76mm CB crank and 5.4 rods FK8 cam

[Mike Cott]

Hi, this is my first post on the forum, been reading through all the posts for months and found loads of great reading material.
I'm building an engine to go in my camper I have a 76mm CB forged crank with 5.5 CB unitech rods, will this combo work well and which B&Ps would suit ie 69mm or stroker? I'm having my case machined at the mo so trying get my head round what I need to order to get going. Any help is much appreciated and I know that people's views are all different and mostly valid but all from experience id imagine.
Cheers
Mike

[Zach Gomulka]

100% stroker.

[Mike Cott]

Just been reading up, stroker pistons should be close zero deck height too 😎
Are forged a must or would cast be ok?

[Zach Gomulka]

 I believe with large bore stroker pistons you'll only have a choice between hypereutectic and forged, for a low rpm camper engine the hyper's will be fine.

[nicolas]

both can work. personally i would use strokers. what i also would do is have the case machined where the barrels seat. that way you have a fresh flat surface to work with and it is easier if a shim would be needed to lower the CR.
as for the size of the pistons, i am still tempted to believe 90.5's will outlast 94's, but it can be used both, budget wise it is the same work and money.

[Mike Cott]

Hypers it is as I only travel around 800-1000 miles a year in her each year, the guy that is machining my case has suggested That he bores out to 90.5 and have 94mm barrels machined to fit this way the case doesn't need to be decked. I trust his judgment as he is a well known guy in the uk and has been building engines for customers for good while.
Cam choice is my next question, thinking an Engle w120 for this as they are readily available at a decent £ and have a good review on what this would be a 2109cc

Thanks for your input guys 👍🏻

[andy198712]

Hypers it is as I only travel around 800-1000 miles a year in her each year, the guy that is machining my case has suggested That he bores out to 90.5 and have 94mm barrels machined to fit this way the case doesn't need to be decked. I trust his judgment as he is a well known guy in the uk and has been building engines for customers for good while.
Cam choice is my next question, thinking an Engle w120 for this as they are readily available at a decent £ and have a good review on what this would be a 2109cc

Thanks for your input guys 👍🏻

i have a 2110 so 82x90.5 and have the 86B, i got it from stateside tuning in the uk, and find it great, loads of bottom end pull, idles fine, although i'm cheating with EFI. and can be had at about the same cost as the 120. although it really wants 1.4 rockers, so if you already have 1.1 rockers....

[Zach Gomulka]

My knee/jerk reaction is that's more cam than you want for a camper engine. What heads/carbs/exhaust?

[brian e]

I did a 76x92TW with B pistons and 5.5" rods. Ended up with I think a .010" spacer to make a perfect .045" deck.  I built it for an early bus with a straight axle conversion.  I used a set of Tims S1 heads and a fk7 cam, and 40mm IDF's.   It worked awesome, and was a near perfect daily driver engine.  Minimal case clearance work. 

A web 218 or a fk41 would also be good choices.  The new CB Panchito heads are awesome also. I did a 2234cc with a 218 and Panchito's. It also had great low end power.

Brian

[Zach Gomulka]

I did a 76x92TW with B pistons and 5.5" rods. Ended up with I think a .010" spacer to make a perfect .045" deck.  I built it for an early bus with a straight axle conversion.  I used a set of Tims S1 heads and a fk7 cam, and 40mm IDF's.   It worked awesome, and was a near perfect daily driver engine.  Minimal case clearance work. 

A web 218 or a fk41 would also be good choices.  The new CB Panchito heads are awesome also. I did a 2234cc with a 218 and Panchito's. It also had great low end power.

Brian

Yeah, that's what I'm thinking. 218 and Panchito's. Make the power where you'll use it.

[Mike Cott]

I've not purchased anything else just yet so not limited by certain parts ie carbs or heads. I'd struggle to find anyone who supplies webcam cams in the uk, although they look a good cam for low end torque so the fk7 is a great call and I could get my hands on one of those easy enough, which ratio rockers tho?   Panchitos look the business also, good flowing heads with 44s?

[andy198712]

http://www.rjvolksperformance.com/engine-parts.html

scroll down there, he has most cams, FK's and web ect

[Mike Cott]

That's a great website, thanks sells quite a lot of top quality great. Do you know of anymore sites like this besides the usual heritage etc

[Mike Cott]

Just took a look at the rods I have and the box has 5.4 on it not 5.5 as I thought 🙄 How check this ?
So I could use the 69mm B&Ps now?

