STR12 edelbrock crossram fitment

[Illahe]

Just so you understand what a Street Tunnel Ram is - if you think about the vertical runners on a tunnel ram, stick the four fingers of both hands up in the air palm to palm in that configuration, since it is a Mopar small block pair the fingers of each hand, offset them a bit and then fold the finger pairs flat so they are horizontal. Now you know what the inside of a street tunnel ram looks like under the top plate. There are long runners and the carb on the left side of the engine feeds the cylinders on the right side and the carb on the right side of the engine feeds the left side cylinders.
View attachment 1716492339View attachment 1716492338
This by the way is why it never made any sense to me that Edelbrock offered six pak, single centered four bbl ,and single Dominator tops for the STR intakes on Mopar RB motors.

TA heads?

 

[str12-340]

yep, TA heads... Since 1978 on this motor.

 

[highwaystar]

My 68 GTS

 

[highwaystar]

Pix

 

[str12-340]

My 68 GTS

Does that one have a billet top too???

 

[RustyRatRod]

I believe edelbrock has stated that the core boxes went missing decades ago and they have zero intention of ever remaking. I have one on a 410 stroker, that I initially used the dual 4 barrel fitech EFI on, but later I switched to dual quick fuel 450s. Runs great, and I didnt bother with the internal mods, I have never had any issues with backfires or anything like that.

Cause you're smart enough not to over fuel the piss out of fit.

 

[hemi446]

Here is a picture of the engine in my sons 67 Barracuda. It's a 426ci with two Holley Sniper throttle bodies. Sorry the picture is not better. The engine has changed since the picture was taken. He is working on putting A/C back ing the car.

 

[shags72]

I'm familiar with what they are and how they generally look under the cover, I've just never seen one close up to be able to get dimensions. I doubt it will be easy and possibly is far beyond my capability, but should be a fun effort. I surely will document the success or failure here when the time comes.

If you are going to fix the top, you might consider some ribs on the bottom to strengthen the top. The cast top ain't very thick and it's just cast aluminum with the weight of the carbs,etc. sitting on it too. My system has a CNC milled top from aluminum billet. I got it at the Nats 20 years ago and it was the last of 20 a machine shop made. If there were enough folks that wanted one of these I'd be glad to remove the lid over the winter and give it to a shop with CNC capabilities to make a run. It would be a LOT easier to do it copying an existing billet top than copying a cast top.

Holidays have me running ragged and couldn't put any time to responding with any real thought to it, so I have a few minutes and wanted to respond to you sir. I am going to fix it for sure. I will need to look at the underside better to see where and how to reinforce it. Here are some pics of the intake. My brother is an excellent welder and he's meticulous with aluminum welding. Thankfully! If all goes to he!! with the repairs I may be asking for help on a lid. I really am a ways from putting the engine together. The money I just spent on this flippin intake has put me behind on purchasing all the things to finish it, but dang I just had to get it! My first thought was after I bought it was, damn does it fit under the hood? LMAO shoulda asked this before, but you've answered that question exceptionally well! I am really happy that it can be done and I won't have to change the hood that I freaking love! So thank you for your responses and insight and will be asking for more help in the future when it comes to some of the connections, like transmission throttle pressure setup and all that. Again Thanks!

 

[str12-340]

By the way, the whole point of the Street Tunnel Ram manifolds were to get the advantages of a regular tunnel ram while fitting under a stock hood.

 

[shags72]

By the way, the whole point of the Street Tunnel Ram manifolds were to get the advantages of a regular tunnel ram while fitting under a stock hood.

Thats what I'm after! 340 solid roller 10.5:1 Trickflow aluminum heads etc. Still under design but mostly thought through and getting ready to purchase parts.

 

[highwaystar]

Does that one have a billet top too???

I believe it is a billet top. It is polished. I run 2 Holley 650 vacuum secondaries with a 1" spacer underneath because I have the room with the scoop. Secondary metering plates and adjustable vac pod to bring 4 barrels in a bit earlier. It dead hooks at track and never no hesitation. It's a street motor with J heads. Runs 8.00's in the 1/8th in good air. I would like to put better heads to it, but it's just a street car.. Very happy with the intake. not many of them around.

 

[A56]

I've had this unused one for almost 10 years. From what I recall it was a display in a speed shop. The adapter plates are also from Edelbrock. They're for mounting Holley's sideways.

