Hey fellers,

About a year ago, I replaced a 360 with a rebuilt 390. The guy that built the engine said the heads were for a 392 truck engine. The ports are visibly larger, but that's all I know about them. The new engine is also slightly cammed, and has a new Edlebrock 4bbl and intake, and headers. It sounds sweet

The problem is smoke and oil. It smokes out of the passenger side only, and only on warm restarts. It uses about 1 quart of oil every 75 to 100 miles. It now has about 1000 miles on it. It's been the same since new. It's also noticeably slower than the old 360. Zero to 70 is pretty sweet, but tops out at about 80ish.

The guy says the oil usage is because he installed chrome rings and it will eventually stop.

If the oil usage was due to the rings, wouldn't it smoke out of both sides? Carbon in the oil, etc? The oil is clean.

A friend suspects the heads. Lower power, smoke on warm restarts and oil usage, he says all are related to the heads.

Thoughts and comments please.

 

392....no such thing. 391, now we are talking.

The 391 FT motor is based on the FE--on paper, most of the dimensions including bore and stroke are the same.

FT heads usually have smaller ports and valves. They also have an exhaust cross over that prevents FE manifolds--intake and exhaust--from working on them.

Oil smoke can be caused by bad valve seals. Ford neoprene umbrella seals fall apart and clog oil returns.

Smoke on one side could also be caused by PCV issues if the PCV is plugged into a manifold runner on one side of the engine, vs. the under-carb plate that Ford used.

Depending on the specs, the cam could be all wrong for the motor. A 390 car motor will have pistons that come up to at least .030 from the deck. A pickup spec motor will be more like .100 down the hole. 9.5 CR vs 8.5ish.

I do not know nor do I know where to find the specs for FT head combustion chambers. If they are larger than the FE head, compression drops.

The oil use is excessive. Have you done a compression check?

Chrome ring sealing can be an issue, but with that amount of oil consumption, I'm surprised you can keep it running. Cylinder honing is important with those rings.

Back to the heads as suspects for your problems--yes, the valve seals are a suspect. Especially the smoke on warm restart. But the amount of oil you are using is well beyond most valve seal issues.

If it is ok to 70, what happens at 80? You might have fuel issues if it accelerates to a certain point then goes flat.

But I'd run down the oil thing first. They say the best break in is to run them hard. After 1000 miles, I think you are approaching tear down time.

BTW, why use chrome rings in an engine like this?

 

392 wasn't that a Chrysler Hemi engine ?

 

392:

New: http://www.allpar.com/cars/dodge/pho...8/392-hemi.jpg

Old: Chrysler 392 Hemi Engine | Fire Power Engine | 1957 and 1958 Chrysler Engine For Sale

International: http://www.binderplanet.com/photopos...adstar_392.jpg

 

Thanks mtod, I appreciate the info.

 

Not a scholar on the FE's but weren't they a 2bbl and 4bbl head design.

 

There were head differences for perfomance engines vs. sedan and station wagon motors. For the 352 & 390, there were compression differences between 2bbl and 4bbl motors which were achieved with different pistons. In '66 & up Ford sold these as "390 2V-Regular Fuel" and "390 4V Premium Fuel". Mercury had a PF 2bbl motor with the same compression as the 4bbl.

2bbl vs. 4bbl carb could make difference in your insurance rates in those days, so besides the 4 cents per gallon difference in gas costs, cheap people like my dad could save insurance money too.

The 352 & 390 were the only '60s FE motors with the 2bbl option.

In pickups, the 360 was never offered with a 4bbl. The 390 was offered with a 4bbl in some applications, but afaik, was otherwise identical to the 2bbl offering.

The 351C had different heads for 2bbl vs. 4bbl versions.

 

Elbob, Look between the 2 middle plugs and post the number & letters that you find there. Should be like C6AE and 6090-J (just examples) See if both sides have same ID.


John