newbie here, great site so far, I have a 66 SS clone, 454 block .030 over with a 427 crank, a lil hotter than normal cam, 100 cc heads, fresh valve job, running a MSD 6AL ig box, with a MSD vac Dist., aluminum crosswinds intake,(oval port) edelbrock 750cfm, aluminum hi flow short waterpump, new 2 row 1" aluminum radiator with high volume fans(2) approx 3300cfm of air, wired to start at 180 degrees with sensor in head, have a 160 degree thermostat(all new). a 4 spd tranny, no auto tran cooler, running 3.3x 12 bolt, 255 60 15 rear tires,my timing is set to 30 degrees with the port vacuum unplugged and capped at 2500 rpm, 9 degrees at idle and with the vac plugged on the port, left side of edelbrock, it jumps it to about 53 degrees, I think that is most of the details, now for the problem, this thing runs like a striped azz ape, I can ride all over town, roasting the tires if I want, idle and it will not get hot, but, I start down the hiway tach in 2500 area and it starts creeping up on temp, I want to know if my timing is too high with the vac hooked up, any suggestions, what should it be all in? folks, this is starting to wear me out
help with 427 timing and temp trouble
markmc59
1 - 9 of 9 Posts
newbie here, great site so far, I have a 66 SS clone, 454 block .030 over with a 427 crank, a lil hotter than normal cam, 100 cc heads, fresh valve job, running a MSD 6AL ig box, with a MSD vac Dist., aluminum crosswinds intake,(oval port) edelbrock 750cfm, aluminum hi flow short waterpump, new 2 row 1" aluminum radiator with high volume fans(2) approx 3300cfm of air, wired to start at 180 degrees with sensor in head, have a 160 degree thermostat(all new). a 4 spd tranny, no auto tran cooler, running 3.3x 12 bolt, 255 60 15 rear tires,my timing is set to 30 degrees with the port vacuum unplugged and capped at 2500 rpm, 9 degrees at idle and with the vac plugged on the port, left side of edelbrock, it jumps it to about 53 degrees, I think that is most of the details, now for the problem, this thing runs like a striped azz ape, I can ride all over town, roasting the tires if I want, idle and it will not get hot, but, I start down the hiway tach in 2500 area and it starts creeping up on temp, I want to know if my timing is too high with the vac hooked up, any suggestions, what should it be all in? folks, this is starting to wear me out
3.5 hours from post to rut-roh, you realize that people have jobs, kids, other real life stuff?
what's the timing with the vacuum advance hooked up at 2500? That 53 is not a problem, but the 9 at idle is. You'll probably need to re-curve the dist so you can 18 or so at idle, 34-36 at 3000, 15 more with vac. Recommend you hook the vacuum advance to manifold vacuum after setting the timing with no vacuum hooked up at all.
DO you have or have access to a wideband O2 meter? That Edelbrock 750 is not a particularly well-thought of carb and you can't rely on the mix being right. At 2500 with a large primary carb it may still be running mostly off the idle transition circuits. There's nothing that sez they're able to flow enough fuel in that scenario. The behavior patterns of these carbs is not well known like a Holley.
If you get the timing fixed I'd recommend borrowing a known good Holley and trying it on there. You can rig the fuel lines and throttle linkage good enough for a test drive.
So, what is the temp getting up to? You realize that 230 is a normal operating temp on a modern engine? If you're trying to get it so the temp gauge never gets over 180 you're wasting time and money IMO. That is a thing of the past, it's well known by now that most engines are real happy at about 210. running 160 is a loser, condensation problems, dirty oil, needing more jet, dirty plugs, etc.
what's the timing with the vacuum advance hooked up at 2500? That 53 is not a problem, but the 9 at idle is. You'll probably need to re-curve the dist so you can 18 or so at idle, 34-36 at 3000, 15 more with vac. Recommend you hook the vacuum advance to manifold vacuum after setting the timing with no vacuum hooked up at all.
DO you have or have access to a wideband O2 meter? That Edelbrock 750 is not a particularly well-thought of carb and you can't rely on the mix being right. At 2500 with a large primary carb it may still be running mostly off the idle transition circuits. There's nothing that sez they're able to flow enough fuel in that scenario. The behavior patterns of these carbs is not well known like a Holley.
If you get the timing fixed I'd recommend borrowing a known good Holley and trying it on there. You can rig the fuel lines and throttle linkage good enough for a test drive.
So, what is the temp getting up to? You realize that 230 is a normal operating temp on a modern engine? If you're trying to get it so the temp gauge never gets over 180 you're wasting time and money IMO. That is a thing of the past, it's well known by now that most engines are real happy at about 210. running 160 is a loser, condensation problems, dirty oil, needing more jet, dirty plugs, etc.
