WOW! Looks healthy to me. What's the complaint face for

 

impressive! 275 tq!

 

Holy shat! Hell yes! Why the hell would anyone be upset about that? I'm getting my j37a4 heads ready RIGHT NOW as a matter of fact for my forged motor that will be up and running soon. Wow, that's what, over 350hp at the crank maybe....depending on trans of course.

 

Haha, thats my car. I made 324/280 and now about 330whp with the ported intake runners

 

Its about 330whp now. 370-380 at the flywheel figuring for 12-15% drivetrain loss

 

What fuel are you using?

Good show

 

Just 93 octane

 

It's a J36 build so did you up the compression much?

 

J36 bottom (89x96) with J37A4 heads results in 11.5 compression ratio.

 

I'm not trying to thread jack - just trying to find an answer or at least a path to an answer and tons of searching led me this thread. Am I correct in assuming that swapping the J37A2 / A4 (VTEC on both exhaust and intake) on to my J35Z3 (in the car and running great right now - just looking for more power staying NA and it's my daily) is more straight up for me since I don't have to swap any of the crank trigger / sensors etc since I am running the J35Z3 ECU? I already have the J37 IM and TB on my 3.5 and it's been tuned and I'm more than pleased - but more power is more power. I'm tempted to buy both and check them out, but what head gasket should I go with?

If PM is more appropriate then let me know. Any help here is greatly appreciated.

 

I think Robert already has a J35Z3 bottom end with J37A4 heads on it, so he would know exactly what to tell you.
But I think you should use the head gaskets that go with the bottom end and bore, so that would be the J35Z3 gaskets.

 

Thanks. I PM'd him, but I figure with work, projects and five kids (I have one that's pretty much grown I can't imagine 5) he might be busy. Also wondering if I need to change anything in regards to the J35Z3 oil pump (like a pressure relief spring etc for the difference in volume the dual VTEC heads want to see).

 

go with the j37a4 gasket. Gasket much match the cylinder heads with the j35z3 there will be an lip of 1mm or 0.5mm all around, but also you need to check if the coolant and oil galley match up. I am not sure for the j35z3 motors.

 

I was assuming that the J35Z3 block/heads have the same water jacket design as the J37A4. If that is the case, then the gasket matching the bore size should be used, so J35Z3 gasket.

 

I was told to use the j35a8 (89mm)gasket on my j30a5 (86mm bore) block. So that is where I am getting the use the j37 gasket on the j35 block. If I used the j30a5 gasket it would get raped

 

Your case might be different due to the larger bore delta. I'm assuming that the combustion chamber on the J37A4 heads is slightly smaller than the 90mm bore.
Robert is going to have to chime in. I'm sure he knows.

 

If you're just wanting to swap the heads over, then the j35z will make an ideal candidate. Not because any specific design advantage, but because it's the engine that I used when I did the same swap. No issues whatsoever. I used them with the older, but THEN more capable, j35a8 ECM and wiring harness. Not too sure what capabilities the j35z ECM is now able to do but it has much better potential. This is mainly due to its higher resolution crankshaft trigger wheel which essentially allows for more accurate tuning.




I agree 100% with Eric on this. Good thing about swapping out the stock R70 castings (j35z) for the j37a4 heads is they share the same cooling system design where the coolant is blocked by a control spacer that forces cooling on the block before the head. Older models (such as the j35a8) don't have this design and the two cooling systems "clash" in a sense.

Yes, busy with life. Seen your PM a few days ago but I get so many asking advice through them that I generally won't answer unless I see the topic in a thread so that others can also gain/learn from it. Otherwise, it makes you feel like a free tech service so if you (or others) need help, ask openly in a discussion please and I will gladly share what I've learned with you guys.

​​​​​​​
From memory, the chambers of the j37a4 chambers are 89mm and the head gaskets were nearly 91mm.


Hope this all helps.

 

Just want the extra mid range and possibly some upper RPM power gained with VTEC on both exhaust and intake, not to mention the cams are more aggressive. I've already talked to my tuner about another dyno / tune session.
The power of this motor now is just downright wicked fun. And I've driven LSx, BBC, SBC etc. It's my daily - I don't want to get stupid.





Actually that was in fact one of my questions as well. Thanks. I was actually going to snag a set of Z3 heads and compare. Now I don't have to - thanks.



Believe me I know. I appreciate the response.



It most certainly does, thanks again. The motor LOVES the bolt on's - even more with the right tune. I hit 270+WHP (DynoJet) BEFORE the tune. The tune was done on a Superflow. The car is so fun to drive now. Responsive in every gear. Low / mid range power gain before VTEC, and lowering VTEC rpm gave nice gains. Benefit to the J35Z3 - the lower compression ratio means the engine LOVES more timing. That's where the power gains were.



The hunt is on for the parts.

 

I'm also interested in doing J37 head swap. I have a 4g 3.5 TL (J35Z), and I'm planning to swap with a J37 head from a 3.7 TL.

From what I have read, it seems like a it's a direct bolt-on? but I got the gasket for both J35 and J37, the tiny ports (for oil I guess?) and the ports for bolts aren't matched. Do you need to modify something to make them fit?

 

Brothers!! need your help. Getting this p0340 cmp sensor code..... got this one before when i tried a 2010 j37a1. Couldnt firgure it out. Back to the same problem again. I did the cam gear and swaped over the crank sensor with bottom timing sprocket for crank. Seems like its something with these newer style heads. The computer cant read it right or im doing something wrong. Any input would help fellas!!

currently doing a j35z6 into 07 tl type s
code is p0340

 

The cam sensor is not the same between these engines, nor are the cam gear part #'s (and therefore potentially the number of HAL pickup events that the ecu expects such as 24-1 or 12-2). Additionally, the cam gear backing plates (of which the front plate sets the sensor position/distance from the cam gear trigger) aren't the same either.