 

[shags72]

I've had this unused one for almost 10 years. From what I recall it was a display in a speed shop. The adapter plates are also from Edelbrock. They're for mounting Holley's sideways.
View attachment 1716494057

Daaaarrooooool. Brand new? Sweet!

 

[A56]

This is an mail that I received from a gentleman at Edelbrock about 8 years ago. I believe he has since passed away.

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Back in the day, when this intake manifold was new Edelbrock suggested to use 2-600 or 2-650 cfm Carburetors.

Remember I said 2-600’s, they were Holley 4776 , and the 650’s were the 4777 Holley Carbs used and recommended by Edelbrock.

But the Holley’s used on the STR intakes were facing forward.
The RPM Range of the STR-12 S/B Chrysler is 3,500-6,500 RPM range, as determined by the Edelbrock Equipment Co. back in the day when they were new.

Sorry to inform you that even after my attempt to look for old literature I came up empty. I have Copied & Pasted the General Installation Instructions for the S/B Chrysler.

This will at least show you the intake manifold torque sequence for you to install this new intake manifold. If I do come across any of the old literature I will get a hold of you.



Sincerely,

Smitty Smith

Technical Sales Coordinator

Media Technical & Application Information

Edelbrock, LLC / Russell Performance Products

2700 California Street

Torrance, CA 90503

PH: 800-221-1666 X 2817

CELL: 310-991-7744

 

[Newbomb Turk]

This is an mail that I received from a gentleman from Edelbrock about 8 years ago. I believe he has since passed away.

----------------------------------------------------------------------------------------------------

Back in the day, when this intake manifold was new Edelbrock suggested to use 2-600 or 2-650 cfm Carburetors.

Remember I said 2-600’s, they were Holley 4776 , and the 650’s were the 4777 Holley Carbs used and recommended by Edelbrock.

But the Holley’s used on the STR intakes were facing forward.
The RPM Range of the STR-12 S/B Chrysler is 3,500-6,500 RPM range, as determined by the Edelbrock Equipment Co. back in the day when they were new.

Sorry to inform you that even after my attempt to look for old literature I came up empty. I have Copied & Pasted the General Installation Instructions for the S/B Chrysler.

This will at least show you the intake manifold torque sequence for you to install this new intake manifold. If I do come across any of the old literature I will get a hold of you.



Sincerely,

Smitty Smith

Technical Sales Coordinator

Media Technical & Application Information

Edelbrock, LLC / Russell Performance Products

2700 California Street

Torrance, CA 90503

PH: 800-221-1666 X 2817

CELL: 310-991-7744

It’s sad that some of these products will never be produced again.

It’s also sad that instructions and such for this older stuff was never really converted to digital media.

I needed a copy of the instructions for installing Hooker 5303 headers. Im not sure when they made the last run of them but if it was the late 1990’s I’d be surprised.

The guy I got ahold of actually went and found a hard copy and emailed it to me. He told me that it wouldn’t be long and they were going to destroy all paper records of all their products. If they weren’t converted to digital media by that time they wouldn’t be.

He said management told him is wasn’t “cost effective” to digitize all that paperwork. In other words, it was cheaper to just get rid of it.

Truly sad.

 

[A56]

It’s sad that some of these products will never be produced again.

It’s also sad that instructions and such for this older stuff was never really converted to digital media.

I needed a copy of the instructions for installing Hooker 5303 headers. Im not sure when they made the last run of them but if it was the late 1990’s I’d be surprised.

The guy I got ahold of actually went and found a hard copy and emailed it to me. He told me that it wouldn’t be long and they were going to destroy all paper records of all their products. If they weren’t converted to digital media by that time they wouldn’t be.

He said management told him is wasn’t “cost effective” to digitize all that paperwork. In other words, it was cheaper to just get rid of it.

Truly sad.

I offered to let Edelbrock use mine if they were going to make another batch, but nope! Just like my NOS '69 Barracuda front fenders that I informed AMD I have, they weren't interested either.

 

[Killer6]

This by the way is why it never made any sense to me that Edelbrock offered six pak, single centered four bbl ,and single Dominator tops for the STR intakes on Mopar RB motors.

Class racing rules, requiring stock carb configurations, ......the dual inline 4bbl. RatRoaster Hemi intakes as well.

 

[shags72]

This is an mail that I received from a gentleman at Edelbrock about 8 years ago. I believe he has since passed away.

----------------------------------------------------------------------------------------------------

Back in the day, when this intake manifold was new Edelbrock suggested to use 2-600 or 2-650 cfm Carburetors.

