M1 360

[rodsvolare]

Have 78 Volare w/30 over 360, MP 484-484 cam
, heads milled .060 for aprox. 9.5-1 comp.,
adj. rockers, 727, 4.10 gears. Changed from
Edelbrock dual plane to M1 single plane and
lost 5 tenths??? Any answers???

[Maxwedge]

single plane manifolds work their best at high rpm and also with as much height as you can get on the carb to enhance the "Tunnel Ram" effect that the single planes are known for.
to make this "height" between the carb and manifold you have to use carb spacers. The more the better. If you dont use the manifold correctly you will will be better off using a dual plane manifold.
once you make all the adjustments(in carb linkage and carb height) you should also check to see if your running rich or lean and adjust the carb accordingly.
I am sure there is more to the story to making a single plane work, but this is as far as my experience goes.
M-Wedge

[This message has been edited by Maxwedge (edited January 15, 2000).]

[DAVE JONES]

I'm not an expert or anything like alot of these guys but but from what you describe your end result seems normal. I am assuming that your description pretty much highlights your motor's plus's. Not that its bad or anything but its definantly not a fire breather. I think you'll find that your single plane has demolished your low end and going back to the dule plane will definantly help to bring it back. dule planes have a tendency to work a strong low end and is great for the street. The singles are usually for the upper end range with the motor set up properly. The experts will give you more insight on this opionion than I can but from what I know the duel with your setup will probably be a much better match. Of course there are alot of other variables that you didnt mention that could also add to your problem but as far as your manifold that just my opinion...good luck with your search......DAVE

[sanborn]

That is a common problem when changing to a single plane manifold. Your low and mid range torque suffered with the M1 and you are probably not turning enough RPM to make it back up. Try bolting a 2" four hole spacer on the M1. That might help to pick up the mid range torque. I don't think it will help low end torque enough to notice.

[The Dartman]

I read your post and thought I knew why the single plane lost so much ET, but you didn't state what kind of converter you run. A single plane intake will build HP over high RPM's and a hi stalling converter will put your launch into the RPM band where you are making HP. This could be supported by checking 60 foot times to see difference.

Your Dual plane intake on your setup would work best with a converter between a stock stall and 2800 or so. A single plane intake makes its power from about 4500 to 7000 (depending on brand/model) so would be better suited to a 2800-4500 converter.

By this same token you wouldnt put a $500 TCI 4500 stall converter behind a motor that has a dual plane (AKA an intake that builds low end HP and torque) since the benefits of the duual plane would be bypassed by the stall speed.

I was in the same boat you were in at one time - I had a 2000 stall with a 340 and a 484/284 with a Holley Street dominator. It ran a best of 14.26 on street tires, with a best 60 foot of 2.05 (real doggy - its always was). I installed a TCI 4500 stall covnerter (got it used for $150) and with little help besides the converter ran a best of 13.70 with 60 foots in the 1.80's.

So am I right? Low stall speed?

If I'm wrong, did you check for vacuum leaks?

[DartGT66]

I think your problem is somewhere else than in the intake. Your cam / intake combo is just the same as was in the Mopar Super Commando 360 crate engine, so there should be nothing wrong with it. Your gears and CR are also in the correct level. You didn't mention headers, hope you have them. The manifolds do not breathe where your engione should make power. Also hope that you have at least 3000 stall converter with that cam. Do a basic checking, compression check, vacuum check, intake leak check, timing check, does your throttle open fully etc. I think you'll find your problems that way, it shouldn't be in the part combo.

[Dart]

Amen on DARTGT66. The jury is still out on the dual/single plane manifold applications, rpm range, etc., etc.

I think you have something else wrong. Keep looking and good luck.

[340king]

I don't like the M-1 for 360 applications because it has a smallish plenum volume. The longer stroke of the 360 makes it real sensitive to plenum size changes. This may not be the culprit, as dual plane intakes do not have large plenums unless they are cut at the divider.

I would try the remedy that Sanborn recommemded, prior to changing back to the dual plane, to see if plenum size is actually the problem. I prefer the Victor 340 on the 360 engine as it has nearly a 3/4" deeper plenum and taller carb side ports.

The other posts have some real good advise on checking things to eliminate possible problems.

[rodsvolare]

Thanks for all the help!!! In answer to some of your questions, I'm running headers, stall that flashes to 3100,(its a cheap
$200 conv., might have to get a good one)
and my 60fts dropped from 1.90's to 2.00's. I'm going to go back and check all the other things you suggested. Thanks again!!

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[PRO]

I'd go back to the dual plane or raise your compression,have you ever checked cranking comp ? I'll bet you dont have as much as you think,if its less than 130 lbs your cam is too big and consequently so is a single plane int.I'd guess your around 9:1.,how thick are your head gaskets? probably fel-pros at .039,if your motor was 8.2:1 stock and you milled heads .060 you'd be 9.1 subtract .2 for head gaskets and you have 8.9:1,you could leave the single plane int and go to a bigger cam/stall,like MP .509 and 4500 stall of course it would be very unstreetable but it would run much faster.For example a super stock 72 340 duster here in GJ COLO (National record holder!!)has to run stock short blk and comp (at 8.5:1) and heads int carb as per rules,variations include headers and whatever stall and gears you want w/slicks,he runs 5000 stall 5.13 gears,the cam is a cheater and must retain stock lift but any duration,his is 338*,it runs consistent 11.90s.....PRO...

[rodsvolare]

Pro cranking comp is 125-130. My motor was closeer to 7.7:1, I used .025 gaskets and with .060 milled heads, figured I was close to 9.5:1 (if may math was right). I'm not to concerned with streeable as I mostley just bracket race this car. the car weighs #3000.

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