I'm new to this forum and I do not own a Camaro but my son has a '69 Z28 X33 car that he's currenlty rebuilding the DZ302 motor so I and my son do have more than a mild interest in the topics at this site. My question is one concerning my '65 Corvette with the original 327/300 horse motor. In the interest of driving and enjoying this car I wanted to improve on the performance. Along with the original 327 cu/300 hp it has a Muncie M-21 4 speed. The rear end is an open 3:36.

The following was done to the motor (I saved all the stock pieces):

Block was bored .030 over
Childs and Albert zero gap rings
Ported and polished the stock cast iron heads (1.94s) --replaced valves with stainless
Replaced the cast iron intake with the 350/365 aluminum high rise intake offered in '64 & '65 Corvettes
Replaced the Carter with a correct carb offered in '64 & '65 (Holley 600 cfm w/vacuum secondary-single pump)
Replaced the stock fuel pump with the higher psi rated 365/375 horse pump offered in '65
Replaced the cam with a Speed Pro CS186R which has a cam profile (480 lift; 230/230) just between the original 350/365
horse offered in '65
Replaced the 1.5 ratio rockers w/1.6 Crane Roller Rockers (which changed the lift of the cam to 512)
Replaced the point ignition w/Pertronix
Added MSD 6AL box
Replaced stock wires with 8mm
Added factory side exhaust (2 and 1/2 inch chambered pipes) to the stock rams horn exhaust manifolds
Added an open air cleaner using a K&N filter
Replaced the fluids in the rear end and trans with Red Line Synthetic
Replaced the clutch
Currently using Mobil 1 synthetic oil
Tuned to run on pump gas (93 Octane)
The tuning was set up so that total timing is at 37 degrees w/13 manifold vacuum

I had the motor fine tuned and chassis dynoed at Automotive Performance Engineering in Clinton Township, MI.
(810-954-3181). As part of their fine tuning, they installed an oxygen sensor in one of the exhaust pipes enabling them to keep the air/fuel mixture at the correct ratio all through the power band. Both Kirk and Rich know their stuff. The dyno runs were all done in 4th gear. They as well as I were a little surprised by the numbers and more importantly the fact that the horsepower plateaus at 5,200 rpm when the cam specs state it's supposed to make horsepower to 6,000. The graph charting the performance shows the rpms continuing to 6,000 but the horsepower just flattens out after 5,200. Jet sizes were changed to be certain the motor was running a little "fat" with no affect.

The consensus was maybe the cam was installed wrong. Both Kirk and Rich believe with all that's been done to the motor, it should be making horsepower right up to 6,000 rpm. They believe there's 25 to 40 more horses to be found in that motor at the rear wheels. So, my son and I spent a couple of evenings pulling away the front of the motor and checking the degreeing of the cam to the cam card. Well, we're done and the cam is right where the cam card specs says it's supposed to be (106 at the intake lobe centerline).

Frankly, I'm stumped. Can anyone offer any suggestion as to why the motor stops making horsepower and flattens out after 5,200 rpms. All the valve springs were compression tested when the heads were done...so valve float is ruled out.

The dyno numbers at the rear wheels are: 216 horses @ 5200 rpm.....267 ft/lbs of torque @ 3000 rpm

I know they measured horsepower in the 60's at the flywheel. If I'm losing 25% through friction before the horsepower gets to the rear wheels, this means my gross horsepower is 288...all these performance mods and I've actually gone backwards from the advertised gross horsepower for this motor in '65 (300 hp). I am puzzled!!

Appreciate any suggestions anyone out there may have on this

Thanks in advance for any help!

Regards,

Jim



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i'am no expert but ,sounds like your running out of carb. or exhaust is very restricted.air/fuel mix may be ok,but the carb. might not flow enuff (cfm).....just a guess....anyone ?

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My68Camaro (http://hometown.aol.com/Dougs68Camaro/index.html)
Doug G.
68 Camaro
406 ci.

