TheAMCForum.com Homepage
Forum Home Forum Home > The Garage > AMC V8 Engine Repair and Modifications
  New Posts New Posts RSS Feed - 390 Crossram SRT-11
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

Click for TheAMCForum Rules / Click for PDF version of Forum Rules
Your donations help keep this valuable resource free and growing. Thank you.

390 Crossram SRT-11

 Post Reply Post Reply Page  <12345>
Author
Message
SC397 View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Apr/30/2009
Location: Michigan
Status: Offline
Points: 2936
Post Options Post Options   Thanks (0) Thanks(0)   Quote SC397 Quote  Post ReplyReply Direct Link To This Post Posted: Feb/02/2019 at 7:36am
I built a 401 a couple of years ago with a Crossram and was limited on compression ratio and cam.  Even with 9.5:1 compression ratio and a Comp 280H cam in it a pair of 600 Holleys were just right for it.  We had it on a dyno watching for a lean or rich condition and it never ran rich.
XRamIMG_3128 by Rick Jones, on Flickr
Back to Top
Boris Badanov View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Dec/14/2013
Location: NH USA
Status: Offline
Points: 3532
Post Options Post Options   Thanks (0) Thanks(0)   Quote Boris Badanov Quote  Post ReplyReply Direct Link To This Post Posted: Feb/02/2019 at 7:40am
In general the carb mixture thing goes like this.

A classic set up. A 360 with a dual plane manifold and a 600 Holley.

Switch to a comparable single plane manifold you will need to enrichen the carb
to compensate for weaker intake pulses "signal".

Throw the carb on a 232 and you will also need to enrichen it.

Throw the same carb on a 454 Chevy and a dual plane and you will certaily have to lean it out.

Dual 4bbls have similar issues and plenum design is a key player.

If possible all things equal in plenum size and you thow a identical
600 Holley as a second carb and you will have to enrichen them because
of the reduced flow through the venturi.

Bigger plenum, like the monster STR-11 plenum and the mixture problem
becomes more of a challenge.

Add to that the different throttle linkages like
synchronised and staged make for more variables.

Accelerator pump volume and rate follow similar lines.

Anyway, start rich for safety reasons.

I have heard that a STR-11 is easy to detonate with a backfire
but I have no experiance with that disaster.


Gremlin Dreams
Back to Top
Ramzilla View Drop Down
AMC Apprentice
AMC Apprentice
Avatar

Joined: Jan/28/2019
Location: arizona
Status: Offline
Points: 74
Post Options Post Options   Thanks (0) Thanks(0)   Quote Ramzilla Quote  Post ReplyReply Direct Link To This Post Posted: Feb/02/2019 at 9:08am
I am open to any and all suggestions. Holly has a 600 slayer series also for tunnel rams.
Back to Top
ccowx View Drop Down
AMC Addicted
AMC Addicted


Joined: Nov/03/2010
Location: Yukon
Status: Offline
Points: 2792
Post Options Post Options   Thanks (0) Thanks(0)   Quote ccowx Quote  Post ReplyReply Direct Link To This Post Posted: Feb/02/2019 at 10:39am
Check this out: http://www.theamcforum.com/forum/measured-plenum-volumes-of-all-amc-intakes_topic96180_page1.html?KW=intake+volume

Here is the chart giving some idea of the relative volumes. Note that the STR-11 is actually about 50% larger in volume than a UR-18. Just because a carb is set up for tunell rams does not mean that it will work perfectly with a cross ram. 

Dual Planes


Edelbrock SP2P (66-69 version)                     1.5 Liters  (6.4 cups)


Edelbrock Performer #2131                          2.5 Liters (10.5 cups)


Performer RPM #7581 Air Gap                        2.6 Liters (11 cups)

 
Edelbrock R4B 1970+                                          4.0 Liters (17 cups)





Single planes:


Edelbrock Torker #3930                                   2.72 Liters (11.5 cups)


Offy Dual Quad with 1/2" spacers                           3.8 Liters (16 cups) 


HLR High rise intake (ported)                                      3.9 Liters (16.5 cups) 


Edelbrock UR-18 with UR-11 Dominator top       5.32 Liters (22.5 cups)


Edelbrock UR-18 with Weiand 1911 top             5.55 Liters (23.5 cups)


Edelbrock (original) STR-11 70' up Crossram     9.32 Liters (39 cups!)


