[redrocket1953]

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

 

[SWHEATON]

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.

Scott

 

[redrocket1953]

Scott
You are a wealth of info. The radiator is a stock Harrison 3 core with the H.D. cooling, so it has the 4 core tanks on it and I'm running a 4 speed. It was just recored for my original 396 and it cooled it great with the 4 blade standard fan and the stock shroud. It would run 180 on a hot day cruising but would heat up to 210 in slow traffic or at an idle. If this runs hot I can have a 4 core put in between these tanks. The cam is the stock G.M. L-71, L-72, LS6 solid lifter cam with 520 lift and 114 degree lobe separation. I run 93 octane pure gas with either some 110 race fuel or Kemco 130 Octane Supreme mixed in with it. My distributor is set up for the 435HP 427 cam and compression. I will get the clutch and stat you stated and see what happens. Thanks a lot for all your input.
Randy

 

[SWHEATON]

Scott
You are a wealth of info. The radiator is a stock Harrison 3 core with the H.D. cooling, so it has the 4 core tanks on it and I'm running a 4 speed. It was just recored for my original 396 and it cooled it great with the 4 blade standard fan and the stock shroud. It would run 180 on a hot day cruising but would heat up to 210 in slow traffic or at an idle. If this runs hot I can have a 4 core put in between these tanks. The cam is the stock G.M. L-71, L-72, LS6 solid lifter cam with 520 lift and 114 degree lobe separation. I run 93 octane pure gas with either some 110 race fuel or Kemco 130 Octane Supreme mixed in with it. My distributor is set up for the 435HP 427 cam and compression. I will get the clutch and stat you stated and see what happens. Thanks a lot for all your input.
Randy

================================
NP!

That stock L6 cam is very mild cam timing for 11.0 comp espcially on todays 93 pump fuel so ensure your mixing for approx 100 octane,i would hate to see you fry a piston due to detonation.

My 396 now 402 has just shy of 10.0 comp/stock type 063 lrg oval port heads with approx same size cam-dur @.05 , .525 lift on a 112 deg lsa and it doesnt like 93 fuel @ WOT in warmer weather where it can detonate at times,but not under normally/lower load driving cond. I also run Kemco with every tankfull mixed for approx 97.5-98 octane.

BTW,Kemco Lead supreme 130 is no longer mfg'd and Max Lead 2k source has also dried up too so unless you have some of that lead additive on hand it looks like you will be mixing more race fuel with 93 octane fuel.

Good luck.

Scott

 

[redrocket1953]

Scott
I was having trouble getting the Kemco Octane Supreame also then about 6 weeks ago I did get a case from the Kemco lady on the phone for the $125 with free shipping. My stock 350HP 1970 402 seems to run fine on the straight 93 octane gas. It still has the stock 10.25 to 1 pistons, stock 350HP G.M. cam and the 290 iron heads. I have never heard it ping once.

 

[69-CHVL]

Randy - hope you dont mind me asking Scott a question...

Scott, what clutch and fan does this look like to you?

Reason I ask is that it cools so well that I'm wondering if its sapping too much HP. Was thinking of electric fan(s), but if it aint broke...

 

[SWHEATON]

Randy - hope you dont mind me asking Scott a question...

Scott, what clutch and fan does this look like to you?

Reason I ask is that it cools so well that I'm wondering if its sapping too much HP. Was thinking of electric fan(s), but if it aint broke...

=============================================

Hi Vince,the fan looks exactly like the clutch fan that was used on the 87/88 monte SS's i had which is same clutch fan used on many diff GM V8 cars with AC or HD cooling for many yrs.

GM may have started using that fan design in 1971-2 ish but am not 100% sure of that.

Thats a great fan for moving a lot of air,i think it's a little better at moving more air then the GM's 772 clkutch fan does, but your fan may use more power as you suspect too.

If memory serves me correct the fan shorud your currently running covers your complete rad which also helps your cooloing esp at idle and or when in traffic @ lower road speed's.

