You have a 327 with raised top probably 11 to 1 pistons and you are pissing and moaning about "only" getting 335 hp on the dyno? Back in 1975 I had a 57 Chevy panel truck with a 327 with 202 heads, 12.5 Jahns pistons and an Engle solid lifter cam and an early Corvette intake with 2 wcfb carbs that would pull the front wheels and street race heads up with a 750 Honda stop light to stop light. I doubt that that engine put out any more than 335 hp. We figured 400 but without headers I rather doubt it. Personally I'd have to think that that 327 you have will put out all the power you can handle and be a hell of a lot more drivable than the one I had.
There is a lot of power to be made from the lobe profile not by putting a "bigger" cam in it, a more aggresive lobe profile of the cam will make more power, it will fill the cylinders more and trick the engine into thinking it has more compression because of increased cylinder psi. I have cam swapped keeping the identical duration at .050 numbers, with just a little more lift and picked up 3 tenths and 6 mph all because of a more aggressive lobe profile.
It is just funny to me what we had to do to this traditional stuff to build hp as compared to what we hear today. Anyway, on a serious note, pretty sure you won't feel 14 hp at the seat of the pants or maybe even in quarter mile time. However, I agree that a different cam would likely help as much as anything. To me, picking cams in today's world (at least what I see my son do), is listening to youtube videos of how they sound and mainly picking based on that. I was more in line of thinking what built the best power with my combination in the rpm range I was was needing to run and my car was set up to. The sound was a secondary.
Sounds like you made decent power from a mix of parts that wasn't necessarily well planned out. You've got more than 1hp per cubic inch, but I've always heard the same about Thumpr cams as the other guys, they're made for noise and not for power. Cam choice will probably bump you up a bit. However, that arbitrary 350hp number doesn't mean much. Will the engine do what you want it to do? That's the biggest thing. I like my stuff to run on 87 because my cars are cruisers and I can't always rely on getting the good stuff at every gas station. Peak power at high rpm doesn't matter to me, as my engines rarely get up there. Good cruise manners are more important to me.
In my opinion... any time you can get an honest one hp per cu, you are not doing bad. I had an older engine builder tell me that 327's were one of the hardest ones to get right. He said even with 2.02 valves, unported, those heads only flow about 190-200 at 450 lift unless you get a pair of really good castings. Gene.
If you want to increase HP - the best way to do it would be with aftermarket aluminum heads (Like AFR 180 Street Eliminator heads), a custom hydraulic roller cam an Edelbrock RPM AirGap manifold and a 650+ cfm Holley double-pumper. With that combination you'd have a good "streetable" engine and be pumping out over 400 HP. I recently built a 383 with AFR 195 Heads, Chris Straub hyd-roller cam, Eddy RPM AirGap, Quickfuel 830 carb - makes 520 HP at 6200 RPM. It is ALL about top-end technology these days.
And another thing, dynos are only as good as the calibration of the dyno itself. If you ran that engine on several dynos, you would get 350 hp easily, maybe yours does make it, if that dyno you used is a little conservative.....
I will bet that Thumper cam can be "adjusted" to make more power... It has a lot more Ex duration so you hear the THUMP-THUMP sound because the Ex valve is sorta closing later (Open more than In) If you degree the cam and "adjust" it to the retard side a couple degrees you will shorten the Ex timing and increase the In timing...right ? Put some high lift rockers on the intake side will help make up the deficit lift on the Intake. The whole idea is to 'trap' more air during the compression cycle...not let it all out on the high exhaust lift. 107 LSA is fine for your application because you got the gear to support it AND for the street you're not gonna wind it above 6500RPM regularly...(unless you have the springs/retainers/keepers and all the high RPM goodies to support it) Please don't tell me you just 'stuck-the-distrib-in at stock degrees !! With that kinda cam you need A LOT of initial and you need it quick like 1200-1500 all in. Limit the total advance to high 30'-low 40's for those 'old timey heads'. IF you think the CR is high 10'-low 11's you prolly gone need racing fuel anyway soooo you won't need to be too careful about spark knock. Keep in mind...anything over one HP per Cu. In. is already a winner. 6sally6
I’d put my money within this right here. This is a known combo of afr and straub cam . Do it and quit screw-in around with it
Maybe not with the cam he has? That cam may have reached maximum HP and begin to nose over, so the dyno operator will end the run wherever the engine stops making HP.
