J35A3 heads are not the same as J32A2 heads
06-01-2016, 02:14 PM
#41
j35/6 Speed Swapped
06-04-2016, 06:46 PM
#42
Racer
Thread Starter
I know I keep saying I'm just around the corner on getting these heads built, but I really am. My valve spring compressor clamp had a handle too short to apply leverage, so I welded on an extension that works great. However, instead of assembling them, I remove all the valves and spring seats and started porting. The logical next step. I'm cleaning up casting flash in the runners, mostly, though I am also smoothing out flow right behind the exhaust valves. I'll probably work on the exhaust some more, but I don't think I'll be polishing that side like I would want to. I know there are benefits, but I'd prefer to start reassembly soon.
06-05-2016, 08:10 AM
#43
Senior Moderator
Both blocks are the same. The only difference in the oil pumps is the pressure valve and spring, the J32A2 parts can be purchased for around $20. The coolant crossover manifold is different but can be made to work. The EGR valves are different and must correspond to the appropriate ECU. Of course the crank, rods and pistons are different. J35A3 has forged crank and rods but they are not comparable to after market forged rods but still better than cast (J32A2 has forged crank only). The heads are the same castings and use the same valve seats even thought the J32 uses a 1mm larger intake vale (with a valve job the smaller valve will flow more, due to less shrouding). Lost motion assemblies were updated for the 03 J32. The cams and springs are different (J32 springs are considerably stronger). The intake of the J35 utilizes are 1" spacer between the upper and lower runners and the upper intake is the same between the two with the exception of the longer trumpets used on the J35 (produces more torque below peak). The TBs are the same with the exception of the MAP sensors and the corresponding MAP sensor must be used with the correct TB (both use the same plug).
If forced induction is in your future use the J35A3. Clean up the casting marks in the intake tract but do not increase the size and enjoy the lower static compression and cams with less over lap. (upgrade the oil pressure spring and valve for good measure)
For some NA fun on the cheap start with J35A3 use J32A2 cams and springs, port from the J35A3 IM to the valves, valve job and mill the head. (.010" is approximately equal to 0.25:1 static compression with J35 rotating assembly). I milled mine to 0.030" with no valve clearance issues and an estimated 10.75:1 static compression (no issues achieving correct mechanical timing with 0.030" milled). I also upgraded the oil pressure spring and valve in the bottom of the oil pump.
Assuming that even if you don't separate the heads and run the long block as is replacing all exterior seals and gaskets only makes good since. Since you have to pull the pan to replace the the gaskets behind the oil pump and pickup, removing one allen plug and dropping the J32A2 oil pressure spring and valve in place is some really cheap insurance.
If forced induction is in your future use the J35A3. Clean up the casting marks in the intake tract but do not increase the size and enjoy the lower static compression and cams with less over lap. (upgrade the oil pressure spring and valve for good measure)
For some NA fun on the cheap start with J35A3 use J32A2 cams and springs, port from the J35A3 IM to the valves, valve job and mill the head. (.010" is approximately equal to 0.25:1 static compression with J35 rotating assembly). I milled mine to 0.030" with no valve clearance issues and an estimated 10.75:1 static compression (no issues achieving correct mechanical timing with 0.030" milled). I also upgraded the oil pressure spring and valve in the bottom of the oil pump.
Assuming that even if you don't separate the heads and run the long block as is replacing all exterior seals and gaskets only makes good since. Since you have to pull the pan to replace the the gaskets behind the oil pump and pickup, removing one allen plug and dropping the J32A2 oil pressure spring and valve in place is some really cheap insurance.
100% On my 3.7 build I used the J35A3 heads for the reason of them having the capability of being able to flow more. I ported, polished and gasket matched which really opened things up. Also polished the combustion chamber side of the head as well.
I used J37A2 cams from the MDX. They are a direct bolt in except for the (cant remember off the top of my head exact mm) 3&5? mm shim on the cam pulley side.
