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Are there 2 different R4B intakes?? |
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Ramblin on 
AMC Nut 
Joined: Dec/20/2008 Status: Offline Points: 130 |
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 Topic: Are there 2 different R4B intakes??Posted: Jan/08/2009 at 4:34pm |
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Did they make 2 different R4B intakes to fit both the early and late engines? If so, how can you tell the difference?
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scott
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Joined: Jul/10/2007 Location: Wildwood Pa. Status: Offline Points: 3501 |
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Posted: Jan/08/2009 at 4:58pm |
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Yes there are two different R4B's. Look at the center bolt holes, the ones that hold the manifold to the heads. If all the bolt holes are in a straight line = 69 & down intake. If the center bolt holes are higher than the outers = 70 up.
Some people slot the center bolt holes in an attempt to make the manifold fit a different year of engine. I never tried it, but some friends have, with poor results. This is due to a difference in the deck height between the 69 down & 70 up engines.
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PHAT69AMX
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Posted: Jan/08/2009 at 5:54pm |
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Deck Height difference is .033 inch nominal, 9.208 '70 & up, 9.175 '67-'69
Per PAS whatever amount is milled from block deck and/or cyl heads, to maintain proper fit,
an equal amount should be milled from each side of the Intake manifold.
Going from short early to tall late block It is like "adding material" instead of milling.
If Mr. Gasket #5844 fiber Intake manifold gaskets are used, they may make up for the deck ht. difference
since they have some thickness to them compared to the stock valley pan.
The valley pan would still be used along with the Mr. Gasket gaskets for oil control.
If the Intake Exhaust Heat Crossover is blocked off, may get away without using a valley pan,
but there is still an increased possibility of sucking oil thru the PCV without it.
Have heard tell of trimming a valley pan to use it along with the Fiber Gaskets
so that only the fiber gaskets are sealing between heads and intake.
Believe it was 74BubbleFender who mentioned doing this.
Main point is, using fiber intake gaskets could make for the early to late deck height difference. |
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amx39068
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Posted: Jan/08/2009 at 6:16pm |
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I've used them on the two engines in both directions and the later intake on the early engine is a pain in the butt to get a correct mill off of. The best reason for slotting is to use the later heads on the early engine and needing to slot the early intake to fit those heads. No issues there other than making sure the elongated hole lines up with the intake bolt hole on the later head. |
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Dan Curtis-Owner and CEO AZ AMC Restorations; Facebook: https://www.facebook.com/amcmusclecars/ & Curtis Real Estate Development
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billd
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Posted: Jan/08/2009 at 8:14pm |
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My R4B is a proper 1970 intake. It came with the car and was a very good fit when I got it.
It's even got the proper AMC number and has "70" stamped on it by someone.
It's a poor fit since the engine rebuild and 71 heads were put on. The angles aren't quite right. There's a bit more gap on the bottoms of the sides than the top.
In other words, with NO gaskets on the sides, intake a dry fit, you could put a thin feeler gauge between the intake and heads at the bottoms of the ports while the top of the intake would be against the heads. When you put it on the engine for the dry fit it "rocks" instead if sitting in snugly and solidly.
No problem on the end seals, that part is perfect.
The later heads were milled -
the fellow didn't keep track of how much he took off but said " typical is .010 "
If the intake port side of the head was exactly 90 degrees from the block side of the head - a perfect right angle, milling would make no difference at all. They'd simply slide straight down in a stright line and the relationship would not change.
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PHAT69AMX
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Posted: Jan/09/2009 at 12:08am |
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Edit Oct 01, 2019 - I had a number of part number errors in this post, confused by the fact that AMC offered the R4B Intake ALONE, or as a "KIT" with a Holley 3916 3V Carb, both with AMC Part Number. New info 2019: per June '72 edition, 1967-72 Parts Manual 448 5729 = 1967-69 Part No. R4B Intake Only 448 5731 = 1967-69 Part No. R4B & Holley 3916 3V 448 8409 = 1970-Up Part No. R4B Intake Only 448 8410 = 1970-Up Part No. R4B & Holley 3916 3V ------ This is true, but alignment of ports between head and intake changes.