<BLOCKQUOTE>quote:</font><HR>Originally posted by DOUG G:
i'am no expert but ,sounds like your running out of carb. or exhaust is very restricted.air/fuel mix may be ok,but the carb. might not flow enuff (cfm).....just a guess....anyone ?

<HR></BLOCKQUOTE>
Doug: that had crossed my mind too but the carb being used is the same carb used on the 350/365 horse motors in '65...600cfm, vacuum secondary, single feed. If it is fuel starvation, it has to be taking place further down the line from the carb. When I body off restored the car I put in all new fueld lines/fuel filter. The motor's got about 3,500 miles on it now.

Jim,

Who did the head work and did they flow it before and after? It is extremely easy to mess up the flow even though the ports will look great; just ask me!! A guy WITHOUT a flow bench (unknown to me) ported my Victor Jr. heads and LOST 36 cfm on the exhaust; the ports look very professional. The car is making 409 h.p. at the tires at 4700 rpm and remains EXACTLY there until he shut the dyno down at 6300 rpm (perfectly flat line). My cam is also not ideal for the application.

In my case it turned out to be an airflow problem; think of the engine as an airpump; if it hits a max h.p. and holds it there (flat line) look hard at the airflow.

Check air cleaner (too low or too small), try running without it, exhaust (headers would definitely make a difference but I think even with the rams horns you should get more h.p. than you are), cam timing, etc.

I will re-post when I get the heads back from the real porter; we're looking to pick up a bunch. It sounds like yours is an airflow problem somewhere. I had a car that picked up 7 tenths in e.t. by switching from a 14X3" K&N to a 14X4"; evidently the 3" was too low.

Jody

<BLOCKQUOTE>quote:</font><HR>Originally posted by Camcojb:
Jim,

Who did the head work and did they flow it before and after? It is extremely easy to mess up the flow even though the ports will look great; just ask me!! A guy WITHOUT a flow bench (unknown to me) ported my Victor Jr. heads and LOST 36 cfm on the exhaust; the ports look very professional. The car is making 409 h.p. at the tires at 4700 rpm and remains EXACTLY there until he shut the dyno down at 6300 rpm (perfectly flat line). My cam is also not ideal for the application.

In my case it turned out to be an airflow problem; think of the engine as an airpump; if it hits a max h.p. and holds it there (flat line) look hard at the airflow.

Check air cleaner (too low or too small), try running without it, exhaust (headers would definitely make a difference but I think even with the rams horns you should get more h.p. than you are), cam timing, etc.

I will re-post when I get the heads back from the real porter; we're looking to pick up a bunch. It sounds like yours is an airflow problem somewhere. I had a car that picked up 7 tenths in e.t. by switching from a 14X3" K&N to a 14X4"; evidently the 3" was too low.

Jody<HR></BLOCKQUOTE>

Jody, Thanks for this insight. Although the heads were not flow tested, I do have high confidence in the work that was done on them. Your idea of changing out the aircleaner is a simple, quick way of determining if that is the problem. Since the motor has been "cleaned up" there may be some argument for going to a 650 cfm, maybe even a double pumper, because the motor is no where near the stock configuration now. You thoughts on a "restriction" has merit. Thanks for the input. Jim

You might need the extra compression that the 365hp/327 had over the 300hp/327. 11.0 to 10.25 I think.
That and fuelie heads (2.02"/1.60" 64/66cc double hump jobbers. 2.5" ramhorn's and the 30-30 cam was spec'ed at 254 duration and .485" lift, (.455" with .030" lash).
I don't think your 230 duration cam will make power to 6000rpm and above like the big Duntov. I figure it won't if it is a hydraulic instead of a solid?? IMHO pdq67

By the way a mildly cammed fuelie engine was awsome in its day in one '58 Vette I knew.

