[SD455DJ]

Originally Posted by jhein

Interesting. Just out of curiosity, what do you think it would do with a 2.25 exhaust system?

Jhein, Just changing the headpipes to the 2.5" mandrel pipes you can buy from our host, that would help a bunch in the midrange.

Also, if your RA manifolds are original factory pieces, don't try hogging them out since they are gray 'pig' iron and prone to cracking especially in the 'thinner' areas. The aftermarket RA manifolds are cast with ductile iron that is much better quality and can be opened up a bit (grinding and extrude honed).

Dennis

[SD455DJ]

Originally Posted by SD455DJ

Jhein, I bought a '70 Tempest a few years ago that had a nicely built 461 (.030" over 400 with a 4.25" stroke), SD Perf ported 6X-8 heads (250 cfm intakes/ 200 cfm exhausts/9.5 compression) with the standard 2.2" outlet RA manifolds tied into 2.5" mandrel X-pipe exhaust system, RPM intake with a Holley 850, and a HFT Bullet RAIV-style cam (231/239/112 @ .480" lift) with 1.5 roller rockers. That car ran 11.90's @ 115 mph on drag radials, 3.42 gears and a tight 'Jim Hand' Continental 10" torque convertor in a TH400. It weighed just under 3700 lbs race weight. So, a well built 455/461 can run pretty well with the smaller outlet RA manifolds. It would probably run 11.80's with the bigger 2.5" manifolds and 11.50 with good headers and a 3" exhaust pipes/mufflers to 2.5" tailpipes.

I'm not sure what hp that equates to, especially the 116 mph pass.

Dennis

I'll add just a quick note about the intake manifold/carb combo. I removed RPM/Holley combo and replaced it with a stock (not ported/modified) '70 iron intake and a 7040264 Q-jet that was rejetted/metered for the engine...and it is still a beast off idle to 5000 rpm. I'm sure it makes more torque off idle at the expense of top end power, but it's still too much for the street with more than enough power to get into big trouble!

Dennis

[jhein]

Originally Posted by SD455DJ

I'll add just a quick note about the intake manifold/carb combo. I removed RPM/Holley combo and replaced it with a stock (not ported/modified) '70 iron intake and a 7040264 Q-jet that was rejetted/metered for the engine...and it is still a beast off idle to 5000 rpm. I'm sure it makes more torque off idle at the expense of top end power, but it's still too much for the street with more than enough power to get into big trouble!

Dennis

I'll have essentially the same setup. Stock intake with a properly calibrated 7040263 Qjet from Ray Klemm.

[SD455DJ]

I will also say that I'm swapping the '70 intake/7040764 combo this summer for a SD Performance phase 3 CNC'd iron intake (the 600 hp version) and a '71 7041267 'big' Q-jet to go with the SD Perf heads already on the engine. They're just meant to go together. Now I just need to get a pair of 2.5" D-port RA manifolds to complete the factory look.

Dennis

[scott70]

Originally Posted by SD455DJ

Scott70, Those are great numbers and minimal losses going to RA manifolds from the headers. Do you have the Dyno printouts for the two? It would be interesting to see when (rpm) the power dropped.

Dennis

First one is April with ra manifolds. 2nd is with headers. Sorry,,haven't looked at these for awhile,,19hp difference. After this it was noticed of being shiny bits in oil and filter,,he built it with bearing clearances way too tight. He tore it back down again, cleaned and made the clearances correct. 3rd sheet from June is after the redo with headers only. I guess the tight bearings were eating up some power as you can see the difference in June dyno. 7040267 carb in all 3 . I have also recently done the intake modification you showed in your picture after the dyno session so I dont know how much or if that added any HP. SD didnt do it,,,I just ground the top myself. I did have SD cnc my # 64 heads to 254cfm i believe.

sheets.https://www.youtube.com/watch?v=-7vZwbCQlUw

[Stan Weiss]

Here is a graph of the 2 HP curves together.

Stan

[jhein]

Just got back from my builders shop. Dropped off all the parts I had, heads, cam, lifters, etc. Laid eyes on my IAII block, that thing is awesome. He'll be starting on it within 2 weeks and should be done 3-4 weeks after that. Now I just have to get the car in to my mechanics shop to have the motor pulled because I still need to get the intake and exhaust manifolds and distributor to the builder, but at least he has what he needs to get started.

Can't wait for Dyno day, and I'm gonna be there for that.