As for the fan clutch,it's looks to be an older std duty fan clutch which doesnt normally cool as well as the HD fan clutch does.

But since your running the GM fan that moves tons of air along with a fan shroud that covers the complete rad vs thre other gm shroud that only covers approx 70-75% of the rad tjhat inceased you motor cooling effciency enough that it does ok with the std duty fan clutch.

That fan clutch looks old so why not try a hayden HD fan clutch for bbc long watherpump (2747) avail from roc k auto for approx $45,just got one in mail from there today for a 70 chevelle 396 i am working on.

Between using a fresh hd fan clutch with the autzone t-stat i suggested to you last yr and bet you could get it to run a little cooler in traffic on hot days not that you were having running hot issues which you werent.

That fan clutch also unlocks some when the motor under load at higher rpm @ WOT so should not loose all that much power when your on it ,but even then it has to be eating up a few hp,thats for sure.

But for a street/strip car like your running i'd be willing to give up a few hp for great cooling from the cooling setup your currently running vs swaping to an elec fan setup that may not do any better then where your at cooling wise right now or maybe not as good.

I have seen a few people that went from a good working stock gm cooling system to elec fans spec'd to cool considerably more HP/Motor then they had which were installed propely but didnt cool as well as the stock setup did.

Just my $.02 on that.

Scott

 

[SWHEATON]

Scott
I was having trouble getting the Kemco Octane Supreame also then about 6 weeks ago I did get a case from the Kemco lady on the phone for the $125 with free shipping. My stock 350HP 1970 402 seems to run fine on the straight 93 octane gas. It still has the stock 10.25 to 1 pistons, stock 350HP G.M. cam and the 290 iron heads. I have never heard it ping once.

=====================================

WOW,you were able to get a hold of someone @ Kemco and get booster approx 6 wks ago,thats great!

Unless you rblt the motor yourself you cant be sure it still has 10.25.1 pistons for higher comp with the short cam timing the stock cam has which is a rcp for detonation on todays much different formula lower octane by 5 pts non leaded/ethnoled/oxygenated 93 octane pump fuel.

Keep in mind GM stated from the factory that you motor had to run a min of 98 octane and i can tell you from 1st hand exp running/driving those motors 35+ yrs ago that in stock form on hot days they pinged on 98 oct leaded sunoco fuel and we had to run 102 sunoco in them to stop the ping when you would get on them .

I have 2 original #'s matching 70 chevelle SS 396's /L34's that i srv'c that have never been appart and they both ping bad on 93 fuel ,they have to run a real lead booster to stop it.

So i'm thinking maybe your motor doesnt have as much compression as you think,maybe has more cam then you think effectively lowering comp some,or you dont have timing at approx 6-8 deg btd where they like to run with a stock GM cam which if base timing was more retartded ,maybe mech adv in stock dist is stuck or not fully advancing along with vac adv not working properly collectively reducing overall timing by a significant amount which could poissibly be why it doesnt ping on 93 fuel.

But a completely stock 396/L34 with 10.25.1 comp with stock iron heads and stock cam with short cam timing that was designed to run on 98 octane or higher leaded fuel that hasent been oxygenated with 10% ethenol added and no lead will ping on 93 pump fuel if running proper amount of timing /10.25.1 comp and short stock cam timing with a bone stock L34 396.

So there has to be a reason why your L34 seems to run ok on 93 fuel with no detonation most of the time.

But also keep in mind hotter motors with 11.0 can run fine on 93 fuel when running a hot cam lowering cyl pressure some/AL heads to reducing temps/stall with auto trans & gear like 3.73-3.90-4.10 both lowering load on the motor/perf dist with no vac adv reducing timing by 10-12 deg or so/etc.