I'd suggest a set of Vortec heads, Edelbrock matching intake, standard ratio rocker arms. Back off the timing a little. Use the thin head gaskets. I think you'll see a 50 HP gain with no other changes with this with power to 6000rpm. I suspect a general mismatch in the heads, cam, intake, etc. When the cam and intake start to produce the heads are quitting. You could install an Edelbrock Performer Plus cam kit and have the same HP as you now have I suspect. Had a 64 Corvette years ago and it still rates as one of my favorite cars. (open rear in a Corvette??)

[This message has been edited by tom3 (edited 11-05-2000).]

<BLOCKQUOTE>quote:</font><HR>Originally posted by pdq67:
You might need the extra compression that the 365hp/327 had over the 300hp/327. 11.0 to 10.25 I think.
That and fuelie heads (2.02"/1.60" 64/66cc double hump jobbers. 2.5" ramhorn's and the 30-30 cam was spec'ed at 254 duration and .485" lift, (.455" with .030" lash).
I don't think your 230 duration cam will make power to 6000rpm and above like the big Duntov. I figure it won't if it is a hydraulic instead of a solid?? IMHO pdq67

By the way a mildly cammed fuelie engine was awsome in its day in one '58 Vette I knew. <HR></BLOCKQUOTE>
pdq67: You know, I'm not kidding myself that I could make a 300 horse/327 ci hydraulic run like the solid lifter 365 horse. But, I didn't think I'd go backwards with what I've done. The motor has the 2 and 1/2 inch ram's horn exhaust manifolds and the chambered side exhaust. The 1.94 heads could be the culprit like Jody said also. I chose this particular cam specifically because its brochure states the power range is 3000 to 6000 rs. The cam card states cam lift for both intake and exhaust is .320". The 230/230 numbers are the duration at .050 lift. So, it is not quite as stout as the Duntov, but significantly different from the stock 300 horse which was 398 valve lift with intake/exhaust of .300" using 1.5 ratio rockers. Looks like the flow characteristics need a close look. Thanks!

<BLOCKQUOTE>quote:</font><HR>Originally posted by tom3:
I'd suggest a set of Vortec heads, Edelbrock matching intake, standard ratio rocker arms. Back off the timing a little. Use the thin head gaskets. I think you'll see a 50 HP gain with no other changes with this with power to 6000rpm. I suspect a general mismatch in the heads, cam, intake, etc. When the cam and intake start to produce the heads are quitting. You could install an Edelbrock Performer Plus cam kit and have the same HP as you now have I suspect. Had a 64 Corvette years ago and it still rates as one of my favorite cars. (open rear in a Corvette??)

[This message has been edited by tom3 (edited 11-05-2000).]<HR></BLOCKQUOTE>

Tom3: Yup, it's a bare bones, one above the base model 300 horse with a factory open 3.36 rear. I had the pleasure of drag racing the car 12 times in August at the Pure Stock Muscle Car Drags in Stanton, MI. What a blast. This was where I confirmed what the dyno said the motor was doing. My best 1/4 E.T. was 15 flat at 94.5 mph. This with street radials (all cars must run the same size tire offered on the car when it was built (all 4 wheels). I know if I just swapped out the rear for a 3.70 posi and changed to a set of polyglas tires, I'd be right at 14.2/14.3. I was shifting right at 5,600/5,700 rs and was going through the traps under 5,000 in 4th. You know Tom3, my goal was to keep it visually as stock looking as possible. If I was to make a street rod out of the car (it is a matching #s--engine, trans, body and frame), I would put a 502/502 GM crate motor along with a Gertrag 6 speed. I'm sure I'd find quite a change in horspower at the rear wheels. I'd also find myself divorced too!! Thanks for your input and suggestions. Regards, Jim

Look's like the heads and stock exhaust manifold are your biggest problem. With that much cam you should be using ported 2.02 int. 1.6 ex. heads, headers, 3.73 or 4.11 rear gear and at least 9.5:1 compression.