I milled the block .060 and heads .030 and didnt have a issue with timing or any clearance issues nor is there any issue with the stock ecu running things.
Oh and IF you decide to bore the cyl walls to accommodate the 3.7 pistons, do NOT have them honed. They must be a smooth bore and cant have a cross hatch pattern. You will eat the rings and have oil consumption issues. I know this from experience.
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03 tls nc (06-07-2016)
06-06-2016, 02:38 PM
#44
Ok, so, I don't think I have read it in any thread....and I have read a few.
The part numbers, for the J37 parts, are different between the '07-'09 and '10-'13 MDX.
Are the parts actually different, or did they just give them different numbers with the refresh of the MDX?
The part numbers, for the J37 parts, are different between the '07-'09 and '10-'13 MDX.
Are the parts actually different, or did they just give them different numbers with the refresh of the MDX?
06-06-2016, 02:54 PM
#45
Both blocks are the same. The only difference in the oil pumps is the pressure valve and spring, the J32A2 parts can be purchased for around $20. The coolant crossover manifold is different but can be made to work. The EGR valves are different and must correspond to the appropriate ECU. Of course the crank, rods and pistons are different. J35A3 has forged crank and rods but they are not comparable to after market forged rods but still better than cast (J32A2 has forged crank only). The heads are the same castings and use the same valve seats even thought the J32 uses a 1mm larger intake vale (with a valve job the smaller valve will flow more, due to less shrouding). Lost motion assemblies were updated for the 03 J32. The cams and springs are different (J32 springs are considerably stronger). The intake of the J35 utilizes are 1" spacer between the upper and lower runners and the upper intake is the same between the two with the exception of the longer trumpets used on the J35 (produces more torque below peak). The TBs are the same with the exception of the MAP sensors and the corresponding MAP sensor must be used with the correct TB (both use the same plug).
If forced induction is in your future use the J35A3. Clean up the casting marks in the intake tract but do not increase the size and enjoy the lower static compression and cams with less over lap. (upgrade the oil pressure spring and valve for good measure)
For some NA fun on the cheap start with J35A3 use J32A2 cams and springs, port from the J35A3 IM to the valves, valve job and mill the head. (.010" is approximately equal to 0.25:1 static compression with J35 rotating assembly). I milled mine to 0.030" with no valve clearance issues and an estimated 10.75:1 static compression (no issues achieving correct mechanical timing with 0.030" milled). I also upgraded the oil pressure spring and valve in the bottom of the oil pump.
Assuming that even if you don't separate the heads and run the long block as is replacing all exterior seals and gaskets only makes good since. Since you have to pull the pan to replace the the gaskets behind the oil pump and pickup, removing one allen plug and dropping the J32A2 oil pressure spring and valve in place is some really cheap insurance.
If forced induction is in your future use the J35A3. Clean up the casting marks in the intake tract but do not increase the size and enjoy the lower static compression and cams with less over lap. (upgrade the oil pressure spring and valve for good measure)
For some NA fun on the cheap start with J35A3 use J32A2 cams and springs, port from the J35A3 IM to the valves, valve job and mill the head. (.010" is approximately equal to 0.25:1 static compression with J35 rotating assembly). I milled mine to 0.030" with no valve clearance issues and an estimated 10.75:1 static compression (no issues achieving correct mechanical timing with 0.030" milled). I also upgraded the oil pressure spring and valve in the bottom of the oil pump.
Assuming that even if you don't separate the heads and run the long block as is replacing all exterior seals and gaskets only makes good since. Since you have to pull the pan to replace the the gaskets behind the oil pump and pickup, removing one allen plug and dropping the J32A2 oil pressure spring and valve in place is some really cheap insurance.
Last edited by SykVSyx; 06-06-2016 at 02:57 PM.
06-06-2016, 02:55 PM
#46
Ok, so, I don't think I have read it in any thread....and I have read a few.
