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What is the relationship of the 6 bolt vs. the 8 bolt pattern to engine type?
Which engines have the 6 bolt and which engines have the 8 bolt pattern? What would be the restrictions if you changed over engines with the variance? Besides the need for a different flywheel. Thanks.
Ron
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posted by
someone claiming to be Richard
on
Thu Jan 27 03:36 CST 2005 [ RELATED]
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74-75 are 8 bolt they are basicly the same for street use the 6 bolt has lighter componets,so is more disireable for racing,outside they are the same,the 8 bolt probably has a few more horses. Race on foever. Dick
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Basically the 8-bolt engines are late production B20's with the B21 bottom end making an early appearance. So in addition to the obvious difference in the flywheel mount, the crank has different sized bearings on the rod throws, the rods are different on the big end (to match the crank) and on the small end (24mm wristpins just like the B21). And the pistons have 24mm wristpin holes as well.
Being late model B20's 8-bolt engines will (at least originally) have had a low compression F head on them. According to those who know such late production F heads have a little more metal in the right spots and can be worked on more to produce better flow - although stock there is little if any difference.
Big bore rebuils are a little easier on 8-bolt engines because you can just use regular B21 pistons. Although it isn't that hard to have a machine shop modify 6-bolt rods to accept a 24mm wristpin either. I just got my bottom end back from the machine shop and they only charged me $60 to ream the rods and interference fit 24mm wristpins so I could use my 6 bolt rods with B21FT pistons.
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I'm JohnMc, and I approved this message.
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John,
I question whether you can use a 24mm pin in an early rod as you describe.
The stock bushing is not thick enough to be reamed out to 24mm.
And certainly you don't mean "reaming it out for an interferance fit" .
John
V-performance.com
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With the bushing completely removed the hole is only slightly too small for a 24mm wrist pin. I had the machine shop install them with an interference fit. I'm guessing you don't like that idea?
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That's a typical Ford piston/pin/rod installation. Millions of them on the road. I don't see the issue.
Nice heads! Someone spent some time on those.
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Mike!
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I just happened to see it on eBay one day while my head was off swapping a cam. From the looks of it, all the work done to it was quite recent. But then the #1 cylinder had sucked something in (probably a Weber air cleaner nut?!? Just a wild guess) which wrecked the motor. The eBay seller had gotten the car (described as 'a race car') somehow and was parting it out - they weren't the person who had built it. The #1 chamber looked worse than it actually was - a moderate number of small nicks that I smoothed out with a dremel.
I can't imagine how much it would cost to duplicate - but it only cost me $160!
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I'm JohnMc, and I approved this message.
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definitely don't like that idea unless its a racecar that will be torn down
every 500 miles or so. And even then it should have a special coating on the pin.
Also don't like the inteferance fit part, which leads me to believe its not freely rotating in the rod end - so the pin is going to rotate in rod, which they weren't designed to do? And you are doing this to save how much instead of getting proper pistons for the 6 bolt rods? And I am usre that you had the block sonic tested to be sure the walls are thick enough to use B21 pistons in the first place?
Really don't mind you doing it, as you may know enough to get away with it, at least for a while. Just don't want everyone else thinking these are acceptable practices and good ways to save a couple of bucks.
John
V-performance.com
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The engine has about 60 - 70K miles on it bored out to 92mm. It had to be honed just a tiny bit more to fit the B21 pistons - I guess they are slightly larger than the ones that used to come with the old IPD 6-bolt big bore kits.
The B21FT pistons were barely cheaper than special 92mm/22mm pistons are, but they are dished. I'm using a modified cylinder head I got on eBay that had been shaved *way* down to about a 12.5:1 CR - higher on a big bore. I took some extra metal out of the chambers, but ran out of metal I thought I should remove before I got a nice volume. So I wanted to use dished pistons to regain some volume. I supose I could spend a lot on a head with more properly sized chambers - but I got this one for only $150 and I'm guessing it would cost over a grand to get something better. So the pistons were more to match the head than the rods. I figured that a dished piston was a better solution than a thick head gasket.
I also figured that if I wanted to pressurize things later on that dished pistons with an F head would be a nice low compression combination. As is used with my tiny head in with tight spacing (decked to 0, .035 copper gasket) they should have mid 10's CR.
If it all blows up (again) I think I'll just buy a rusted out 200/700 Turbo and use that...
