Dual port 1700 85.5 x 74

[Frank Bassman]

Ok, well I know it is a little unusual to be building single port motors nowadays, but I have done research on some of the few people in these forums that have built them and I have concluded that based on my driving style, traffic conditions, and curiosity I want to build a 1600 single port with some twists... I wanted to run my ideas past you guys to see if what I am expecting out of this build is in touch to what it will actually deliver!

I just want to say one thing... I want to use as many stock style parts as possible as far as ignition and carburetion goes, which is why perhaps the combination I am about to describe will seem unusual. I'd just like to hear from those in the know if it will behave as well as I predict it might! I do NOT at this time have money for nice dual carbs, but they may be a possibility in the future!

My goal is to maximize fuel consumption efficiency and make strong low end torque. (Reason for going single port to begin with.) Not looking for a race motor or anything like that. It must look as stock-ish and be able to be worked on in as stock-like manner as possible! I will be cruising this thing at 70 to 75 mph doing between 3200 to 3500 rpm, which is a safe range I would say, and I think would be the cruising sweet spot for this combo.

So, here it goes:

ENGINE INTERNALS

85.5 P&C kit
69 mm crank from CB performance. (toying with 74mm idea, same price)
[Note, this crank is balanced]
New stock CB lifters
CB 2280 "Cheater Cam" (Supposed to be good from idle to about 4k RPM, this engine won't see past 4000 rpm in daily use.)
CB UNITECH Rods (New)
CB Maxi 2 oil pump (26 mm)
Stock VW 1.1:1 rockers (May put them on Empi solid shafts, may not, I haven't decided yet.)

INTAKE

Here is where it gets interesting for me... I am looking at the intake for single ports, and it looks PUNY, and restrictive even for the SP heads to breathe at this displacement. (Maybe why VW went to dual port?) Plus, I do have an excellent 30 pict 2, but with a 24 mm throat size it seems counter productive for what I am trying to accomplish. I have a solex brosol 30/31 pict which may work. BUT, I had a more interesting idea in mind.

Empi single port end castings
VW dual port center section WITH heat risers. (Very important.)
34 Pict 3 perched on top jetted accordingly.

( have a whole parade of them in my stash to choose from, one which I may be inclined to try boring out the venturi on...)

EXHAUST

Empi 1 3/8 header with a glasspack or quietpack or whatever.
(I already have the header and glasspack)

Cooling

VW doghouse shroud with cooler.
Case is a Brazil replacement case
WILL run the thermostat bellows and flaps.
[Note to self: must drill case, tap for stud, and install thermostat stud.]

IGNITION

043 SVDA rebuilt distributor with points
Bosch Blue coil
Use a Ford TFI ignition module. (Points triggered. Running it now with great success on my current engine.)

FUEL DELIVERY

34 Pict 3.

My whole reasoning on this intake setup is the following:

As far as I can gather and have seen, single ports really have a NICE low end grunt in themselves. This is apparently due to the high velocity of the intake charge through that one single opening at the heads.

But the reason I think they "choke up" in stock form is because the limiting factor, provided the exhaust is up the the challenge, ends up being the puny intake manifold and stock carb. (They flow fine for smaller displacement and and lower rpm, but by 3500 rpm they're losing efficiency.)

Dual ports flow more up higher, between 3500 and 4000 rpm, but why is that? Is it the valves? They're the same as single port. Is it the internal head design? Maybe some. But to me it looks like it is the long, thin tube of an intake on top of everything that robs the most breathing capability. Am I missing something more obvious than that?

If I am on the right track, then my next statement would be that putting the massaged empi end castings on the heads (which will be lightly massaged too by the way) and and the considerably larger sizedual port center section with a 34 pict 3 would help this thing breathe very well for what it is that I am trying to do with it!

The thing is, will this engine provide the right vacuum signal for the 34 pict running the 043 SVDA?

I don't really see a reason why it shouldn't, seeing that the internals are the same as a dual port, only the heads are single port? What sez you fellas?

Worst case scenario I could always plop the 30/31 pict on there and throw a 205T vacuum only dizzy on there with an adapter and call it good or change the manifold, whatever.

So, what thinks the jury? Thanks to all who contribute to this thread!

