Hey guys...I'm gettin ready for some 1/4 action and need some info. The thing runs 6.70s in the eighth goin thru about half of 3rd gear. Granted its just got the 210s in it and the 308s never did any better,it lays down about 6200,I shift at 5500 in 1st and 2nd and gets to about 6000 thru the lights. I am about to put the bottom end together changing compression from around 10 to 1 to about 12 to 1 ( advertised 12:1 flattops with around 58 cc chamber) so I may get some upper end back. I wont be changing the cam till I get alum heads,just to get the bottom end broke in so its one less thing to worry about when the heads go on. Is going from a 28 to 29.5 " slick gonna help any or should I go to a 3.90 from a 4.10? I know before when I would run 1/4 I was using all of 3rd gear ,shifting right at the 1/8th mile,I dunno maybe I can hold out 1st and 2nd longer now and use 3rd for the rest of the way. Whatchall think?..fish
Still Sprayin' Right? I would say staying with the same cam and having the same airflow/rpm restiction, drop the gear to 3.90's or even 3.73" and go to a 30" tire. The nitrous tuned in right will still give you a brutal 60ft if the converter will work right. What converter are you running. YOu really need a tight converter to keep it from slipping at the rpm you are running with nitrous. Low rpm is hard to get a converter tightened up where it needs to be. Do you know what rpm your converter if flashing at on nitrous? THe only way you would know it from a data log or playback tach.
Dont know what it flashes at... But my convertor guy is real good,and we get along good...he will go thru it and tighten it up if I need to while its out. What do ya recommend,Rick? Ive got no problem gettin 29.5 x10.5 mickeys on the car,I figured Id need em anyway. I will be changing the cam when I get the new heads ( Bulldog or TA)...what am I in for on valve train..roller or solid..is it worth it? thanks for the help Rick...I really appreciate your input..fish BTW hell yeah on the nitrous,ya kiddin?lol
Fish I would stay will a flat tappet.A roller costs way to much for the gain received.Have the cam custom ground by Scott Brown (Straightline performance),Jay Allen(Camshaft inovations) or Cam Motion.These guys are on the cutting edge of cam design and make big power. For the convertor You will need to keep it tight like Rick said.What does your present convertor flash to on hp?Do you have a clue what it goes to when you hit the can? Honestly I would wait to mess with the convertor until you have the new cam and heads so you can match the combo.I hate pulling the trans more the I have to.
Head Retard.... I'm with H.R.. Go with 3.73's and the 29.5's. you need all the help you can get keeping the rpms's down. THe compression won't give you any more rpm. It may even drop the amount of nitrous you can push thru the motor. WIth the stock bottom end stay away from a lot of compression. It will be just that much harder on it and give you that much less room for error. Lower compression is much easier to tune.
This is the present plan.... get the new engine built,keep the current cam in it (210s) just for one less thing to break in,convertor..it flashes around 3500 ( nitrous is on from the line)..do I tighten it up? Its no problem with it out right now..if so,how much tighter..another option is a 9" convertor my guy offers..is this a better way? I went with 12:1 compression hoping not to have to spray it as hard as before. Buying a new set of tires is not a big deal either. Id like to think the alum heads wont be far away,so the less changes I'll have to make then the better. I agree the roller is expensive stuff,Id rather stay away from all that. I really do think with a few tweaks above it should go thru the 1/4 just fine with 3.73s. I appreciate the help..it wont be long before I get to test these ideas..till then... :beer ...fish
A 9 inch convertor will most likely not lock up on the big end with the bottle flowing.A good 10 will be the ticket. If your present convertor flashes to 3500 on hp on the can it will be 700-1100 rpm higher maybe more depending on how it was built.Just a guess I think a new convertor would need to be around 3000 on hp therefore it ends up around 3800 approx. on the can. 3.73 sound good for a starting point but don't be afraid to swap gears to find the sweet spot.
It will help to get a transbrake if you don't already have one. I take it you have a 10" right now? Just make sure if you get it adjusted that they take some of the "hit/shock" out of the converter so the nitrous won't be so violent. 10" converters can be brutal on the launch with juice compaired to a 8 or 9". I don't think 12.0 compression will change how much your going to need to spray it. I think it will pick up on motor but on spray you won't be able to spray as much which may work out just fine. Guess you'll have to try it to find out. How much could you or did you spray before before it stopped going any faster??