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All good ( except a 92mm bore in a 6 bolt block without sonic testing it ) until we get to what the choice of pistons does to the wrist pin and rod big end. Custom forged pistons, dished or flat top, with pins and rings would be in the $550 - $600 range. They take about four weeks to have made. How much did you save on the pistons after taking into account the extra work on the rods? And then you have a block with cylinder walls that are too thin to begin with, and certainly way too thin for a boosted application. You should have a .155 wall for that - probably double what your thinnest spot is now. Don't believe me, have it tested. Or at least ask other people who have tested these blocks what the results are to give you a general idea of the specs. Just finished explaining to an owner of a turbo b20 that this is why he is blowing past the rings, blowing the dip stick out of the block under boost.
John
V-performance.com
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I must have been looking in the wrong spots for custom pistons, most of the prices I saw were more than that. I think I paid $250 for the B21Ft pistons - incl. pins and rings. From what I had seen pricewise I thought I was paying about $400 - 500 less.
You are probably correct about the boost. If I were going to bother putting a turbo into the PV I think realistically I'd just get a later model B23 instead of expensively trying to do something to the B20.
I'm not exactly sure what the modified head I have is. I at first assumed it was a carb head because of the lack of injector ports and the small metal plate where the large idle air bypass widget goes on an FI head. But it doesn't look like a 'B' head - it has raised and machined injector islands. While I could imagine someone welding and resmoothing the holes in the intake ports, I can't imagine anyone filling in the injector mount bolt holes too. And the way the bolt heads and injector islands are connected (little machined bridges above both center exhaust ports) makes it seem like it is a late model F head. Maybe it was a late model Penta head? Makes putting fuel injection on it a little more challenging.
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Nothing wrong with putting a lot of boost to a B20, just don't hog out the cylinder walls first. Would like to see them at .150.
From what you describe it is probably a late replacement head. Either that or an R sport head, but the R sport heads are pretty easy to identify if off the block as the ports are different.
John
V-performance.com
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Here are a few pics I just snapped of the head. It's just about to go back onto the engine.
Top view showing flat injector islands. Another thing that seems odd to me is the bolt head right above the #1 exhaust port. Not sure what that is for. I haven't checked yet to see if it is connected to the water jacket.
Pic #1
View down the center exhaust ports. They are much roomier than the ports on my F head. The intakes are more roughly finished (good for carbs!) and have the valve guides tapered.
Pic #2
Combustion chambers - I matched the sides to the 92mm bore and took a fair amount of metal out from around the sparkplug trying to get some more cc's (started out with only 33 as I recall). I ran out of metal I thought I should remove before I got as much volume as I wanted. I didn't want to remove any more of the squish area opposite the plug.
Pic #3
It also has hardened valve seats on the exhausts, double valve springs, and big valves - I think you'd probably need to offset bore the guides to get any larger.
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I'm JohnMc, and I approved this message.
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1) there were late heads used in k jet cars that looked like this and did not
have ports for fuel injectors as the injectors were not in the heads. It could be one of these heads that has been ported and milled. There were similar looking replacement heads as well - both for carbs and injection.
2) It could also be an R sport head as these were made from similar looking castings.
3) For a reasonable compression ratio with a 92mm bore, you will have to get above
50 cc in comb chamber volume. What is the depth of the combustion chamber?
4) Stop trying to modify the combustion chambers!!!!!!!!!!!!!!!!!!!!!!!!!
This was obviously a race head, whether R sport from the factory or modified afterwords. It would really be a shame to ruin an R sport head or even a good race head just to use on the street, especially if the modifications don't work.
To get race type compression, and 33 cc would be around 13 - 1, we take .200 " or more off the head. There is no way that you can take enough out of the combustion chamber to compensate for that. Trying will likely remove essential elements of the combustoin chamber shape. Not sure what cam, etc., you are using, but typical race ports, or R sport type III or IV ports would be too big for reasonable use on the street.
John
V-performance.com
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As for the late K-jet cars - what were the manifolds like? I'm putting fuel injection on it (MSnSe) and was planning on putting some injector ports on a D-Jet manifold. I already have two D-jet manifolds. One has sat out in the weather for years and is largely junk - I was planning on practicing welding injector bungs into it. But if I could get a later model K-jet manifold with bungs already in it I'd rather do that.
