79T/A

To say I'm disappointed would be an understatement. My car basically stock made 203 hp and 346 tq. Now I'm making 240 hp at 4500rpm and 318 tq at 3000rpm. Why the loss in torque and not near the gain in horsepower I was expecting? My build is 403 bored.030 with dished piston .020 in cylinder, 7a heads milled .015 2" intake 1.625 ex valves, .040 fel pro gaskets. Erson viking 100h cam, 222 duration @ .050 int/ex 476 lift, muncie 4 speed. The car feels like it has more power on the street. The hp was still climbing at 4500 but torque dropped way off after 3000.

olds 307 and 403

Any port or bowl work done to the heads? Was the cam degreed in?

79T/A

Yes I degreed the cam. No port or bowl work.

oddball

Just to clarify, are you saying the engine has dished pistons (part number? how big is the dish?) and the pistons are 0.020" below the deck surface, AND using felpro head gaskets?

If those are stock style replacement pistons, then you compression ratio is down in the 7's. Add a quite mild cam with low lift, and there's no party happening.

79T/A

They are stock style dish so around 20cc. Sitting .020 below deck. The heads being milled put my combustion chambers to 66cc and should have my compression around 9-9.5 from what I had calculated.

oddball

I stand corrected, about 9.3:1.

That cam won't be a screamer, but it should be a lot more respectable than this. Seems like something is wrong with the carb, ignition, or there's a towel stuffed in the exhaust. Did you keep the emissions stuff?

joe_padavano

You wouldn't put SBO heads on an E-block 400, so why do people put them on a 403?

79T/A

No the emissions stuff was gone when I got the car I'm running manifolds with true duals. I've got some issues with the carb but it's the same one that was on it when I dynod it before.

79T/A

They flow better than the 403 heads and they're a good way to get compression up without changing pistons.

GEARMAN69

240 RWHP with manifolds? Doesn't seem too far off maybe about 300 hp flywheel ?, I bet open headers would pick it up a bunch especially since you have a single pattern cam , if you are keeping the manifolds I am curious what it would do with the old Comp Dual Energy 275 grind. It is designed for the restrictive exhaust and is 219/233 split on a 110 LSA would rock with 9.3:1

If you decide to pull heads later and run headers I would have done the bigger valves 2.07 1.71 and bench flow tested bowl port job and let that big bore breath

79T/A

They stopped the pull at 4500 but hp was still climbing it would have probably made 250-260 at 5500 rpm. I just can't get over the drop in torque. I really thought it would be around 375-400 ft pounds.

GEARMAN69

If its RWTQ I would doubt you would ever see 400 , but it doesnt seem like something is off I agree the TQ is low.. Wha tis your fuel system and igntion ? Timing all in proper like for max power ? Open shaker cold air or was it closed shaker installed and hot air ?

79T/A

My fuel system is mechanical pump and quadrajet. My ignition is a factory hei. I haven't checked to see where my timing comes all in. My shaker is cut so it's pulling cold air. The car is much quicker on the street and it does run better just not quite what I was expecting.

GEARMAN69

That car has a 1/4 return line to the tank right ? I find the factory large can Carter mech pumps do ok over 400 FW Hp but we do remove the old strainers from the tank and make sure the filter in carb does not have the check spring thing the started adding to the Fram replacements. Did you put the lighter advance springs in the dizzy under the rotor ? If you still have stock HEI weight snad springs you need to get a Mr Gasket recurve kit ASAP and swap the springs and weights out and use a dial back light and set the total 35-37 degrees in below 2500 rpm with 93 octane . One more question? Which intake and what temp T Stat ?

79T/A

I changed the springs out in the distributor a couple of years ago I think I used 2 mediums in the kit. I'm running a factory intake and 195 robert shaw t stat.

