AMC 6 Head Port Article

A couple of years ago I wrote an article for a local AMC club on porting AMC 6 cylinder heads. This included the 4.0 HO. The 4.0 head in the article is sitting on my 66 Rambler Convertable with 3 45 DCOE's. Need to build another for my jeep some day. If someone wants to post it to a web site I would be happy to send it to them as long as they provide the link on the forum.

John

[email protected]

Go ahead and post it on my JeepI6Power Group - that's what it's for! If it's fairly short, post it as a message, or post it as a larger file in the "Files" section.

groups.yahoo.com/group/JeepI6Power

5-90

Will do.

Thanks.

Not a problem. It's an "open" archive (membership required, no fees,) so it should go fairly wide. If you don't mind, I may want to distribute it a little further... I'll contact you if I find another likely place.

5-90

Send it to me and I will put it up on my server for you. Size doesn't matter. oops???

I will need an email address to send it to. Send a private message or [email protected] and I will pass.

PM'ed nosigma

digging up an old thread here, did anyone here actually put nosigma's article out on the web? I didn't find it on Kelly's page or Old Man's home page.

I'm seeing a flowbench article on AMC 6 heads on the JeepPower group, files section - is anyone else not? It's an MSWord doc, which may cause you some trouble...

Nosigma - if this is the one you put up, do I have your permission to also convert it to .html to put up on WiP? Feel free to email or PM me anything you want added or called out in the article, and let me know if you want a "final approval" before it goes up - I'll need your email for that.

5-90

Just became a new member of your group Jon. Lots of cool info. you've got there.

Dr. Dyno said:

Just became a new member of your group Jon. Lots of cool info. you've got there.

Click to expand...

Thanks - that's what it's for.

There's also a RENIX-specific group (groups.yahoo.com/group/RENIXPower) if you're into that for some reason. 1984-1990 XJ/MJ w/AMC engine only, please
And, an XJ/MJ Owner's Group (groups.yahoo.com/group/XJOG) that I am trying to make an "information clearinghouse" for us - easier to get through. This covers "everything else" that isn't in the RENIX group.

The main thrust of the JeepPower group (groups.yahoo.com/group/JeepPower) it to exchange ideas and information about the books - things you'd like to see, things you think you ought to see, suggestions, errata, and the like. However, this does result in some useful information also being posted - so (as you've already sorted for yourself,) it's worth a look.

The table is still open for suggestions on Swappology - that book is still going to be a little while in coming, so suggest away!

nosigma said:

A couple of years ago I wrote an article for a local AMC club on porting AMC 6 cylinder heads. This included the 4.0 HO. The 4.0 head in the article is sitting on my 66 Rambler Convertable with 3 45 DCOE's. Need to build another for my jeep some day. If someone wants to post it to a web site I would be happy to send it to them as long as they provide the link on the forum.

John

[email protected]

Click to expand...

Excellent articles John, deserves to be brought back up to the top now that strokers are becoming so popular. Also found these old posts of yours that were very helpful...

Modified 258 Head
4.0L Intake
4.0L Exhaust

good stuff, the article he wrote and emailed to me (guess it's the one I didn't find on 5-90's site) is awesome...

So Nosigma I live in VA to, what would you take to port a 0630 head if I brought it to you?

Also have you ever done any work to the combustion chambers?

Wow.

Some one dug deep to find this stuff...I am glad it has been of some help. The article I wrote up didn't have the bulk of the 4.0 HO mod work in it. The AMC Forum posts contained more info that was written after the article was written.



A few updates..

On my Rambler (66 convertible) 258/4.0 HO head motor I put in larger valves 2.02 in, 1.70 ex (I think thats right, the exhaust may have been bigger), notched the block for a big improvement in low lift flow on the intake, shifted the intake valve .040 or so towards the exhaust to improve flow and to clear the cylinder wall on the bored 258 block to give me .027 clearance from the valve to the bore at .493 lift (not a problem on the 4.0 block). I kept the valve stems the same size, used roller rockers with lash caps and then added long primary tube headers (Clifford custom) and 3 45 DCOE Weber carbs. The cam is a comp cams 4x4 extreme dual pattern. The car is a monster and pins you to the seat from 1000 rpms up to the red line of 5750 (#5 rod journal will break at 5900-6000 if you keep it there very long).

I was in a huge rush to finish up the motor and get the car on a transporter when I moved to So Cal in 2004, move back to Va last August. Believe it or not I never put the finished head (larger valves and 4 angle grind) on the flow bench when I finished it and I didn't make any port castings. It took the machinist over a month to finish his work on the head but it was worth the wait. I don't have final flow values for it. If I ever set up my flow bench again and I have the motor apart I will flow the head. To say I regret not spending a couple hours to do this back then is an understatement.

