After enough work, patience and trying various different solutions, I have given up on trying to make the Holley Carb setup work on this car for autocrossing.  I got it where it could go straight very well but not around corners so it is going away.

THE SOLUTION TO THE HOLLEY: GO WEBER!

I've ordered a wrap-over intake manifold from Atkins and a Weber 48 DCO from Webersdirect to put on the car and get away from spending so much time getting the drivability needed for autocrossing.  We might (but I doubt it) lose a bit on the hill climbs as I think the Holley might make more top end power, but is not worth it given the crapping out it does on every corner.

Intake manifold got here...casting isn't  very good and there are no vacuum ports in it at all, so I've port matched the manifold to a certain extent, opened up the bolt holes so it will mount, modified the manifold gasket as the manifold has blended both the 5th and 6th ports with the end housing ports...this will require some port matching later when the engine is done and blending the two ports at the bridge between them for better intake flow.

So far, this is where I'm at:

Carb should be here tomorrow.  I'll have to figure out what to do for linkage, not sure what velocity stacks come with it, if any, sort an air cleaner and re-route the fuel supply and return hoses.  Should be ready to run this weekend and I should get a good idea how it seems then.

I've ordered different jets, needle and so forth to have a better base-line from which to tune the car. 

Hopefully, we'll have some time to get it on the dyno to tune it before running toward the end of September.

Carb came on Thursday...couldn't find any linkage setup that would work connecting the stock throttle cable so had to make my own.  This is where I'm at today.  I've moved the fuel pressure regulator to the firewall...drilled and tapped the intake manifold for the brake-booster and vacuum fitting for the fuel pressure regulator...made the linkage bracket (looks simple but took some doing, belive me!) and hooked up the linkage similarly to how the Holley worked.

The carb didn't fit on the manifold (like the manifold didn't fit on the engine...very poor quality manifold work!) but I was able to "pursuade" it by enlarging the holes a bit and "relieving" the carb throttle bodies a bit where the nuts and washers are supposed to go.  I've set this up to be "soft mounted" with "O" rings and spacer...have those and hope everything will fit when all is said and done.  I will have to do some "customizing" of the mount washers (they're too big in diameter to fit) and have ordered some small head AN aircraft locknuts to fit the studs. (the studs that came with the carb are metric...the holes drilled in the manifold are SAE, so nothing fits as it is supposed to without some special fabrication of some sort.  I ended up using the studs that came with the Holley as they are SAE but 5/16-18 to fit the manifold and 5/16-24 to bolt the carb down and fortunately, they make the 5/16-24 aircraft nuts (AN-5 I think) that should give me the clearance needed.  They use a 3/8" wrench instead of 1/2" and are flange head with .520" diameter flanges on them...so should work. 

This is where I'm at so far. 

I've ordered fittings and 3/8" hose to do a new fuel return line.  The stock one was 6mm and far too small to be of much use at this volume of fuel so this should help with the fuel pressure regulation.  From the looks of it, the small return line is what they used to regulate the fuel pressure...who knows.

So far, I've not found an adequate air-cleaner solution so for now, won't run one.  I ordered the screens that attach to the velocity stacks but according to Bob, they really restrict the inlet.  I will probably not use them unless testing on the dyno and finding otherwise.  The only other solution I can see is going to shorter velocity stacks (not cheap but they do make 35mm tall ones (v. 60mm ones that are on the carb now) then the K&N filter will work...otherwsie, I won't use it as it is less than an inch from the velocity stack to the end plate of the air-cleaner and this can't possibly be good for air-flow (in my mind anyway).

Well, it runs now.  Final parts came from Pegasus today.  Took the usual amount of “customization”.  There was a lot of fuel dumping out the intake when first turning on the fuel pumps…not sure what that was about but seems to have stopped.  Idle isn’t that great but tolerable…kind of like having a long duration cam in the car. This was expected being there is no isolation between the middle and end housing ports.  The sixth ports have a lot of overlap (close very late) so no wonder.  The Holley had primaries and secondaries that dealt with that issue but we shall see if it matters at all. Had some interesting stuff go on during fire up but seems to be ok now.  Car will bog badly on full throttle from an idle but doesn’t seem to have any crapping out like I experienced when revving it statically with the Holley and from middle to higher rpm, seems ok so far.  Has a lot of “stand-off” if giving it throttle…might be a fire hazard without an air cleaner so will look into that in due course.  Still don’t know what to set the float level at…no information anywhere on these floats for this carb. 

