just changed the throttle body cable and throttle body on my 3.9 to a v8 set up. pretty easey to do but the intake holes on the intake manifold are smaller than the in holes on the new trottlebody. any body run into this problem before and what and how??? to fix.

 

I would just use the v6 bolts with a new TB gasket. Unless it's really different in size you should have no problem. center it as best you can and torque it down.

 

i'd like em to be close to the same size for preformance. i got a flap sand wheel today so i can make em larger but i don't want all the dust and shavings to fall into the intake.

 

IF your going to match the bore pull your throttle body and your intake. take em down to a machine shop and get them matched

 

sorry dude, I miss read your post... I agree with kurby... yank the intake off and either have a shop do it or pull the plenum off and do it yourself. while your in there you might consider doing intake mods to help it breath better at the upper rpms, cutting the runners down and opening up the injector bores will help out alot.

 

thats cool, hopefully it'll be easey to get the intake man. off. i think i can grind the mani. my self. i've heard of doing some of the mods you said, but i have no idea what a runner is or how to cut it down and also what should i use to open the injector bores, like a simple grinder?

 

it takes a steady hand but i used a roto zip with dremel cuttoff wheels and an oversized mandrel. cuts the runners like butter. then I used a cutting bit to open the bores... here's some pics.



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thanks for the pics. i drilled out the intake holes on the mani with a number of tools and it actually looks pretty good. could use a bit more but i had to put it back together so i could get to work. i've noticed a big upper rpm improvement in power and a little loss on the lower end. if i continue to work on the runners and do all the high flow improvements, will it continue to weaken the lower end on the power band?? i try to do most of my driving below 2k rpms with only the accasional lead foot.

 

yes you might loose some low end. when you change the runner length you are changing the toque curve some. the bigger benifit is on the top end. when i did my 2000 5.9 motor, cutting the runners 1.5" really helped out alot. I did a 2nd manifold and only cut off .25" to see how it affected the performance. .25" was a waste of energy. 1~1.5" was the way to go. the torque difference wasnt that noticeable from .25 to the 1.5 on the 1st manifold.

do some research on it 1st before you cut them. depending on what else you may do to your motor it may be worthwhile to do it. when your tuning a motor think of it as a teeter totter... one end goes up & the other end goes down. if you were building a motor from scratch its a different story. the base motor, stroke lenght & cam design really IMO ... will determine how much torque your going to get out of it

how do you like the v8 TB on there?

 

ya i think i'm happy with it. its pretty drivable w/ the 5spd v6. and it gives it the extra go when i want it. i've done a custom cai and put on the worked over throttle body only. I've heard the v6 exhaust flows very well so i'm waiting till it needs a new one before i do the exhaust. Thanks for the info. i think thats what i'll do with the runners, cut em down .25 inches at a time and see what happens or at least start from there, i don't want to loose too much low end.