J heads... dead horse!

Old November 26th, 2018, 12:45 PM
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A dead horse is still a dead horse. I've been saying "I've been beating a dead horse since 1975."
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Old November 26th, 2018, 12:57 PM
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Originally Posted by VORTECPRO View Post
You should have used the right seat, small Inner diameter.
Just wondering why you would suggest that. Granted the low numbers would have stayed the same. But the gains from my second test were from opening the exhaust bowl. Let me know what you are thinking. Thanks
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Old November 26th, 2018, 12:59 PM
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Smile

Originally Posted by VinMichael View Post
Dead horse won't really be beat until we see a dyno shootout for who can build the most powerful J headed 455 with stock stroke . Maybe make it worth the time with a $500 - $1,000 buy in.

That would be entertainment.
To the death??
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Old November 26th, 2018, 09:24 PM
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Originally Posted by ChevyZ06 View Post
To the death??
thatís the Spartan way
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Old November 27th, 2018, 01:51 PM
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Originally Posted by VORTECPRO View Post
This is a stock G head tested on a 4.155 bore @ 28 inches, small valve.

200/122 .300/172 .400/196 .500/209 .550/215 .600/220 .700/226.
I see you too have the stingy bench!
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Old November 28th, 2018, 06:53 AM
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Originally Posted by ChevyZ06 View Post
I see you too have the stingy bench!



I probably would just say its calibrated, both my flow benches are very close when it comes to data. Are you going to go any further on the J head development?
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Old November 28th, 2018, 06:59 AM
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Originally Posted by ChevyZ06 View Post
Just wondering why you would suggest that. Granted the low numbers would have stayed the same. But the gains from my second test were from opening the exhaust bowl. Let me know what you are thinking. Thanks
I would just prefer to be able to cut the bowl to the same dimension as the rest, then go from there. I also like the ductile iron seats because they cut better.

Last edited by VORTECPRO; November 28th, 2018 at 07:04 AM.
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Old November 28th, 2018, 11:21 AM
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Originally Posted by VORTECPRO View Post
I would just prefer to be able to cut the bowl to the same dimension as the rest, then go from there. I also like the ductile iron seats because they cut better.
Your absolutely correct on the seats. I was going to keep this a secret but I have a new set of 2.07 1.72 SS valves for this project. When I installed the seats I had planned on using the large exhaust valve . To be honest I am not sure if I am going to use them now because I am kinda happy with the numbers. The engine that I am building is for my personal 1970 Cutlass S. 1974 455 long block that I found in the local pick-n-pull. Low compression, I have a tiny cam, and I found an O4B intake. If someone twisted my arm I might be forced to use the big valves.

Last edited by ChevyZ06; November 28th, 2018 at 11:41 AM.
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Old November 29th, 2018, 11:42 AM
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I raised the port roof area around the guide boss about .150 Only a few cfm at usable lifts. I think that my J heads might be maxed out with what I would call moderate porting.
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Old November 29th, 2018, 03:04 PM
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Originally Posted by ChevyZ06 View Post

I raised the port roof area around the guide boss about .150 Only a few cfm at usable lifts. I think that my J heads might be maxed out with what I would call moderate porting.

Onto the larger valves next to see what changes?
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Old November 30th, 2018, 04:55 AM
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Most suggest only the larger intake valve, experts say on mild build like yours, that large exhaust valve will do more harm than good. Larger intake valve, yes. I have a 2.05" intake valve on my #6 heads with stock exhaust 1.56" valves and the bowls opened. The other set of #6 heads has 2"/1.625" valves with port and bowl work with the crossovers filled, I may add 2.07" valves.
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Old December 4th, 2018, 11:06 AM
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Well the big 2.07 valve does help the J heads BUT there is a catch. From what I can tell so far the J head does have some potential. My goal with this project was to see if the J head could be a good usable casting with minor modifications. Right now I have to say that the answer is no. I have increased the flow numbers substantially, but this is not a DIY port job. The casting is very picky and requires a skilled head porter with the right tools to match the numbers that I have. What I mean to say is that some head casting respond to the basic mods better than other castings. My back ground is with mostly Mopar engines. Mopar has two basic castings for the Big Block engine. One casting responds greatly to nothing more that a big valve and a basic bowl port, The other castings actually loses CFM when a big valve is installed. But with skilled porting the second casting will out flow the first maxed out. With the J head installing a big valve and bowl porting is not going to give the same results as the same modifications on the C heads. I built a set of C heads a few years back that I installed big valves and bowl port with gasket match. I will post the numbers with the "finished product" on my J heads.