****************************I looked at your above question again.****************************If you are verry confident with the porting on your heads(probably casting #461 or 462),I suggest you swap valves in your heads to a set of 202/160's.Make sure you have the chambers relieved.This should get you about 20 HP.
If you are at all questioning the porting of the heads,do yourself a faver and buy a set of World Products S/R Torquers with 202/160 valves and 67cc combustion chambers.Have them pocket ported!World Products recomends that you only give the S/R's a pocket port and gasket match, anything more may mess up the flow.When in factory form S/R Torquers are only slightly superior in flow to the 461-462 heads.So this change alone will not give you any big numbers.If someone messed up the flow of your heads thats another story.

Loose the 1.6 rockers, they are more trouble than what they are worth at this horsepower level.

You should switch to a set of 1&5/8 inch headers.Rams horns are prety good for stock,but can't even compete with small tube headers.If you refuse to run headers,you should at least have the Rams horns Extrude Honed to improove there performance.

I believe you would be much hapier with a good old 650 double pumper,though a 700 might be better.A 750 will be too much.It will be much snapier with that 4spd and will help your HP.

You also need a set of (at least) 3.73 gears(I'd rather see 3.90's) with that cam and cubic inch combo.



[This message has been edited by mutant 68 (edited 11-09-2000).]

Hello there Jim, First off, You and your son have very desirable cars, must be a lot of fun to take the two out on a run through town. Second, the horspower rating was achieved diffently in 1965 than what you are doing on the chaissis dyno. The 25% loss through the drivetrain is an estimate. You are running through mufflers, air cleaner, timed and jetted for todays fuel at your elevation/weather/air conditions, among other differences. So comparison's are not an acurate means of determining lack of power. Third, the cam that you have is on a 109 L/C w/ 74 degrees of overlap. It is going to make power all through the band but more so beyond where your intake, heads, manifolds and carb. are going to support. The 2.02 heads as sugested here by others, along with a double pump carb( 650 to 750 cfm)and an RPM style intake (LT1,Edl 7101,Stealth), and headers will allow it to run where it wants to make it's power at. The 327 is a higher RPM motor. I will sugest that a 383 shortblock, even with your heads,cam, rams horn manifolds, but still change the manifold and carb. You will get, I am estimating, about 375 hp(more with bigger heads though) and 450 ft lbs torque. That you will feel as night and day difference. Still retain the stock apearance and a lot of fun with the go pedal depressed. My opinions on this one, but I feel that you would like it. Galen

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S/B Chevy Lover
67 Camaro street car
10:50's @ 128 on motor w/383 cid
79 Z28 w/383 9.1:1 3.73:1 Restoring stock apearance
13:40's @ 101 stock exh.& intake& Qjet
smog legal
Camaro Lover

<BLOCKQUOTE>quote:</font><HR>Originally posted by ScottB:
Look's like the heads and stock exhaust manifold are your biggest problem. With that much cam you should be using ported 2.02 int. 1.6 ex. heads, headers, 3.73 or 4.11 rear gear and at least 9.5:1 compression. <HR></BLOCKQUOTE>
Scott B: According to you and Mutant 68, I should be shopping for a set of 2.02 heads and "clean these up"! I had made up my mind to shop for a 3.70 posi for the car after watching a stock 365 horse 64 Vette w/a 3.55 posi consistently run 14.3's. Mutant 68, are you suggesting the 1.6 ratios are providing too much lift, in effect keeping the valves open too long? Does this have a direct affect to low end performance...coming out of the hole? I'm kinda reluctant to swap the ram's horn manifolds (a factory visual appearance) that I don't want to give up. I figure I'll leave 10 horses (my guess) on the table not doing this. But, like Mutant68 says, I may be able to recover that by extrude honing them. That 650 double pumper keeps staring me in the face too. A good friend of mine told me from the get go to go with a 650 double pumper...again, I chose the factory look. Doesn't it sound like I want my cake and eat it too??? You know, you give up something, to get something!