Remember I said 2-600’s, they were Holley 4776 , and the 650’s were the 4777 Holley Carbs used and recommended by Edelbrock.

But the Holley’s used on the STR intakes were facing forward.
The RPM Range of the STR-12 S/B Chrysler is 3,500-6,500 RPM range, as determined by the Edelbrock Equipment Co. back in the day when they were new.

Sorry to inform you that even after my attempt to look for old literature I came up empty. I have Copied & Pasted the General Installation Instructions for the S/B Chrysler.

This will at least show you the intake manifold torque sequence for you to install this new intake manifold. If I do come across any of the old literature I will get a hold of you.



Sincerely,

Smitty Smith

Technical Sales Coordinator

Media Technical & Application Information

Edelbrock, LLC / Russell Performance Products

2700 California Street

Torrance, CA 90503

PH: 800-221-1666 X 2817

CELL: 310-991-7744

Sounds about like what I'm planning. I have a 600 dp holley and might just double it up. But I'm still wanting the 660 center squirters. Just a lotta money. But so was this flipping intake! Lmao. Those were designed for dual quad use from the literature ive read.

Do you have the documents he mentioned? Id like to have them if possible.

 

[A56]

Sounds about like what I'm planning. I have a 600 dp holley and might just double it up. But I'm still wanting the 660 center squirters. Just a lotta money. But so was this flipping intake! Lmao. Those were designed for dual quad use from the literature ive read.

Do you have the documents he mentioned? Id like to have them if possible.

There aren't any documents. Just what he referred to as installation instructions and that's the torquing sequence which for whatever reason I cannot copy and paste here. I get a "image file invalid" message.

 

[NC Engine Builder]

I put zero confidence in there suggested rpm range after running one. It definitely makes excellent low end torque on my 408, intact it's much stronger than the M1 and 750 DP that I pulled off. The 4" stroke helps, but the crossram pulls right off idle with zero problem

 

[A56]

I put zero confidence in there suggested rpm range after running one. It definitely makes excellent low end torque on my 408, intact it's much stronger than the M1 and 750 DP that I pulled off. The 4" stroke helps, but the crossram pulls right off idle with zero problem

That was from Edelbrock in 1968. (These were produced for 4 years 68-72 Don't you think after 57 years things might have changed just little bit?

 

[Newbomb Turk]

I would discourage you vehemently from using 660 center squirters.

Those are my least favorite carb of all time.

I’d adapt two BBD Carters on it first.

Hard to tune and no matter what they drive like rancid owl ****.

Just my .02

 

[NC Engine Builder]

That was from Edelbrock in 1968. (These were produced for 4 years 68-72 Don't you think after 57 years things might have changed just little bit?

I dunno, the design of the intake hasnt changed in the last 57 years. Also it could be that intake was designed around 340 cubic inches, so perhaps the 4" stroke might be the biggest difference. All I know is it runs excellent, has tons of low speed torque. It definitely is NOT the high rpm race only type that everyone used to claim.

 

[gzig5]

I dunno, the design of the intake hasnt changed in the last 57 years. Also it could be that intake was designed around 340 cubic inches, so perhaps the 4" stroke might be the biggest difference. All I know is it runs excellent, has tons of low speed torque. It definitely is NOT the high rpm race only type that everyone used to claim.

You'd probably see the same low end torque difference between any intake you switched between a 340 and 408, wouldn't you? I'm sure the individual builds on each motor would affect it but a 408 is generally going to outpull a 340 on the bottom end, like you said.

You mentioned the STR was stronger than the single plane M1 on your 408. Would you expect the similar result for the STR over a good dual plane like an RPM AG on a 340? (like the one you put together for me this year)?

 

[NC Engine Builder]

You'd probably see the same low end torque difference between any intake you switched between a 340 and 408, wouldn't you? I'm sure the individual builds on each motor would affect it but a 408 is generally going to outpull a 340 on the bottom end, like you said.

You mentioned the STR was stronger than the single plane M1 on your 408. Would you expect the similar result for the STR over a good dual plane like an RPM AG on a 340? (like the one you put together for me this year)?

I not sure, like everything, its probably effected by lots of variables, and ultimately dyno testing would be needed to make any real determination. But just guessing, because the STR has straight runners with good length, it COULD make more torque on a stock stroke engine as well, compared to a air gap. From my limited experience with the STR, I think it could benefit from the carbs being turned sideways, and a spacer made to raise the lid another inch or so.