I got to 42.5 cc's before I stopped. I'm not planning on taking any more out. I've already driven then head around as modified by me for about 6 months before I had the rod bearing spin. I didn't notice any particular problems with it - it owuld puing with regular but not with premium. I was using it then with an 'R' grind cam with 1.6:1 roller rockers. I've got an Isky VV-81 for this time around. I was planning on using a KG Trimning KG-19 but they didn't have any in stock when I was buying the parts for the rebuild. This was with 42 DCOE Webers (36 chokes) and an old 4:1 header. Not quite big enough carbs and not the greatest header design - but they came at great prices. Gotta save money on the old Volvo to spend on bicycles!.
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I'm JohnMc, and I approved this message.
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What years were the manifold mounted injectors used? I've been halfheartedly looking for something like that but haven't seen anything yet. All the K-Jet B20's I've seen have head mounted injectors. I'd much rather use a manifold with mounts of some sort already on it instead of drilling and welding a regular D-jet one.
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I'm JohnMc, and I approved this message.
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posted by
someone claiming to be Rhys
on
Sun Feb 6 14:56 CST 2005 [ RELATED]
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Every B20F K-jet I have ever seen has head mounted injectors. The bracket is different from the D-jet, but the mounting point and the manifold for that matter, are the same.
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i also have never seen a b20 k-jet manifold w/ the injector bosses in it. i have piles of k-jet manifolds. i did notice there are two different castings. but neither have injector bosses. if there is one i would like to see it.
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Does anyone know what year the transition was made from a 6 bolt to an 8 bolt flywheel? I just bought an engine(B20?) from a guy who states it has a 6 bolt flywheel. What would that be in a B20? A B20A or B20B? He says it came out of a 122. At this point it's going to be a "learn how an engine works", engine. Something I can tinker with in case my B20E needs work in the future. It would be nice if it could be used in the car if needed. From the research I have done, the 220 series was made until 1969. The 130 series was made until 1970. So the engine could be an A, B or E. The only thing he is sure of is that it has a 6 bolt flywheel and it has been sitting in the garage for 30 years. For $ 125.00, I couldn't pass it up. My son and I pick it up Saturday. Thanks for your time.
Ron
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Only the last two years of the B20 had 8-bolt flywheels, the '74 and '75 model years. In the U.S. market, those were all F models, with low-compression heads and mechanical fuel injection. In Canada, a carbureted version was also sold.
'69-'73 are all 6-bolt, using the identical crank as a B18. If the head doesn't have injector ports, it's almost certainly a B20B (we didn't have the A in the U.S.). It's true that the 130 was built until 1970, but they were not sold in the U.S. -- '68 was the last model year here, and it had a B18. Unless the car was brought in from outside the U.S., odds are the motor in question was not its original motor.
(All this assumes that YOU are in the U.S. -- apologies if I'm assuming that incorrectly.)
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Phil, I'm in NY. I do not know where the 122 was from. The only thing left is the engine. I'll ask some questions on Saturday. When I bought the 1971 P1800E the owner gave me an extra head and flywheel. The owner said it would give me 30 extra hp if I put it on. At the time I just took the information at face value. But having done some research on the B20's, the B20E had the highest hp of the B20's. The B20F dropped to a lower rating. So at this point all I know is that I have an extra head. I don't even know if it's for the B20E. I'll get the engine home and start the learning experience. It's good to know that there are experienced people out there who have already been down the road I will soon start.
Ron
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The '71 E motor was rated at 130 hp, while the '72-'73 F (the years it had the same injection as the E) was 112 hp...
Identification: Look at the center head bolt on the manifold side. On the E head, the bolt contacts a little raised island in the casting that doesn't extend much beyond the bolt. On the F head, that island runs all the way past the injector forward of the center bolt.
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Your '71 E should have a 6 bolt engine, unless the engine was swapped at some point.
It is possible that your '71 E had an F head put on at some point. Hi octane gas did a sort of dip for a while, and it got very hard to drive the 10.5:1 B20E's around without doing something to lower the compression. Thick headgaskets were one way, later model F heads were a better way. Perhaps someone did that to your engine and kept the 'E' head? Either way, I don't think you'd get 30 more HP from putting a stock E head on in place of an F head. Maybe it's been worked upon? In any case, gasoline quality has come back somewhat since then, and you can again use a 10.5:1 compression head if you like (and you don't mind paying extra for premium). You can measure the thickness of the head from the bottom face to the top machined face to see what type it is.
If your 'spare' motor is a B20 it will have a fairly prominent cast 'B20' on the block. Right there underneath the #1 sparkplug area more or less. Hard to miss if it is there. If it isn't, it is a B18 - nearly identical engine with smaller pistons (and valves).
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I'm JohnMc, and I approved this message.
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