Will see if I can get some dyno time before running the end of the month at Marina.

We had a good session tuning the RX-7 over at Bob’s on Saturday.   Did quite a few “tweaks” to the carb including larger accelerator pump jets, longer stroke accelerator pump rod, different accelerator pump bypass/exhaust jet.  We didn’t change the mains and air-correction jets I had previously installed but did replace the needle and seat with the one that came with the carb due to the new one I put in was poorly made and had some chatters in the drilling causing it to leak…exhibit the lack of quality in after-market parts.

Bob installed his UEGO and checked A/F ratios which seem to be in the ball park and drove the car on a few test runs checking same.  His input was VERY positive saying it is a huge improvement over the Holley.

Interestingly, I sourced online an article on some dyno work that was done comparing some after-market throttle bodies to a Dellorto side draft (assuming it is the typical 48 on the top half wrap around on stock half bottom manifold) and to the Holley.  What the results showed was that both the fuel injection and Holley produced more power at maximum rpm, in the middle the Dellorto out performed both the others by quite a bit.  The cross over for the throttle bodies was at 6500-6700 rpm, for the Holley was about 7200 rpm.  At 6500 the Dellorto put out what appears to be about 15-20 hp more than the Holley though which tapers down to around 5500 rpm where they appear to both make about the same.  The difference is less between the Dellorto and the throttle bodies though showing what appears to be about an average of maybe 10 hp more for the Dellorto from about 4700 rpm up to the cross over, which is rather abrupt at 6500 rpm at which time the throttle bodies continue to approve and from about 7000 rpm on appears to make about 15 hp more than the Dellorto.  The most it appears the Holley makes more than the Dellorto is around 10 hp at 8000…we don’t go much beyond that so where the Dellorto falls off at about 8300 is relatively meaningless.  Further, I think our 40 Weber DCO and the one piece wrap over manifold will produce better results than the Dellorto and the manifold they used…just a guess although probably wouldn’t be much.  All in all, an interesting report even if on a “street ported” engine (ours is stock and will produce quite a bit less in the power department…not sure how that would affect the differences but one would think it would be relative).

The drivability is more important than the power…it will be interesting to see how it goes around corners...hopefully without crapping out like the Holley which was impossible in that regard...went in a straight line well but we go around corners.

Ran very well...BIG improvement in drivability.  Still needs further tweaking and of course we still have the other mods that need to be done including aluminum flywheel (have now...need to install with new clutch); transmission with synchros that work (we'll replace the trans at the same time we install the flywheel...we've got two spares but not sure what condition they're in); LSD needs rebuilding so it actually limits the slip...

We just ran AAS in Santa Clara and the car was REAL good but we did cord one of the front tires so they are shot.  The Hoosiers lasted half as long as the Kumhos and cost 25% more so we'll be going back to the Kumhos...the Kumhos feel better too and we seem to be better able to find the appropriate tire pressures, have less rubber and rock pick up so less maintenance as well.  From a per run standpoint...it appears the Hoosiers are almost 3 times the cost over the Kumhos too.  We'll get a new set just before next season and will rotate the Hoosiers on the rims to finish out the couple of events left this year.

I just purchased an aluminum flywheel and corresponding stock-size clutch and anticipated putting them in along with one of the spare gear-boxes to see if we have one with synchros that work.  I know we've got two more spares but will try the one out of the car to see if it is good or not...need to know one way or the other.  Aluminum flywheel will save aobut 10# over the stock setup but inertia will be further enhanced by the 4# counterweight being more toward the centerline of the eccentric shaft so I'm looking at having a lot better acceleration with this setup.  We'll also try yet a larger accelerator pump nozzle as we're already bigger than the largest made so we'll drill a pair to see if we can continue improving the Weber brief flat-spot (car now backfires like a bitch on deceleration too!).  So far, I'm real pleased with everything we've done (except for the Holley but mistakes will be made).  Car is fun to drive, handles very well, needs more grip but overall happy with the balance and drivability improvements made.

