100x71 Type 4 Build For Local Course Racing

[bugguy1967]

I have an ongoing 100 bore x 71 stroke build on STF. I chose to start it there because it's a valuable resource, and I don't want it to go away. It's here:

https://shoptalkforums.com/viewtopic.php?f=1&t=152009&sid=feaab525cc9f33940a95d6259663f734

I estimate the entire build will cost me about $4500, which isn't too bad for the power I'm aiming for.

I'll post updates from hereon out...

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"A petrol engine can start readily, run smoothly and give every appearance of being in good order, without necessarily being in good tune." - Colin Campbell, "The Sportscar Engine"

[Stripped66]

Impressive build; thanks for documenting the work and attention to detail!
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[bugguy1967]

Thanks Stripped! I have an older version of your engine as my screen saver 😅.

Think my #1 bearing's thrust interference is too tight, messing with the radial clearance. I need to investigate. It's not spinning as smoothly as I'd like. The bearing measured fine in the saddle.

Think I put this gear backwards 🤔. Thought that raised area was a built-in racer spacer....nope.

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"A petrol engine can start readily, run smoothly and give every appearance of being in good order, without necessarily being in good tune." - Colin Campbell, "The Sportscar Engine"

[bugguy1967]

Check Everything! The #4 exhaust valve hanging up on a casting bump after the thrust bearing:

Did some quick filing, and got some needed clearance. I'll do more later. Just need to do cam timing and see where my decks are.

_________________
"A petrol engine can start readily, run smoothly and give every appearance of being in good order, without necessarily being in good tune." - Colin Campbell, "The Sportscar Engine"

[bugguy1967]

JFats808 gave me this tool years ago: it's one of the best tools I have - just a stock lifter with a half pushrod epoxied in.

Case is closed up now.

_________________
"A petrol engine can start readily, run smoothly and give every appearance of being in good order, without necessarily being in good tune." - Colin Campbell, "The Sportscar Engine"

[bugguy1967]

Really good conversation so far guys!

Cut my 48 intakes down to 44. Manley doesn't have a single groove Type 4 valve smaller than 48 for the intake. It's pointless to have a 48mm intake valve unless you're up in the 280+ horsepower range. I'll clamp the barrels down and figure what I need to cut tomorrow. The offset side of the piston points to the top of 1 and 2, and down on 3 and 4, so the arrows need reversing for VW apps.

Really good news: a nice guy sent me some Pauter rockers. They may go on this. Not sure yet.

The lower head studs are shorter than the tops.

_________________
"A petrol engine can start readily, run smoothly and give every appearance of being in good order, without necessarily being in good tune." - Colin Campbell, "The Sportscar Engine"

[Clatter]

Ha!
I didn't put together that the other thread was you..

What is that pushrod tool? A way to measure lift?
Always did them in matched pairs to do 'split overlap' and verify cam timing.

I NEVER trust an arrow on the top of a piston anymore..
Those China AAs they just put it on for decoration.
Nobody ever told them what they were for..
Measure the pin offset and you'll see.


No wonder those lifter heads hit the cam.
They're from a different kind of motor!

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Bus Motor Build

What’s That Noise?!?

[Wreck]

those rockers are rarer than rocking horse poo .

[bugguy1967]

[bugguy1967]

[bugguy1967]

Pretty sure my LSA is 112° 😕. It's advertised as a 106°. May not be a bad thing though. I'ma do more investigating later. I want the majority of my power to be from about 4K-7.5K. You think 112 is fine?

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"A petrol engine can start readily, run smoothly and give every appearance of being in good order, without necessarily being in good tune." - Colin Campbell, "The Sportscar Engine"

[bj]

where did you get that pulley and hub from?

i got mine from Steel Buggin (if i remember right), but doesn't look like your pulley...the pockets on mine aren't machined out all the way.

BJ

[bugguy1967]

[bugguy1967]

With that Q cam, I'm around 290°@.050". I expected it was going to fall short, but was dead-on. Looking at a smaller cam around 275°, so I can run around 12.2:1 cr on 91, and peak at 7,500ish rpm. That Q wants to rev beyond 9,000 rpm.

Don't take those exhaust numbers to the bank. Measured fast with a small pulley.

Anybody know how to pop this sensor out without damaging it? Thinking the only way is to grind it and punch it out.

ARP flywheel bolts arrived

Measured dome volume. 100mm piston, .106" dome height, the flat portion was .250" down the hole - 44cc. If I'm not mistaken, that's 5.91cc.

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"A petrol engine can start readily, run smoothly and give every appearance of being in good order, without necessarily being in good tune." - Colin Campbell, "The Sportscar Engine"

[Wreck]

CB2300 . 274 @'0.050 . in open 31 BTDC close 63 ABDC , 0.428" lift at the cam .

or a Web 86C .

[bugguy1967]

[Wreck]

[Bad bug]

Bugguy1967, How much torque will you be putting on those flywheel bolts. I need a set for my oxyboxer, also are the liners you will be running birals.

What fluid did you use in your burette.

[bugguy1967]

[sweetlokin66]

Great thread - with that CR are you looking into e85?
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Turbo type 4
http://shoptalkforums.com/viewtopic.php?f=3&t=134157

66 NA hard top

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