GEARMAN69

Put a 160 in it, TQ and HP drop off a lot on a all iron engine once it gets past 170-180 degrees. Best track times are usually at 140-160 degrees as well as dyno pulls. 195 stats are stock yes since 1968 but not for HP reasons.

captjim

There is no way that you can back up that statement.

GEARMAN69

Go hot lap your car on the track and get back. It's always quickest after the biggest cool down and a quick access to the starting line. Also I recall even cutlassefi talking dyno numbers at different water temps. Your full of it Jim

captjim

Nope. The issue in your statement is with the words "a lot" and "all". You can never say "all". A 20 degree jump in engine temp will not result in a big loss nor in all engines. I had a 9 to 1 355 that ran BETTER with a 180 stat, don't know if it was ring seal, or what. Also, on lower compression engines, heat = cylinder pressure which = power and torque. Too much is bad, but 180 degrees, on SOME engines, is not too much. So, instead of calling me names, how about posting some actual facts??

cutlassefi

One thing you all are fogettting, hotter water temps means hotter, then consequently THINNER oil. More power. BUT there's a trade off for sure.
Iron heads typically like cooler temps, to a point. Then fuel puddling etc comes into play. But you need to tune for the temps you're going to run. I for one would like to see what the spark and fuel curve is on this build. That might tell us what we need to know.

GEARMAN69

Jim I didn't call you any names, Yes some engines do OK at 180 and I bet you had a aluminum intake too. I was speaking of all iron intake heads etc.. Mark yep that is true on oil and to your point I mean engine warmed up fully once then coolant temp cooled back down but oil still plenty warm before a run or a pull. All I was also going to add was if someone doesn't feel.or see the improvement of how strong it should be at the lower temp it can also be that they may have not re-calibrated the very lean factory carb settings which would need to be done in.order to take advantage of a 160 running temp. Proof in what really, all I can do is share a lifelong of experience on the drag strip in every vehicle I have had always ran better times cooled down some to below the OE 195-200 temp. It can be as much a 1/2 second difference in the 1/4 mile and would show a big difference on a dyno pull as well. To get a bigger dyno numbers and also simulates cool down technique at the track is a flush or lowering of coolant temperature after engine and oil is warmed first yield about 30 more HP on his iron head BBC on a dyno pass and this replicates the difference in a lower temp at the track. Even my old Silverado ran consistantly in the mid 15's instead of low 16's on average in the summer when I did the 160 T stat swap. MY old GTO went from a hot lap with a hot iron intake only running a 13.1 or 13.2 to a 12.6 just getting the iron intake cooled down along with coolant temps. The cooler coolant in the head and intake passages immediately makes more TQ with the better denser charge in the A/F mixture . Puddling and stuff or boggy if its stone cold yes sometimes but that is why I said it needs a full warm up oil and all then settle back down with a cool off and a 160 stat is how to run the iron intake engine street and strip dyno what ever. That is why I push for folks to get the better aluminum new style radiators and an otherwise factory fan shroud and AC style fan clutch arrangements and a 160 stat if they are running iron heads and iron intake. If you switch that to a aluminum intake and iron heads and your in the South or fairly warm climate I still run the 160 but add aluminum heads to go with aluminum intake then you will see my say the 180 is the way to go with all the heat loss and efficiency.

GEARMAN69

When I said "all" it was an "all iron engine" not all engines .... referring to burning ace hot iron intakes and heads no likey a 195-200 degree water temp for the HP.

captjim

Youare making a ton of assumptions and changing the narrative. How many performance cars are running cast intakes? Also, you are adding another 20 degrees, from 180 to 200.

I will re-state my position; IMO there are a lot of mild street cars that are daily driven that will run better with 180 stats, and that includes driving around, not just ET or dyno results.

