[SD455DJ]

Dan and I finally had the opportunity to run the ’70 Tempest with the XV code 400 (330 hp/430 lb-ft torque) at the May 12 & 13th F.A.S.T. race at Martin US-131 Raceway Park. This is the first time it’s been out in public since I got the car 4 years ago (already!), also the first time on the dragstrip, so, we were pretty excited and nervous how it would perform. The engine was dyno’d over 2 ½ years ago, so, after a quick once over of the fluid levels, bolts, lugnuts, brakes, fuel lines, hose clamps, double checking the timing (36 degrees all in by 3200 rpm), and pumping up the G70’s to 40 lbs. all around, we were ready to race. Oh, we added 6 gal. of 110 leaded race gas ($72!!!) to the 14 gal. of Shell 93 E10 ($5.10/gal.) just to guard against any potential detonation as it was 88 degrees both days! We left the carb jetting alone from the dyno session (73 jets/43 rods primaries & CG (.0774M tip) secondary rods on a ‘K’ hanger) and never touched again over the next 2 days (plugs read great each day). The 3.42 gears are definitely not ideal for racing (went through the traps at around 4900 rpm), but it is a street car, not purpose built and/or optimized for the pure stock drags…however, 3.73’s or 3.90’s would be much better suited for the track.

The three best passes were 13.1843 @ 103.88 mph, 13.2045 @ 103.09 mph, and 13.2182 @ 102.90 mph in the oppressive heat with OK 1.92 – 1.97 sec. 60’ times. The worst times were in the 13.40’s when the line was slick and spun hard. It was fairly low humidity on Thursday, but shot up on Friday. I heard that the DA’s were 2200’ on Thursday afternoon and over 3500’ on Friday afternoon (unsubstantiated – maybe someone could verify?). Regardless, we are very happy with the cars performance, right where we were hoping it to run.

Another surprise was the weight…3815 lbs. with me in it…way heavier than I was expecting…by 150 lbs.! So the AMA weights are real close for this car as optioned (3643 lbs. + 165 lbs. (me) = 3808 lbs.) with a full tank of gas, no spare tire though (in the trunk that is…not my waist). It’s still 300 lbs. lighter than my ’70 RAIV/TH400 Judge (OPH – Roger – you were right on with the weight!).

We’re quite confident with some further sorting out of the suspension (pretty stiff and little to no front end lift) and cooler weather, it could run high 12’s. The lower mph is indicative of the small valves (lower air flow) of the heads, the log exhaust manifolds with the 2.1” outlets, and fighting the 3.42 gears. But, it was a blast getting back on the track as it’s been since 2007 (15 years) the last time I raced in the pure stocks (or anything for that matter!).

Dennis

[will slow gto]

Originally Posted by SD455DJ

Dan and I finally had the opportunity to run the ’70 Tempest with the XV code 400 (330 hp/430 lb-ft torque) at the May 12 & 13th F.A.S.T. race at Martin US-131 Raceway Park. This is the first time it’s been out in public since I got the car 4 years ago (already!), also the first time on the dragstrip, so, we were pretty excited and nervous how it would perform. The engine was dyno’d over 2 ½ years ago, so, after a quick once over of the fluid levels, bolts, lugnuts, brakes, fuel lines, hose clamps, double checking the timing (36 degrees all in by 3200 rpm), and pumping up the G70’s to 40 lbs. all around, we were ready to race. Oh, we added 6 gal. of 110 leaded race gas ($72!!!) to the 14 gal. of Shell 93 E10 ($5.10/gal.) just to guard against any potential detonation as it was 88 degrees both days! We left the carb jetting alone from the dyno session (73 jets/43 rods primaries & CG (.0774M tip) secondary rods on a ‘K’ hanger) and never touched again over the next 2 days (plugs read great each day). The 3.42 gears are definitely not ideal for racing (went through the traps at around 4900 rpm), but it is a street car, not purpose built and/or optimized for the pure stock drags…however, 3.73’s or 3.90’s would be much better suited for the track.

The three best passes were 13.1843 @ 103.88 mph, 13.2045 @ 103.09 mph, and 13.2182 @ 102.90 mph in the oppressive heat with OK 1.92 – 1.97 sec. 60’ times. The worst times were in the 13.40’s when the line was slick and spun hard. It was fairly low humidity on Thursday, but shot up on Friday. I heard that the DA’s were 2200’ on Thursday afternoon and over 3500’ on Friday afternoon (unsubstantiated – maybe someone could verify?). Regardless, we are very happy with the cars performance, right where we were hoping it to run.

