67 390
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Joined: May 2003
Posts: 11,141
Likes: 25
From: south louisiana
Originally Posted by Green Streak
I am looking at a running 67 390 currently in a 67 Tbird. The motor apparantly has not been opened up. What fuel and additives should I run in it?
TIA Greg
TIA Greg
Postmaster
Joined: Jul 2003
Posts: 2,711
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From: Pittsburgh
It'd also be a good idea to run lead additive in it since it'll have non-hardened exhaust seats.
And what baddad457 said is correct. I have a 67 T-Bird with a stock 390 and it'll barely run on premium. The neat part about it is if you put a more aggressive camshaft in there, the motor will "think" it has less compression so you'll be making more power on cheaper gas.
I'm also kinda in the market for a 67 T-bird aircleaner housing for my bird. If it's there let me know.
Justin
And what baddad457 said is correct. I have a 67 T-Bird with a stock 390 and it'll barely run on premium. The neat part about it is if you put a more aggressive camshaft in there, the motor will "think" it has less compression so you'll be making more power on cheaper gas.
I'm also kinda in the market for a 67 T-bird aircleaner housing for my bird. If it's there let me know.
Justin
FE "Freakin Expensive"
Joined: Dec 2003
Posts: 6,461
Likes: 4
From: Smith Mountain Lake, VA
If I were you..I wouldnt run a lead additive... I would pull the heads and get hardened exhaust Seats installed...as with the additive you'll end up with Lead fouled Plugs and lead build-up on top the pistons and the Valve's making it very prone to Pre-detonation
Dont ask me how I know this..LOL.. I just do....Lets just put it this way ..It had to do with my old motorhome and a 6000 mile trip !! I thought at Hyw..speeds it would have kept the lead cleaned out.. It didnt..I change plugs 3 times on the trip! JMO...
RJ
Dont ask me how I know this..LOL.. I just do....Lets just put it this way ..It had to do with my old motorhome and a 6000 mile trip !! I thought at Hyw..speeds it would have kept the lead cleaned out.. It didnt..I change plugs 3 times on the trip! JMO...
RJ
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Joined: Jul 2003
Posts: 2,711
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From: Pittsburgh
I run lead in all but two of my vehicles. Only time i ever had an issue lead fouling plugs was if i'd dump the whole can (designed to treat 20 gallons) into the 10 gallon tank on one of my VW's.
The other thing is I only run lead every other fillup. That way what has built up from the lead has time to wear down, but not completely off before getting hit with lead again.
Justin
The other thing is I only run lead every other fillup. That way what has built up from the lead has time to wear down, but not completely off before getting hit with lead again.
Justin
Trending Topics
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Joined: Apr 2006
Posts: 506
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From: mid-MO
I pulled out my junk 351M out of my 79 f250 and put in a 390 out of a 67 car and i have never run lead additive in it. It runs like a top, so I dont know if i just got lucky and it didnt mess up my valve seats, or if it really doesnt hurt to run straight 87 octane.
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Postmaster
Joined: Jul 2003
Posts: 2,711
Likes: 2
From: Pittsburgh
Depends on the '67 motor. If it's a 2bbl car motor, they'll live on 87. A 4bbl car motor in good shape will barely run on premium.
The thing about lead is while you're running the motor you'll probably never notice a difference. It's when you pull a head off and valves are sitting 1/4" deeper into the head than others.
Justin
The thing about lead is while you're running the motor you'll probably never notice a difference. It's when you pull a head off and valves are sitting 1/4" deeper into the head than others.
Justin
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Joined: Jul 2003
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From: Pittsburgh
Yeah, the 2bbl motors run lower compression than the stock 4bbl motors whcih is why yours is running on regualr gas.
It's very gradual. If you pay attention you'll notice but they typical person won't. Besides, the difference is taken up by the hydraulic lifter for a while before anythign starts to really happen. When the lifter can't take up anymore slack, you'll start getting a slight backfire and miss which will eventually go to a full blown dead cylinder.
Justin
It's very gradual. If you pay attention you'll notice but they typical person won't. Besides, the difference is taken up by the hydraulic lifter for a while before anythign starts to really happen. When the lifter can't take up anymore slack, you'll start getting a slight backfire and miss which will eventually go to a full blown dead cylinder.
Justin
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Joined: May 2003
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From: south louisiana
My 68 Merc's 390 was also a 2 bbl motor but it was the high compression 2 bbl. This is basically the 4 bbl engine with 2 bbl intake and carb. There were both low and high comp 2 bbl motors. I think the Mercs got the high comp versions. But either way the low comp 2 bbl still has 9 or 9.5 to 1 and still might have problems with low octane gas with a stock cam.
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