J heads 2.07 valve tricky port work
.50 37
.100 69
.150 110
.200 148
.250 179
.300 205
.350 221
.400 227
.450 229
.500 231
.550 232
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Old December 4th, 2018, 11:09 AM
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C heads 2.07 valve bowl port gasket match

.50 32
.100 70
.150 106
.200 143
.250 173
.300 195
.350 212
.400 227
.450 236
.500 242
.550 246
.600 251
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Old December 4th, 2018, 11:14 AM
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One thing to keep in mind is that the J head has a smaller port volume and will in my opinion out perform the C heads in some applications. If you are building an engine similar to mine, low compression, small cam, dual plane intake. Or if you are building a small displacement engine. I think that the ported J will work great!
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Old December 4th, 2018, 02:55 PM
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Some of my other projects. Pontiac 6X heads. Pontiac heads are also very challenging. This set flows just a little more than my J heads. But not much!
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Old December 11th, 2018, 01:11 PM
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Both valves are 2.07 dia. Both valves are 45 degree with 30 degree back-cut. Valve on the left reduces the flow 16 CFM. Go figure
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Old December 11th, 2018, 02:21 PM
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Hi
Originally Posted by ChevyZ06 View Post

Both valves are 2.07 dia. Both valves are 45 degree with 30 degree back-cut. Valve on the left reduces the flow 16 CFM. Go figure
The right valve appears to have a reduced amount of material were the stem transitions to the back of the head of the valve
the stem also looks reduced in diameter.

Last edited by Bernhard; December 11th, 2018 at 02:32 PM.
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Old December 11th, 2018, 03:11 PM
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I have machined one of the valves to regain almost 12 cfm. I will try to post a picture of it tomorrow.
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Old December 12th, 2018, 05:18 AM
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Looks like the right valve has a thinner margin, wider seat width, slightly undercut stem with polished face... what changes on those parameters made the most difference?
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Old December 13th, 2018, 02:14 PM
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Originally Posted by 83hurstguy View Post
Looks like the right valve has a thinner margin, wider seat width, slightly undercut stem with polished face... what changes on those parameters made the most difference?
The picture doesn't show very well but the factory valve is shaped very much like a nail, the stainless valve has more of a tulip shape. I am grinding as much of that shape away as I can. The more that I change the shape, the better the port flows. But I'm running out of valve material.
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Old December 13th, 2018, 06:40 PM
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Is there any risk that the valve will become weak and fail under load?
What would worry me is that the valve was designed with a lower grade of steel . Is the grade of steel up to supporting your new improved valve design.
Have you tried multiple back cuts on the valve?

Last edited by Bernhard; December 13th, 2018 at 06:43 PM.
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Old December 14th, 2018, 11:05 AM
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Originally Posted by Bernhard View Post
Is there any risk that the valve will become weak and fail under load?
What would worry me is that the valve was designed with a lower grade of steel . Is the grade of steel up to supporting your new improved valve design.
Have you tried multiple back cuts on the valve?
Probably not with the way I drive I did try multiple angle of back-cut. With the shape of the factory valve I had to machine quite a bit of material away. I will try to post a picture of the finished product soon.
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Old December 26th, 2018, 07:32 PM
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Finished product to regain most of the CFM loss
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Old December 26th, 2018, 07:35 PM
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I CCed the intake ports. I think that you guys will be shocked when I post the numbers. Spoiler! They are tiny!
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Old December 27th, 2018, 06:30 AM
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Originally Posted by ChevyZ06 View Post

Finished product to regain most of the CFM loss
Nice work.
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Old December 27th, 2018, 06:53 AM
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Originally Posted by Bernhard View Post
Nice work.
thank you
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Old December 27th, 2018, 08:55 PM
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Waiting to see the finished product installed on the freshened up 455!

Also, are you sure that those stock pistons will hold up ok? We did have a badger replacement piston that broke a ring land on us on one of Dad's 455's. You know, those pistons that you going to reuse have never seen the higher side of 3500rpm..... and they are 50 years old and embrittled now.
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Old December 27th, 2018, 10:47 PM
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Originally Posted by Battenrunner View Post
Waiting to see the finished product installed on the freshened up 455!

Also, are you sure that those stock pistons will hold up ok? We did have a badger replacement piston that broke a ring land on us on one of Dad's 455's. You know, those pistons that you going to reuse have never seen the higher side of 3500rpm..... and they are 50 years old and embrittled now.
you mean the pistons are BATTLE HARDENED!
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Old December 27th, 2018, 11:00 PM
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Originally Posted by ChevyZ06 View Post
you mean the pistons are BATTLE HARDENED!
they are from a battle ship, that is for sure!
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Old December 28th, 2018, 05:22 AM
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This is a great thread! Keep up the great work!
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Old December 28th, 2018, 11:26 PM
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I've said for some time that "J" heads with some work would make great street heads. Nice street cruiser with some pop.