[ozzo]

Few years ago i did a 1776 with single port 34pict3 with empi endcasting and bugpack single quiet. It was my daily driver on a t2. I liked it. If you want stock parts why replace crank and rods? I used stock with 90.5 pistons.

[FreeBug]

I know it's not what you want to hear, but you would be soooo much happier with dual 34 PDSITs on there, as far as driving is concerned. Sorry, had to say it.

Otherwise, sounds good, yes to quiet pack, yes to solid rocker shafts, double yes to the 74 mm crank. Smooth out the intake ports, give it good valve /seat job, custom length pushrods, and swivel feet. Intake idea will work, but seriously consider small duals.

If you keep the single carb, get one of the heat risers to join up with the exhaust manifold as close to the collector as possible, maybe even the warm-air intake on the stock late-model plastic airfilter.

[Frank Bassman]

Oh, yea I should have mentioned about the crank and rods... Well CB's crank is stock replacement, only it is counterweighted and balanced. My crank needs to be replaced anyways...

74 mm stroke puts me up to 1700 though. Seems appealing but I'm not sure it would do me many favors as far as gas mileage goes, which is important to me.

Same for my rods. They're in not the best of shape and rebuilding them would cost me the same price or more as CB's new set. So, it seemed like a sensible option to opt for the CB ones. I have not yet ordered parts... I'm waiting on comments here.

Thanks for the reply!

So, what distributor did you run with that intake and the 34 pict? It is really good to know it worked out by the way, thanks for sharing!

-Frank

[Frank Bassman]

Hey Freebug, thanks for the input as well, didn't see your post.

I will totally go to dual carbs eventually, because it is just the thing to do. Right now I cannot, but being a straightforward swap, I can always do that later!

How much do you think gas consumption will suffer with the added displacement though? Right now I'm hitting 27 city, and I hit 32 on the highway last weekend. Have been getting that consistently! Mind you, I drive sedately, and it IS a dual port, so there are some different nuances there which could tip the consumption up or down, I don't know which way though in my particular case!

Also, ozzo, do you know more or less how much power you were making on that motor as opposed to a stocker 1600?

-Frank

[ozzo]

Stock distributor correct for 34 pict3 vacuum and centrifugal advance 205 bosh.

I have a comparison in a 4th gear acecelaration on flat from 40 to 80 kmh where i m faster than a stock 1600 of 2 seconds.... but can t say if it is because of exhaust or displacement

[GTV]

IMO, mileage shouldn't suffer at all IF you drive it in a similar manner. It will take less throttle to make the same power at a given rpm.
My .02 on crank and rods, 69mm DPR welded counterweight crank and stock rebuilt rods. Nothing beats original German quality. Or a welded 74mm with 5.325" rods (to keep the engine stock width). Also have a stock flywheel lightened.
_________________
EMPI Power Rules!

[Frank Bassman]

Ok cool, so the distributor subject is a non issue. Schweet!

As far as crank size and vendor selection, here are my concerns.

Stock 69 mm makes everything very easy. Everything just sort of bolts up nicely.

74 mm would up my displacement a respectable amount for what I am doing. (still pretty conservative at 1700 cc's)

But it would entail clearancing of the piston skirts, and it would also widen up the engine some. (assuming those 5.4" CB rods, which seem very nice and are a good price too!)

Which would then involve potentially adding cylinder head shims to get the deck right.

And another thing is the custom pushrod length. I'd have to cut myself some custom length ones for the stroker wouldn't I?

What if I run 5.325" rods? Would I then be able to run the stock pushrods I already have? (They are used but in nice shape.)

As far as DPR vs a new CB crank... Any reason to not buy the CB one? It is a forged chrome-moly crank that is balanced and apparently counterweighted already. (I spoke with CB today about it.)

Not saying I'm not open to DPR, but since I'm buying so many parts from CB I figured why not get the crank from them too?

Thanks again!

-Frank

[GTV]

A 74mm crank with 5.325" rods will come out extremely close to stock width, mathematically only pushing the piston up .029" per side. You will want to tighten up the stock deck height anyway, so when it's all said and done with .040" deck you may not end up any wider at all. To get .040" on a stock build means you will have to trim the cylinders down.

I trust and prefer German cranks. Same goes with DPR.
_________________
EMPI Power Rules!

[Dr OnHolliday]

Your proposed build is similar to mine and will work fine.

