A&A Piston Durability

[rick m]

Larger venturi was the first mod.

RM

[rick m]

Here is a short video of us breaking in the 1915 bus motor cam. It has oiling mods that ensure 45+ lbs of continuous oil pressure. The motor never got over 175 degrees during the break in. The 34 Pict is modified for 10% better air flow to work better with the modified dual port heads. Heads are open chamber hemi design with un-schrouded valves, modified exhaust ports, stock cam modified to use a bolt on cam gear, 1.25 rockers, aluminum push rods, EMPI I Beam rods, electronic distributor, and aftermarket exhaust. The motor is now in it's Bay Window bus home doing some road trips to get 500 miles of break in on the motor.  It will be leaving with the owner back to Reno, Nevada, later in the month.

 http://youtu.be/icR41tdK2co

Rick Mortensen

[Zach Gomulka]

Good news Rick. Should be a great motor. What did you settle on for CR?

[Frenchy Dehoux]

 
    Rick what size main jet did you have in the carb. And idle jet. And where did you have the total timing set at.

Thank
Frenchy

[Cheesepanzer]

Can you please describe the carb mods?

I can't recall which month/year exactly, but I believe it was Hot VW's that had a feature in the 1979-1981 time frame that showed how to modify your solex carb for more flow.  (It might have been Trends, but I thought it was Hot VW's.)  I fooled around with a PICT 30 carb using the tips in the article and definitely noticed improved performance.  As I recall, basically think "porting" and smoothing out of the rough edges where air flow occurs from top to bottom.  One mod was removing the choke.  The other was filling in an aluminum "botton" with JB Weld.  Smooth out the screws on the butterfly.  And if you choose, open the venturi up.  You'll need to adjust jetting (I went up a couple of sized in the main jet as I recall).

Hope that helps.

[rick m]

Frenchy,

Enlarged the venturi to 1.10 from the stock 1.0".  We tried different jets but landed on 150 main, 85 Air Correction and 85 idle.  It liked the bigger idle jet and really smoothed it out from the idle circut to the main jet circut  We used the stock settings on the two adjustments on the left of the carb....about 2 1/2" turns on the small adjustment screw and 2 1/2 to 3 turns on the larger screw.  Idles nice, runs incredibly smooth through the whole rpm range.  We did not have to adjust the throttle plate way out to get it to run well.  I left the butterfly in the carb with the holes to give it a little air on the idle which helped not having to screw open the throttle arm for the air at idle.  Compression ended up at 7.4 to 1 with the open chamber heads.  I think we ended up at 64cc.  I had Mike Fischer flycut them and we started at 59cc ending up at 64cc after my chamber modifications.

We set the timing at 5 degrees before TDC at idle.  It is about 34 degrees at full advance (around 3200-3400 rpms).  Just a note.  The owner supplied CHINESE 009's with unknown electronic module went away before 100 miles on the road.  We pulled it out and put in an older 009 and pertronix.  This is one of my first rounds with the CHINESE crap (ignitions) and I would NEVER run one on my own personal car.

Never read the HVW article.  Just did what makes sense to get the carb to run well with a larger motor.  I will shoot some shots of it running in the bus next time it is over.  It sounds really healthy for a stock carb being used. We had it up to 80mph on a road trip up to Wickenburg. Did not even slow down on the little grades.  Ran smooth as glass throughout all rpm ranges and gears.  Made me want to duplicate the motor for my wifes play buggy.

The next motor build will be my wife's 1915cc engine with ported heads, mild cam, typical off road exhaust and goodies.  Will post shots when we get it done and on the engine stand for cam break in and miscellaneous jetting & tuning adjustments.

Rick M

[modnrod]

I just love these engines Rick, they are a ripper little mild streeter engine set up, and I think the modded Solex carbs suit them best. They start first pop, great economy, heaps of grunt off idle, really SMOOTH and about 30%+ more power from stock (with stock capacity). I call them Superstockers, coz there's no way something that looks and idles stock should have anywhere near that much stick! 
Definately not for everyone though, they won't run mid-14s for sure.

Just one question, about your heads (and no, it won't lead to the usual crap about semi-hemi's........). What deck height did you use with this set-up? I assume you used the AA stock flat tops?

Are there any "special" tricks or guidelines (like % of squish band left or distance to cylinder wall remnant, concave/convex/flat machining angles, etc) when you do your heads?
(apart from what's in your thread).

[rick m]

ModnRod,

Nothing real special on this set of heads. Deck ended up .058 .  Ran flat tops in this motor since we ran a stock cam and the total lift is around .360 with the 1.25s.  Besides the open chamber and unschrouded valves I did some exhaust port work since that is primarily where the stock dual port needs help. Polished the chambers (not a shiny polish) to eliminate all sharp edges and potential detonation spots.  When I get a short video of the motor in the bus, I will post it. The 1915 with the combo we used is very responsive and has great bottom end and cruising power.  Runs smooth as silk!

I am building a couple more motors with some different mods on the heads.

My next personal motor is a 90.5 x 84.  I am using REVMASTER heads (best castings I have ever seen). Great mods to the heads to ensure the torque stays true the way they casted the combustion chamber support and upper (outer) stud bosses.  Will do a host of mods to these heads and run an even tighter and true "0" deck to the head/combustion chamber. Piston mods done for clearance and squish. Will not run a big cam in this combo either but will have some very nice heads but only 40mm x 35.5 valves.  Will post progress shots and engine stand time when we do that motor too.

Rick M

[modnrod]

Thanks Rick, looking forward to the write-ups.
Regards,
Dave

[j-f]

There is a tech article in a French VW tech magazine about modifying the stock 34PICT. They remove the venturi and add a "fuel centering tube", manifold is an Hi flo from CB. They even modified them for turbo application with very good results.

[andy198712]

whats the oil mod you mentioned in the video description if you dont mind sharing?

[Cheesepanzer]

Can you please describe the carb mods?

I can't recall which month/year exactly, but I believe it was Hot VW's that had a feature in the 1979-1981 time frame that showed how to modify your solex carb for more flow.  (It might have been Trends, but I thought it was Hot VW's.)  I fooled around with a PICT 30 carb using the tips in the article and definitely noticed improved performance.  As I recall, basically think "porting" and smoothing out of the rough edges where air flow occurs from top to bottom.  One mod was removing the choke.  The other was filling in an aluminum "botton" with JB Weld.  Smooth out the screws on the butterfly.  And if you choose, open the venturi up.  You'll need to adjust jetting (I went up a couple of sized in the main jet as I recall).

Hope that helps.

Found it!  In case anyone wanted to check out the carb mods article:  Hot VW's - May 1980