TrickSix
Famous Member
How about these?
https://ebay.us/m/5eU0pW
https://ebay.us/m/5eU0pW
All Small Six Winter Project: Better breathing with a large log
- Thread starter awasson
- Start date
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- large log head
This relates to all small sixes
I like that those would be larger than the stock exhaust valves and at 1.46875” is smaller than 1.5” and might be able to cut the original seat for it.
The stems are oversized. I’m not sure if that is an advantage but it doesn’t bother me. The only concern I would have is that they are Sealed Power and not OEM so they may not be made of suitable material for an exhaust valve. Does anyone know if that’s the case?
Good find. Thanks for posting those.
As of a 16 months ago Sealed Power parts of this nature were still USA made. I can not confirm it since then.
I think they are probably still USA made but I wonder if the material for the intakes and exhausts are different. I understand that the OEM valves were the same material for intake and exhaust so there isn't a risk of burning them when you used an intake as an exhaust but I haven't heard anything about the aftermarket valves. I've used sealed power rings on a couple of engines and they never disappointed me.
Engine Fan
Well-known member
Not sure if this is relevant.Intake is : MEL V5328 from rockauto.
They are for a 1990 Toyota Pu 2.4l gasoline l4. The exhaust valves are for the same engine.
Perfect fit for my big log head. Valve guides cut for 8mm stems and seals, springseats cut for ls size springs. With The ls valve locks, one will need a 2mm lashcap. Other valve locks might work beter in locating the stem abow the retainers.
Good luck!
1.456" exhaust valve
1.77" intake valve
Found under "New tri Weber engine build."
Alrighty… I haven’t really done much to the head aside from stripping it, pulling the valves and springs and taking stock of things. It is a typical C9DE head. I thought maybe it had 1.75” intakes but I put a vernier caliper in them and they are the 1.649” valves and and the exhaust are 1.38”. I’ll get a set of 1.75” valves for the intakes and 1.5” for exhaust. I might as well build the head as best as possible since I’ve got it all apart.
This is the first ford 6 head I’ve stripped and it’s interesting. The exhaust valve stems really do take a beating compared to the intakes. The keepers on the intakes came apart fairly easily and the valves slid out easily. On the exhausts you really have to give the keepers a smack to get them to unstick and the valves had to be knocked out with a brass drift because the top of the stem was just slightly expanded compared to the rest of it. None of the valves were stuck but all 6 exhaust valves had to be knocked out (not hard but you couldn’t just pull them out) and all 6 intake valves were like butter. They just dropped out.
In terms of porting, the ports are better than I thought in terms of requiring some clean up. I don’t intend to do any reshaping but I’ll remove casting flash and blend in areas that restrict flow around the valves. On a cursory inspection, there doesn’t seem to be a lot of grinding necessary. It’s a pretty smooth shot from the log straight into the combustion chamber. I have the falcon book for reference and will be following it when I do the porting.
I have to CC the head and then figure out how many thousands I’ll need to take off to bump up the compression ratio.
Question: Are there any recommendations about static compression? I am using 94 Octane which is alcohol free around here. With the small log head I’m a little below 9:1 ratio. I’d like to bump it to an actual 9.5:1 or 10:1 if that’s feasible. I don’t know for sure but I think these heads retain more heat than a typical cast iron V8 cylinder head so I’m not sure how much compression I can run without detonation (especially in the summer). Is 10:1 too much or can I even go as high as 10.5:1? It’s going to be NA. If I decide to boost this engine, it’ll be with a different head.
This is the first ford 6 head I’ve stripped and it’s interesting. The exhaust valve stems really do take a beating compared to the intakes. The keepers on the intakes came apart fairly easily and the valves slid out easily. On the exhausts you really have to give the keepers a smack to get them to unstick and the valves had to be knocked out with a brass drift because the top of the stem was just slightly expanded compared to the rest of it. None of the valves were stuck but all 6 exhaust valves had to be knocked out (not hard but you couldn’t just pull them out) and all 6 intake valves were like butter. They just dropped out.
In terms of porting, the ports are better than I thought in terms of requiring some clean up. I don’t intend to do any reshaping but I’ll remove casting flash and blend in areas that restrict flow around the valves. On a cursory inspection, there doesn’t seem to be a lot of grinding necessary. It’s a pretty smooth shot from the log straight into the combustion chamber. I have the falcon book for reference and will be following it when I do the porting.
I have to CC the head and then figure out how many thousands I’ll need to take off to bump up the compression ratio.