Gene
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Old December 29th, 2018, 06:41 PM
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Originally Posted by ChevyZ06 View Post
Well the big 2.07 valve does help the J heads BUT there is a catch. From what I can tell so far the J head does have some potential. My goal with this project was to see if the J head could be a good usable casting with minor modifications. Right now I have to say that the answer is no. I have increased the flow numbers substantially, but this is not a DIY port job. The casting is very picky and requires a skilled head porter with the right tools to match the numbers that I have. What I mean to say is that some head casting respond to the basic mods better than other castings. My back ground is with mostly Mopar engines. Mopar has two basic castings for the Big Block engine. One casting responds greatly to nothing more that a big valve and a basic bowl port, The other castings actually loses CFM when a big valve is installed. But with skilled porting the second casting will out flow the first maxed out. With the J head installing a big valve and bowl porting is not going to give the same results as the same modifications on the C heads. I built a set of C heads a few years back that I installed big valves and bowl port with gasket match. I will post the numbers with the "finished product" on my J heads.

J heads 2.07 valve tricky port work
.50 37
.100 69
.150 110
.200 148
.250 179
.300 205
.350 221
.400 227
.450 229
.500 231
.550 232

Your thread is making me want to duplicate the 455s builds I built in 1980s, just to see what kind of power they made back in the day, of course you could save me the trouble by just bringing yours up and putting it on the dyno. These are the most fun type of builds-carry on!
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Old December 30th, 2018, 02:45 PM
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Originally Posted by VORTECPRO View Post
Your thread is making me want to duplicate the 455s builds I built in 1980s, just to see what kind of power they made back in the day, of course you could save me the trouble by just bringing yours up and putting it on the dyno. These are the most fun type of builds-carry on!
I totally agree. Some day I would love to build a F.A.S.T. car to compete in that competition. Something unusual maybe. Like my 1976 TA.
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Old January 7th, 2019, 07:27 PM
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Interesting thread to come across . I just acquired a 455 to make the move away from the small block olds stuff I have been doing. It came with some "ported" J heads and it has big valves. those heads where on a 455 that ran 11.50's in a 3600 lbs car . Once I really have the time to mess with the engine I plan on having the heads flowed. Im curious what they flow as the previous owner has no flow sheets.
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Old January 8th, 2019, 06:58 AM
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Originally Posted by coppercutlass View Post
Interesting thread to come across . I just acquired a 455 to make the move away from the small block olds stuff I have been doing. It came with some "ported" J heads and it has big valves. those heads where on a 455 that ran 11.50's in a 3600 lbs car . Once I really have the time to mess with the engine I plan on having the heads flowed. Im curious what they flow as the previous owner has no flow sheets.
So am I !
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Old January 8th, 2019, 07:06 AM
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Mine is a low budget build ..got the heads and a long block with forged slugs. I'm just using whats there. Now correct me if im wrong but doest cam profile play a big roll in helping poor flowing heads.
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Old January 8th, 2019, 10:43 AM
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Originally Posted by coppercutlass View Post
Mine is a low budget build ..got the heads and a long block with forged slugs. I'm just using whats there. Now correct me if i'm wrong but doesn't cam profile play a big roll in helping poor flowing heads.
Any place in the chain, that's weaker or stronger than the rest changes the outcome, but can not change the less than perfect imbalance and make it all ok and equal.

The cam needs to be chosen for the range of power wanted and is practical, and playing to the strength of what the airflow is works out the best. Over caming and running slower and worse than it could be is common. But if you want that lope of a race car then you will join the majority that have over camed, for the airflow and rpms that are actually there or needed.

The air flow stays the same in the heads and intake, or out the exhaust. The cam changes when or the time this is happening.





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Old January 8th, 2019, 11:28 AM
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Originally Posted by Firewalker View Post
Any place in the chain, that's weaker or stronger than the rest changes the outcome, but can not change the less than perfect imbalance and make it all ok and equal.

The cam needs to be chosen for the range of power wanted and is practical, and playing to the strength of what the airflow is works out the best. Over caming and running slower and worse than it could be is common. But if you want that lope of a race car then you will join the majority that have over camed, for the airflow and rpms that are actually there or needed.

The air flow stays the same in the heads and intake, or out the exhaust. The cam changes when or the time this is happening.
Best advice that I have ever been given on cam selection is "pick out the cam that you want, then order one step smaller".
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Old January 8th, 2019, 11:31 AM
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I have never over cammed an engine. The only reason i asked is because back in the stocker days head modifications where limited and many ran "cheater cams" i belive they had to measure at OE specs so i assume the ramp profiles where changed to help the heads flow better by . Just from what i know atleast.
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Old January 8th, 2019, 11:33 AM
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Originally Posted by ChevyZ06 View Post
Best advice that I have ever been given on cam selection is "pick out the cam that you want, then order one step smaller".
Better than what I suspect most do, and that is try and cheat the system with one step bigger.
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