Thanks!! Regards, Jim

<BLOCKQUOTE>quote:</font><HR>Originally posted by Galen W. Rouse:
Hello there Jim, First off, You and your son have very desirable cars, must be a lot of fun to take the two out on a run through town. Second, the horspower rating was achieved diffently in 1965 than what you are doing on the chaissis dyno. The 25% loss through the drivetrain is an estimate. You are running through mufflers, air cleaner, timed and jetted for todays fuel at your elevation/weather/air conditions, among other differences. So comparison's are not an acurate means of determining lack of power. Third, the cam that you have is on a 109 L/C w/ 74 degrees of overlap. It is going to make power all through the band but more so beyond where your intake, heads, manifolds and carb. are going to support. The 2.02 heads as sugested here by others, along with a double pump carb( 650 to 750 cfm)and an RPM style intake (LT1,Edl 7101,Stealth), and headers will allow it to run where it wants to make it's power at. The 327 is a higher RPM motor. I will sugest that a 383 shortblock, even with your heads,cam, rams horn manifolds, but still change the manifold and carb. You will get, I am estimating, about 375 hp(more with bigger heads though) and 450 ft lbs torque. That you will feel as night and day difference. Still retain the stock apearance and a lot of fun with the go pedal depressed. My opinions on this one, but I feel that you would like it. Galen

<HR></BLOCKQUOTE>

Galen: You're right on about the fun factor! Thanks for the kind words. Sorry for my getting wordy here, but my adrenal is flow'n when the subject is increasing the fun factor in drivin' my '5. I've been a car nut all my life and a Vette nut in particular. The BowTie really has bitten us. My oldest son has a sweet 68 Ro drop top with the factory 3speed and factory 3.08 posi. Beautiful car! He's been bitten to improve his performance also. I turned him on to this site and he's salivating right now. Galen, I realize the parasitic loss of horsepower as it's transferred through the drivetrain is an estimate, but, wouldn't it be a reasonable one? If you took a bone stock, factory specs, 300 horse/327ci with no power assists (does power antenna count? HA), then use the 75% to 80% factor to it, should'nt I end up with an approximate rear wheel horsepower of 225 to 240 horses at the rear wheels? The factory chambered side exhausts have got to flow better than any through the muffler set up, right? You know, regarding the cam selection, I think there ought to be more information on the cam brochures to aid one in eliminating going through all these motions in order to get a positive match (more horsepower/torque) in a street/strip application) Hell, maybe it already exists and I just haven't scratched the surface. Sort of like a cam forum where you state the cubes associated with a particular cam and the manufacturer maps out the what-if components to achieve suggested horses and torque at the flywheel. Then, the guestimated parasitic loss can be factored in which should approximate the chassis dyno pulls. Am I off here in lala land?

Galen, thanks for your ideas and listening to my heart beating faster!! My license plate says it all: 6T5RUSH!!

Jim,

The bottleneck I beleive is in the stock ram horn exhaust manifolds. They are relatively restrictive even for a moderately cammed motor. I would replace then with a header setup.

At higher RPM's, my guess is that the motor can not ingest any more fuel mixture because it can not efficiently expel the exhaust out the exhaust manifolds. This problem I beleive is even WORSE that when the engine was stock because you SHOULD be flowing much more fuel BUT with the restriction the car may actually run WORSE than the stock setup because of the exhaust manifold restriction.

You may also be undercarbed by about 100CFM but this in itself would NOT keep the motor from reving past 5200.

36 to 38 total degrees timing should be about right. Dyno powertrain losses are about 22% for an automatic and 18% for a standard.

[This message has been edited by sr71bb (edited 11-06-2000).]

[This message has been edited by sr71bb (edited 11-06-2000).]