Scott

 

[redrocket1953]

Scott
I bought this 70SS with the L-34 in 1972 from the family of my best friend who was killed in Vietman. It had 2356 miles on it when I got it so I can say 100% for sure that it is still stock. In the mid 70s a guy who was the king of distributor curving worked his magic on the distributor. Thats the only thing thats not stock. I took the L-34 out to put gaskets in and freshen up the engine paint. I had the 427 out of my 69 Vette that a tree jumped out in front of back in 74 and took the whole right side off of the car. I bought it from the insurance company saving the 427 and the M-22. It sat in my shop until last fall when I went over it and thought I would try it in the Chevelle and put the original away for safe keeping. This will give me the year to decide what else to check over on the 402 as it has 47,000 miles on it now. Instead of the tri-power setup I am running a LS6 intake and carb setup so it still looks 1970 and fits with the cowl induction. I think I had more pinging issues back in the late 70s on that gas as thats about the last time I remember it pinging but I really don't get on it too much because I worry about hurting the original engine. I have never put any ethanol gas in this car, I always can find 93 octane pure gas. Thanks for sharing your knowledge as it has helped me out a lot.

Randy:beers:

 

[SWHEATON]

Scott
I bought this 70SS with the L-34 in 1972 from the family of my best friend who was killed in Vietman. It had 2356 miles on it when I got it so I can say 100% for sure that it is still stock. In the mid 70s a guy who was the king of distributor curving worked his magic on the distributor. Thats the only thing thats not stock. I took the L-34 out to put gaskets in and freshen up the engine paint. I had the 427 out of my 69 Vette that a tree jumped out in front of back in 74 and took the whole right side off of the car. I bought it from the insurance company saving the 427 and the M-22. It sat in my shop until last fall when I went over it and thought I would try it in the Chevelle and put the original away for safe keeping. This will give me the year to decide what else to check over on the 402 as it has 47,000 miles on it now. Instead of the tri-power setup I am running a LS6 intake and carb setup so it still looks 1970 and fits with the cowl induction. I think I had more pinging issues back in the late 70s on that gas as thats about the last time I remember it pinging but I really don't get on it too much because I worry about hurting the original engine. I have never put any ethanol gas in this car, I always can find 93 octane pure gas. Thanks for sharing your knowledge as it has helped me out a lot.

Randy:beers:

======================

RANDY,NICE HISTORY ON YOU CAR.

AHH!!,i knew there had to be somethin,it makes a difference that your running fuel that has " no ethenol in it " and also thast maybe the guy that recurved the dist took a little timing out of the mech adv and vac adv if still running it too.

So collectively thats likely why your stock L34 doesnt normally ping in most driving cond.

Yr's back when Sunoco added 10% ethenol to thier highest oct fuel avail in my area at that time which was Ultra 93 thats when my mild cam'd 396 now 402 with approx 9.8 compression would dertonate under hard load/mostly WOT ,but it never detonated on non ethenoled 93 ultra.

Scott

Scott

 

[69-CHVL]

=============================================

Hi Vince,the fan looks exactly like the clutch fan that was used on the 87/88 monte SS's i had which is same clutch fan used on many diff GM V8 cars with AC or HD cooling for many yrs.

GM may have started using that fan design in 1971-2 ish but am not 100% sure of that.

Thats a great fan for moving a lot of air,i think it's a little better at moving more air then the GM's 772 clkutch fan does, but your fan may use more power as you suspect too.

If memory serves me correct the fan shorud your currently running covers your complete rad which also helps your cooloing esp at idle and or when in traffic @ lower road speed's.

As for the fan clutch,it's looks to be an older std duty fan clutch which doesnt normally cool as well as the HD fan clutch does.

But since your running the GM fan that moves tons of air along with a fan shroud that covers the complete rad vs thre other gm shroud that only covers approx 70-75% of the rad tjhat inceased you motor cooling effciency enough that it does ok with the std duty fan clutch.

That fan clutch looks old so why not try a hayden HD fan clutch for bbc long watherpump (2747) avail from roc k auto for approx $45,just got one in mail from there today for a 70 chevelle 396 i am working on.

Between using a fresh hd fan clutch with the autzone t-stat i suggested to you last yr and bet you could get it to run a little cooler in traffic on hot days not that you were having running hot issues which you werent.