Do what is needed to make these fit as they should, even if they don't bolt right up to the j35z6 engine. HAL sensor and trigger positioning is critical.

 

My thoughts exactly. To watch someone tear down and then rebuild an engine is like some kind of hocus-pocus to me.I once had a panic attack after tearing apart my 300ZX to put in a stereo system (only car at the time and I only had 6 hours before I had to be somewhere, not too bright), so I will never ever take an engine apart.

 

For all those head swap guys out there. I need the proper head bolt torque and rocker saddle torque specs for the J37. head gaskets in the wife's '10 MDX, and finishing up the repair but cannot find any info other than J35 and earlier. I know the J35 and J37 are nearly identical but I cannot imagine that every bolt torque is identical, nor why there are zero specs available on the web for the J37. (I have new 12 pt. blots that are torqued to 22ft# right now and am eagerly awaiting an answer so I can button it up)

Please help, Todd

 

These are for a 2010 TL with a J37. Good luck.

 

It humors me how often people work on their car without a service manual.
Or at least a one day subscription to Honda Service Express.
https://techinfo.honda.com/rjanisis/logon.aspx

 

Thanks CL ! That was the same info I was finding for all the J35 w/12 point head bolts.

I did order the Bishko manual but it's lost somewhere in shipping and I needed this done asap. I don't trust online manuals, nor the companies that offer them. Too many times my info was stolen or sold and have had to get new credit cards etc. I will only deal with known reputable companies for online sales and was not aware that Honda offered that service. The local Acura service manager was nice enough to dig those specs up for me on Friday morning since he knew this was for my wife's car and not a customer.

Happy to say the MDX is all back together as of 8pm Friday and Momma is happy to have her girl back (and I have my Mega cab Diesel back). Today is rear diff, "transfer case" and 1x3 trans service, once she gets back from the local craft show.


I did post another question in the Gen 2 forum regarding the rocker bridge locating dowels that no one has replied to. I've also engaged the local dealer, who was clueless, as well as other avenues. It relates to the front head vs. rear head and a hollow dowel vs solid. If any of the builders here can give me info on that, it would be awesome. for the time being, I put a hollow dowel in where the solid was on the front head as I couldn't reason that having oil was a bad thing. https://acurazine.com/forums/1g-2g-m...oiling-983983/

Todd

 

Any updates on cams?

 

Hey guys, I'm going to be trading out my j37a1 head to a j37a4 head. I know my current PCD won't be able to fit on the new head but will the 4th gen TL PCD be a direct bolt on without issue? Some help here.

 

Yes, 4th gen TL pre-cats will work on any later style J-series head. That includes 09-14 TL (all), 10-14 TSX V6), 10-13 MDX/ZDX and 08-14 Accord V6.

 

I’m been reading along to this, and waiting for today to come. Got a set of 37a4 heads for my 08 accord coupe with the 35z3. From what I’ve read, I can just swap the cams, rocker bridges, the oil spring, relief valve, and valve covers. I don’t want to swap heads out now, my timing belt broke 3 months ago, and my current R70 ones just got rebuilt with a full port and polish. This is possible correct? Thanks in advance for your assistance, I appreciate it.

 

You should be able to just swap the cams and valve springs into your R70 heads. You will have VTEC on intake side just like you have now, but
the exhaust would always be on the high cam profile. But there is little difference between low cam and high cam profiles on the dual VTEC cams.

 

Hey all. I read through the whole thread and didn't see this asked / answered. Quick question on the heads of the 4th generations. I have access to a 2012 TL w/ 3.5L. I have an 07 Tl Type S. Would using the 2012 heads be better? From what I read the 2012 has vtec on intake and exhaust. Probably not as good as the 3.7L heads though, but I think better than what I have? I'm pretty much fully bolted on, except for cats which would good since I'd have to change those anyway. Thanks!

 

The base J35 does not have dual VTEC. However the R70 cylinder heads on that engine flow the same as the RKG heads, which flow notably better on the intake side, than the J35A8 heads.

 

So it would still be am improvement and upgrade then. I might try it out and see what happens. Would compression stay the same?

 

The results for the work involved to swap heads just doesn't make sense IMO.

 

Compression would be up 0.2 due to a 1cc smaller chamber. But you would also need the pre-cats from the later engine because the later style heads have a different exhaust port shape.
Listen to teh CL.

 

Thanks for the info. I actually scored a spare j35a8 from a wrecked type s the other week. I plan on rebuilding it anyway, so there wouldn't be that much more work involved. I also have high flow cats on my list to buy, but haven't yet. So if I go this route, I'll just buy the ones for the newer heads instead. While I was at the junkyard I saw the 2012 Tl. Hence why I'm considering the head swap. Otherwise, I completely agree it would not be worth the time or money. Still not sure if I want to do it though. If it was dual vtec then I'd jump on it but since it's not... I'm throwing it around in my head still.

 

@Euro-R_Spec_TSX Do you know if J37A4 heads match to a J32A3 (base 08 TL) motor? Will it work to run the J37A4 cam in a J35A8 head?

 

neither will work.

 

Do you know why the J37A4 cams won't work? Just want to know. Are there any cams that are better than stock that will fit in a J35A8 head?