STR12 edelbrock crossram fitment

[Earlie A]

because the STR has straight runners with good length, it COULD make more torque on a stock stroke engine as well, compared to an air gap.

Agree.

It's sort of an interesting cross between a single plane and a dual plane as far as the crank angle separation between intake pulses.

 

[Newbomb Turk]

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.

I already tested the 1 inch spacer on those and it makes more power. I forgot how much but the customer was glad he paid for it when we were done.

We also tested that engine with a 1 inch spacer under each carb. It made 7-8 more across the board but lifting the whole lid was in the mid 20’s across the board at least.

I had a local company make the spacer for me from the gasket. I put the holes in it and then did a bit of blending and sent it.

If you have the room you can raise it an inch. I’m pretty sure another 1/2 inch would help it a bit more.

That thing looks like it has a bunch of plenum volume but it doesn’t. I don’t remember how I figured that out now.

That’s why we tested 1 inch spacers under each carb. We wanted to make sure the gains weren’t from just getting the carbs away from the plenum floor.

It really needed two 750’s instead of the 650’s he used. It would have made more power yet.

Edit: that was on 360 inches. For 400 inches I would have used two 850’s.

 

[NC Engine Builder]

I already tested the 1 inch spacer on those and it makes more power. I forgot how much but the customer was glad he paid for it when we were done.

We also tested that engine with a 1 inch spacer under each carb. It made 7-8 more across the board but lifting the whole lid was in the mid 20’s across the board at least.

I had a local company make the spacer for me from the gasket. I put the holes in it and then did a bit of blending and sent it.

If you have the room you can raise it an inch. I’m pretty sure another 1/2 inch would help it a bit more.

That thing looks like it has a bunch of plenum volume but it doesn’t. I don’t remember how I figured that out now.

That’s why we tested 1 inch spacers under each carb. We wanted to make sure the gains weren’t from just getting the carbs away from the plenum floor.

It really needed two 750’s instead of the 650’s he used. It would have made more power yet.

Edit: that was on 360 inches. For 400 inches I would have used two 850’s.

my thinking is the carbs are sitting so near the edge of the port outer wall, and relatively low, that raising the lid would allow the air to make the turn easier. If I ever get the dyno up and going I'd like to do some testing on that thing. I believe there is a fair amount of power to be found, like your results showed. I had a few lids made at a water jet shop, with different carburetor placement. Would be interesting for sure.

 

[A56]

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.

That's pretty much where my point was headed. Motor improvements.

 

[str12-340]

Back in the glory days the Ramchargers had enough resources to test manifold performance for all their HP engines. They had enough engine dyno time that they could run a manifold/carb combination and change jets and stuff a step at a time to maximize output for a particular use. All this was then published in the Direct Connection engine book where they recommended the best combination of parts and set up for a particular drag racing application. Unfortunately these were strictly racing applications and not applications for street cars.

 

[mayhem]

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

Back in the glory days the Ramchargers had enough resources to test manifold performance for all their HP engines. They had enough engine dyno time that they could run a manifold/carb combination and change jets and stuff a step at a time to maximize output for a particular use. All this was then published in the Direct Connection engine book where they recommended the best combination of parts and set up for a particular drag racing application. Unfortunately these were strictly racing applications and not applications for street cars.

I just sold a pair of 660s (List-4224) to a nostalgia Gasser fellow on the East coast after briefly considering them for a street/strip crossram Hemi Dart. The center squirters were designed to be race carbs from the start and, as stated above, they are a beeotch to tune. Just as the WCFB gave way to the AFBs, AFBs morphed into AVSs and AVSs begat the Thermoquads, the 660s are old tech compared to more modern Holleys. There are far better choices for your STR today. Listen to NbT and sell the 660s to fund the better carbs.

Been there, done that.