Question: Are there any recommendations about static compression? I am using 94 Octane which is alcohol free around here. With the small log head I’m a little below 9:1 ratio. I’d like to bump it to an actual 9.5:1 or 10:1 if that’s feasible. I don’t know for sure but I think these heads retain more heat than a typical cast iron V8 cylinder head so I’m not sure how much compression I can run without detonation (especially in the summer). Is 10:1 too much or can I even go as high as 10.5:1? It’s going to be NA. If I decide to boost this engine, it’ll be with a different head.
I have learned -been told- that when you get into the upper limits of compression, it’s more about dynamic compression and that is related to how aggressive your cam is and its set up for timing. An aggressive cam will lower your dynamic compression. How much can be figured but not much info on how the small 6 reacts.
I file the mushroomed stems first, makes it better all round. Lifters do the same thing, on those I drop them out the bottom. The exhaust gets worked harder because it is opening against the higher exhaust pressure and the heat does not help.
Most of the flow gains are within 2'' of the valve.
Most of the flow gains are within 2'' of the valve.
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I think that's what I was looking for.
Back in the day when everyone would come to my garage to smoke and have beers while I was assembling some kind of frankenstein engine, compression numbers were confidently thrown around as though we knew what we were talking about (we didn't)
Yep, next build I'll get those TRW 12.5:1 compression pistons and this beast is going to rock So, I ran some actual numbers with real specs and it looks as though I currently have 7.87:1 Dynamic Compression and dynamic cranking pressure is 159.81 PSI. I have not checked what my actual cranking pressure is but it seems reasonable.
I have read a few opinions about dynamic compression and the common consensus says that for pump gas, the most you want is 8.5:1.
If I bump up my static compression to 9:1 static compression, my dynamic compression will be just over 8.5:1.
That is, if I am reading my cam card correctly. The card says intake opens/closes at 32° ABDC @.050 which is what I used. I used the tool here: http://www.wallaceracing.com/dynamic-cr.php
I don't know the duration of the stock cam on the small6. If it were a big6, both cams above INCREASE dynamic compression. Almost all the aftermarket cams do, they have less gross duration than the stock cam. They also increase dynamic by increased effective .050" duration cylinder filling.
When crunching camshaft stats, keep in mind that all measurements are in crankshaft degrees, except the LSA (Lobe Center) which is in camshaft degrees. Thus Don's cam @ 108* LSA has FOUR degrees less gross duration for the same duration # than a cam @ 110* LSA. Don's cam, even at 274* would still increase compression over a stock cam (remember, example is on a 300)
Stock (big6) cam: 268* intake duration @ 110* LSA. , retarded 4* This cam closes the intake valve 68* after bottom dead center.
Your Clay Smith cam: 264* intake duration @ 110* LSA, advanced 4*. this cam closes the intake valve 58* after BDC. That's 10* more piston upstroke with the valve closed on compression stroke- more dynamic compression.
On a big6 with EFI head, using awasson's cam above, the stock cam has 6.8:1 dynamic compression, the Clay Smith has 7.3:1. The Clay Smith would require 93 octane gas in a 300, the stock cam 87 octane.
To calculate intake valve closing point: (gross duration divided by 2) + LSA - 180.
If all the boxes are filled in correctly, this is the compression calculator to use. Don't guess, small changes in deck clearance, gasket thickness and head volume make a notable difference in CR. If I'm searching for maximum compression for a given fuel grade, I find the target intake valve closing point, then calculate "backwards" to the cam duration that meets that parameter. This is why the Crower cam on my 240 build is retarded 1* rather than advanced. Flat top pistons, and 26 thou shaved off the block. I am able to use regular gas- barely. If the cam was advanced, no way. It has 9.65:1 static compression and 7.4:1 dynamic. According to this forum, the small6 can withstand higher compression numbers on a given fuel grade.
https://uempistons.com/p-27-compression-ratio-calculator
When crunching camshaft stats, keep in mind that all measurements are in crankshaft degrees, except the LSA (Lobe Center) which is in camshaft degrees. Thus Don's cam @ 108* LSA has FOUR degrees less gross duration for the same duration # than a cam @ 110* LSA. Don's cam, even at 274* would still increase compression over a stock cam (remember, example is on a 300)
Stock (big6) cam: 268* intake duration @ 110* LSA. , retarded 4* This cam closes the intake valve 68* after bottom dead center.
Your Clay Smith cam: 264* intake duration @ 110* LSA, advanced 4*. this cam closes the intake valve 58* after BDC. That's 10* more piston upstroke with the valve closed on compression stroke- more dynamic compression.
On a big6 with EFI head, using awasson's cam above, the stock cam has 6.8:1 dynamic compression, the Clay Smith has 7.3:1. The Clay Smith would require 93 octane gas in a 300, the stock cam 87 octane.
To calculate intake valve closing point: (gross duration divided by 2) + LSA - 180.