 




^^^^^^these intakes were volume tested at roughly a junior high school level of accuracy (maybe).
I duct taped the ports, made a bolt on end plate to keep most of the water in, and filled them with measuring cups.
Test was run twice on each intake, so it should be pretty accurate.

All intakes are as cast/not ported (except for the HLR intake).


I ran mine on the street with 10.4: compression and the old Group 19 camshaft. It ran ok, though you could feel that it was struggling to keep up at lower rpms. It did feel good at high rpms though!

Chris 


Edited by ccowx - Feb/02/2019 at 10:41am
Back to Top
Ramzilla View Drop Down
AMC Apprentice
AMC Apprentice
Avatar

Joined: Jan/28/2019
Location: arizona
Status: Offline
Points: 74
Post Options Post Options   Thanks (0) Thanks(0)   Quote Ramzilla Quote  Post ReplyReply Direct Link To This Post Posted: Feb/02/2019 at 3:09pm
What carbs did you run.
Back to Top
ccowx View Drop Down
AMC Addicted
AMC Addicted


Joined: Nov/03/2010
Location: Yukon
Status: Offline
Points: 2792
Post Options Post Options   Thanks (0) Thanks(0)   Quote ccowx Quote  Post ReplyReply Direct Link To This Post Posted: Feb/02/2019 at 3:30pm
If you are asking me, I ran vintage Holley #4776 600 dp's with the air horns milled, no chokes and 4 corner idle. I don't recall the jetting, but it would have been in the 80's, large cams on the acc. pumps. My car is a stick and has 4.10's in the back, which went a long way towards drivability.

It took forever to warm up and was unforgiving when cold. Once it was warm it did fine, though you could feel that it was lazy below about 2000 rpms or so. The cam I have is good for scavenging in the mid range, combined with the headers, and once everything was moving it felt pretty good. 

Chris 
Back to Top
PHAT69AMX View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Jul/07/2007
Location: West Virginia
Status: Online
Points: 4241
Post Options Post Options   Thanks (0) Thanks(0)   Quote PHAT69AMX Quote  Post ReplyReply Direct Link To This Post Posted: Feb/02/2019 at 5:56pm
Something to maybe research for crossram information is the 1968-69 Chevy 302 Crossram.  Much more "activity and information" out there on the web for those.  There's actually surprisingly quite a bit of AMC info over on the 1st Generation Camaro Forums, Camaro Research Group, CRG Web Site and Forums.  One must create an account and log in to the CRG Forum in order to be able to see all the posted pictures.  The info is mostly within the Trans Am Camaros section under Crossram Intakes thread and the Traco Fans thread over there, old magazine articles, quite a bit of applicable info.  Where I was researching Holley History trying to find out what was the 1st Holley Double Pumper Carburetor is what led me to the CRG Forum information.  imho research showed the 2nd Design 302 CR Holley List 4295 was the 1st Double Pumper.  Here's a collection of pictures of Holley Choke Horn markings showing the fast and furious Holley Carburetor "developmental progress" that was taking place during the mid to late 1960's.  And a picture of a developmental Chevy 302 CR short lived 1st Design List 4210 GM Engineering modified with a custom shooter which preceded and led to the 2nd Design List 4295 true Dual Line Center Inlet Mechanical Secondary Double Pumper, 585 CFM ( 4x 1-9/16 Dia. Butterflies ).  imho at the very same time GM working with Holley also developed the 1st 850 CFM ( 4x 1-3/4 Dia Butterflies ) Dual Line Center Inlet Mechanical Secondary Double Pumper which became holley List 4296 and was OEM on the qty (69) Fred Gibb 1969 all aluminum 427 big block ZL-1 Camaros and "secretly" imho on the L-88 Corvettes.






