Sounds true to the Holley philosophy of being a "barely controlled fuel leak" My real fun toy is the Charger though it too is restricted by my brief to remain a cruiser but with a as much extra power I can muster within those parameters. The engine started life as a 440 magnum with 480ft/lbs torque, but has had a full rebuild starting with an acid bath and then new everything including lots of aluminum and is now small block weight. It has a revised timing street Hemi purple shaft with 485 lift and runs a 3.55:1 8 3/4" diff with a planned 4.36 to take advantage of the Gear Vendor for a final drive of 3.35. Currently running a Holley 780 vac secondary much to my disgust because I couldn't find anyone familiar enough with the Edelbrock I had. Bring on the Sniper! It has TTI extractors and a twin 2.5" X pipe system and registered 260kw or 350bhp at 5000rpm (the dyno sook stopped at 5000). It ran 14.06 at Heathcote in 37 degrees percolating fuel and bogging down. I've since fitted Edelbrock RPM performer heads which made a monumental change. It now breathes easy and revs like a small block. we think it should do between 13.5 and 13.2. This is why the Plymouth isn't going to a very get a hard time.
You'll be pretty happy with the smoothness and low-end punch out of the box, but squeezing the best economy out of it needs a bit of skull-work. They set them on the rich side so you can bolt it on to pretty much anything and it will work.
Thank you Gerg. My main concern was to make sure I'd selected the right size carb. Sounds like the Demon should meet my needs apart from that accelerator pump issue. The carb fits on the spread bore Wiand twin plane without fouling the secondary butterfly and it looks like it fit under the bonnet but it'll be tight. My cam has .454 lift and 110 LSA (Comp cam 268H) It will run a DUI dizzy so the combo is a bit milder than yours. It won't see much hard driving other than the occasional "squirt". The car only weighs 1335kgs even with the V8, so the combo should work well. 318s were almost strangled with the 2 barrel carb and respond well to being able to breathe. So thanks again this info is invaluable.
G'day mate, love the Mopars, maybe start a build thread in Brothers From Other Mothers.
A mate has a stout alloy headed 408 stroker in a VK Charger punching out 530hp at the crank. It gets along nicely I must say. Before that, he had a bog-stock 318 with a 4-barrel bolted on. It was a bit of a chugger. All bark and no bite.
Regarding the carby; even after tuning, I still have some issues with how well it does some things. Although it's been 2 years since turning a wheel, and you do forget a lot in that time, I can remember that cruising was great, WOT was good too, but it still had the occasional flat spot on acceleration off the mark.
I pulled the accelerator pump apart and found that the cup seal on the pump plunger is a bit flimsy and sometimes didn't seal, so I stuffed an o-ring inside it to try and give it some preload against the bore wall, also putting in a stronger spring to try and build pressure more quickly in the chamber. Both fixes were only partially successful. The squirter still has an occasional delay when first hitting the accelerator. I think the circuit also suffers from drain back.
The stupid thing is that this was a clean-sheet design, where they could easily have used a Holley-style diaphragm pump that's tried and proven. Demon is even owned by Holley, so that would be a no-brainer. But no, they re-hashed the Thermoquad pump that is clearly flawed in this instance. They used other Holley things like secondary jets, electric choke, squirters, etc so I dunno what they were thinking.
Another drama you may come across is the fitment to a standard Mopar manifold. The Thermoquad was a spread-bore pattern but this Street Demon, despite having uneven primary/secondary bores, uses a square-bore pattern. So you'll need to run a spread-to-square adaptor, which on some cars will give hood clearance issues.
To avoid these dramas, you could opt for a refurbed Holley spreadbore that would bolt straight in place of your Thermoquad.
Don't get me wrong, I love the Street Demon but they could've done a much better job, being a new design and all, they had the opportunity.
My 302 is very mild in the scheme of things. 204/214 cam, around 0.5" lift, 112 LSA. Tri-y headers, cats, 2.5" twins with x-pipe. Heads have been skimmed about 0.040 (estimated) from stock so that equates to about 10:1 comp. Ports were tidied up by me, just a bit of bowl and guide work is all, mostly inlets. 3-angle seats, stock valves. 115lbs springs on the seat, stock rockers for now.
Flywheel has been shaved by 1.5kg from stock. It buzzes to 6000 no probs since the heads went on, so I'm predicting (once back on the road) that it will have a bit more pep than before. I'm also running an MSD Programmable with a map sensor connected. All through a 6-cyl T5 box.
Hope this helps paint a picture of what kind of mild small block the Street Demon is suited to.
Moparmartin got a reaction from gerg in Holley Street Demon 1901