oldford

hello im new to classic cars and im restoring?? a but not orginal 1966 mustang ..... i bought a 1988 5.0,, HO roller engine..... and done all my switches to make it work ,,but i may of overlooked a ONE.. important issue......... i left the stk cam for the fuel inj in.... and put a 4bbl intake and carb on it,,,,,it seems to run great under power at high rpm,s and idles great in park (but when i put it in drive.. at idle..... foot on brake it runs ext ruff) ......14 hg vac@ idle in park..... 6-7 hg vac@in drive at idle ......23 hg vac steady @ 1/3 throdle.......... so i think the cam may the issue ........... anyone ever done this swap and not change cam b4

Hamutoff

If you are saying that you put a 5.0 HO with the roller cam in your 66 mustang and then used a carburator, then YES the cam is a wonderful cam! IT works awesome when switched to carb.
Please tell me what did you do for a distributor?
Also its possible you may have vaccuum leaks....maybe try spraying around the intake with carb cleaner but be careful have a fire extinguisher handy[&:] listen for the idle to change... if it does then the area you just sprayed is leaking

For fun and to learn I swapped a 1986 5.0 into a 1989 formerly 4 banger.... I used the distributor from the 1985ish cars, had it recurved for nitrous and the vaccum adv pulled... even with a single plane intake the car idled so damn smooth.... so very streetable so steady, I really really wanted to daily drive it but of course no way in CA!!!!

http://www.thatmetalbox.com/89lx_mus...stang_main.htm

Well it was lots of fun!! I did 95% on my own and it was the first time working on a fox car.... swapped the engine, trans, rear, fuel tank, stripped the interior, fun and easy!!!! I used soild motor mounts and beautiful MAC longtubes (for gt40p heads I was gonna use) too bad I only got to run it a few times and without the nitrous that was planned it was a co-owned project I put about $1200 into then my buddy said NO I OWN IT ALL NOW MY PRECIOUS!!! and the car has sat moludering and rotting in his backyard for 3+ years now!!!!!!!!!!!

well anyway It got me loving the fox cars!!!!!!!!!!!!!!!

Hamutoff

uhh you DID put a steel gear on the distributor you choose, right?

oldford

i put in a single wire HEI distributor with a chrome/moly gear

Hamutoff

Chromoly is an abbreviation for "chromium-molybdenum steel"
do you think you might have a vacuum leak, did you use the cork end gaskets on the intake manifolid... sometimes using these ... may lead to leaks

67mustang302

What's your idle speed in gear? IT may also be just too dang low. But if the idle speed is ok, then yeah, start looking for a vacuum leak first. And carbs don't give a crap WHAT cam they're used with. That's one nice thing about carbs, if the engine will run, a carb can get it to idle(if it's set right).

Gary H

I have a 95 engine in my 84 with a carb. Pulls 18" vac at idle. Vac leak, timing issue or mis adjusted rockers.

oldford

(i used rubber on the intake) ..... latter TODAY I WILL SPRAY. IT DOWN WITH STARTING FLUID AND LOOK FOR VACCUM LEAKS ILL NEED TO GET MY TAC BACK FROM A FRIEND TO CHECK PERCISE IDLE SPEED .. .. I WILL POST ALLL I FIND AND MY FINAL REPAIRS AS I FIND THEM ..... I SHOULD KNOW MORE LATTER TODAY....... THANKS FOR ALL THE INFO SO FAR

oldford

well ive done some timing And carb tuning and it is still a little ruff at idle and can step on it And lay a 50 foot mark on the pavement it has great power above 1000 rpms but im still suspicious of the cam .......... i forgot to add the motor was originally in a manual trans car ..... and i think you need to choose a cam for manual or auto trans for perfection .........if any one reads this and knows it the manual cam might make a difference at idle please let me know

HACKGT350

you obviously have a vacuum leak at idle it should be about 19 20 hg of vacuum. like said about spray around with carb cleaner on all gaskets and all and see if you can find that leak. youll know it will change the idle drasicly