raytex

My 65 car was original a 327 with factory air.
The 327 engine has been replaced with a 396 (Chevelle) in the mid 80s.

Which fanblade should I use not to have "heating" issues?
When I bought the car it was overheating, the previous owner installed a electric pull fan. This was with a 327 support, shroud and radiator.
I have removed the electric fan and installed a 396 shroud, radiator support (added the AC holes) and a BB aluminum radiator with a new AC condensor.

Should I use a 396 5 blade 17" or a 64-65 18" 7 blade or maybe a 66-67 18" 5 blade?

please advise

Ray

stingrayl76

I'm no expert but since you are using the 396 fan shroud, I would normally say to use the 396 5 blade fan. However, considering the added A/C you are going to need as much airflow as possible so you will need to determine which fan moves the most air and will clear the shroud. Hopefully someone can chime in ad provide the airflow information.

JohnZ

Frequently, the fan used with A/C has deeper pitch (blade angle) than a non-A/C fan; although it may have the same number of blades, it will move a lot more air.

I'm not familiar with the 396 shroud/fan sizing, as that combination never had A/C - maybe one of the 396 guys will chime in with alternatives.

TheSaint

Since it is a AC car it just as likely that it had a 7 blade fan according to the Vette Vues Fact Book
Well, i must say that the book have been wrong before..

avideo

Seven Blade Flex fan to pull the maximum air through you radiator. Whatever is the largest size your radiator shroud will allow.

raytex

Ok thx I will just do that and meassure the fanshroud and see what is acceptable.

raytex

Of course it had a 7 blade , 34.5 degree pitch fan blade with the original shroud. When I got the car there was a plastic fan blade installed.
Now it has a 396 shroud, I will measure the max possible and either get a 64-65 18" 7 blade 34.5 degree pitch or the 396 17" 5 blade which also has a 34.5 if I understood correctly.

Clearnce fan blade to shroud should be how much?
1/2 inch?

Ray

67vetteal

A 1/2" should do it. Any closer and your running the chance of it touching when you throw a few Hard Shifts! Our engine mounts do get softer through the years and allow the engine to rotate a little bit under strong acceleration. Al W.

TheSaint

After what i have read it is not all "off course" factory AC cars had 7 blade fans.
Factory AC cars was delivered with a 5 blade fan because if they was out of 7 blade fans they installed 5 blade fans
That is what i read

midyear

I ran a 74-75 7 blade fan (notched blade) and heavy duty clutch on my 67 427 air car for years with out overheating issues, its been what I used on other big block cars to help them cool better as well. may not look right, but did the job.

raytex

Then my problem is solved.
But why would they do that?
5 blade 24.5 degree pitch or 7 blade 34.5 degree pitch.
If GM does make an issue about the number of blades and the pitch degree of the fan
Guess any fan will do then.

TheSaint

I think it was Noland Adams Volume 2 i read that they used 5 bladed fans if they did not have the correct 7 blades at hand

409/409

What is the correct pitch and number of blades for a 1966 427/390hp???

JohnZ

5 blades (each 4" x 5.68"), "W" stamped on the back side of one of the five "arms", 32* pitch, P/N 3888366, flat-head rivets, 17-1/2" diameter.