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master
Joined: Jan 2003
Posts: 5,485
SoCal
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I was hoping you jump in Brian...
The plugs are a bit dark and the wideband says rich a bit....
But I should really be faster than just a jet change ?
Dan If you are starving it for fuel (either by jetting or fuel supply) you can lose 1-200 HP! You basically kill the engine. I'm not saying this is your problem, but typical 750 carbs with no PV's are jetted around 78-80's...and you have 2 carbs so think about it...it's an easy test. If nothing gets worse or better, it might be fuel supply. Make sure you check everything else out too...I still say dyno testing is the best way to start with a new combo to get you close on tune up, and also easy way to make sure engine is healthy and happy...i.e. valve train issues is one that comes to mind. Brian
Brian Hafliger
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Re: Pormance on my 408
[Re: Wedgeman]
#2108162
07/11/16 09:10 PM
07/11/16 09:10 PM
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Joined: Jan 2003
Posts: 5,485 SoCal
Brian Hafliger
master
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master
Joined: Jan 2003
Posts: 5,485
SoCal
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I was thinking the converter might be in fault......... This is where MPH data would help tremendously but also lack of fuel or fuel supply will show low MPH too....
Brian Hafliger
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Re: Pormance on my 408
[Re: Wedgeman]
#2108164
07/11/16 09:11 PM
07/11/16 09:11 PM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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I was thinking the converter might be in fault......... I dont think its a conv issue.. its got a strong 60'... what are your rpms at the line.. if its slipping hard up top the rpm will tell you... I think its all a fuel issue.. either jetting or supply EDIT You might want to change the needle and seats to .120s... but normally with 2 carbs the .110s work fine.. but something to think of
Last edited by MR_P_BODY; 07/11/16 09:22 PM.
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Re: Pormance on my 408
[Re: Wedgeman]
#2108196
07/11/16 10:05 PM
07/11/16 10:05 PM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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I recall last year going richer without success........the reason why I got myself a wideband
That's why I'm not sure going this direction will help, but I will keep an open eye on that this week-end....
Dan You need the MPH... if you jet up 4 sizes and if nothing changes or if it doesnt slow down (MPH) then you have a supply issue... could be a needle and seat being to small also... do you have a fuel gauge you can see during the run... and dont use a oil filled gauge... if its under the hood and filled it will show a lower pressure.. thats the oil heating up and pressing back on the gauge
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Re: Pormance on my 408
[Re: Wedgeman]
#2108417
07/12/16 01:01 AM
07/12/16 01:01 AM
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Joined: Jan 2003
Posts: 5,485 SoCal
Brian Hafliger
master
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master
Joined: Jan 2003
Posts: 5,485
SoCal
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What can happen on tunnel ram setups is they can pull a ton of fuel at high rpm causing performance loss in excess of 100HP and even pull enough fuel to sometimes cause the engine to rpm limit!
Hard to see when your trying to drive the car, shift, and all. Might be why the plugs are black?
Brian Hafliger
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