Just put together a 327 with Edelbrock aluminum heads. It was running 210-220 off and on going down the road on a reliability run last weekend. I thought the gauge was whack because when I’d hop out and shoot the radiator and intake with an IR gun, it would read 180. The mechanical probe is in the drivers side head, and I figured out later the head would read consistent with the gauge. So, the top of the engine is 180 and the heads are 210-220. What’s up with that? I did change the gauge and had the same results. I figure some may ask about the timing. Well, the way my 38 Chevy is configured with the grille shell and accessories on the engine is real hard to see the timing marks, but I can try again. I timed it to ear and it runs pretty good. so, is this normal for aluminum heads? Compression is a little over 9:1
Well, I don’t know. I need to figure something out to see the timing tab because the doghouse of a 38 Chevy and the AC compressor is in the way so it’s really hard to see. Timed it by ear.
Because, the intake and radiator are not in direct contact/sealing the combustion chambers. The heads will always run hotter than either of those two components. You usually compensate for that depending on where your temp sensor is located.
No my timing light is pretty basic. I’ll try it again tomorrow, I went out tonight but figured my neighbors wouldn’t be too happy me winging it to 4 grand with straight pipes this time of night. tell me what kind of timing light I need, I might upgrade
A timing light with a knob on the back, that you can turn to set how many degrees advance it has, while looking at the marks reading "TDC". What you do is turn the knob until the TDC (zero advance) marks are lined up. Then read what the knob it set to. The number on the knob is the actual timing advance. For a normal small block Chevy, you want around 34 degrees, at 3000 RPM or so, with the vacuum advance hose disconnected.
37-39* total advance around 2000-2500 rpm , let the idle timing fall where it will and try it . Is vacuum advance working and connected correctly ?
The temp sender in the head is right next to the exhaust so it will tend to read hotter than a sending unit on top of the intake. Also, the head is going to radiate cylinder temps as well, adding to that. Not as much of that going on at the thermostat housing. I have a similar situation as you do on my '55. Gauge reads 15-20 degrees higher than the EFI handheld. I trust the handheld.
Any one of these , If you Line up the Original marks, at top center,,# 1 ,, You can put another mark on the block and a harmonic bounce anywhere you want to make easier visual to be seen, Autozone , most have @ least 2 models On shelf
You'll need 3 hands to use a dial advance timing light , one to control the engine rpm , one to hold the timing light & one to set the dial ! Easier to use either a degree damper or a camper with a timing tape. Dependent on the engine &fuel grade , 37-39* total advance may be a good way to melt pistons
I disagree on 3 hands , yes Would be difficult if you only have one arm/ hand. New timing Lights ""No dial"" You can hold with One hand & use your thumb on same hand ( Not missing a thumb) up /down ****ons & One one hand on throttle, for total , I know you know 2Old2Fast , But others way Not know , Like Op has already Bringing Up Ac in the way making difficult to see, So If Op lines up by hand tuning to 0 "" line"" on damper /harmonic bouncer & then 0 on tab , Make a mark thats more visible On both Bouncer /damper & Block Now a new Time tab location , the Two lines =0 TDC ,,.. We can get a little trickier & use ,make timing marks on Intake & distributor... that will more likely really confused the OP.. This just to find where its set Now Timing, Then there is more steps when it comes to Moving / turning Distributor to avance / retard, "" If "" & more likely not a stock engine ,, Op added heads so more likely Not a stock cam . They /Op will need to know how to set total plus or minus Advance limiter inside the distributor, & maybe a timing curve
To add to my post #16, if know how to use the newer Timing lights , lets say if need to add 4 degs , you can use the function to put 4 degs minus, will flash 4 degs less , turn distributor to Advance, when ""mark ""on (while flashing) bouncer /damper lines up with "" O"" on tab , you just add 4 degs , This light about $75 many usable functions, 2 & 4 stroke , Tach /Rpms Volts & I believer dwell I also Believe , I have 2 different models One will work on a mag ,
My timing light is digital. You just dial in the total you want, say 36 total, then when the mark lines up. Lock it down. I am guilty of setting it by ear, then once the light is on it, I find out that I must be deaf.
I prefer timing by vacuum to timing by light. The exact number of degrees don't really matter except as a point of comparison, the engine wants what it wants and a vacuum gauge will tell you what it wants. Second, aluminum heads always run a little hotter since they more readily absorb heat and some of that will translate into coolant temp. The flip side of this is that the combustion chamber is actually cooler as there's less of a temp gradient across the 1/4" or so of aluminum that separates the combustion from the coolant.
Since you didn't mention how hot the iron heads were, I can only ***ume they cooler. If the only thing you changed was the heads, then YES, the aluminum heads are hotter. Aluminum gives off heat faster than iron, your temp probe is in the head, so it reads hotter. Move the probe to the thermostat housing. My 250 inline six would always show 200 + going down the road till I moved the probe out of the head and under the thermostat. It now reads 180 where the coolant leaves the engine.
I use the dial timing light to see what the timing is, and then adjust it as needed, and check again, repeat until it's right. This only takes the two hands that I have. I don't like turning the distributor housing on a running engine.
The one thing I did change besides the heads is the location of the sender. It was in the intake before, now the head, so I don’t know what the iron heads were running as far as temp. I’ll check the timing tonight but I may just move the sender back to the intake and go on with my life.
Well that's ( not turning the distributor....) a new one , never heard of that before .Why not , I might ask ?
You can instal the temp sensor in many location & you will see different temp readings , & also on sbc /bbc you will get different readings between driver compared to p***enger side, I have played with as many 8 temps gauges , All where calibrated and do***ented before installing in the cooling system, different readings where they where located in cooling system.. SB2 gm engine ( block /heads) took & solve this issue with a more stable temp throughout the cooling system, ""Setting"" Timing with Vac gauge , Yes engine like what it likes, But then You need to know how to start most of time after running temps , ( kick back /slow Tunning ) because of so much initial timing, Most time your initial timing will be anywhere from 18- plus, then you will need to start Like you would a Mag , Then you will need to know how to Limit the Total Timing , So Lets say your mild engine like 19-20 initial your total will be some where 45 ish or Higher ,, So you will need to know how to take A round 10 degs out ,,, the more to total More needs to be Limited,, Most sbc bbc like a total @ WOT 32-39 ish total ,,,
Not trying to be a smart A$$ but Timing Lights have changed a lot / Technology in p*** 30 years, I still have an old Sears one that was made in the 84 ish with a knob on it. I don't know 2Old2Fast , I work on so much different engine combos including diesels I have multiple tools 1 -10 cylinders, and other crazy ideals I come up with,, I also have two legs that are old 1928, 1939 & 1964 mill,,, I am not that old in my 50s , Breaking & playing with this **** since around 5 in the county, Fram fixes , shop right down the street.
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