However, bare dp heads outflow bare sp heads by a lot....not an issue with turbo tho
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1965 Type 1 sunroof Baja / about 70k miles on self-rebuilt '74 1600 and counting / SP heads and aftermarket valve keepers / non-doghouse shroud with external cooler and filter / 1.5 qt extended sump / Weber 32/36 DFAV progressive carb / 009 dist with Pertronix / 1.25 ratio rockers and ball adjusters / 1.5" stainless steel J-pipes and carbon steel baja exhaust

[modok]

[Alstrup]

VW 1600 single port stage 2.
Completely stock appearance.

69 x 85,5 mm. Fully balanced.
Stock 200 mm flywheel.
Stock clutch.
Rebuilt stock rods balanced +/- 0,5 gr.
CB 2280 camshaft, stock german lifters, stock pushrods cut to length.
26 mm shadek oil pump.
Sgl port cylinderheads, 35,5 x 32 mm. Ported to 30 mm inlet, guides shortened 6 mm. cut back on intake valves, 8,5-1 CR.
Rebuilt Bosch 205 SVDA distributor w. Ignitor module. Blue Bosch coil
34 mm PICT3 carburettor on CB center section. Empi sgl port end pieces.
Stock heater boxes, stock Ernst muffler. Stock ´68 Ghia 1500 air filter.
https://www.thesamba.com/vw/gallery/pix/1117015.jpg
If you will be using a better than stock exhaust system I can recommend to add 1,25 rockers on intake alone. It -will- cost a hairswith torque below 2800 rpm. if you use a 4-1 header, but it will add a little power and stretch the torque a little upwards from there to peak.
This particular engine got a TT std plus muffler (shorty header) http://exhausts.turbothomas.com/index.php/vw-exhau...er.htmland the 1,25 rockers on intake this spring. The shorty header makes the engine keep the power and torque down low, but after a slight rejet it now pulls 68 hp at 4500 rpm and the peak torque improved to 128 Nm at 3000 rpm. Plus that it, almost of course, runs cooler on the Autobahn, which was the primary reason for switching to a freer flowing muffler.

T

[VWCOOL]

Single port heads and single carbs do NOT give you better low-down torque than DP heads and dual carbs.. its just that these engines are so relatively weak up top that torque is the only thing the drivers notice

Save your money on aftermarket rods, crank and rockers (retain or find/use the stock stuff) and buy some DP heads and some Kadrons (for instance)

[FreeBug]

There's more to it than numbers on paper. Single ports (especially with dual carbs) seem to glide along in a way dual ports just don't. It's very intangible, but I totally understand those who want to "hop-up" a single port. I love them.

[Alstrup]

[Frank Bassman]

Well a lot of good info here! I'm doing my best to digest it all! First of all thanks!

Good to see that someone built a similar engine. Now at least I know I'm on the right track. Thanks Dr. Onholiday!

Modok- No, I'm not running a progressive, it must be someone else. (Maybe Dr. On Holiday?)
You make complete sense in what you pointed out about stock parts. I was vague when I described what I was going to use and, no, chinese does not mean stock. In my head I was thinking "stock replacement." So when I was looking around at the cost of rebuilding my stock rods vs buying them new, I saw CB's UNITECH rods at an affordable price and thought "these look like nice quality for my build..."


Same thought process went along with the crank. Since they have such good reputation, I figured a new CB crank "balanced, forged, blah, blah, blah..." would be sufficient and give reliable service for years in this particular engine. But I will give the guys at DPR a call and see if the price for a crank for me is in my range of possibilities.

NOTE: I am still debating the 74mm stroke 1700 vs the 69mm stroke 1584. If I go with the 74 mm stroke, I'd have to go CB because the DPR crank would be utterly out of my price range. If anyone's got experience with these CB 74mm cranks, please let me know if I can expect catastrophic failure or if I'd be ok running it! It will be a sensibly driven engine! (I doubt It would be a bad choice... but I have to ask!)

Perhaps I am jumping the gun, but from what I have heard CB performance is one of the leading vendors as far as parts quality and customer service, as well as having some specialized parts that are difficult to source elsewhere! (Did I miss something?)

