|
drilling TQ throttle plates? ***UPDATE***
#1256766
06/24/12 10:31 PM
06/24/12 10:31 PM
|
Joined: Mar 2005
Posts: 862
Iowa State fan
kilroy
OP
super stock
|
OP
super stock
Joined: Mar 2005
Posts: 862
Iowa State fan
|
Ok Im running 440 at 10.1cr, eddy heads, single plane intake, PCV hooked, choke hooked, and a purple shaft ...661 cam. (250 something @50, .557 lift), fuel pressure reg set at 5.5psi. Initial timing set at 20* total limited at 38*.
Ok with the transition slots square I have a ridiculously low idle of about 500 and usually less, which it will do but not well when running around town. Its much happier when it idles at 750 to 800 rpm. The mixture screws are set at between 1.5 to 1.25 out. after that I dont notice any other gains.
To get the idle speed I would like the transition slots are severely over exposed.
I dont want anymore initial, and I have tried it up to 30* but really was unhappy with the overall results.
I have spent the last 2hrs doing google searches trying to figure out the best method to get about 300 more rpm at idle am I at the point of drilling?
Just for the record, no vacuum leaks and NO im not switching off my tq.
Last edited by kilroy; 07/01/12 08:31 PM.
1973 Charger, former SE, former auto
I'm not trying to be difficult, it comes naturally....
|
|
|
Re: drilling TQ throttle plates?
[Re: superbeedave]
#1256778
06/25/12 12:37 PM
06/25/12 12:37 PM
|
Joined: Jan 2003
Posts: 5,270
Missouri
MY340
master
|
master
Joined: Jan 2003
Posts: 5,270
Missouri
|
I drilled 1/16" holes I believe on my TQ with a MP508 cammed 340-4spd and also trimmed one coil off of the metering tree spring to make it lighter. 22 intial/38 total timing advance also with no vacuum advance hooked up. These mods and adjustments do work and normally help with larger cams on street cars.
1970 FE5 Duster 360/904/3.91's SOLD
1973 TB3 SpaceDuster 340/4spd/4.10's SOLD
Moparless for now but when the opportunity is right I'll have another one.
|
|
|
Re: drilling TQ throttle plates?
[Re: kilroy]
#1256780
06/25/12 01:49 PM
06/25/12 01:49 PM
|
Joined: Jan 2003
Posts: 1,760
Windsor, ON, Canada
Diplomat360
top fuel
|
top fuel
Joined: Jan 2003
Posts: 1,760
Windsor, ON, Canada
|
Look up this thread of mine. Much smaller cam (238/244 @ 0.050") but same problem never the less. Car has done a lot of sitting around, due to other reasons, but I'm about to re-start the work on it. Will be up and running within the next week or so, and this particular issue is near & dear to my heart! LOL I'll be watching your thread...
|
|
|
Re: drilling TQ throttle plates?
[Re: superbeedave]
#1256781
06/25/12 08:16 PM
06/25/12 08:16 PM
|
Joined: Mar 2005
Posts: 862
Iowa State fan
kilroy
OP
super stock
|
OP
super stock
Joined: Mar 2005
Posts: 862
Iowa State fan
|
Quote:
I have done alot of research on this particular case and here is what I have discovered with you only running 7-8 inches of vacuum your TQ now thinks it is on a much smaller engine. Carter and Edelbrock carbs. were designed to run with 12 inches on up. The reason your idle is so low is because your not pulling in enough air and gas into the intake thru your idle circuts. The idle air bleeds are too small and you would most likely have to go to bigger jets to compensate for the low vacuum that is not pulling enough fuel thru. Also depending on which springs you have in the TQ you will have to go to probably the 3 or four inch and not the orange which is rated at 5 inches which may cause your rods to lift up some at idle and then will be bypassing the idle circuts. So drilling the plates is the most likely thing to do but your not doing anything to the fuel thing just the air thing. Does any if this make sense? And by the way, I have a 94 Chrysler Power magazine that has an article on Big Cam Blues. If I could post this entire article I would, it is very helpfull!
The tree is not the problem it is not bouncing at idle, but anyways I dont quite think this is right. Idle circuits are Idle circuits. You maybe right about them not pulling enough fuel or air but changing the rods, springs, or main jets will not effect the idle circuit because there is no air flow pulling fuel through the main circuits and boosters. Kinda like a holley's PV circuit is active during idle but since no fuel is being pulled through the boosters it doesn't change the idle circuit richness (but as soon when fuel starts flowing through the boosters all that changes.)
I can idle, I just need some MORE idle rpms without exposing more of the transfer slots.
Last edited by kilroy; 06/25/12 08:17 PM.
1973 Charger, former SE, former auto
I'm not trying to be difficult, it comes naturally....
|
|
|
Re: drilling TQ throttle plates?
[Re: kilroy]
#1256783
06/26/12 12:16 AM
06/26/12 12:16 AM
|
Joined: Jan 2003
Posts: 1,760
Windsor, ON, Canada
Diplomat360
top fuel
|
top fuel
Joined: Jan 2003
Posts: 1,760
Windsor, ON, Canada
|
The other option to consider would be to drill out the normal air by-pass passages even further (the ones I showed circled in RED in my photos) and then enlrage the passege in the base plate that actually feeds air into the motor as it by-passes the throttle blades. Since I have no access to any type of drilling equipment (and boy, you have to be super careful and precise there, I'm thinking a machinist type of a job) I simply couldn't try this. The additional problem, certainly in my setup, is the fact that I am running an open plenum spreadbore-to-squarebore adapter. Therefore, the signal, as little as there is of one with the bigger cam is bled off even further by the opposite bank. I am currently on a hunt for either a 4-hole spread-to-square bore adapter, or a Canton Racing 85-254 spacer which should preserve some of the signal. Either way, it's a crap-shoot...
|
|
|
Re: drilling TQ throttle plates?
[Re: Diplomat360]
#1256784
06/26/12 01:20 AM
06/26/12 01:20 AM
|
Joined: Mar 2005
Posts: 862
Iowa State fan
kilroy
OP
super stock
|
OP
super stock
Joined: Mar 2005
Posts: 862
Iowa State fan
|
Ok boys here we are. I didnt want to drill the air bleed by pass in the base plate because I wanted to be able to put the carb back to normal so I did drill the throttle blades. I started at 1/16 which didnt do boo. I moved up to 1/8 because when I unplugged the pcv hose and cranked out the idle mixture screws it responded with more idle speed. What I ended up with was 9/64 holes and somewhere between 2.5 and 3.25 turns on the idle mixture with an idle of 850rpm. I also have less than .035 (give or take, its hard to hold a carb upside down and compare with a feeler gauge) of transfer slot exposed, just barely over square. The car seem to be happy, so am I. I will take it for a long drive later this week and update more.  Again my original was 1.5 turns on mixture screw at 850rpm but with over half of the transfer slots exposed. Im sure I could drill some tubes, but I think essentially I am doing the same thing only not messing with the other circuits or transition into those circuits by not drilling out the bleeds on the low and high speed. No matter how you look at it, it takes a certain amount of air+fuel to equal speed.
Last edited by kilroy; 06/26/12 01:25 AM.
|
|
|
|
|