Another surprise was the weight…3815 lbs. with me in it…way heavier than I was expecting…by 150 lbs.! So the AMA weights are real close for this car as optioned (3643 lbs. + 165 lbs. (me) = 3808 lbs.) with a full tank of gas, no spare tire though (in the trunk that is…not my waist). It’s still 300 lbs. lighter than my ’70 RAIV/TH400 Judge (OPH – Roger – you were right on with the weight!).

We’re quite confident with some further sorting out of the suspension (pretty stiff and little to no front end lift) and cooler weather, it could run high 12’s. The lower mph is indicative of the small valves (lower air flow) of the heads, the log exhaust manifolds with the 2.1” outlets, and fighting the 3.42 gears. But, it was a blast getting back on the track as it’s been since 2007 (15 years) the last time I raced in the pure stocks (or anything for that matter!).

Dennis

Wow, 13.2 @ 103 is really moving for a car with logs, 3.42s and a 2800 cam. You guys sure know how to squeeze every last drop of performance out of these stockers. Bravo!

[SD455DJ]

Originally Posted by will slow gto

Wow, 13.2 @ 103 is really moving for a car with logs, 3.42s and a 2800 cam. You guys sure know how to squeeze every last drop of performance out of these stockers. Bravo!

Thanks W.S.GTO! If we built the 400 to the max the pure stock rules allow, I could run as much as 11.5 to 1 compression (1.5 over advertised 10.0), and any hft cam (actually have a 2801 in it now) that maintains 16 in. vacuum at 1200 rpm (changing to 18 in. this year). Higher compression would allow a bigger cam to maintain 18 in. vacuum, so possibly the 2802 could work, but I think the small valves and log manifolds would be corks (with the 2802 cam) above 4000 rpm and counter productive...not to mention the tradeoff of less torque for higher horsepower wouldn't allow better et's in this particular engine (would work well in a RAIII with bigger valves and RA exh. manifolds!). A 3.73 or 3.90 gear would be more ideal too. With some front suspension work along with all the above, it could run 12.70's at 108 mph. If it weighed closer to 3650 lbs, there's a another .15 seconds lower et!

Dennis

[KSZR]

Originally Posted by SD455DJ

Thanks W.S.GTO! If we built the 400 to the max the pure stock rules allow, I could run as much as 11.5 to 1 compression (1.5 over advertised 10.0), and any hft cam (actually have a 2801 in it now) that maintains 16 in. vacuum at 1200 rpm (changing to 18 in. this year). Higher compression would allow a bigger cam to maintain 18 in. vacuum, so possibly the 2802 could work, but I think the small valves and log manifolds would be corks (with the 2802 cam) above 4000 rpm and counter productive...not to mention the tradeoff of less torque for higher horsepower wouldn't allow better et's in this particular engine (would work well in a RAIII with bigger valves and RA exh. manifolds!). A 3.73 or 3.90 gear would be more ideal too. With some front suspension work along with all the above, it could run 12.70's at 108 mph. If it weighed closer to 3650 lbs, there's a another .15 seconds lower et!

Dennis

Dennis,

My 72 Lemans with 400 .030 over, 068 cam, cast iron intake, log manifolds, HO racing carb and distributor kits, dual snorkel, crush bent quiet exhaust, 3.55 12 bolt, 200 4R does a best 1/4 mile on my dragy of 14.59 at 95.

Going to upgrade to a 2.5" Pypes mandrel system, which sounds like a huge improvement.

What would I gain by going to ram air manifolds over logs? Wondering if its worth it.

Kent

[SD455DJ]

Originally Posted by KSZR

Dennis,

My 72 Lemans with 400 .030 over, 068 cam, cast iron intake, log manifolds, HO racing carb and distributor kits, dual snorkel, crush bent quiet exhaust, 3.55 12 bolt, 200 4R does a best 1/4 mile on my dragy of 14.59 at 95.

Going to upgrade to a 2.5" Pypes mandrel system, which sounds like a huge improvement.

What would I gain by going to ram air manifolds over logs? Wondering if its worth it.