The heads are the bottleneck As good as they are,Ive come to figure it out.When I had the 308s in there it didnt do anything different than the 210s. What transbrake is a good one..never had one. I'll get some 3.73s on the way,and some 29.5 s too. Think I need to tighen up the convertor? Rick,the last time I sprayed it was the 2nd step of tuning the double cross..first was 40 squared with 5.5 lbs of FP,29* timing,900 lbs BP. Second step was 46 squared ,27* timing,950 BP,5 lbs FP...this came about after tweaking on it some..found it liked more bottle pressure and less fuel pressure,timing didnt really matter but I take out alot to be safe. I'm pretty sure I pinched a ring and lipped the junk pistons..it was going faster every pass ending with a 6.72 with the piston going away. I figure I'll probably be going on up to 65 jets in the double cross as long as stuff looks good. What kinda ring gaps should I be using on this motor...its got 4.35 bore with wiseco's..Ive heard about larger gaps on the second ring...Ive been recommended .030 on top ring and .035 on 2nd ring..whatchall think? Thanks for the help,its gonna be finished soon...fish
Hmmmm.. Well if that second ring gap of .035" is the "new trick" thats news to me. Sounds like way too much! .030"-.032" top will work. I want to say my second ring was .016-.018"?.. Its been a while. Limited heads or not I would go with a little bigger cam like a 230/245 116 or 112 LC cam TA sells for a good temp hydraulic cam. Just install it 6 degrees advanced? (cylinder pressure would be too high) You need a 11" converter to work with that 112 TA cam. :laugh: I'm going to say you can NOT run 12.0 comp with that 112 cam AND try to spray nitrous to it. It is even too much for a 230 duration intake timing. YOu won't be able to or have a hard time keeping head gaskets in it. Also if you don't have the ring lands down .300 on those Wiescos they will eat a ring land too with the cylinder pressure you will be pushing. The cam will make too much cylinder pressure to even run like it should on motor. Don't look at the cam rpm as the whole picture. It's where the cam makes it's power at and the rpm your motor sees going down the track even if your shifting at 5200 or so. Its not that the bigger cam will make much more average power but it will have more power in the right rpm range. Holding 1st and 2nd longer won't change the rpm you go thru the trap unless it is slowing you down. An easy way to get the cylinder pressure down is to go up a bit on you head gasket thickness as a temp fix until the Aluminum heads. You can retard the cam but it will hurt more than help and wouldn't be the right fix. What cc's are your iron heads?? How far will you pistons be below the deck(i'm guessing .005 since they are advertised as 12.0 pistons). What gaskets will you be running? If your iron heads have 66cc's and the pistons have 10cc reliefs, your looking at about 11.92 with .040 gaskets and .005" below the deck on the pistons. If your stuck with the compression then try something like the 242/250 115 LC TA cam installed 2 degrees advanced. This should keep your cylinder pressure in the lower 200psi range. Also you can also run a .075 gasket and that would also drop your compression 1 point. I'm not try to tell you that you can't build it the way you are but giving you something to think about before you get any further into it. I never ran a th400 transbrake so I don't have any first hand experience. I would think any of the big name trans companies would offer a decent transbrake. A Griner brake is suppose to be one of the best but it also carries a $700 price tag. :shock: I hope I didn't give you too much to think about. One more thing, being you spend a good bit of time below 5250 rpm's, the nitrous shot may be, say, a 200hp shot but the torque will keep going higher the lower the rpm's go below 5250. HP is Tq x's RPM. So your 200HP shot at 3000 rpm is 350 TQ.
More nitrous stuff.... Cross bar plate setup.... try this site for some nitrous info. :Brow: http://www.americandragracing.com/xmb1/forumdisplay.php?fid=26
Cam If you think the little cam will hurt it,I'll change it. I see the cam as the "baby" cam,I was gonna break the motor in with it,make some 1/4 passes on HP,then start with the nitrous. I can call Scott Brown and have him grind me a n2o cam for my setup to do what I want it to do. I was planning on puttin a pretty thick headgasket on it coz the heads have been milled a little bit more than .100. They are 67 400 heads with stage1 valves...maybe in the 60cc or maybe less cc range. When it comes time for heads theyll have 72 or so chambers. Maybe I should just wait and buy heads before I do anything at all,might be the smartest thing to do. I was just kinda curious just what the thing was capable of with iron...on to the next brainstorming session..thanks for the help ya,ll...fish
Cylinder Head Flowing Theres a guy here in Lexington that said he could flow my heads. Ive never had this done and I reckon the obvious numbers will be flow off the seat mid lift to .600 or so intake and exhaust. Im going to have the fella CC the heads too. Looks like I'll probly have to use a cometic head gasket ,just will depends on chamber volume.Is there anything else that yall would recommend having checked while this is done? And how do I get in touch with Scott Brown after this is done?..thanks ..fish
You will need the flow #'s it would also be good to find the actual cc of the intake runner and cross section.While at the guys shop you might as well cc the cambers therefor you know what you got. Scott Brown racemufflers.com Jay Allen camshaftinovations.com
Thanks for the info Kevin... I'll get as much info as possible from the guy for the cam to get ground. I reckon I'll wait til after the heads get flowed to do anything to the convertor. Hopefully I can get the most from the iron heads to be happy for awhile. The alum. change-over is gonna take some big money,and I want to make sure I get the right stuff the first time so I dont waste money. Itd be nice to use the Bulldogs if I can use my existing intake and headers. I have a fella that will trade his 3.73 gears for my 4.10s so thats less I have to worry about and I actually have a set of 30" tall tires,but theyre old MT ET Street 12.5 wide tires,so they may not work enough. I'm just want my 1st 9 sec timeslip,thats all this is about...thanks for all the help guys..its gettin close...fish :beer