Am I missing it or did you not give the compression ratio. My 67 327/350 was a factory 11 to 1 and while it produced plenty of power the factory exaggerated about horsepower ratings. A few years later they trimmed the numbers down to something that was closer to the truth. You can always recurve the ignition and throw in some octane in a bottle and try it then. While you may want higher dyno numbers, the real problem here is that your curve doesn't match the cam. I'm not a believer in double pumpers for anything under 400 cubic inches. You might try a bigger carb but keep the vacuum secondaries as they add to the overall performance by not bogging the engine with too much fuel before it's ready for it. I've had great luck with Demon Carbs and suggest you check their web site and give them a call for a recommendation. They'll ask exactly what you have and then compute the airflow that you'll need. Talk to the cam manufacturer about the rocker ratio and see what they think. I don't understand the geometry well enough to know if that could cause the lack of power over 5200 but I think it is possible since you've changed the effective lift and therefore the engines ability to pump air through it. Sounds like you have a nice car and I applaud your efforts to maintain the stock look rather than chop it up in search of mystery horesepower.

Jim,
It does sound like you want your cake and eat it too??? My first car was a 65 corvette coupe and I had the 327 rebuilt to 327/365 specs. It had 11:1, 30/30 solid cam, torquer intake, 750DP Holley, 202 heads pocket ported, headers. 3.36 gears, M20 4spd. That thing screeeeeeeeamed!
You should get a set of S/R torquer heads have them pocket ported and gasket matched, Weiand Stealth intake, headers, 3.73 posi, and hang the #$&@ on. That vette will be a beast!!

Jim,

The 2.02"/1.60" stock 365hp/327 heads were right on 66cc's. I got a set that I cc'ed. They are factory relieved around the intake valve to flow better then the 1.94" /1.50' heads, but are about 2 cc bigger.

The 365hp/327 HAD 2.5" ramshorn exhaust manifolds on it , NOT 2.25" or 2.00" like the lesser engines did. My stock '67 350SS Camaro had 2.25" logs on it.

The 11.0 to 1 CR., big ramshorns and 2.02"/1.60 heads with the 30-30 "fuelie" cam ran great. All this together is what made it go.

This is why I point all this out to you. By the way, the Hydraulic cam will make about four percent less power then an "identical" and I mean "identical" timing spec's wise solid due to the solid cam having more aggressive openning and closing rams. pdq67

Hey Jim,
A split pattern cam with more lift and duration on the exhaust side would help with the restriction of the rams horn manifolds. I also think you are under carbed, try that 650DP.

A wide ratio Muncie would also make your vette alot snappier down low.

If it were mine I would take the original 327/M21 out, store it in the shop and drop in a 383/M20 combo dressed to look original.


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67 RS/SS 350 700R4
69 SS clone unfinished
72 454 Weekend Racer

Hi Jim,

Just a shot in the dark, but my father's '61 Corvette had a similar problem that took us weeks to figure out. The engine is an American Speed built (Moline, Il) 355. The dyno sheet indicates 400+hp and 440+ lb-ft torque with Extrude-Honed stock manifolds. After we got it running in the car, the engine would totally fall on its face around 3500 rpm. We chased many different leads trying to figure out what was going on, but to no avail. I messed around with it one afternoon and neglected to put the air cleaner back on, took it for a cruise, and jeee-zus the thing plain ripped! I checked out the air cleaner's fit, and the dropped base was so deeply inset that only 1/2" of space remained between the air horn and the air cleaner lid. Finally tracked down an air cleaner which allowed for more flow (hard to do with the Corvette's hood clearance). The car runs great now. I assume the mid-year Vettes have similar hood clearance issues, so check it out. Good luck!

squarles,
Heck, with the 383, the M-21 would get enough torque to go OK.

RPOL72,
You have an EXCELLENT point with respect to the air cleaner clearance.

Jim,
Please don't get me wrong, I'm not saying go backwards, forwards or even up-side-down. I'm just trying to say that the 365hp/327 had to be a matched engine because it's kinda like an L-88, if it's not right on, it won't go!!!

