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GüteAndTite
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 Posted: Tue Oct 04, 2011 12:29 am Post subject: |
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| Bluemanx212 wrote: |  If you put in a real cam you will hit the rod and that looks like a stock or worn one with not much lift! That is one of the reasons why people are wanting to use some type of ratio rocker to get more lift! Use a piston in a cylinder to see where the rod actually is when you turn it overas well. |
I didnt post that pic, but I will myself most likely being using the high lift cam from joe ruiz, im fine with shaving the caps as necessary. i realize that 74mm is the limit! ive heard of guys using 86mm custom pistons with porsche 86mm cylinders, but that seems like it requires moving the studs and welding and what not- a little farther than i think necessary.
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engineerscott
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Joined: August 22, 2005
Posts: 448
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| Posted: Wed Oct 05, 2011 8:12 am Post subject: |
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| Mr. Motorhead wrote: |
Converted 83mm cylinders
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Are there any overheating issues associated with cutting away that much of the fin area from the 40HP Big Bore cylinders? Have you measured the head or cylinder temperature? Did you cut the fins by hand (dremel?) or did you put it on an end mill?
Thanks, |
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Mr. Motorhead
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Joined: January 06, 2004
Posts: 538
Location: Practitioner of 36hp alchemy
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| Posted: Wed Oct 05, 2011 9:07 am Post subject: |
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| engineerscott wrote: | | Mr. Motorhead wrote: |
Converted 83mm cylinders
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Are there any overheating issues associated with cutting away that much of the fin area from the 40HP Big Bore cylinders? Have you measured the head or cylinder temperature? Did you cut the fins by hand (dremel?) or did you put it on an end mill?
Thanks, |
Ball endmill was used to clean out the stud slots, 9" sanding disc on my belt sander using an zirconia-alumina abrasive was used to shape the fins. Die grinder is used to knife edge and finish the fins. I have not been able to get a CHT over 330 degrees F (my highest at Bonneville), been running around town at about 315 degrees F. Head temps checked on all four cylinders at the plug with a thermal couple and a Tgam to double check the VDO guage (within 3% +/-) Static compression is at 8.9/1. Runs cold blooded as you would expect a 36hp to do. No sump, no extra cooler, 170 degree oil temp at its hottest run on a 100 degree day a couple weeks back.
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engineerscott
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| Posted: Thu Oct 06, 2011 8:06 am Post subject: |
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| That's some fine work you did on sculpting the fins. Looks like a stock cylinder pretty much. I should have known that cylinder/cylinder head temps wouldn't be too much of an issue, it is only a modest increase in displacement. I'm just used to 40HP cylinders that have a lot more fin area, seeing it cut back to the contours of a 36HP cylinder is just a little startling. |
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Mr. Okrasa 
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Location: Newport Heights, Califa.
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| Posted: Fri Oct 07, 2011 7:31 pm Post subject: |
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I have been experimenting with 912 Porsche biral (aluminum fins / iron liner) cylinders with success. While these cylinders are NOT recommended for use in racing
applications in a Porsche car, they work great in a VW application. The biggest bore here would be 83.50mm. Since they require alot of machinework,
they are not for everybody. Enjoy. Mr. Okrasa
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1950 Split Window 356 Coupe / #5369 / Adria Blue Metallic
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gimmesomeshelter
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| Posted: Sat Oct 08, 2011 2:15 pm Post subject: |
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Hello-
Here's a pic of a 36HP case with a 912 crank installed.
In the background you can see the mods that were required to fit the late model 356 bearings into an early case.
Cheers,
Paul |
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GüteAndTite
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Mr. Motorhead
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Joined: January 06, 2004
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Location: Practitioner of 36hp alchemy
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| Posted: Sat Oct 08, 2011 11:07 pm Post subject: |
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| guteandtite wrote: | | gimmesomeshelter wrote: | Hello-
Here's a pic of a 36HP case with a 912 crank installed.
In the background you can see the mods that were required to fit the late model 356 bearings into an early case.
Cheers,
Paul |
Is the flywheel end of the crank different than the 36hp?
