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390 Crossram SRT-11

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Ramzilla View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ramzilla Quote  Post ReplyReply Direct Link To This Post Posted: Jan/29/2019 at 6:16pm
Not sure if I understand the signal issue with dual carbs. Mite need a little more info. But thanks a lot to all of you.
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wheelz View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote wheelz Quote  Post ReplyReply Direct Link To This Post Posted: Jan/29/2019 at 6:42pm
There is a member called crossramrambler I believe who runs the STR-11 with Edelbrocks carbs who may be able to provide more real world experience in your set up.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote glennrock Quote  Post ReplyReply Direct Link To This Post Posted: Jan/29/2019 at 7:12pm
G'Day….. I am an AMC'r and also work for Doug's Headers, I appreciate the post, please call me when you are ready to purchase your headers and I will give you the "good guys" price.
72 Jav/AMX 401 4-Speed

1st and Last Owner
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Jmerican Quote  Post ReplyReply Direct Link To This Post Posted: Jan/30/2019 at 1:47am
@ wheelz. Correct. They filled the booster Venturi to make a 625 a 500. To me they look terrible. I can’t imagine they work well enough to produce more signal for a given Venturi size. They should have done better. But that would require new tooling to mold the bolt in Venturi and main body casting. It’s an average at best carb. Yeah, the new avs2 looks ok, yes I’ve seen it in the flesh. It’s no Holley. The boosters might interchange from afb to avs2. I imagine the internal calibration would be very different. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote myrambler Quote  Post ReplyReply Direct Link To This Post Posted: Jan/30/2019 at 12:11pm
Check with Dan Curtis, he has an AMC restoration shop in AZ and builds motors too. Great guy with a lot of good AMC advice. He is amx39068 on the forum. He has a web site to check out and several you tube videos of engines start ups and break ins. If only he was closer to Iowa!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote super-bee_ski Quote  Post ReplyReply Direct Link To This Post Posted: Jan/30/2019 at 12:31pm
I was going to put that manifold on my 69 SC but after talking to Dan, I decided not too, I will "build" another engine someday and install the Cross ram
PS: you do not have the dog Leg head, it flowed much better on the Exhaust side than our "69 SC Head" but I just had my heads ported from Valley Head Service, Northridge CA
Funny thing is, they have been in Business since the late 50s and Larry the owner helped design the "Dog Leg" head!
I had a MILD Street port job.
Good luck!
-1977 Gremlin X 4-speed AC LEVI with 500,000+ miles on her!
-1969 SC/Rambler "A-paint scheme"
-Her name is "Abby"

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ramzilla Quote  Post ReplyReply Direct Link To This Post Posted: Jan/30/2019 at 6:30pm
Thanks I will let you know. Are 1/58" the only size for SC Rambler I think there are clearance issues to go Bigger. And what about how far they hang below frame. And also ground clearance. Thanks Much
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 68st343 Quote  Post ReplyReply Direct Link To This Post Posted: Jan/30/2019 at 6:51pm
Hello all, was wondering if any of the efi setups like Sniper system have been designed to run dual throttle bodies on 2x4s, maybe a o2 sensor on each exhaust for the "tune info" to the computers. I remember a post about one member trying to use chevy efi on 2x4 but can't find the outcome of it. Thanks john
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ramzilla Quote  Post ReplyReply Direct Link To This Post Posted: Feb/01/2019 at 10:50pm
I have done some research on Carbs for tunnel rams. Looks like Holly has what I want. Slayer series carbs 450CFM for tunnel rams. They come in a matched pair. If any have tried these let me know. It is still a way down the road before I get to the motor. Thanks in advance Larry
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Post Options Post Options   Thanks (1) Thanks(1)   Quote ccowx Quote  Post ReplyReply Direct Link To This Post Posted: Feb/02/2019 at 12:05am
I am not going to go into a giant battle about the specifics of various carbs on a cross ram, but having run one on the street for several years, I will tell you this much. DO NOT lean it out. These manifolds have a massive plenum to fill quickly when you open the throttle and if you do not have adequate accelerator pumps to fill it, it will have a lean backfire that can blow the lid off with enough force to actually rip all the bolts out and damage your hood. Don't ask why I know. 

They are noted for this issue and that is why I would pay attention to your accelerator pumps more than anything else when choosing a carb. The temptation is to lean it down, but the issue is too much air, not too much fuel. You need to have the jetting correct for mixture when cruising of course, but you also need to be able to cover the sudden influx of 900-1200 cfm of air being suddenly dumped into your engine. Unless you have enrichment to match, you will have a massive lean out.

Treat cruising and acceleration as different things. You won't wash out any rings because the accelerator pumps are simply keeping the mixture correct with sudden throttle openings. It will still be 13:1 or so. Once the engine catches up to the throttle position, the accelerator pumps stop working and then the jetting in the carb will take over and keep it at the proper mixture for best cruise. Again, what you DO NOT want is to have it go to 30:1 as soon as you hit the pedal. You will be dreaming fondly of washed out rings, believe me!

Chris  

PS: Just for the record, I used a set of #4776 Holley 600 dp's with the air horns milled off. 




Edited by ccowx - Feb/02/2019 at 2:55am
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