I have a 69 435HP 427CID engine that I am putting in a 70 Chevelle and have some cooling questions. I have a 1970 original 772 fan and was wondering what Hayden clutch I should use with it. The engine is original inside with the 11 to 1 pistons and the solid lifter cam. There is no air and a 4 speed car. I just need to know what fan clutch would be the best option. Thanks
A 70 bbc chevelle with stock fan shroud & 772 7 blade clutch fan & stock long water pump i'd run haydens HD 2747 fan clutch that was used for AC-HD cooling option .
Iv'e installed that fan clutch in more then a few 69-70 chevelles (including my 69 w-bbc)with street perf bbc's and it works very well,better then the stock/std duty fan clutch which i found to be margianl in some apps.
I also rec running a hi flow milodon water pump along with an autozone duralst 15356 t-stat too.
I run the above mentioned setup with my moderate perf bbc with just shy of 10.0 compression along with an original Harriosn rad just restored with a hi efficiency core (4 tube/4 core) and in 90+ deg HHH temps it runs 180-185 max in traffic and 175-180 when at cruise.
I just bought one online from Rock Auto for $45 for someone's car 70 chevelle ss 396 i'm currently working on.
Napa also has a good DH fan clutch for your car/motor (bbc with long pump) that's pt# 271303 ,but may cost a few more $.
BTW,you didn't mention anything about a fan shroud and you absolutely need one (stock/original type) for proper cooling or it will heat up esp when in traffic.
You also didn't state what type radiator you have and it's age,a tried 15-20+ yr old rad weather it's a 3 oir 4 core will likely not do well esp when in traffic on a hot day.
For optimal cooling efficency since your likely running some kind of non gm aftermarket perf cam in your 427/435 dont forget you need to run significantly more base timing then stock gm cam used from factory.
In many cases approx 18 deg (sometimes 20 deg with hot cam) base timing is a good place to start along with approx 18 deg mech in dist all in by 2500-2600ish rpm.
Then when running 18-20 deg base timing + 18 deg mech that will = 36-38 total which is also a good place to start with total timing for a street perf motor.
For a street perf motor if there's enough vacuum at idle its also helpfull to run a vac adv limited to/setup for 10-12 deg max .
Lastly,you say your motor has 11.0 comp[ ,i hope you running a farly lrg cam that will effecvtively lower cyl pressure enough to tollerate todays carppy 93 octane pump fuel.
GM stated the from the factory those 11.0 comp motors perf bbc's had to run on a minimum 98-100 octane leaded fuel so i hope you dont think it will run ok on todays much lower 93 octane pump fuel.
Keep in mind today's lower octane pump fuel is also oxygenated /has 10% ethenol added/and has no lead which is a totally dif fuel formual then those old gen motors were ever designed to run on in the 1st place which could lead to bad detonation with mild cam timing/11.0 comp/stock type cast iron heads on today's very different formula lower octane pump fuel.