Whats wrong with my truck?? Too Slow !

[85s10racer]

OK, So last Thursday I took my truck to the track to try and put down some good numbers, but It just wasnt wanting to budge.



First run I ran a 14.72 @ 92mph

Second run was slightly better .

60' ...2.31

330.. 6.275

1/8... 9.482

MPH .. 76.06

1000... 12.303

1/4... 14.713 @ 93.16 mph



Im running a 85 S10 Regular cab Short bed, No interior.

8.8 Rear with 3.73 posi, 26x8.5x15 slicks

327 bored .030 over with 882 heads decked, pocket ported, not sure of the cam but its more than mild, has choppy idle. Im running a Holley Street Dominator dual plane intake with a Holley 650 double pumper. HEI distributor with Autolite plugs and Accel 8mm wires. Trans is a TH350 with 2400 stall.



Whats going on guys, the truck launches with no hesitation and Im 99% sure its not spinning off the line. It just doesnt seem to want to pull hard.

http://www.s10v8.com/images/smilies/icon_confused.gif

[spacecadet]

Just my opionion, I am not a drag racer guy anymore.



The 882's are 76cc which will give you @ 8.5 compresion. which is great for street use on cheapest pump gas. With them angle milled alot they might be as low as 70cc. Which might get you 9.0 compresion with a set of .015 steel shim head gaskets. The porting should have helped if done correctly. Chebys need help on the exhaust side, Do you have headers and free flow mufflers?

[355V8S10Tahoe]

85s, What piston tops are you running with those 882's? Like Space said, those are 76cc chamber heads and you may have a low compression ratio if you don't have something more than just flat tops... The 327's that I've seen before have always had some slightly dome toped pistons in them... I think back in the day, 327's never had an emissions designed head on them either, just a thought, I may be wrong...



On another note, I have a set of 882's that are small valve heads off of a 400 small block that was in a big GMC high lift truck, I think these heads I have are about 78cc (not sure) but what really surprised me was they have tiny 1.72 intakes, 1.5 ex. and a restriction ridge in the exhaust ports, I hope your heads don't have that and if they did, your porting work opened it up... I think these heads I have are just good for boat anchors or very heavy paper weights... http://www.s10v8.com/images/smilies/icon_razz.gif

[85s10racer]

I have flat top pistons, The truck had a set of 1967-68 1.72 inch heads for 307-327 on it when I bought it, I changed them out for the 882 with 1.94" valves from a 1978 Corvette...It made a huge difference, before the engine stumbled and bogged really bad, but now it just takes off and revs really good. Just not running the times it should. As for the exhaust, its headman shorty headers with about 4 feet of pipe that dumps right at the cab/bed gap, with no mufflers.

[Melonhead]

327s are not very torquey motors. The set up may need more gear. What is the RPM at the end of the trap? The double pumper and the 2400 stall may also be fighting each other. Possibly more stall needed. I also agree on more compression.

[Truckman91]

I did a quick calculation of your compression and came out to 7.75:1.



76cc heads, 9cc valve reliefs, .025" deck height, Head gasket bore 4.166, Head gasket thickness .041.

[grimpuppy]

On 2008-02-25 08:13, Melonhead wrote:

327s are not very torquey motors.





327 Is a big bore short stroke motor. That equals no low end torque. You will need to match the cam, torque converter, and gear for optimal times. Most combos can overcome a little mismatch, but with a low torque motor like the 327 it will really magnify the problem. Bottom line is a 2.31 60 ft is not going to cut it. If it aint spinning, then you need more gear and maybe more stall. Or you can go with torque in a bottle (nitrous).

[stonebreaker]

The thing that jumps out at me is the 60 ft time - 2.31 is terrible. That's about what my impala ran bone stock, when it had a 1400 stall converter.



With the low compression you're running, probably the cheapest solution is a cam with less overlap to improve your dynamic compression, although ideally you might want to think about domed pistons, new heads, a stroker rotating assembly or maybe even a supercharger, if the budget allows.