Can the 36hp flywheel just be bolted up? Or what is the difference here? |
Drill four more dowel pin holes, flywheel bolts right on.
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30 years experience in the sales of new and used auto parts!
36 horsepower parts for sale at http://www.aircooledresearch.com/
Or the new site at http://www.bugparts.com
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http://aircooledresearch.com/docs/donate.html
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GTV
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| Posted: Sun Oct 09, 2011 7:05 am Post subject: |
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How long are stock 36hp rods?
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grueni
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| Posted: Sun Oct 09, 2011 11:13 am Post subject: |
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| GTV wrote: | | How long are stock 36hp rods? |
130mm
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GTV
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| Posted: Sun Oct 09, 2011 11:15 am Post subject: |
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Thanks! Doing some rod ratio calculations...
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GüteAndTite
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GTV
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| Posted: Sun Oct 09, 2011 12:28 pm Post subject: |
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Corrections welcome... 356/912 rods are 136mm. Chevy journal rods for VW's are available from 5.325" to 5.8".
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GüteAndTite
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| Posted: Sun Oct 09, 2011 12:46 pm Post subject: |
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| guteandtite wrote: | | grueni wrote: | | GTV wrote: | | How long are stock 36hp rods? |
130mm |
What are the lengths on these rods:
VW 36hp: 130 mm
Porsche 356: 136mm
Porsche 912: 136 mm
Chevy: 135.25mm to 147.32mm ( 5.325" to 5.8") |
Of the above rods, which is best or which must be used with a 74mm crank?
a 74mm crank increases the outward travel of the piston toward the head 5mm, plus with porsche rods it becomes 11mm. The engine becomes 22mm wider total if you shim the cylinders out to keep the pistons from going out to far past the cylinder and hitting the heads. Do I have this right?
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GTV
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| Posted: Sun Oct 09, 2011 12:55 pm Post subject: |
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Yes... If the same pistons are used. I don't know about 36hp engines, but with a later 1600 you can get stroker pistons that have a .220" (5.5mm) higher pin height to keep the width down.
I imagine that the stock 130mm rods are perfectly adequate as long as they are rebuilt/balanced properly and have good bolts. When used with a 74 crank you bring the rod ratio down from 2.03 to 1.75... As long as the skirts clear the crank it should work(?).
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GüteAndTite
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GüteAndTite
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| Posted: Sun Oct 09, 2011 3:09 pm Post subject: |
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| GTV wrote: | Yes... If the same pistons are used. I don't know about 36hp engines, but with a later 1600 you can get stroker pistons that have a .220" (5.5mm) higher pin height to keep the width down.
I imagine that the stock 130mm rods are perfectly adequate as long as they are rebuilt/balanced properly and have good bolts. When used with a 74 crank you bring the rod ratio down from 2.03 to 1.75... As long as the skirts clear the crank it should work(?). |
well with vw rods, and a 74mm crank, the pistons would have to be shaved down 5mm, which is a lot, i wonder, what is a reasonable thickness cylinder spacer to put between the cylinder the case or the cylinder and the head? can you do 5mm ? or will that totally jack the valve train geometry? whats the most that could be done with a spacer and also the most that can be safely shaved off the piston top?
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Official 58-60 "Early Big Window" Convertible Thread & Registry
http://www.thesamba.com/vw/forum/viewtopic.php?t=426481
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http://www.thesamba.com/vw/forum/viewtopic.php?t=462533
61-67 Delanair Air conditioning Thread
http://www.thesamba.com/vw/forum/viewtopic.php?t=457944&highlight=air+conditioning |
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gimmesomeshelter
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| Posted: Sun Oct 09, 2011 9:12 pm Post subject: |
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Hello-
| Quote: | | Point out what you did to the case? |
1) Machine oil groove into 2# & 3# bearing saddles (the bearings aren't thick enough to contain the oil grooves themselves, so they have to be moved to the bearing saddles).
2) Machine tab slot into 2# & 3# bearing saddles (the bearings aren't thick enough to be held by a pin, so slots to hold the tangs need to be added.)
Paul |
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GüteAndTite
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