[brian e]

Just took a look at the rods I have and the box has 5.4 on it not 5.5 as I thought 🙄 How check this ?
So I could use the 69mm B&Ps now?

With the taller A pistons, you will end up with tall spacers and a wide engine.  If it is close between using an A or a B, I always go with the B style.  They usually have the shorter skirt, shorter pin height, and lighter weight.  All good things to have in a piston.  If you use the 5.4 rods, you will need to get the case decked or the barrels trimmed to get the deck down.  This is nice because you can dial the deck to exactly what you want, and the engine will be narrower then stock, but it adds extra cost, and you might need to trim the piston skirts to keep them from hitting the crank cheeks.     

I did like both the 218 and the FK7, and both Tims and Panchito's heads.  If your bus is light and you prefer a little more zippy of an engine, I would probably pick the FK7.  For a heavy bus with more low end, the 218.  The Tims heads are about $150-200 cheaper once the Panchito's have the options you need.  Both will work good.  The 218 can use stock rockers, and the FK7 will need ratio rockers.  I would shoot for about .500"-.520" lift with the FK7.

I think you could use 40mm IDF's w/ 32mm vent's, and a 1 1/2" header. 

Brian

[DWL_Puavo]

I've got 76x90,5 B stroker pistons, mildly ported 1600 heads with 37mm inlet valves. I made the engine with W100 and now 1,25 rockers, dual 36 dells (30 venturies) and 8.6:1 static compression, deck height is 1,1mm. Stock 1600 rods. Now it's driven for a few thousand km's without any problems, but would definitely up the cam a bit, maybe to W110 or equivalent. It's very civilised dynoed 100hp / 5200rpm engine that's easy to drive and pulls my -72 doppelkabiner just fine.

With stock rods I had to deck the engine case a bit to get the deck height I wanted. Then had to file head bolts a bit so that they didn't touch the rockers. And I had to shorten the stock alu pushrods for about 1cm to get ideal rocker geometry. Empi/bugpack/general exhaust header fits without excess force. Air deflector plates on the top of heads also fitted just about as tight as they can be, and same can be said for the stock pushrod tubes. So altogether quite a lot of small modifications but all quite simple and easy to do yourself. Also about all of them of the sort you really can't measure beforehands

[Zach Gomulka]

I'd swap the crank for an 82mm.

[Torben Alstrup]

I'd swap the crank for an 82mm.

I would not! 76-78,4 stroke is great for campers.

T

[Zach Gomulka]

I'd swap the crank for an 82mm.

I would not! 76-78,4 stroke is great for campers.

T

Yeah but the 5.4's with a 76 is just a bit of a pain.

[Mike Cott]

In what way Zach? Setting up the spacing on the cylinders for the deck height

[Zach Gomulka]

In what way Zach? Setting up the spacing on the cylinders for the deck height

Stroker pistons also have shorter skirts to clear the crank/opposing rod cap at BDC, expect to have to do clearancing there. You'll need roughly .140" of spacers, which makes tins fit terrible. It can be done but it's more work. I'm just not a fan of wide engines. Or overly narrow engines, either. There are many combos that are easy to build and end up very near stock width, why make it more difficult?

[modnrod]

To the OP.......
I have some Isuzu pistons (why? Uhhmmm, yeah, well.....never mind  ) to go with my 76mm crank and stock 5.394" rods. They have a 36.6mm pin height, and so when all mocked up I have a 0.040" deck height. Perfect for most.
If I had the stock VW pin height (39.6mm), then they would stick out the tops of the cylinders by 2mm, so I need to add 3mm somewhere to make it all fit.
If I had the "B" VW pin height (35mm) then they will sit 2.6mm down the cylinders, so I either need to machine the cases or each cylinder by 1.6mm to make it all work.
This is why Zach is saying they are a pain.

The easiest way to get it all going, since you are still collecting parts, and without spending a heap of money (because large VW parts like crankshafts outside of the US cost at least twice as much), is to front up for some new rods, and yes, "I" beams will do the job perfectly well, no need for "race rods" here. If you already have the stock height "A" pistons, then get some 5.325" length rods, throw some thin shims under the cylinders and you're done.
The other option if you have "B" pistons, is to front up for some 5.500" rods and bolt it all up.