GRAND DADDY of ALL Holley Double Pumpers
The 1st HOLLEY 850 CFM DP LIST # 4296
GM OEM # 3955205 on '69 CHEVY CAMARO 427 ZL-1 and
The 1st HOLLEY 585 CFM DP LIST # 4295 
GM OEM # 3957859 on '68 302 CrossRam 2nd Design





Derived from '57 Ford List 1850 600 CFM Vac Sec,
to '67 Chevy List 3810 '67 'Vette 327 Vac Sec,
to '68 Chevy List 4210 585 CFM Mech Sec Single Squirter 2x4 302 CrossRam 1st Design,
to '68 Chevy List 4295 585 CFM Doubel Pumper Early-Mid 1968 2x4 2nd Design,
->'68 SBC 302 CrossRam 2nd Design Carburetor =

-> the FIRST HOLLEY DOUBLE PUMPER ! Holley List No. 4295 ! c/o Chevy & BILL HOWELL !<-

then to '69 Holley List 4584 585 CFM Mech Sec Single Suirter 2x4 AMC 390 CrossRam.
The AMC 390 CrossRam got handicapped with reapplied "throwback" 302 1st Design List 4210 Holley Carbs.
'68 302 Trans Am Camaro and '69 ZL-1 Drag Camaro both got the 1st two Holley DOUBLE PUMPER CARBS,
'69 390 Hurst S/S AMX CrossRam got Mech Sec Single Squirter 2x4 Holley Carbs...
Seems maybe GM was afraid of some Rambler somethin'...
Holley List 4776 600 CFM Double Pumper is the same basic dimensions as all of the above:
4x 1-9/16" Dia Butterflies, 1-1/4" Dia. Primary Ventury, 1-5/16" Dia. Secondary Venturi




Edited by PHAT69AMX - Aug/12/2019 at 11:32pm
Back to Top
bikerfox View Drop Down
Supporter of TheAMCForum
Supporter of TheAMCForum
Avatar

Joined: Aug/02/2009
Location: USA
Status: Offline
Points: 2895
Post Options Post Options   Thanks (0) Thanks(0)   Quote bikerfox Quote  Post ReplyReply Direct Link To This Post Posted: Feb/02/2019 at 10:32pm
Originally posted by myrambler myrambler wrote:

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!

Agreed and he's a frequent flyer on some of facebook's amc sites.

He also knows of a place in Phoenix that will re-arch your leaf springs at a reasonable price.

Good luck!
1969.5 SC/Rambler and 1970 Javelin
Back to Top
amcenthusiast View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Jul/02/2012
Location: central Texas
Status: Offline
Points: 1210
Post Options Post Options   Thanks (0) Thanks(0)   Quote amcenthusiast Quote  Post ReplyReply Direct Link To This Post Posted: Feb/03/2019 at 1:24am
Fall in love with the Indy Cylinder head 'mod man' dual quad intake instead?
Link to XRV8 Race Parts website: www.amcramblermarlin.1colony.com
Back to Top
super-bee_ski View Drop Down
AMC Nut
AMC Nut
Avatar

Joined: Nov/13/2012
Location: Edwards AFB
Status: Offline
Points: 482
Post Options Post Options   Thanks (0) Thanks(0)   Quote super-bee_ski Quote  Post ReplyReply Direct Link To This Post Posted: Feb/03/2019 at 11:52am
Yes:
Dan IS the Man...he's only 7 hours drive from my home...tee-hee-hee...

-1977 Gremlin X 4-speed AC LEVI with 500,000+ miles on her!
-1969 SC/Rambler "A-paint scheme"
-Her name is "Abby"

Back to Top
 Post Reply Post Reply Page  <12345>
  Share Topic   

Forum Jump Forum Permissions View Drop Down



This page was generated in 0.109 seconds.
All content of this site Copyright © 2018 TheAMCForum unless otherwise noted, all rights reserved.
PROBLEMS LOGGING IN or REGISTERING:
If you have problems logging in or registering, then please contact a Moderator or