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Mark, typically losing cooling at speed is a radiator/airflow issue. Dont know much about aftermarket radiators, but my stocker is three rows.
53 is a ton of timing, but thats not the issue. BTW retarded timign typically makes the engine run hotter, not advanced timing( which can cause pinging).
Hey hey, dont fret, Monday night football in Buffalo, man, I couldnt pull away from the TV!
I think the rads too small to handle a rat. Everyone says crossflow aluminum aftermarket are the cats arse, and then they spend big $$ and have cooling issues. I use a Harrison oem 3 row and I;ve never had any issues ever, with compression as high as 10.75:1. Stock shroud ( IMPORTANT!), only thing I changed was my "schoolbus" 4 blade fan for an 8 blade late model Z28 clutch fan. No electric fans, which require relays, and mar an otherwise stock engine bay. Point is, stock stuff works well, even in the hottest we get here, which isnt as hot as Dallas.
??? you have a flow/size issue, is my guess. Try a shroud and oem-style clutch fan. ALTHOUGH I must say that when I spoke of my "schoolbus" fan here years ago ( it sounds like a schoolbus to me), the boys in Texas SWORE by 'em. THey do pull a ton of air, a ton more than those fans you have. I didjt like spinning the thing to 7400 is all.
FYI, a mid 80's Blazer K5 rad fits and is configured nearly the same way, but with plastic side tanks and an alum rad.
20 reads is nothing around here, adn I thought you Texas gentlemen have thicker skin!
I'm not going to let Tom remove you, you sunovab... Until you get that 427 behaving properly!
53 is a ton of timing, but thats not the issue. BTW retarded timign typically makes the engine run hotter, not advanced timing( which can cause pinging).
Hey hey, dont fret, Monday night football in Buffalo, man, I couldnt pull away from the TV!
I think the rads too small to handle a rat. Everyone says crossflow aluminum aftermarket are the cats arse, and then they spend big $$ and have cooling issues. I use a Harrison oem 3 row and I;ve never had any issues ever, with compression as high as 10.75:1. Stock shroud ( IMPORTANT!), only thing I changed was my "schoolbus" 4 blade fan for an 8 blade late model Z28 clutch fan. No electric fans, which require relays, and mar an otherwise stock engine bay. Point is, stock stuff works well, even in the hottest we get here, which isnt as hot as Dallas.
??? you have a flow/size issue, is my guess. Try a shroud and oem-style clutch fan. ALTHOUGH I must say that when I spoke of my "schoolbus" fan here years ago ( it sounds like a schoolbus to me), the boys in Texas SWORE by 'em. THey do pull a ton of air, a ton more than those fans you have. I didjt like spinning the thing to 7400 is all.
FYI, a mid 80's Blazer K5 rad fits and is configured nearly the same way, but with plastic side tanks and an alum rad.
20 reads is nothing around here, adn I thought you Texas gentlemen have thicker skin!
I'm not going to let Tom remove you, you sunovab... Until you get that 427 behaving properly!
I agree with Tom and Gene, Your radiator is too small.
I had the same issue with my 67-396, so I went with a new stock size 3 row harrisson, a new 5 blade fan and clutch and most importantly a new fan shroud.
With a 160 deg. standard thermostat and the sender in the intake, it would sit @ 200 deg. all day in traffic or on the freeway and even on a stinking hot 100+ deg. day.
Your timing should be somewhere in the 12-14 initial and 36-38 BTDC total area as well
I had the same issue with my 67-396, so I went with a new stock size 3 row harrisson, a new 5 blade fan and clutch and most importantly a new fan shroud.
With a 160 deg. standard thermostat and the sender in the intake, it would sit @ 200 deg. all day in traffic or on the freeway and even on a stinking hot 100+ deg. day.
Your timing should be somewhere in the 12-14 initial and 36-38 BTDC total area as well
Do exactly what Tom M suggested before you do anything else espe because the ignh curve you currently running is not good,the 9 deg initial at idle with an aftermarket perf cam is very retarded (9 deg retarded) as Tom stated.
The motor will have a heck of a lot better low to mid range rpm when inc the initial from 9 to 18 with a perf cam.
Then if it still runs hot at cruise after you get the ign curve correctly adj just like Tom M stated chk to ensure your not running too lean on fuel calibration. You may need to change the meter rods and or mains in your edel carb to fatten it up a bit of thats the case.
If getting the ign curve corrected & ensuring the fuel calibration isnt too lean and it still runs too hot at cruise it could be simply an airflow issue while at cruse. Thats because with some setups the fan/s are doing decent job of cooling at idle but when you get up to cruise speed the fans esp if elec with shrouds/mounting frames can actually block the air from easily passing through the radiator to cool the motor thats now generating more heat at cruise rpm.