As far as the lifters, they are stock, just from CB performance.
As far as rod length, well, all the 5.325" rods I find are an arm and a leg for me. I think I'll end up buying the UNITECH rods and be done with it.
Been reading about them in the forums on this site and I haven't found any cons YET. I am still reading

Alstrup, I've been bumping into some of your posts in other threads. Very interesting stuff you write!

Those specs on the Single Port Stage 2 1600 are very appealing. Very similar to what I had in mind! I'm just wondering what kind of shimming you had to do with the cylinders to set up your deck height, and what case you used! Though I do know that every case is different... hence the mock ups to actually figure out exact dimensions!

68 horsepower is very very respectable out of a 1600! And that torque figure is very nice as well! Those are the numbers I can use to compare mine when I get it dynoed. (Eventually...)

I know duals end up flowing better easier, but I have those single port heads, and after seeing someone fire up an old single 1500 the other day that had been sitting out in the rain for years, (after diss-assembly and cleaning of course) and hearing how nicely it ran, I decided I MUST build one with a twist!

I am ordering parts between now and mid-week next week. Still doing my research some more. Hopefully this thing will turn out to be as interesting as I picture it to be!

-Frank

[spencerfvee]

there was a guy I think he lived in Hawaii not sure he built a milage motor I think he got 50 mpg it was in hot vws mag . he used I think a 1300cc motor or maybe it was a 1500cc motor motor.1300 heads small valves . single port heads dual carbs heavy pulley 6 volt fly wheel that's more heavy than a 12 volt fly wheel I am sure others can tell you more about the motor than I can .. also CB built a milage motor its on there website they used dual port heads off of a fuel injection bug motor .all I can say is. I don't care much for china cast cranks . and there selling china cast rods now . .remember its easy to change heads and cyls. but a big pain in the ass to change a crank .all ways do the bottom end the right way the first time . just my two cents good luck with your build . I all ways liked single port heads for a street motor spencerfvee

[modok]

Gotcha. I hate the fact the chinese can recycle our junk into a new crank cheaper than we can fix one........... but that's how it is.

CB has maximum bang for buck ratio but they have sold a lot of junk too.
Cb will recommend the lightweight lifters with ALL their performance cams, so, I would recommend engle lifters instead.
Cranks from them are as good or better than the others(tho they do all kinda look the same).
There's really nothing wrong with the stock cranks either. below 4500 rpm you don't need counterweights!
A useable stock crank is only worth about 80$, so if you don't find one in the engine I'm sure we can get you another.
But......... you know you want to go 74 stroke!!!

You can replace the springy washers on the rocker shaft with solid ones and that's all you NEED to do. So instead buy some rocker shims and a HD gland nut!

[Alstrup]

Yeah. However, at that displacement I´d rather machine the case for more bore today. I have built my share of 1745´s, and while I do like them and they -do- have a tad more bottom end pull compared to a 1776, I think I´d take the 1776 today for its simplicity. Especially if the engine would be a "slow rever" as a sgl port typically is.
When the case is machined you can also get it decked. If the machinist knows what he is doing he can machine the case to the desired deck within approx 1/10 mm. That brings us to the OP´s question about how i got my deck height right. If the cases do not need machining I simply machine the cylinders to the desired length. Cylinders with stock 1600 pistons typically gets shaved by about 0,5 mm to get the deck down to 1,05 -1,2 mm max. (Some people claim that it doesnt matter, but IMHO it is paramount to get the burn as efficient as possible both to gain power, but also have a better burn/temperature control and finally a much cleaner emission when the engine is dialed in.)
I use bolted rocker shafts on anything other than stock cams. I also use Porsche style adjusters. Reason is that when it is all cuddled in place, - in lack of a better term, you get way less valve train noise - and better valve control. It all ads up

[ozzo]

I was using progressive on my 1776 single port.
I did some changes in the time on this engine and i made some comparison

Single quite pack compared to stock: you feel it more smooth on highway.... you really feel the difference and notice that stock chokes it.
Let s say it also goes 10 km/h more

Solex 34 stock venturi vs 28venturi: i should have played more with tune but i noted a little more top and felt some less power at bottom. This is especially driving on methane... on fuel the bottom lack was less noticed.

Progressive carb: probably double carb will be even better but because of the use of methane this carb is much easier.
With the change in exhaust you feel it more smooth, with the change in carb you feel it more strong.... it is like a boost you notice when second butterfly opens.

I would suggest this 2 hop up on any engine