1967-69 with AMC Part Number 448 5731 = Intake & Holley 3916 3V Carb
1967-69 without AMC Part Number purchased directly from Edelbrock 1970-91 with AMC Part Number 448 8410 - ( typo corrected ) = Intake & Holley 3916 3V Carb1970-91 without AMC Part Number purchased directly from Edelbrock and reportedly,
R4B's are out there marked with AMC Part Number 448 5729 = 1967-69 Part No. R4B Intake Only ,
For a visual of the difference in the 2 center mounting bolt locations on each side,
look at the slotted holes in those locations in an Intake Valley Pan Gasket.
Options other than slotting holes,
enough material in the heads to drill & tap additional holes in the alternate location,
or plugging holes in intake with aluminum rod, welding, and re-drilling relocated holes,
or drilling additional clearance holes in the intake rather than slotting.
Edited by PHAT69AMX - Oct/01/2019 at 4:04pm |
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billd
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Posted: Jan/09/2009 at 7:22am |
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I agree with your comment on port alignment - not sure if I worded mine or not, was hoping to say the angles and fit would not really change, but "hole alignment" would because the holes would move straight down by the amount shaved off, ports included.
There's a formula I have in a performance book on heads, porting, etc. that calculates how much to remove, the angles involved, etc. Not all heads have the intake port surface 90 degrees from the block side of the head so there's a formula to use.
Mine - not sure if you can read the number or not - I'll bet it's the last one youmention, though, unsure of years. Note the "70" stamped on mine - but by who, when, etc.:
 Edited by billd - Jan/09/2009 at 7:25am |
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amx39068
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Posted: Jan/09/2009 at 7:57am |
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something sounds odd regarding the changes due to the later model heads. I would think that the intake would be higher not lower if the heads were milled creating the same sort of alignment issues that exist with using the later model intake on an early engine. |
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Dan Curtis-Owner and CEO AZ AMC Restorations; Facebook: https://www.facebook.com/amcmusclecars/ & Curtis Real Estate Development
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PHAT69AMX
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Posted: Jan/09/2009 at 11:48am |
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Agree, if an early intake is used on an early block along with late model dogleg heads
no machining of the intake is required, only modification to the center mtg holes,
be it slotting the intake, or "preferably", tapping additional holes in the late model heads
in the early model locatons to avoid modification to the intake.
Use of the fiber gaskets can be a way to fit an early intake to a taller late model block & heads
since the early intake may be too narrow and sit to low between the late model heads.
If a late model has milled heads and/or block deck height, the early intake may fit just right
without using the fiber gaskets.
Understanding is the objective is no exsposed edges where the ports meet.
If intake ports are slightly smaller than head ports, some misaligment can be accomodated.
If a late model Intake is fitted to an early engine will milled heads and/or block,
chances are the intake will sit too high and need machined to fit properly.
billd, in the picture of your R4B Intake,
the Vacuum Nipple on the drivers side, and brass plugs on the pass side,
I don't recall seeing those on other R4B's, wonder if that's the difference with 448 5729 ?
No R4B's are on hand to look at.
Dan C. , any R4B's on hand to compare to billd's ?
Do they have that drive side nipple and pass side ports ?
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amx39068
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Posted: Jan/09/2009 at 11:58am |
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I have an early intake sitting on the other SC/Ramblers engine on a stand and will take some pics today. If I recall correctly it is an AM logo'd early R4B. I also have another early AM logo'd R4B intake with elongated center bolt holes and it si installed on a 390 with 502-2 heads but that one is unfortunately all wrapped up in shrink wrap awaiting final payment and shipment to its new owner. Edited by amx39068 - Jan/09/2009 at 12:00pm |
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Dan Curtis-Owner and CEO AZ AMC Restorations; Facebook: https://www.facebook.com/amcmusclecars/ & Curtis Real Estate Development
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