Drop the L-88 cam into an 11.0 to 1CR. 425hp/427 and you get an underpowered 427 engine. The same goes for the 30-30 Duntov cam in a 300hp/327.
10.25 to 1CR. or less just doesn't quite cut it. BUT, it will run better then with the stock cam.
Drop a 30-30 cam into a powerpack 265 with 4.11's or 4.56's behind it and watch the rpm's make the hp. I'm talking 7000 to 8000rpm's or until she comes apart.Of course, the little 265 would run alot better with 11.5 to 1 CR.
Hope all comes out OK. pdq67

A couple of valid points have been made here.

1-Lowering the compression by 1 point will reduce the hp by about 3 percent.

2-Factory heads w/ 202/160 valves are factory relieved to unshroud the valves.If you opt to switch to 202/160 valves (with factory heads) this mod should be performed or you will not recieve the full benifit of the increased airflow on the intake side.

3-Solid cams Offer more HP and TQ when the duration is roughly the same.Solids need about 6 degrees more at .050 because of loss due to the valve lash.

4-Your choice of the 230 deg duration @ .050 cam into a motor with 331 C.I. means that you will be down on H.P. and T.Q. on the low end.

5-There is a possibility your engine might be stumbling in the higher end because of your choice of using the Rams Horns.Causing an effective corke.It is true ,an engine can only ingest as much air as it can expell.You will probably be leaving more than 10 HP on the table(even after the extrude hone process)by keeping the Rams Horn's at this HP level.

6-Because of the corke in the exhaust( rams horns),when you chose a cam you should have chose one with a longer exhaust lift and duration to help offset its shortcommings.

7-Make shure the closest thing to your carbs vent tube is at least 1 &1/2 inch away.The further away the better!Having anything closer will effect your carbs meetering of air/fuel.This happens mostly at the top end.This can be dramatic.The best air cleaner assembly I have seen and used(I have tried many-Moroso,K&N,ETC.) is withought a dout,the FACTORY unit used on the 450 HP 454's in 1970 Chevelle's,and on the 396's in Nova's.It offers a large droped base,even further than the aftermarket. It's still available from the factory and you can also get it through many reproduction companies for about $70.Always use the tallest filter you can fit without hood interference.

8-When you use a relatively large cam with a relatively small engine it will make the motor respond like the cam is much larger,reducing botom end and adding top.
As such you must gear the engine where it will be effective.With this cam I would pick a set of 3.90 gears.

9-If you have a close ratio trans and 3.36 gears this is not a good combination.The close ratio trans has a high first gear and will compound your lack of torque(remember the C.I. to duration factor)and make it hard to accelerate from a stop.
Using a wide ratio would be much better.They have a lower first gear and will be much more streetable.

I told you to loose the 1.6 rockers because the heads you are runing probibly don't flow up to 512 lift, even with the porting.Now if you had Pro Flow valves that might be another story.The 1.6's will add lift,but at the same, time they will add duration.Again mooving your powerband further upstairs.



[This message has been edited by mutant 68 (edited 11-16-2000).]

The points I was making are

(1) The 365hp/327 ramshorns are bigger then the 300hp/327, thus more flow.

(2) The power produced from the lowering of dynamic compression due to the BIG Duntov not being matched to what it is supposed to run with will be less then just the drop in compression due to CR. being down .75 of a point if compression is 10.25 vs 11.0 to 1

(3) The solid cam has to be spec'ed at lash to be the same duration as it's hydraulic counterpoint, and lift isn't all that critical until you get to wanting everything you can get from a cam. And due to being able to smack the lifter harder, the solid will make it's 3/5 percent more power, plus not pump up and float the valves earlier then the hydraulic. IMHO pdq67

Jim -

Lots of good info above - I'd agree that the heads aren't flowing enough and the ram's horn manifolds are choking it off (after all, it's just a big air pump). If you're going to drive it primarily on the street, I'd stick with vacuum secondaries - double-pumpers are popular to talk about, but they're a pain on a street-driven car. Vacuum secondaries respond to what the engine wants, and the opening point and rate are easily tuned (especially with the Holley quick-change diaphragm cover and spring kit). You haven't gone "backwards" - the 327/300 was rated as "SAE Gross" dyno horsepower, which was totally unrelated to the engine in the "installed" condition; a 327/300 set up and rated in "SAE Net" conditions (post-1980 method, much more representative) probably didn't make more than 220-230 real horsepower at the flywheel.