That fan clutch also unlocks some when the motor under load at higher rpm @ WOT so should not loose all that much power when your on it ,but even then it has to be eating up a few hp,thats for sure.

But for a street/strip car like your running i'd be willing to give up a few hp for great cooling from the cooling setup your currently running vs swaping to an elec fan setup that may not do any better then where your at cooling wise right now or maybe not as good.

I have seen a few people that went from a good working stock gm cooling system to elec fans spec'd to cool considerably more HP/Motor then they had which were installed propely but didnt cool as well as the stock setup did.

Just my $.02 on that.

Scott

Thanks Scott! Yes, I have that shroud that I *think* is for a SB car. Runs 167* right now (was 40* out today) since I put the 160* T-stat as you suggested from AutoZone. Not bad for 600HP along with a 2 core rad huh? In the summer, it will run around 180* Only complaint I have regarding the AZ t-stat is the variance in temps - anywhere from 166-to around 182*. When I had the 180* Moroso high-flow, temps stayed around 185-190*. I would try a 160 Moroso, but I'm afraid it may run too cool, so I'll just leave well-enough alone.

I was considering the electric fans b/c my EFI can control up to 2 fans, thought it would free up some power an mileage. But again, it aint broke...

 

[SWHEATON]

Thanks Scott! Yes, I have that shroud that I *think* is for a SB car. Runs 167* right now (was 40* out today) since I put the 160* T-stat as you suggested from AutoZone. Not bad for 600HP along with a 2 core rad huh? In the summer, it will run around 180* Only complaint I have regarding the AZ t-stat is the variance in temps - anywhere from 166-to around 182*. When I had the 180* Moroso high-flow, temps stayed around 185-190*. I would try a 160 Moroso, but I'm afraid it may run too cool, so I'll just leave well-enough alone.

I was considering the electric fans b/c my EFI can control up to 2 fans, thought it would free up some power an mileage. But again, it aint broke...

================================================

If you had a 3 or 4 core rad temps would run more stable ,thats for sure.

Again,that fan clutc h looks to have had better days /looks failrly old ,why not treat it to a new hd Hayden 2747 fan clutch from rock auto for only $45 while your at it?

I say that because when the finish starts to come off by thermal spring area that generally means the fan clutch is getting old.

Does it have much resistance when installed on motor when you turn ther fan when motor is cold /off and does it also whir from fan airlfow with fan clutch locked up for a min or so when motor is 1st fired up cold?

If it doesnt do that its time for a new fan clutch but just from the aged look of the fan clutch i'd can it since it's off asnyway.

Heck,you do everything else right so dont let that go and then mid some run into cooling issues in the middle of traffic on a hot day trying to get most time/miles out of what currently looks to be an old getting tired fan clutch with plating comming off it by the thermal spring.

Scott

 

[69-CHVL]

================================================

If you had a 3 or 4 core rad temps would run more stable ,thats for sure.

Again,that fan clutc h looks to have had better days /looks failrly old ,why not treat it to a new hd Hayden 2747 fan clutch from rock auto for only $45 while your at it?

I say that because when the finish starts to come off by thermal spring area that generally means the fan clutch is getting old.

Does it have much resistance when installed on motor when you turn ther fan when motor is cold /off and does it also whir from fan airlfow with fan clutch locked up for a min or so when motor is 1st fired up cold?

If it doesnt do that its time for a new fan clutch but just from the aged look of the fan clutch i'd can it since it's off asnyway.

Heck,you do everything else right so dont let that go and then mid some run into cooling issues in the middle of traffic on a hot day trying to get most time/miles out of what currently looks to be an old getting tired fan clutch with plating comming off it by the thermal spring.

Scott

Scott, its stiff when cold and yes it moves ALOT of air when first started and seems to taper off. Prior owner painted it, and some of the paint is flaking off. It takes a while for this thing to warm-up which is one of the reasons for the electric fan consideration. If I dont go electric, I'll replace the clutch - why not, replaced everything else so far!!

Sorry Randy!!!