tell me if this makes sense guys...

all done with my 340 intake/4bbl swap onto my 318 which had a 2bbl and stock 318 intake. BONE STOCK 73 road runner.

the car started up and idled fine, however, after it got hot, i noticed the RPMs gradually got higher and when i shut it off, i would get the puff sound like it backfired and smoke would come out of the air cleaner. it was also hard to start when hot. a friend of mine suggested i mess with the timing, so i did.

i found that i had to retard it just a hair from stock setting for it to run almost perfect. i would have thought i would have had to advance it going to a bigger intake and carb, but hey i'm a noob, so what do i know.

does that sound right to you guys?

thanks

Sounds like a vacuum leak.

thanks for the responses guys...

i did get it to work after screwing around with the timing however. it was nice and hot and idling fine. no upswing like before. i also noticed it started much quicker and easier after changing the timing. would that still be symptoms of a vacuum leak?

my post was mainly to see if you normally have to advance or retard the timing when installing bigger intakes and carbs.

thanks!

That shouldn't matter as much as the cam change. If it runs good at 32* leave it.

it is advanced more with the small 2-v carb

if it want less take some out..which you did..let it ride

get a vac gauge and put it on the full vac port on carb

advance it to get the highest vac reading... back it down one full #...if it 18,back it down to 17 on the vac gauge

adjust curb idle to 800-850 rpm,then adjust the air mixture screws on the carb to get highest vac reading on the gauge and adjust curb idle to were you want it set at

use a timeing light and see where the adjustment is at,keep it for referance later.

run it on a wot blast..you want no ping or just a slight ping on a hard wot blast

I do mine this way and get them down to 600-650 rpm and will take a full throttle stomp with out any bog,pop,miss,sputter.(I do have the LD4B/600 carb,VooDoo roller cam,headers,duels,3.55 gears to work with it also)

the thing to do with a stock 318 thats just got a 4-v swap is add duels and fine tune the carb and timeing

find what it likes and run it..cant go by stock book setting once it gets mod-o-fried

to me that is the fun of adding a 4-v to a 318..test & tune baby

I'm assuming stock untouched '73 dist? What Scratchn said. set the initial w vac gauge method then shorten the slots to get 35 toatal (vac adv disconnected/plugged)then toss the heavy thick spring w the long loop & sub in a thinner one like maybe a mr gasket or one of the MP light springs & play w spring combo, LASTLY rehook/adj vac adv. Lot of gain 2 b had reworking a stock curve.

with a stock SB,that is the reason I like the older points dist,it has a slightly better advance curve in it over the smog elect ones for hot rodding in stock fourm.