Depending on what solution you pick for the engine, a new torque converter will knock a big chunk off that 60 ft time, too.

[Scotty_S-15]

OK, my thoughts:

* Like Stonebreaker & Grimpuppy said, that 60 ft. time needs special attention. And you're not even spinning the tires? Also, the MPH is down from what you might expect, so, no too good there either.

* So we're sure you have big chamber heads? That does suck, you need more compression.

* Even knowing that the compression is low, the times posted still aren't so good. I'd look next at the cam. I'd degree it, document it all, then review the cam stats. AND, check the lift at all rockers to make sure the cam isn't partially wiped.

* Where is your timing at? And, have you double checked TDC, to make sure that the marker is accurate?

* Or, if the budget allows it, just spring for a new set of heads and cam. With well matched heads and cam, you've got something that'll run low 13s easy, even with the existing converter.

* Sure the 327 will have a little less on the bottom than a 350, but the 2400 converter should put you back on equal ground with a 350 with a 1800 converter.

[85s10racer]

So, I should get a bigger converter? And maybe some 4.10 gears?

[Scotty_S-15]

On 2008-02-25 16:31, 85s10racer wrote:

So, I should get a bigger converter? And maybe some 4.10 gears?



NO! don't mess with the converter, at least not until you figure out what's wrong with your engine. Sure, more converter might help, but it sure isn't gonna cure what's wrong with the engine. And judging from what you told us, there is something definitely something wrong with the engine, or the combination is totally mismatched. Just to reiterate, the heads and the cam are the big question marks. Other than the heads and cam, sounds like a nice setup. Maybe the cam is even OK, we just don't know what it is.

................. And of course the "tune" could be a mile off, which is why I asked earlier about the spark advance.

.................. And BTW, did you mention what your use of the truck is? ........ daily driver, sunny day driver/weekend warrior, or track only?

[wheelspin]

if that guys numbers are right and you have less than 8:1 compression I 'd without a doubt save up and put a blower on it.seriuosly nothing crazy but you have the perfect setup it would really rip then! you can put one of those weind's for under 2k, run about 10-12 lbs of boost. and your gonna hit your head against the back window!

[adh383]

I say less cam--- less carb--more gear----BETTER HEADS-- what are the cam specs?

[85s10racer]

I have no idea what the cam is, I didnt pull it out when I swapped heads.

[adh383]

does it have a good lick to it?

[85s10racer]

On 2008-02-25 22:35, adh383 wrote:

does it have a good lick to it?





Yea, it has a choppy idle

[Melonhead]

A simple idea to see what is going on with the engine is to monitor vacuum. Install a vacuum gauge in the cab and connect it to the intake, not the carb. Have a buddy with you to monitor the gauge while you take off. If i am correct with combo you have the vacuum will die under a load and come back at the top end. That is because the secondaries are opening too soon to allow the engine to maximize the fuel. All you are doing is slowing down velocity of the air charge on take off.

[Scotty_S-15]

On 2008-02-26 07:19, Melonhead wrote:

A simple idea to see what is going on with the engine is to monitor vacuum. Install a vacuum gauge in the cab and connect it to the intake, not the carb. Have a buddy with you to monitor the gauge while you take off. If i am correct with combo you have the vacuum will die under a load and come back at the top end. That is because the secondaries are opening too soon to allow the engine to maximize the fuel. All you are doing is slowing down velocity of the air charge on take off.



A good point. That's why I'm a big fan of vacuum secondary carbs..... when set up properly, there is only as much carb as the engine needs, never too much.

.......... But I'm thinking it's more than something that simple, mainly because the 92 mph 1/4 mile speed indicates HP is down even in higher RPM ranges.

[Melonhead]

Thanks Scotty http://www.s10v8.com/images/smilies/icon_biggrin.gif http://www.s10v8.com/images/smilies/icon_biggrin.gif