Finally, saying " Your full of it Jim" IS calling names, not debating or disagreeing with a point I made. It is also grammatically incorrect

GEARMAN69

Ok Jim sorry for call you names LOL
Can you just answer me that your 180 was also in a aluminum intake. Not sure about all the assumptions you say I have. 30 years plus experience does not count I guess. A lot of cars with 160 stats may still hit 180 BTW if they have original brass radiators and in the summer same as a 195 will easily hit 200-205 in the summer so it is relevant. Pushing the 160 for a guy running an iron intake is the way to go to pick up more TQ while cruising around and also on his dyno pull. Simple stuff, carb tuning , timing, and T stats first. Whether it gets a better intake and badly needed headers later IDK he didn't say.

olds 307 and 403

You need to figure out your timing curve, betting even with 2 medium springs it isn't all coming in till over 3000 rpm. I could never get an HEI with stock weights, no matter what springs to fully advance till 3000 rpm. Maybe try one light spring. It still won't fix the high rpm adding extra timing but have a feeling you won't be revving that high anyways. I bet your Qjet is now on the lean side. You could go up one primary jet size and maybe try different secondary rods or a richer apt setting. Where is your cam degreed? That might be affecting where the power is coming in. The 4A heads do suck bad but at least opening the bowls under the larger valves should have been on your list for the 350 heads. I have a fresh set of #6 heads with 2.05/1.56" valves for my 403 stroker. I am going to carefully open the bowls with a grinder and polish the chambers. Even cheap full length headers would be worth 25 non rwhp and tq. A set of headers like ARH probably a good amount more but $$$.

79T/A

I'm actually surprised it's not running lean, the air fuel chart from the dyno was really good. I installed the cam straight up. I installed two light springs yesterday and I'm going to borrow a dial back timing light and figure out how to use it to determine my timing curve. I'm about to pull the trigger on a smi stage 2 qjet I think the throttle shaft bushings on my carb are wore out and causing a slight vacuum leak.

captjim

This was the statement you made that I did not agree with,
"Put a 160 in it, TQ and HP drop off a lot on a all iron engine once it gets past 170-180 degrees."
You made no mention of intakes or radiators. Yes, mine had a Performer on it, as will most mild performance engines, it is one of the first upgrades to be made. If you had stated,
"Most iron-headed engines, especially with stock intakes, will run better on the cool side", I would agree 100%. But, that is not what you said.

To the OP, are you using the same dist and carb from before?

GEARMAN69

Your funny Jim , " I said a lot of all iron engines " meaning many engines of all iron construction. I just didn't word it to your liking but I explained myself numerous times. and you do agree to my intent so nice to agree ole james

79T/A

Yes same distributor and carb with no changes.

GEARMAN69

BTW Mr 79TA what US state or region do you reside in ?

1BOSS83

Record you base timing at idle and subtract is from your total timing with the VA disconnected and all open vacuum sourced plugged.

Not looking for an arguement but 36+* is a little high. I'd try 32*/33* for awhile before attempting to run a more aggressive curve.

79T/A

I'm located in western Ky.

79T/A

Thanks for explaining how to do that.

GEARMAN69

For between $1.40 - $5.46 a bunch of choices on 160 thermostats Stant, AC Delco , Motorad on Rockauto

http://www.rockauto.com/en/catalog/p...amp%3B%2Brelay

olds 307 and 403

Around 36 is a good number especially if he is running premium fuel. 32 sounds low to me, I am currently running around 33-34 only because I slowed down my advance due to pinging. That is where it ended up after the recurve but will bump it to 36 at the track.

79T/A

Thanks. I am running premium.

79T/A

Another question guys. If my timing curve or fuel is not correct would that cause the almost 30 ft pounds of torque I lost?

GEARMAN69

Lower the operating temp 40 degrees and your 30-ft lbs Will come as long as carb is good and timing and unrestricted air

Fun71

My HEI was advancing too early with the factory weights and two light springs - it was getting mechanical advance at idle speed! I discovered the best setup was one light and one medium spring from the Moroso HEI Advance Curve Kit.

RetroRanger

my experience as well 2 mid was two strong and 2 light was to weak. 1 mid and 1 light did the trick i used the moroso kit as well