The engine ran pretty well on the dyno, we have a few issues with the TI ignition system and I think its causing a misfire after 6300 but....all in all, it came out ok. Ofcourse I expected more out of it as usual but... We have some data to make changes on and go from there. First mistake we found was the carb is only a 650 cfm (#4777) and NOT at 750 cfm (#4779), once I noticed that, I knew it was going to hurt us. Next restriction is the fact we are running stock vette side pipe manifolds...they are 2.5" outlet and pretty restrictive overall.... But that's the way we are running it in the car so...it is what it is.

1965 396/425hp
1965 block, .060 over bore, 4 bolt
Racetec custom mini dome pistons, .015" out of the hole
Scat 4340 rods
GM #6223 forged crank
MLS .053" head gasket (block was previously decked a bunch)

Heads

GM #208, rect port closed chamber heads
Milled/CC'd
2.25", 11/32" intake valves/bronze guides
3 angle valve job
No porting or bowl work--all stock

Calc'd compression is 10.0-1. It has 175 psi cranking pressure

Cam

CStraub hyd roller
237/245@.050, .620/.556, 109 LSA
Crane Gold roller Rockers.

Stock 1965 425hp Winters intake--no porting or plenum mods
#4777 Holley 650 cfm double pumper.. Worked excellent on the dyno, but we saw 1.7hg vacuum at wide open so...its a little too small.
Stock Vette side pipe exhaust manifolds
Stock TI (transistorized) ignition system(with wires arcing and misfiring all over the damn place)











Yeah the curve is pretty ugly up top, we suspect the wires arcing to each other through the stainless braid sleeves may be the culprit. We will be changing wires before it goes in the car. We are also gonna pull a valve spring and check pressures to make sure they are where they are supposed to be since its been ran. It shouldn't nose over the way it did up top. Unfortunately, we wont get to dyno it again so, we have to live with the final results but I will be changing a few things before it goes into the car. Like rebuilding the original 1965 Holley 780 cfm carb, new wires, recurve the distributor(It had a very short curve in it)....

Once it goes in the car, the side pipes are going to choke it to death anyway so no point in really trying to extract every HP out of it but... I would have like to have made 500 hp with it but...no dice.. Not with these manifolds.


Going in this:

 

Not bad, really. As you observe; a little tuning is in order. Nice collection, by the way.

 

How is the idle and vacuum? How easy does it start.

 

Starts easy, idles great. Definitely has some thump...

Steve on TC just brought it to my attention that the #4777 carb is actually a 650DP..... We thought the carb was a #4779 750hp....

So no doubt that little carb hurt us...But the engine ran great with it and the fuel curve was very nice without even changing jets. We will probably send the original '65 holley 780 cfm vac sec off to Holley to be restored and run it....Although I hate vac sec carbs.

You were pretty close on your guess to peak at 6500....It peaked at 6300 but then picked up a miss....It may have peaked at 6500 had it pulled clean all the way there.

I think it would have made 450hp if it had pulled clean to 6500...

I figure there is 10-15hp in the carb and another 10hp in whatever is causing the misfire after 6300... So probably 450-460hp in perfect tune through manifolds.

They dynoed a 1970 LS6 yesterday, completely blueprinted to stock specs, it made 460hp through 2" dyno headers.... I think we would have beat that with the same headers and way less cubes.

 

We had a customer we dyno'd with his BG claw 850 then went to an AED 850. It was 50HP. 400 CID with a dual plane intake needs 894cfm at 6300 rpm.

Your dynoing this as it will be in car and with Factory components for originality. You put an HEI in that thing with a good 850 AED carb and it will be right at 500HP.

 

Yeah I was half a$$ tempted to swap carbs, Joe at Owens Racing had a 775 Demon carb we could have thrown on it but...with it missing after 6300, I didn't want to pull on it any more. Gotta determine if its ignition or something spring related. The builder is going to double check his measurements on the installed height. The valves are .100" longer then stock, so he had to shim the springs accordingly... He did have the numbers with him but he said they were around 200lbs on the seat so...It should have been plenty to prevent valve float... And the valves are pretty light with the 11/32" stems.

What do you recommend for preload on the 4603 Morels?

 

Preload needs to be 1 full turn. No oil over 15W-40.

 

Oil was 10w40 Valvoline VR1 dino oil. The preload is 1/4 turn. Maybe we need to add some preload.

I know on my Morels in my 496, it didn't matter if they are 1/4 turn or 1 turn, they were still noisy cold, but pretty quiet hot... Ran the same ET/MPH both ways.

I'll talk to the builder and see if he measured preload when adjusting them, or just ran them 1/4 and locked em.

