honestly im embarrassed to say....it was 13 something on motor cant remember ET, on those the slips are qat my shop..i've ran faster in stock 302's lol. it was just BRUTAL...so i re-jetted and changed plugs then sprayed it to run some 11.5's @ 115 where my car should be atleast on motor.
Was that with slicks or drag radials,what size tire and gear are you running?That combo should run 11,s depending on drive train.
You should also keep in mind that the air-gap is/was originally designed for 302 inch motors well before the strokers really got popular so it's airflow potential will be limiting without some port work. It's also designed(as all these 180* designs are intended) for smaller camshafts. A large 2' open spacer would be absolutely mandatory to help band-aid this plenum starved combo. Now I'm not saying that there aren't plenty of folks running some good numbers with a dual plane.. but in most racers minds they're only ever intended for use as a intermediate street/strip type setup with stock displacements and cams up to about 230-240*@.050. Then put some decent AL heads on and you may as well just block off one of your 4 barrels since it becomes near useless. Plenty of tests floating around the internet and drag strip combo's that will teach you what you're giving up here. If you have even close to a decent rear gear.. and especially if you do.. this car is light(point being.. heavier cars run better numbers with a dual plane and light cars just simply don't need em' for the strip) I'd be using no less than a Vic JR with this combo. Extended rpm range and power awaits you.
lol.. well.. I guess it's totally unanimous then. Valve float it is. But that still takes us back to my #5 point above. Is this a roller cam.. or flat tappet? Roller should have at LEAST 150 lbs on the seat with 160+ being even better. Flat should be at least 135lbs. Otherwise.. well.. you know the rest. Ti retainers will give you another 300-400 rpm before the same thing starts to happen all over again. If it is indeed valve float?.. step up to a beehive setup(MUCH lighter retainers even in steel and light as a feather in Ti).. and/or move up to stiffer springs.
it was on 26x8.5 M/t slicks. and 4:10 gears..i also expected 11's on motor. The cam is a Flat tappet.
I googled your cam and 2 things immediately stand out to me. 1st. You're using an XE series cam with fairly aggressive ramp rates and adding rocker ratio only makes them more aggressive. This can and often does cause valve springs a tough time keeping up with things. 2nd. You have a hydro flat cam with standard style flat lifter which are notorious for pumping up well past 6,000 rpm. Add these 2 things up and you're likely overtaxing the springs ability to keep up with the lobes and rocker ratio which then allows/causes the lifters to pump up and stand the valves off the seat. Step up to stiffer springs and/or Ti retainers and watch the rpm capability rise. Also.. and not to sound like a broken record here.. running a dual plane with those shorter gears and this big'ish cam is leaving some ET on the table. You flash right through the meat of a dual planes gain in 1st gear that its potential gain is being limited to just the upper gears. Put a Vic JR on that motor and gain 20 horses and another 500 peak rpm. What rpm you turning at the stripe?
i've been trying to find a used Vic jr for a few months now, don't feel like buying a brand new one..might have one lined upi find out monday if he still has it, i cant remember what rpm i was turning across the line but it was on the verge of valve for sure...i've already have 3 sets of springs here taking up space..buying another set is just going to make me angry. but it does seem like the most logical thing due to the fact the valves are floating..
Word of advice. Sell your other cookie cutter springs and buy these. The 1.8 installed height will fit the RHS heads valve height(+.100 length) perfectly. The retainers are most likely under half the weight of your existing stuff. I use the Ti springs too which makes them killer light. "Zoom zoom" ain't just for Mazda's if you catch my drift. http://www.compperformancegroupstor...reen=PROD&Product_Code=7228-16&Category_Code= I and a few others that I know absolutely love these springs and they'll likely outlast the motor itself plus they can take over-revs till your cam/power band runs out completely and you nose over the cliff. Downside is that there is no damper to act as backup if a spring breaks. You'll still bend valves and nick up piston crowns.. but at least they might stay put to keep you out of major damage. They're still relatively new bit I haven't heard of anyone breaking one yet though. Unlike the beehive's which many including myself have broke through the years. PS. The manifold above is much more similar to a Super Vic than a JR. You'll end up just a tad softer down low and in the mid-range that the JR would be on that combo. I have a knock-off like that one and the cross section area is huge with heavy taper. Plus.. they need clean up and port matching to get along well with the heads port entry. On the plus side.. no spacer would be required with the size of that plenum. The Vic JR would still likely respond to a 1" open without softening the bottom up.
My Spring rates are 121 @ 1.8 and 343 @ 1.2 the ones you listed above are; 136 @1.800" 412 @1.170 Is that quite a huge difference in rates?
Those springs are fine for a traditional ramp design but not even close for your setups valve acceleration characteristics. The difference is ginormous when you consider that those ultra-light mass springs can EASILY rev past your existing 1.4x" even if they had the exact same spec. Then figure you'll add 10% greater spring rate added with the new ones(and they'll also be much lighter too) and it's easy to see that they will more easily stay up with your cams aggressive ramps and the increased rocker ratio. Plus.. you'll gain power everywhere too. I've had up to 1.8 ratio rockers on a 288 XE roller and you need LOTS of extra seat pressure to keep them from bouncing off the seat. Some more extreme environments can even cause lofting too. Not good for valvetrain life or power. At the very least.. get some 1.5x dual springs with the lightest retainers you can top them off with. The other thing to keep in mind is the bleed rate characteristic of the lifters you're using here. Even with better springs.. they may not like going much past 6,500 anyways. Don't get me wrong here.. I do firmly believe that you have valve control issues going on here and lifters standing valves open is the secondary effect.. not the primary. Just saying there may be limiting returns up towards 7,000 rpm. PS. I beleive that I have some small steel beehive retainers(same design/part # that the conicals use) that I'll sell you cheap as an early x-mas present if you do decide on the spring swap.
Installed height is 1.8 with the springs I have, could I not shim them down to say.. 1.7 and get more psi?
Groberts is correct,that intake will be a dog for what you want to do,also you will have to ck the cam centerline.You are probably going to have to retard that cam to move the revs up.That`s a pretty decent cam & from what I`ve been researching lately on stroker mtrs you want to get your intake valve to close around 60degrees to get good cyl fill.Stepping up to that 750 & better exhaust will make a huge Diff.
I'm with groberts here, there's just too many "what ifs" here. If the OP did the heads, then the cam definitely was not degreed. The heads would have had to been on the engine to degree the cam. The intake is too small too for a 347 to rev past 6400. My 331 is done(pulling) by 6500, but will rev to 7000 with it's dual plane 3x2 setup. It will not float the valves til 7 grand with it's hydro roller Z cam and the springs that came with the Canfield heads. And ditto for the rpm drop with the cam as opposed to a 302 inch motor. RPM range listed for that cam is only a "suggestion" based on several factors, displacement being one factor.