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JohnZ
'69 Z28 Fathom Green

I hope I don't make anyone mad here,but differ I must.I have owned light cars and heavy cars,all with 350-383 cubes built from mild to street strip.All of them have been street driven,given some were daily drivers,some were not.

In all of my experiances with these cars and engines with different drivetrane configurations, I have found that every time I bolted a vacuume secondary Holley to them I was displeased with the performance.
Don't get me wrong here,I'm not saying that vacuume carbs are junk.They have there place...it's just not with me.I do have a selection of carbs to use 650,700,750,750 that flows 820cfm (modified by Bary Grant),and an 800 all of wich are double pumpers.I also have owned two (3310-2 and 3310-4)750vs carbs(with rear meetering blocks) and one 4150 600(wich I felt was way to weak).All of wich I floged heavily trying to set up in an optimum state to different combo's,only to be slaped in the face when I bolted on a double pumper.
I have always strived for the perfect tuneup.So much so that my friends call me"THE TWEEK" .I am always trying to tweek this,or tune that in order to get my rides to run optimum.When at the track my friends let me tune there cars because they now I have the patience to adjust everything in sight.

Once a Holley is dialed in not much goes wrong unless you leave a bolt loose,have to low an air filter,or use a substandard fuel filter.Holleys are known for stuck needle and seat assemblies for this reason.No carb responds well to dirt.They may be the worst when it comes to this.If you spend a little $$ and get a decent fuel filter,this will never happen.Also they aren't that great if all you do is bolt it on and go.They just love to be tickled.

I love Holleys,they are probably the easiest to tune of all of the carbs,except for mabey a Predator.



[This message has been edited by mutant 68 (edited 11-16-2000).]

I agree, I have had some really great cars, that ran better with a DP than a vacuum secondary. If gas mileage is the goal, them a DB is out of the question though. I have had good luck with vacuum carbs on near stock motors, but I will be the first to admit that after that, they are beyond me!

Also, IMHO, Holley gets a bad "problem" rap. How many times have you seen someone running around without any air cleaner? Not only does this give the cylinder wall and rings fits, but I am sure it don't help the carb any. Holley has to many small passages not to.

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Mark

1992 Firebird 355/Six Speed
1991 RS 350 / 700-R4
1987 Toyota Pickup 383 / 500 + HP 10.963 @ 119.95 Slicks / 11.997 @ 114.23 Radials
http://personal.lig.bellsouth.net/~racer383/

[This message has been edited by Mark W. Winning (edited 11-10-2000).]

To DougG./Camcojb/pdq67/Tom3/ScottB/Mutant68/
Galen W.Rouse/sr71bb/mcpc/squarles/RPOL72/
JohnZ/and Mark W. Winning

I want to thank you all for your input on this. You know DougG, you, in your brief response, hit on this flow issue and the rest of you gearheads gave me a lot of specific reasons why this was the issue. I now know it's flow...whether it's carb or exhaust.

Where I am with this car is one of striving to maintain the stock look AND increase the fun factor in its performance. You know, these cars were meant to be driven...I'm in that camp. I'm definitely going to spring for a 3.70 posi.

I know cruising on trips gas mileage will fall. But, screaming down the road at 100 mph isn't as much fun as GETTING THERE!!!

THANKS AGAIN to all for all your input on this Missing Horsepower question.

Regards, Jim Karam (6T5RUSH)

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