 

1/4 turn does not allow the lifter to recover. Some have gained 600 rpm with going from 1/4 turn to 1 full turn. This will equal power gain also.

You need to find this information as this will also hurt power greatly.

 

10/4

I'll get with the builder tomorrow and have him go 1 turn on it... Maybe that's why we were developing the miss up top.... Also maybe it will quiet the valve train down some.

Although I've ran my morels with as little as 1/8 turn preload and it never made any difference at all in noise or performance with going from 1/8 to 3/4 turns.....I ran them at 1 turn once....then after a spring swap went back to 1/2 turn. Never noticed any type of change...

 

great numbers ! the A/F ratio is right on .

 

I'd put an 850 DP on that bad boy.

 

Yeah that would probably be the best for all out HP.... We actually have the original #3124 Holley 780 CFM vac sec, we are gonna rebuild that and throw it on, then we can use the stock fuel line/filter assembly... Should gain some flow/power and look stock....I just hate vac secondaries...but I can't probably make it work well


Gonna drive it with the 650 on it first just to learn the behavior of the engine...get used to how it runs, then when I put the rebuilt 780 on it I'll know how it should act.

 

should have pulled the carb off the 496 and gave it a go,

Nice car, gona be a blast with the BB

Took a ride in a 67 a few days ago with a warmed over 327 and open side pipes, it was a blast and sounded great.

keep us posted,

Neal

 

Chris set me up with an AED 850 love the carb. Nice imrovement and tailor made for your car.

 

Hi Neal, how are you man?

Yes I thought about my 850 on my 496 after the fact.. The Dyno shop is an hour away from where I keep my 71'... Plus the jetting on the 71' is way different and I'd have to pull that carb all apart too... Just not enough time.

Once we discovered the burble after 6300, we decided to call it a day until I can get new wires on it, as well as test a valve spring.

We'll get it in the car in a month or so and tune on it from there... It should run plenty good with 3.70s and a 4spd...

I hope your car is running well..

 

everything is good, been working a lot

been working on the small stuff,

finally got all the Dragvette stuff installed and some upgrades to the ignition (new coil) all that is left there is the 6AL programmable.

Haven't seen you much on the C3 forum, hope your not giving up on the green beast.

Neal

 

She lives finally, after a year of being down.

Cam sounds pretty damn good in this motor if I do say so myself.. Got a little "thump" for sure... Its a Straub Tech 237/245* @ .050, .620/.566" lift, 109 LSA hyd roller.

I re-adjusted the valves today with more preload and I found 2 that were way off.. I wish had checked them myself before dynoing it, I have a feeling two cylinders may not have been 100%...



I still have to finish dialing in the timing curve, put the ignition box back on and tie up all the wiring harness behind the distributor so excuse the mess... It will be right in a few days.

Also I have some custom 2.5" ID Classic Chambered pipes we are going to build side pipes out of so it will flow much better then the choked out 1 5/8" ID stock side pipes..

Hopefully we'll make the maiden voyage in another week or two..

I will soon start rebuilding the original 65' 780 cfm vac sec so we can put the factory fuel line, filter, PCV tubing back in...not to mention gain 130 cfm worth of flow over the tiny 650 DP that is currently on there.

 

Very nice...So how does the new engine feel versus the old one...Looks like Gross HP is about the same as stock--+16 HP..Torque Difference?

 

I haven't drove it yet... and I only drove it once with the previous engine which had a flat cam and ran terrible..

Yes this one only made 441hp but it had a few things going against it.. Questionable spark plug wires that were arcing, two rocker arms that apparently were set incorrectly by the builder during assembly..(I just reset the valves today adding preload and found two that were flopping on the valves).. Then the aforementioned 650 carb mistake vs the 780 cfm that comes on a stock one...

I am pretty confident that this one would make an honest 460hp+ now with the small issues resolved and a 780 carb with manifolds, and probably 490-500hp with 2" headers.

In regards to a stock 396/425hp engine in true oem form, first off, they were dynoed by GM with headers and no exhaust in the SAE gross rating era (to the best of my knowledge and research), where as we dynoed ours thru stock manifolds, that's an easy 30-40hp loss.. And then the factory 396 probably didn't make a TRUE 425, it was probably a bit less due to varying tolerances...(ie. pistons down in the hole like ours was).

I'm sure ours even with less compression is likely a bit quicker then a stock 396", especially once I get my custom side pipes built with 2.5" ID classic chambered pipes and true 2.5" head pipes, vs. the stock side pipes with 1 5/8" ID and crinkle bent head pipes that neck down to 2" in some spots and known to kill 50-60hp+.

I may eventually chasis dyno this one and see what it makes with some tweaks...for now I just want to finish everything and get it cruising for the spring.