SalikDDD

well, i'm posting in here again since most of you guys are more engine orientated than most in the classic section.

heres what i'm running

331 stroker 9.5-6:1 compression
edelbrock performer rpm heads
edelbrock performer rpm intake
1" 4 hole spacer
Holley 670 street avenger (70/73s, lightest spring blue pump cam #2)
headman longtube headers
comp cams xe276hr w/ 1.6 rockers

running in a 67 mustang w/ C4 - 3.73 rear / 2800-3000 stall with traction bars etc. blah blah

i cut a 1.8 60' time with the bars after a good heat up of the tires, launched at around 1000-1200 rpm and shifted @ 6000.

track died later on so i was hitting 1.9's and 1 2.0 but still ran a 12.65 @ 108, 12.7 and another 12.6 all at the same speed.

i cannot get off the line with any more rpm's it will just light the tires up, i run 275/50/15 bfg drag radials with about 20 passes on them and i do a healthy burnout. tires are at 10-12 psi.

now my main thing is, i have a cam that was designed for 1.7 rockers. if i moved to the 1.7's am i going to gain anything that i have lost, and also if i moved to a open hole spacer instead of a 4 hole?

i'd think my car would be making more power than what the times tell me, my car is 2982 lbs with me in it. - so any help would be appreciated before i dump some money into rockers or anything if it's not gonna make a diff.

67mustang302

What do the plugs look like. I always get back to the same thing and no one wants to listen. Take pictures of the plugs and post them, they'll tell you what's going on inside the chamber. It doesn't hurt to invest in a scope(like a doctor uses on your ears) or borrow someone's to look at the very base of the porcelain insulator where it meets the plug, you should have a visible greyish ring about 3/4-1 full turn or wrap around the base.

Yeah, going to the 1.7's will prolly be worth a bit of power since you're getting more lift and the cam was designed to work with them. But make sure the tune is right first before you start chasing other problems, you'll just end up going in circles. Once you know the tune is correct, THEN you can start worrying about where a potential power loss is or traction.

Keep in mind too that you can tune some of the throttle response and low rpm power out of the carb to help with the 60's of you so choose.

maroon89lsc

ive heard that they run best with 15-20psi the tire i mean,have you tried to run them that high in psi?do you have your traction bars adjusted.do you also have chassis stiffing stuff like subframe connectors or a 'cage or any thing of that sort?

SalikDDD

ran em at that high of a psi also. tried all kinds, it burned em off with the old 289 running 14's and the 98 burns em off also no matter what psi.

plugs are perfect - which is why i never mentioned them. if i'd of thought they'd be a problem i'd of said so, but since it's spot on i never bothered. we thought it'd be running lean at the top but that's not the case either, pulls steady fuel pressure all the way through - even went through a jaunt down the track, shut the car off and pulled em. - had fatter jets in the rear and it blackened em. so we got it all worked out.

mjr46

well I see a few things that may slow you down and please don't take offense to any of it, 331<347 go with the xe 282 cam , 185 heads, rpm intake is okay..I have the air gap and a 650 dp carb, with that set up above I'm running 11.50's @118+ but I do have a friend with a 347 with a similar set up in comparison to yours running 12.30's @108-109ish on a c-4 with 3400 stall, et drag radials may help you out but with only a trap of 108 it'll be hard to dip lower than low 12's, how's your suspension???

mattdel

i'd consider a trans brake. 1000-1200 is a low launch RPM. 2k launch would put you in 1.5 60's i'd bet

67mustang302

Just because your plugs "look fine" doesn't mean everything is fine. Almost everyone who thinks they know what plugs should look like, has no idea what the heck they're looking at. No offense. By looking at a plug you should be able to tell idle fuel, total timing, heat range, low rpm/part throttle fuel ratio, mid range and WOT fuel ratio. You need to know what part of the plug to look at and what you're looking for. Blackening plugs on a single run for instance, indicates a WAY rich condition. A single pass down the track on a brand new set of plugs, they should still look brand new when you pull them, aside from a barely visible fuel ring that you can only see with a scope, and a very minor coloration change that will indicate timing and heat range. It's making decent power with a 108 trap, but I'd be willing to bet you're leaving some power on the table.

Also consider engine internals. The choice of rotating assembly will effect how quick the car is. Piston and pin package weight plays a huge role in engine performance. Did you use a heavy cast piston or a light forged piston? Is the crank heavy? There's a bunch of things to consider. It might just want to be shifted at a higher rpm as well. Best average power may put you shifting at 6,500 and not 6.

mjr46

...more like 5k!!!! with a 5k launch and no wheel spin I cut a 1.55 60ft

SalikDDD

i can get off at 2k+ but it boils the tires off is what i get at also.

suspension is stock 4 leafs in the back, 66 289 springs in the front with some tockico or some **** struts - traction master traction bars, whole motor is forged. crank, rods, pistons etc. so i dunno, lot of people said just go to 6 and let it rip so.. also i've been kinda wuss to run it to 6500 anyway lol

guess these BFG drag radials are just *** for 60' times

also the heads were ported so i bet they flow more than their 170cc originally did but when i called comp cams they were like 'blah blah do not go over a 276hr for a street car etc blah blah blah' so.. i went with what they told me lol :/ damnit.

SalikDDD

if it's better in the long run to get a 282 instead of buying the 1.7 roller rockers for this thing then let me know, the car gets driven almost every day and has great street manners.

i also forgot to mention... plz don't laugh..

i run a 2 1/4" exhaust.. haha - i was thinking of going to 3 but i don't know