Bob stepped up to the plate and did the aluminum flywheel install.  Had some "issues" with throw-out bearing clearance.  Found out the pressure plate sent with the flywheel was thicker at the fingers than it should have been so it wouldn't work.  We decided to use the stock pressure plate we had which looked fairly new when we put it on so I'll have to see if I can send back the higher capacity pressure plate for a refund.  So got the motor in with the replacement spare transmission I got with the Spec RX7 car.  Found out it was a later model transmission like the others we have and is longer than the early 1st gen in the car.  This means we had to cut the transmission tunnel to fit it into the car but a good modification to do given the better availability of the later transmissions and the fact we have two others in case this one turns out to not be a good one.  Also found the new transmisson mount raised the back of the transmission jsut a little so we had a few (and still have) exhaust clearance problems.  We'll also have to figure out how to fabricate a new transmission to tunnel boot setup.  I ordered from Summit a Hurst generic part as well as a Nomex outer boot...will replace the on-transmission boot as well so there should be three total once done.  Bob will work on the fabrication before we run the car hopefully Sunday in Oakland.  He did test drive the car around the neighborhood (at Bob's...neighbors must be annoyed) and said it seemed good...transmission seems to have synchros so far and it certainly seems to rev quicker as it should with 10# less rotating mass on the flywheel! 

I'm hoping to make one more season on this engine which smokes badly.  We identified it having a "weak" rotor (#2) when we got it but doesn't use all that much oil.  So, hopefully, we can sort all the other issues next season then do the engine in the 2011 off-season and then the car should be good for at least 10 seasons with just maintenance and whatever we might break.  We shall see. 

Ran the first event with the new flywheel.  Bob was the only one that drove and got 1st place in CSP.  Had traction problems on the slick surface and worn-out tires but still did well enough.  Was only a bit over 2 seconds slower than the overall fastest car out of 142.

The LSD was re-packed with thicker plates before the last event.  Due to my having back surgery in December 2010, I still haven't driven since (since Oct. 2010) putting in the new aluminum flywheel, replaced transmission with synchros that work and now with an LSD that should work a lot better.  Our tires were shot but last time out in February (Boondoggle) Bob said it was fine, no suggested adjustments...didn't sound like it crapped out on hard cornering (I came to the conclusion that our cutting out problem on cornering was related to the pickup in the stock tank not picking up under hard cornering with low fuel so we'll be running with about 1/2 tank from now on.

Finally ordered and received a new set of Hoosiers but decided to go narrower to the 225/50-13 instead of the 255/45-13 we were previously running.  They wore funny (the Kumhos wore perfectly but I didn't want to put 2005 manufactured tires on the car which are the ones Tire Rack is still selling) and I couldn't get a good handle on the tire pressures (typical problems I've always seemed to have with Hoosiers) although pretty much got them were they seemed to be good just before cording the tires.  The new tires will be 1" taller but 1" narrower than the 255s and the same size as the Kumhos except about .8" taller, which I think might prove to be an advantage for off-corner grip v. cornering grip.  I will be putting them on the 9" Keizer wheels the 255s were on, which are considerably lighter than the 8" Revolutions we ran with the Kumhos.  I rebuilt the Keizers as they were leaking (typical) and I hope they will now hold air.  I had this problem with my last set of Keizers, even when new from the factory...I fixed those the same way by taking them apart, cleaning them pu and sealing them properly so we'll see.  Next round out may be at Marina/AAS but we're entered in the Medford Oregon "Enduro" for the weekend of the 18th of March regardless.  We'll have Saturday to practice and try to get up to speed before the Sunday event.  Hoping for good weather!

I'm looking forward to getting back to the fun of driving for all this work and investment...after not driving for almost 6 months!