Kent

Kent, Certainly RA manifolds will help with a 3-8 hp & lb-ft of torque gain through the rev range of 2000 rpm and above, especially the larger outlet repops (RARE's 2.45" ID outlets). All exhaust manifolds benefit from 2 1/2" mandrel bent headpipes (Pypes makes them for logs and RA's) to make the most power gain along with mandrel bent pipes to complete the exhaust system. Going to RA manifolds (either stock 2.1" or the 2.45" oversized) will accommodate more power gains in the future should you decide to upgrade your engine, so, IMHO, it's never a bad idea if you can afford it...but, the 68-72 std. A-body log manifolds hold their own on relatively stock builds. I'd be more tempted to open up the outlets to 2.2" on your logs (stock outlets are 1.875" and 1.95)" and save your money if you don't have future plans to make more power with your 400 (B-Man has an excellent thread on opening up his log manifolds and making his own 2.5" mandrel bend headpipes). I think logs are fine up to 350 hp, however, the law of diminishing returns kicks in fast at 350 hp. I know my XV 400 engine that made 380+ hp would have made 400 hp on the dyno with RARE 2.5" manifolds. I didn't open up the outlets on the log manifolds since I race it at the Pure Stock Drags and have to be legal.

Your 400 will be quicker by 0.1 to 0.2 seconds (I think Ccass mentioned this earlier in this thread) quicker with just the manifold change and you'll get another .0.2 to 0.3 second drop with the full mandrel bent Pypes exhaust system.

Dennis

[KSZR]

Originally Posted by SD455DJ

Kent, Certainly RA manifolds will help with a 3-8 hp & lb-ft of torque gain through the rev range of 2000 rpm and above, especially the larger outlet repops (RARE's 2.45" ID outlets). All exhaust manifolds benefit from 2 1/2" mandrel bent headpipes (Pypes makes them for logs and RA's) to make the most power gain along with mandrel bent pipes to complete the exhaust system. Going to RA manifolds (either stock 2.1" or the 2.45" oversized) will accommodate more power gains in the future should you decide to upgrade your engine, so, IMHO, it's never a bad idea if you can afford it...but, the 68-72 std. A-body log manifolds hold their own on relatively stock builds. I'd be more tempted to open up the outlets to 2.2" on your logs (stock outlets are 1.875" and 1.95)" and save your money if you don't have future plans to make more power with your 400 (B-Man has an excellent thread on opening up his log manifolds and making his own 2.5" mandrel bend headpipes). I think logs are fine up to 350 hp, however, the law of diminishing returns kicks in fast at 350 hp. I know my XV 400 engine that made 380+ hp would have made 400 hp on the dyno with RARE 2.5" manifolds. I didn't open up the outlets on the log manifolds since I race it at the Pure Stock Drags and have to be legal.

Your 400 will be quicker by 0.1 to 0.2 seconds (I think Ccass mentioned this earlier in this thread) quicker with just the manifold change and you'll get another .0.2 to 0.3 second drop with the full mandrel bent Pypes exhaust system.

Dennis

Thanks! I'll go for the RA manifolds and 2.5 X Pypes system.

My goal is to be faster than my wife's Mach E in the 1/4(13.8)! Fun!

What is the next step without just going to a stroker? From reading posts maybe 2801 or 2802 cam? Worth it over the 068?

3.73s might be nice over the 3.55s since I have overdrive.. But the 200 4R does have a much lower 1st gear than a T350 or T400.

Kent

[SD455DJ]

Kent, Might as well ante-up for the 2.5" outlet RA manifolds since you are going that route along with the Pypes mandrel 'X' system. Can't go wrong there and it will support more power down the road (up to 500 hp easily). I personally would get the kit without the mufflers and purchase the 18" case DynoMax UltraFlo's or Magnaflow's separately, which are both straight-thru design, yet fairly quiet, but support lots of power. I have both and they both perform very well.

I see you have #16 heads and I'm assuming the '68 large valve variety. I would certainly follow the same recipe we did on the XV 400 engine on yours. With the large valve heads with .040" quench, lower 10's for static compression, the 2802 cam, etc., I would expect an easy 420 hp/480 lb-ft torque. With your new exhaust system and a fuel delivery system to match, you should have no problems running high 12's at 106+ mph. I'd stick with the 3.55's for a while since your first gear multiplication ratio is 9.7625 with the 200R4's 2.75 first gear...that's like having 3.90 gears with a TH400/TH350! You will have a major traction problem with this build...and lots of fun!

Dennis

[KSZR]

RA manifolds on, tailpipes installed. Getting closer.

[KSZR]

Cool, that is impressive. Sounds like fun.

What do you run for a convertor?

[SD455DJ]

It has a tight 10" Continental convertor built for a 461 with 550 lbft. of torque, so it feels like a stock convertor (13") behind a 406 with only 450 lbft. torque. It breaks the tires loose at 2200 rpm power braking it. I will be swapping in a factory 13" convertor to see if there would be any difference in the launch. It's tight in all driving situations and tugs into gear like a stock convertor, not to mention creeps at idle like a stock convertor.

Dennis