If all the boxes are filled in correctly, this is the compression calculator to use. Don't guess, small changes in deck clearance, gasket thickness and head volume make a notable difference in CR. If I'm searching for maximum compression for a given fuel grade, I find the target intake valve closing point, then calculate "backwards" to the cam duration that meets that parameter. This is why the Crower cam on my 240 build is retarded 1* rather than advanced. Flat top pistons, and 26 thou shaved off the block. I am able to use regular gas- barely. If the cam was advanced, no way. It has 9.65:1 static compression and 7.4:1 dynamic. According to this forum, the small6 can withstand higher compression numbers on a given fuel grade.
https://uempistons.com/p-27-compression-ratio-calculator
All this "dynamic compression" is mumbo jumbo, its still a calculated value based on the reduced stroke of the piston based on the valve positions. This makes NO allowance for the VE of the engine, which is the all important thing. If the cylinder is only 80% full of mixture then the "dynamic compression" will be further reduced. The idea of bleeding off compression with long duration cams is counter production, you want the highest VE, and CR that the engine can stand with whatever fuel your using, this is determined by a combination of factors, NOT just the CR.
If you read some of Ricardo's work where he had variable compression engines to test fuels and other factors involved with detonation, they found many factors influencing knock. So for us mere amateurs the only way is by experience with what we run on the roads as our dynos. There is also a variety of fuels available to us and different methods of measuring the octane rating. RON, MON, and an averaging calculation the the USA seems to use.
The only place I can see that "dynamic compression"is in two stroke engines where compression cannot take place until the exhaust port is closed.
So in conclusion, I see no value in using the DCR to estimate knock limit of any particular engine might behave, there are so many other factors influencing the "maximum usable compression ratio" that its pointless. The CR as calculated in the normal way (USV+SV)/ USV is most reliable.
As a for instance I run a CR of 9:1 with a manifold pressure up to 200kPa with an alloy head, cold air intake and a blower of unknown adiabatic efficiency, I run propane with a stated octane rating of 105 RON, this gibes some knock at large throttle openings. i run igniton timing at 25BTDC.
My two pennth worth, discuss.
If you read some of Ricardo's work where he had variable compression engines to test fuels and other factors involved with detonation, they found many factors influencing knock. So for us mere amateurs the only way is by experience with what we run on the roads as our dynos. There is also a variety of fuels available to us and different methods of measuring the octane rating. RON, MON, and an averaging calculation the the USA seems to use.
The only place I can see that "dynamic compression"is in two stroke engines where compression cannot take place until the exhaust port is closed.
So in conclusion, I see no value in using the DCR to estimate knock limit of any particular engine might behave, there are so many other factors influencing the "maximum usable compression ratio" that its pointless. The CR as calculated in the normal way (USV+SV)/ USV is most reliable.
As a for instance I run a CR of 9:1 with a manifold pressure up to 200kPa with an alloy head, cold air intake and a blower of unknown adiabatic efficiency, I run propane with a stated octane rating of 105 RON, this gibes some knock at large throttle openings. i run igniton timing at 25BTDC.
My two pennth worth, discuss.
this is getting above my pay grade. At this point all I can do is go by what I am told.
Thanks @Frank You have recommended that calculator to me before for calculating my CR. I just didn't realize it did Dynamic too. I reran the numbers.
Regarding Intake Closing Point (degrees) ABDC. I installed my cam straight up to the cam card within about 3/4° so if I use the calculation of (gross duration divided by 2) + LSA - 180, I get: 264 / 2 + 110 - 180 = 62°
The calculator page suggests Intake Closing Point (degrees) ABDC @ 0.050 lift plus 15 degrees which would be 32 + 15 = 47°
Running those numbers with Intake Closing Point (degrees) ABDC at 62° I am at:
- Static Compression Ratio: 8.649:1
- Dynamic Compression Ratio is 7.125:1
I get what @aussie7mains is saying with "All this "dynamic compression" is mumbo jumbo" but it is making some level of sense.
I think I can safely go to 9.5:1 and still run my 94 octane.
Based on what I'm seeing here with current dynamic compression at about 7:1, I should be able to run regular gas. I will give that a shot and see how it runs.
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This is my card:
I’m at around 10:1 static and hoping to use 91 octane. I have been told I’ll be ok and that it will be interesting to see.
Sooo, I’ll see
But, famous last words: you’ll be ok!!
Wow... Is that what you are running right now with 10:1?
What kind of carb / distributor and timing are you running and how does it idle?
You'll be fine
Mine is a little choppy when it's cold but it is happy to rev smoothly at any temperature. It's just not super happy idling, if I start it from first start of the day, until it's been running for a minute or two with some assistance on the throttle. Then it's perfectly agreeable.
Here's a video I did of it yesterday. It had been warming up for a couple of minutes.
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