head work?

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71violet

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Hi everyone. My first post here, very impressed with the tech info and attitudes on this forum. I have a tech question for my small block. It's in my E-body but don't boot me because I have a real 71 340 Duster that's getting closer to completion, well, I offered it to my brother and am helping him finish it. I'm in the pursuit of some low-buck power if it's there because there's an SRT4 in town with 25 pounds of boost that I don't want to get spanked by (if it hasn't exploded by the time the snow's gone) .Anyways, I'll list the specs of my engine then ask the question.
73 cuda , full interior
360
stock iron heads (don't know what they are but not magnums)
KB 107's
purple cam part #4452992 (280advertised/ 474lift)
ceramic coated Hedman headers
RPM intake
Demon 750 carb
MSD 6AL
727 with shift kit, stalls at about 2,500
8 3/4 , 3.91

It goes pretty good (mid 13's I'd guess) but I'm thinking it would be worth porting the heads. I've done a bit of porting, with positive results, so, assuming that I do a decent job blending the bowls, valve guide bosses and gasket matching. What kind of hp gains MIGHT I expect? I won't hold anyone to it, I know there're all kinds of variables, I'm just talking an estimate, a range even. It seems to me the heads would be holding this combo back and I would have alot to gain. As a bonus I can do it at work on night shift and get paid for it :eek:) Trying to confirm that it's worth the effort.
Other tricks up my sleeve to smoke that Neon: (can't believe I even said that sentence, no offence to Neon/srt-4 owners but it doesn't seem right lol) I know I'll kill him off the line and think I can do better yet with traction bars and stickier tires. Will also have sub-frame connectors on by spring. Thanks in advance!
 
Welcome.I dont know what gains you will have, but dont use traction bars get a pinion snubber.
 
I'm sure it would be easier to speculate if we knew what heads you are running now, casting numbers, valve sizes, etc...

How's the weather up there in the great white north?
 
your going to need to know what heads first...even then though, it may be hard to speculate since it depends on how intense the port job is

oh, and dont put trac bars or a snubber....get yourself a good set of springs...either superstock ones, or clamp up the fronts on the ones you have now on the front segment and unclamp the rears...that should do the trick...trac bars are for chevs and fords since they didnt have the tech built in like the mopar designs
 
IMO, a pocket porting with what ever valves you have will result in a small gain but a nice one. I'm not screaming half a sec. or better, but, alot is also inthe rest of the combo.

You stall is low IMO
S/S springs and a adjustable snubber, not the MP unit

Also, the cam is a 13 second cam. Your in the ball park of the cams design.

What is the Neon running. By the way, there no joke since the weight to power ratio is well in his favor. If you know what the Neon runs, truly runs, we can set you up to run faster. (If you want....)
 
weather ain't too bad here lately, -10 C lately for a high. So no traction bars eh? I had an extra leaf but took it out to get the stance I wanted (low with 17"). It has never wheel hopped but thought it might with a little more power and more traction. I'll try to get some numbers off the heads tomorrow or Monday (motor was built when I got the car) Always been a Mopar nut but never really had my hands "in" one, just chevy's. Don't have a problem camming it up from what I have if that's what she needs. Next size up in the purple shaft line or a comp stick? Want to stick with hydraulic lifters and stock rockers for now (but rockers are a possibility too.)The Neon has supposedly run an 11.7 with slicks, and I don't have to beat it, but that thought has inspired me to get tweaking on the fish. The converter I don't want to change so goin up in the cam will still work for this combo? Edit here: the neon (srt4 as he prefers it called) will not have very sticky tires, he doesn't seemed concerned 'bout that. I rode in it and it goes like a scalded cat, but not off the line.
 
watch out for those SRT 4's, they can really fly...one guy here was takin all the muscle cars to camp spanky with an srt4 neon at pinks- he actually ran too fast and got eliminated...your right off the line you'll eat him, but once he spools up he's gone (my buddy Tom in his 11 second T/A didnt know what hit him when that mopar 4 banger creeped up on him lol)

that cam you have though is like rumble said, not much better than a 13 second cam...id go with something that has atleast .500 lift at the valve, but keep in mind if you go with a bigger cam your probably gonna need a different converter to optimize it

and there's more et to be had from things like chassis and weight, so look into that stuff as well
 
keep the info coming guys, I'm taking it all in. I tried to get a casting number off the heads, all I could get was a 4 digit 1701 on one runner, a 360 on another runner, 3 digits on another runner, too hard to make out but something like 15C ?? Do these mean anything? Do I need to take the rocker shaft off just to get the number? Didn't feel like pullin that cover off this a.m. after a nightshift but I'm sure glad I did. Sweet surprise! Aftermarket rockers (they aren't in the receipts I got with the car) Maybe these red springs are aftermarket too? Bigger cam is more feasable now. I'll try to post a pic of the rockers. Crane?
download
What would my compression ratio be at with the KB107's assuming zero deck?
 
The car runs ok, but you have a bit to go there even with the parts you have. If the Cuda is the typical 3600lbs with you in it the engine should be making around 350hp as it sits. That would put you closer to 12.90s if it was set up properly. My question is what is not working right? If it were me the first thing I'd do with an unknown engine is to take cylinder pressure readings off it, then pull a cylinder head. The reason being you have to know where you're starting from. I think the cam probably isnt the best, and the pistons are most likely not set to the right deck height. So the engine is lazy. So that's what I'd do. I'd bee looking for (good) pressures around 160psi. If it's lower, either the cam's off, or the pistons are in too far down in the hole. Easy fixes in both cases. You can also check the quality of the valve job. Becasue stock heads with a good valve job will make more power than average heads with porting. Porting should be the last thing you do. I dont think the convertor or rockers eed to be changed. And I think if you put traction bars on it most other Mopar owners will know you like GMs...lol. Put the leaf back in, by the multi-hole front spring brackets, and use the higher hole to drop the rea. You may need to shim the hell out of the axle to get the pinion angle back in line but that's no big deal. Then set the snubber properly and you'll get more of a jump on the Neon.
 
yup can do comp. check. I really don't think it's lacking any power for what it is. I've had a few cars in my time. It's only got a few thousand miles on it, I can only launch about 1/2 throttle for the first few feet, spins a bit hitting 2nd. That's with the 17" tires, the 15" Eagle tires would just spin all the way through 1st and into second (trying to leave easy then nailing it). I'm hoping it was decked. I've never had it on the strip, just estimating the 1/4. I know amount of tire spin is a silly way to judge power, It just feels it's working well. It pings on anything less than 91 octane, I think the timing is at 34 total (couple years ago I set it). But, absolutely before tearing it down I can make sure it's healthy. got it on the traction bars LOL, wouldn't want anyone to think that. Pinion snubber is inexpensive and simple. I assume you can cruise around with one and not have it bottom out, while it can still do it's job on the launch? Any info on what my heads are from the info on my last post?
 
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