Thread: How to tell 390ci 300hp from 375hp

Tweet

I have a 61 T-Bird and do not know how to tell what Holly 4B engine I have. Markings on engine? Data base of Vin or serial Numbers? The serial number plate list style as 55.

Anybody have some ideas

Thanks

Ed

I just read the new guy identify thread. I will crawl around and get the various numbers discussed.

What were the differences between the two engines?

Ed, the block will have HP markings on it. Look on the right side of the block where your casting number is. You should see a HP cast into the block. All 375 and 401 HP 390's have this HP mark.
G.

G,
I've been having problems with right and left.
You are talking about the number on the generator / pasenger side?

Ed

If it's the original engine it's an easy question. It's the "Z" code 300HP version (the Z is found in the Vin on the door tag).

There were no optional or special order engines available in the 61 Birds.

The 62/3s had the optional "M" code engine available. This was the higher compression Tri-power motor.

The Tri-power is a nice upgrade to the engine, but if you go looking for one make sure you get the T-Bird version as it's shorter to fit under the Thunder Chicken hood and the 406 versions won't let the hood close.

Originally posted by EdBird
G,
I've been having problems with right and left.
You are talking about the number on the generator / pasenger side?

Ed

It is allways seen from the drivers seat.
Drivers side = left side
Passengers side = right side

Well, unless you happen to be in Australia, then left and right is all messed up again..............

Originally posted by Dave Severson
Well, unless you happen to be in Australia, then left and right is all messed up again..............

And using a mirror under the hood will compound the mess up more.

Geez, thanks Walt. Now you have me confused. If I'm using a mirror and standing backwards, then...........

Check to see if you cast a reflection in a chrome hubcap,,,,if you dont,,, then it's a good bet you have been bitten by the hotrod bug,,and shall forever more,, "Haunt the auto swapmeets"....Booowahhahahhahhh

Ed yes it will be above the casting number around the generator area. The HP letters are around 1/2" tall. Mike is correct though about the Z code 390. This would not be a HP block if original. The 390HP, 406 and early 427 blocks have this HP identfier. It's also on the rear of the block and inside by the cam bearing and main bearing areas. G.

EDIT: Also the HP is cast in the lifter valley of the block.

Best way to tell which is which is to stand on the loud pedal!

.