The part numbers, for the J37 parts, are different between the '07-'09 and '10-'13 MDX.
Are the parts actually different, or did they just give them different numbers with the refresh of the MDX?
The part numbers, for the J37 parts, are different between the '07-'09 and '10-'13 MDX.
Are the parts actually different, or did they just give them different numbers with the refresh of the MDX?
06-07-2016, 11:43 AM
#47
100% On my 3.7 build I used the J35A3 heads for the reason of them having the capability of being able to flow more. I ported, polished and gasket matched which really opened things up. Also polished the combustion chamber side of the head as well.
I used J37A2 cams from the MDX. They are a direct bolt in except for the (cant remember off the top of my head exact mm) 3&5? mm shim on the cam pulley side.
I milled the block .060 and heads .030 and didnt have a issue with timing or any clearance issues nor is there any issue with the stock ecu running things.
Oh and IF you decide to bore the cyl walls to accommodate the 3.7 pistons, do NOT have them honed. They must be a smooth bore and cant have a cross hatch pattern. You will eat the rings and have oil consumption issues. I know this from experience.
06-07-2016, 03:14 PM
#48
Racer
Thread Starter
06-07-2016, 05:02 PM
#50
Racer
Thread Starter
I hear people say that, but I have zero idea where they're getting that from. It sounds like anything else that's repeated on the internet.
The J32A2 got more aggressive cams than any other engine that used the P8E casting heads. Does it not make sense that they would increase valve size to accommodate the increase in camshaft profile? The J35A8 has larger valves than the J32A3/J35A5 and all other second-gen J-series. It also has the most aggressive camshafts (save the J37 variants). For no other engine have I ever heard people say that a manufacturer increased valve size for emissions purposes.
I used to think that there might be some credence to the argument that the J32A2 heads on a block that did not have a J32A2 or J35A8 piston would cause clearance issues with valves. Not only was the information perpetuated, but people claimed to know of others having problems! After looking at the top of a J35A3 piston, I'd really like to have a conversation with those people. The reliefs are just small dimples and offer plenty of real estate between the faces and the edges of the valves.
The J32A2 got more aggressive cams than any other engine that used the P8E casting heads. Does it not make sense that they would increase valve size to accommodate the increase in camshaft profile? The J35A8 has larger valves than the J32A3/J35A5 and all other second-gen J-series. It also has the most aggressive camshafts (save the J37 variants). For no other engine have I ever heard people say that a manufacturer increased valve size for emissions purposes.
I used to think that there might be some credence to the argument that the J32A2 heads on a block that did not have a J32A2 or J35A8 piston would cause clearance issues with valves. Not only was the information perpetuated, but people claimed to know of others having problems! After looking at the top of a J35A3 piston, I'd really like to have a conversation with those people. The reliefs are just small dimples and offer plenty of real estate between the faces and the edges of the valves.
06-07-2016, 08:17 PM
#51
The J32A2 got more aggressive cams than any other engine that used the P8E casting heads. Does it not make sense that they would increase valve size to accommodate the increase in camshaft profile? The J35A8 has larger valves than the J32A3/J35A5 and all other second-gen J-series. It also has the most aggressive camshafts (save the J37 variants). For no other engine have I ever heard people say that a manufacturer increased valve size for emissions purposes.
I used to think that there might be some credence to the argument that the J32A2 heads on a block that did not have a J32A2 or J35A8 piston would cause clearance issues with valves. Not only was the information perpetuated, but people claimed to know of others having problems! After looking at the top of a J35A3 piston, I'd really like to have a conversation with those people. The reliefs are just small dimples and offer plenty of real estate between the faces and the edges of the valves.
06-07-2016, 11:40 PM
#52
Pro
iTrader: (6)
Both the the heads J32A2 and J35A3 use the same head casting and they use the same valve seats! The valve seat is the ultimate limiting factor to flow followed by shrouding. A larger valve on the same size valve seat equal greater shrouding and less potential flow. Back in the early 2000's Honda in one of there tech articles eluded to the valve increase as being utilized for emissions.