1 bolt,

I am living in a rental house and porting is a very very messy job. My flow bench is not set up and my air compressor isn't set up either (ie I cant do any porting or flow bench work right now). I would be happy to meet with with you, share my notes and help you port the head at your place.

For a high rpm motor and a big cam the extensive porting is really worth while but for an off road motor bigger valves, and a lot of easy cleaning up of the bowl, throat and flashing will give you big benefits at lower lifts and lower rpms. I wouldn't suggest doing much to the runners so you can keep the velocities high for low rpm off road work. This is the sort of stuff you can do with a drill, a couple of cutters, a cheap abrasives kit and an Dremel with a flexible shaft. Send me a PM and we can set up a time to meet.


John

1 bolt,

Forgot to mention the combustion chambers. Yes I did work on them. In my mill I sloped (10 degrees) the wall on the quench side and put a very fine radius on the edge to prevent a hot spot. After valves were installed I CC'd the chambers and then using the mill raised the roof to get a 9.875 compression ratio. Blended the plug boss too. The valve cutter was a radius into the bowl and after valve seat cutting the seat was blended into the bowl using a dremel with a fine grit small roll. The clearnece between the piston and and the quench side of the head is only .017 at 5500 rpm (taking rod stretch into account. The squish, improved swirl and shearing of the fuel mist (wet flow testing) allow me to run 91 octane with 38 degrees of total advance all in by 2400 rpm without any pinging or detonation under full throttle at all rpms. The head is part of system. The dynamic compression, not static is a huge part of what makes the head/engine work as are the webers which allow the cam to be very docile. It idles very well at 500 rpm but I keep it at 750.

John

nosigma -
Before I cut-and-paste those articles, do you have plaintext articles you could send me? The last few months have been OBE for me, and I just got to looking at them again.

If you don't mind, I'd like to put them up in the WiP Tech Section - you'd get final review, full credit, and I'd like to put your byline up as a hotlink to email for you (if it's not any trouble.)

I'd also appreciate details of your mods (and pix, if you have them!) and I'll have to peruse the AMC fori later as well. This is quite interesting to me - but I've probably got more of an engineering bent than most people here...

The best tech for the porting itself is in the old AMC forum posts linked a couple of posts above. The article (with flow charts) is in MS Word. You are welcome to post them and use them as you want. Credit is always appreciated. Send me an email at [email protected] and I will reply with the article attached. Some of the data in the AMC Forum posts came after the article was written and is far more valuable to someone actually working on a 4.0 head. The article is mostly a comparison of stock and lightly modified heads with a lot of graphs and commentary.

John

Thats some tight quench clearance! But tighter is better as long as nothing hits...dang thats as tight as I used to run my TZ350 motors.

John,
Yeah, it wasn't easy to find. "Valve Shrouding" was the combination that led me to the old posts, then I tracked you down here. The one thing I haven't been able to find is your follow up results on the exhaust work in the "new forum" after the mirror polishing work.

I'm building up a 7120 head right now with 1.970" int and 1.560" exh magnum valves to go on my 0.040 over 4.6L stroker, and accurate porting information on the 4.0L H.O. heads is few and far between. I've already milled the '99+ intake manifold and an adapter plate to accept a Fastman 4.7L 68mm throttle body and opened up it's ports a little leaving a 0.100" step on the bottom to help prevent reversion. This should provide plenty of available air for the intake, but I could always take out the bottom step to really open it up.

I'm aiming for a combustion chamber volume of 62cc, but with a cylinder bore of only 3.915", unshrouding the valves is my biggest concern (hence the reason I'm not using 2.020" int valves). I'm not sure I understand how you notched the block either to improve the flow.

There's a good head build going on at JeepsUnlimited that I've been following if you want to comment on the work that he's done so far.

New Big Valve stroker motor 4.6L

Everything that I've read of yours so far has been a really big help, so any other tips or guidance you can provide would be much appreciated.

I believe he notched a 4.2 block (not required on a 4.0) if my understanding is correct. The smaller bore on the 4.2 puts the cylinder wall in the way....I have seen other info of a similar manner in discussions on the Hesco site where someone was wanting info on using a Hesco head on a 4.2 with big valves.

Even with the stock 3.895 bore of the 4.0L the valves are bore shrouded. Going 40 thou over isn't going to improve it very much, and going 60 thou bigger on both valves is going to make it worse. This is a shot of a 7120 head on a stock '95 block.