But the elec fans can pull or push enough air at idle to keep it from getting hot because the cooling system is not relying on getting its cooling from air passing thru the rad on its own at idle. But at cruise the rad does rely on air passing through the rad on its own and even the car is going 50mph while cruising some elec fan setups can at times interfear with/block the airflow when at cruise.
If you can without going nuts just remove the elec fan setup and see if that reduces the temps when at cruise but make sure you get your ign curve fixed 1st because its way retarded with inital at 9 degwhen it should be approx 18 deg. That wastes fuel,looses power,gives poor throttle resp,cam make motors run hotter,etc. But you will likely need to re-curve/adj the mech adv in dist for 18 deg (all in by 2800-3k rpm) to run with 18 deg inital for 36 total along with apporx 14-15 deg vac adv for better fuel economy & throttle resp when at part throttle/low load cruise.
Get tuning /testing and let us know how you make out as you try these things out & retune the ign curve.
No offence but the 12-14 deg initial thats suggested above is too retartded for most all perf cams by approx 4-6 deg which is substantial . I have been installing perf cams in sbc/bbc for 36+ yrs and know from 1st hand experince of dilaing in the ign curves for street perf setups that 12-14 deg initial is too retartded i most cases . Yes its better then the 9 initial he is currently at but its still not enough. Running 4-6 deg retarded on initial will still loose power & waste fuel vs running 18 initial so keep that in mind.
Scott
The motor will have a heck of a lot better low to mid range rpm when inc the initial from 9 to 18 with a perf cam.
Then if it still runs hot at cruise after you get the ign curve correctly adj just like Tom M stated chk to ensure your not running too lean on fuel calibration. You may need to change the meter rods and or mains in your edel carb to fatten it up a bit of thats the case.
If getting the ign curve corrected & ensuring the fuel calibration isnt too lean and it still runs too hot at cruise it could be simply an airflow issue while at cruse. Thats because with some setups the fan/s are doing decent job of cooling at idle but when you get up to cruise speed the fans esp if elec with shrouds/mounting frames can actually block the air from easily passing through the radiator to cool the motor thats now generating more heat at cruise rpm.
But the elec fans can pull or push enough air at idle to keep it from getting hot because the cooling system is not relying on getting its cooling from air passing thru the rad on its own at idle. But at cruise the rad does rely on air passing through the rad on its own and even the car is going 50mph while cruising some elec fan setups can at times interfear with/block the airflow when at cruise.
If you can without going nuts just remove the elec fan setup and see if that reduces the temps when at cruise but make sure you get your ign curve fixed 1st because its way retarded with inital at 9 degwhen it should be approx 18 deg. That wastes fuel,looses power,gives poor throttle resp,cam make motors run hotter,etc. But you will likely need to re-curve/adj the mech adv in dist for 18 deg (all in by 2800-3k rpm) to run with 18 deg inital for 36 total along with apporx 14-15 deg vac adv for better fuel economy & throttle resp when at part throttle/low load cruise.
Get tuning /testing and let us know how you make out as you try these things out & retune the ign curve.
No offence but the 12-14 deg initial thats suggested above is too retartded for most all perf cams by approx 4-6 deg which is substantial . I have been installing perf cams in sbc/bbc for 36+ yrs and know from 1st hand experince of dilaing in the ign curves for street perf setups that 12-14 deg initial is too retartded i most cases . Yes its better then the 9 initial he is currently at but its still not enough. Running 4-6 deg retarded on initial will still loose power & waste fuel vs running 18 initial so keep that in mind.
Scott
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14,300 Posts
Perhaps those 20 folks didn't really have any answers that would help. At least they TRIED by reading your post in the first place.
Are your fans pushers or pullers? Do you have them installed on the correct side of the radiator? For example, if they are pullers but are mounted in front of the radiator, when you are out on the highway the fans are playing against the natural inflow of air and the result is that insufficient airflow is passing through the radiator yet at slower road speeds the fans would still be able to move enough air through it to keep things happy.
Also, your radiator seems pretty small. You should probably replace that 160 degree thermostat with at least a 180 degree, high quality, high flow unit. Make sure your radiator cap is rated at 15 pounds and is in good condition. Thirteen pound caps give up too quickly and allow the coolant to not entirely do it's work.
Is your temp gauge sending unit in the head or in the manifold?
And without a doubt, address the ignition and timing issues as outlined above before changing anything in the cooling system.
None taken, I was just being conservative, without knowing the C.R., cam specs and fuel he uses ? It's a guessing game.
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