Port the runners, in-large the bowls, gasket match everything and when you have your valve job done have the back cut the seats. There is a considerable amount of flow potential in these heads but without changing the seats the J35 valves will flow more.
SykVSyx when I built me J35 I was on a mission to build a 2G J35 type S engine of little money. I failed to research the oil spring used by the J37. The J37 spring should work and for your questions about the J37 MDX internals check out Youngones thread he has researched it.
Port the runners, in-large the bowls, gasket match everything and when you have your valve job done have the back cut the seats. There is a considerable amount of flow potential in these heads but without changing the seats the J35 valves will flow more.
SykVSyx when I built me J35 I was on a mission to build a 2G J35 type S engine of little money. I failed to research the oil spring used by the J37. The J37 spring should work and for your questions about the J37 MDX internals check out Youngones thread he has researched it.
Last edited by 03 tls nc; 06-07-2016 at 11:43 PM.
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SykVSyx (06-08-2016)
06-08-2016, 12:16 PM
#53
Senior Moderator
^
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03 tls nc (06-18-2016)
06-08-2016, 12:17 PM
#54
Senior Moderator
06-08-2016, 01:01 PM
#55
Thanks, Kris.
As you may recall, I am going for a 300whp(minimum of course, because why not dare to dream!) N/A setup, so, which cams would be the best for that goal?
Seems to be a bit of a toss up between the '08 TL-S ones or the MDX ones, as discussed on the top threads on here about it.
As you may recall, I am going for a 300whp(minimum of course, because why not dare to dream!) N/A setup, so, which cams would be the best for that goal?
Seems to be a bit of a toss up between the '08 TL-S ones or the MDX ones, as discussed on the top threads on here about it.
06-12-2016, 07:11 PM
#56
Senior Moderator
I think either will suit you just fine. I have the 3.7 cams and cant complain. Only complaint i have is is i still havent gotten my ass around to getting a larger TB/Dual TBs installed. I know the motor is starving for air up high.
06-13-2016, 08:48 AM
#57
Moderator
iTrader: (1)
Aren't the J37A1 cams and J35A8 cams pretty similar specs wise? Pretty sure that's what I read somewhere in Yungone's thread.
My RL can move respectably in the upper RPMs considering it's nearly 4k lbs.
My RL can move respectably in the upper RPMs considering it's nearly 4k lbs.
04-28-2022, 10:52 PM
#58
Yes, they're the exact same block. Much of the misinformation comes from people who spout of things with no basis at all, or basis in some logic that makes no sense. Part number comparisons and real-world analysis just aren't relateable concepts for some people. I'm not free of criticism myself. I began this thread seeking to refute something that had been widely spread as fact. While I did help to clear some of the confusion up, I did so by speaking before I had all of my information straight.
The J35A3 pistons have a lower dome volume which will cause a lower compression ratio.
The J35A3 rods are slightly shorter to accommodate the longer stroke.
The J35A3 crankshaft has a longer stroke.
Other than those, the J35A3 short block uses the same part numbers as the automatic J32A2. The 6-speed J32A2 uses an oil pump with an additional threaded mounting boss for one of the MT-specific crankshaft position sensors.
The J35A3 pistons have a lower dome volume which will cause a lower compression ratio.
The J35A3 rods are slightly shorter to accommodate the longer stroke.
The J35A3 crankshaft has a longer stroke.
Other than those, the J35A3 short block uses the same part numbers as the automatic J32A2. The 6-speed J32A2 uses an oil pump with an additional threaded mounting boss for one of the MT-specific crankshaft position sensors.
04-29-2022, 06:20 AM
#60
Burning Brakes
That's good to hear. I must have read this thread at least 5 times. I also talked to p2r about valve options with their ported p8e heads. Although 35mm and 36mm use the same seat, they recommended using clay to check the valve clearance with 36mm valves.