My personal pick would be a 76 x 92 thick wall, with some of CBs new Panchitos or plain 049s with good seat cuts, whatever cam you like around 280/240, and whatever exhaust sounds the best to you..........but that's just my preference, yours will be different of course.
It will be a nice cruiser when done, you'll be happy.  

PS: I just read Zachs post, but put it up anyway.

[Zach Gomulka]

If you already have the stock height "A" pistons, then get some 5.325" length rods, throw some thin shims under the cylinders and you're done.

The other option if you have "B" pistons, is to front up for some 5.500" rods and bolt it all up.

The first option gives a lower (better) rod ratio, but the short rods will give you even more piston skirt clearance issues. The short rods are lighter but the A pistons are heavy. You'll still need .060"-070" spacers (mathematically speaking), which is acceptable.

The second choice has a higher, less than ideal rod ratio, uses lighter B pistons but longer, heavier rods. It will come out very, very close to stock width and be an easier engine to build. It is the better choice, IMO.

[Mike Cott]

The options I have are

1; use the 5.4s I have now and shim the barrels for the A pistons
2; swap out the 5.4 and get a longer set then machine the  B  barrels to suit

Just to keep things simple in my head of what to do for the best ie; engine width and machining costs. Options 1&2 have implications on what barrels and pistons I use.

Remember I have the 5.4s not 5.5s I first thought when I started the thread and I DONT have any barrel and pistons yet

As you can tell I'm a novice at this 😃

[brian e]

Build this.  It will work awesome.

76 crank
5.5 I beam rods
AA 92mm TW " B" p&c's.
CB Panchito heads with CNC chambers, bored for 94's, single springs.
Web 218 w/ stock rockers on solid shafts, elephant foot adjusters
HD Aluminum push rods
8.5--9cr, w/.040" deck
40mm IDF's w/32mm vents, CB offset linkage and manifolds.  Make sure the manifolds are ported!!
1 1/2" sidewinder header
case machined for full flow.  26mm aluminum pump, steel FF pump cover. 
HD 200mm pressure plate, Daiken super disk

There will be minimal case clearance work, and the deck should set up with minimal shims.  You could use Tims Stage 1 heads also.  I have had both on the flow bench, and they are really close.  The CB's are slightly smaller ports, with a couple CFM more.  Both run awesome. 

You should be able to sell your 5.4 rods pretty easy. 

Brian

[Mike Cott]

Ok so since last post I may have purchased something that potentially will be a little bit of fun so the engine may take a different route

[Mike Cott]

Update on parts I have so far

76mm  CB CRANK
Case is machined 94mm full flow
CB 5.4 uni rods
FK8 cam
30mm shadek pump

So I need lifters, heads, B&P's and carbs ignition etc
I'm looking to go drag racing with the rail once I've got the parts together and built up, thinking
48 Ida's
Steve tims stage 2 heads
Not sure on the ignition side of things, but that will be a while till that comes into play

[Zach Gomulka]

Sell those 5.4's and pick up some 5.5's with stroker B pistons. It will make your life easier. FK8 and stage 2's will work great. You'll need 1.4:1 rockers as well.

[Mike Cott]

Zach, do you mean with regards to setting up the deck height??
The case is having to be spot faced as they're worn a little round the barrel seat, would my machine man be able to set the deck height if he knows what is going in it ie crank and rods etc?
Yep 1:4 rockers are a given, as for the heads Steve Tims are great value for a quality head I just need them sending across which Is playing with the what if they have an issue the after sales would be an issue being across the pond

[Zach Gomulka]

Zach, do you mean with regards to setting up the deck height??
The case is having to be spot faced as they're worn a little round the barrel seat, would my machine man be able to set the deck height if he knows what is going in it ie crank and rods etc?

You're really fighting this switch to longer rods, aren't you? 

No. Why would you remove material/strength that you don't have to? You could machine the decks deeper to correct for deck height but you would have to mock the engine up first and take actual measurements, don't just use maths. IMO that will also effectively ruin the case for the next time it gets built/upgraded.

I could keep going on and on about this but it looks like you're going to do it your way. I'm not saying it can't be done but you're certainly making it harder on yourself.