Without extensive port work those heads wont make near that amount of flow. Tests done on them show flow rates in stock form being down around 170 or slightly better. Any modern aluminum head flows huge amounts better, even the entry level heads.
Yep, and considering the cost of dyno time, if bragging rights is the motivation some creative "fibbing" at the weekly bench racing session will get the same results.
Yeah, I've seen several engines alleged to have 500+ horsepower get shut down by a car with a stock engine factory rated at 350 horsepower.
I hear dyno numbers all the time especially on the engines I run at Bonneville. They are all 50-75 hp more than me and 10 miles an hour off our record. 330 hp is ok with what you say you have; I believe the shop doing the work could have a better job on “blueprinting” your parts.. Your cam would not have been my choice either. A 30-30 solid might have given you the 350 you wanted and sounded good too. You didn’t mention where it was set either. 6* advanced can turn a dog into dynamite if it was a few retarded to start with …
Jimmy brought up a valid point. Ask the shop if they degreed the cam? The camshaft is the heart of the engine and it's amazing how much power is lost when it isn't degreed. I have never assembled an engine and not checked cam position. I was fortunate to know Chet Herbert when building my first Chevy small block and he was instrumental teaching me how important cam shaft position was. My stock 327 11.25 with double hump 2.02/160 valves put out 325 to the rear wheels. This was in 1964.
Yeah, it would be nice to see the dyno sheets to see what exactly is going on. Without that info it's just a guess.
Whats the static cranking compression Psi ? So many what a 283 & 327 they need rpms 6500 plus & cfms of air 10:5-1 plus for a drag , A 400 with 300 500 blue racer 1985 194 or 202 just port match turning 5,500 - 5,800 With 9:5 will mop a 327 with eas
In the end, how much HP do you want to gain and how much are you willing to spend to get it? The last 20% of the HP always costs about 2 - 3X per HP of what the first 80% cost.
What RPM is max torque at ?? [330.5 ft/lbs] This RPM is max cylinder fill before volumetric efficiency drops off. 336.5 hp at 5700 RPM = 310 ft/lbs which shows VE dropping off but still pretty good. You should pull the heads off and install 2.02 intakes and 1.60 exhausts with a decent competition valve job on the seats. Back cut the intakes and radius the exhaust valve faces. AND leave the throats alone in the heads but blend them towards the seat The idea is to create a "Bell-mouth" shape in the throat / seat which gives a decent amount of velocity in the 0.050" to 0.200" lift range [the valve spends more time "off the seat" than at maximum lift] Do this and you'll probably still have the same torque 400 rpm further up So 310 ft/lbs at 6100 RPM = 360 hp These mods don't affect low down driveability. And DO NOT gasket port match the intake and heads .I've seen the results on a flow bench where this stalls velocity [think of 2 trumpets facing each other! it is the opposite of a venturi] This ^^^^ I agree with. Sometimes you can't go wrong with simply leaving things alone
Your HP and Torque should move your coupe around at a decent clip. Did you set up your distributor curve for performance? Degreeing the cam and getting the right ignition timing curve may well put your engine over 350 hp. Unless your racing or looking for bragging rights I think that 327 will put a smile on your face IMO.
Mid 13s with ease.... that combo is desirable fun, should last years. We built an engine very similar,cam was 0.447/0.447 it was in 3x different cars. I'm having a ton of fun with 283 220hp. It runs on pump gas, and I don't adjust valves on it in 5yr.
Move the cam timing and try, 1.6 rockers then better heads and cam choice and more RPM. you have basically a corvette short block with so so heads and a cam that's not ideal. You want race car performance you need to give up some drivability on the street out of that 327. If it runs good and sounds good and your not racing it id leave it alone and run it . Over 300HP is more than many had in the 70's 80's on the street. Look like the 11.25 pistons I had in 81 with milled 461 heads . 2.02 valves won't gain a lot untill over about 4500 on up . My 327 ran 12.99 in a chevelle with 5:13 gears and 30" slicks a lot more cam and 1.95 valves . I figured it was about 360 HP at about 7000 RPM . ITs only a 327 and with 11.25 to one on pump gas your going to be pulling timing out and giving up HP. Even some ebay heads for $900 will make more power now and let you run nearly a point of compression more than cast Iron . Paint them and nobody knows
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