64 327 300hp problems HELP!

[milkdud99]

ok i think my engine is possesed!

I recently took apart the engine my great working 327 300 hp vette. Got it bored to 60 over, new pistons, put the new valve guides and seats in it to run unleaded fuel, new high performance oil pump pushing 60 psi at idol, new cam from crane(113942), new lifters and pushrods, new timing chain and gears, new fuel pump, rebuilt the carter AFB 625 cfm carb, new spark plugs gapped at .035, new taylor spark plug wires, new mallory distributor, new ignition coil, new valve spring which are 125 pounds, and a turned down crank! the problem is, it has NO power like it had before. After timing it 8 deg advanced and adjusting the rocker arms, it feels like my 77 beetle could kill it and that only has like 85 hp or someodd!

Its weird... it purs like a kitten at idol and when free reving it, although it does have a very very very slight lag in the carb. but when it goes for a drive on the road... it goes no where!!!

i have tried to think of everything i can do....i NEED HELP!!!
One guy at crane said it might be too much cam for the car, and another guy said it should be running just fine.......

original cam

New cam
I Dont know what to do to get this thing runnin great
any ideas i would greatly appreciate!

 

[WayneC]

Sounds like a timing issue. Since the Mallory (mechanical advance?) distributor is new to this engine, it may be worth installing the old stock distributor to see if that improves driveability.

Other possibilities that pop into my mind: obstructed exhaust (such as heat riser stuck or installed upside-down), improperly-routed spark plug wires (small block will run pretty smooth even with several cylinders not firing), anemic fuel pump, clogged fuel filter or fuel tank pickup, bad fuel tank cap vent, kinked fuel line, restricted airflow through the air cleaner, improperly-adjusted valves, wrong cam timing at installation.

 

[black_81_vette]

seems like either the timming is way off or theres the remote channce the valves are too tight . Is the cam mechanical or hydruolic? Also make sure your gettin enough fuel too

 

[BarryK]

This is probably a waste of your time to read this as I don't know a thing about fixing motor troubles and the specs on your cam compared to the old cam might as well be written in Latin for my understanding of it, but I figured it's worth a shot anyway..........
Do you get power anywhere at all across your RPM range or is it low power completely from low to high RPM? For example, my '65 stock 327/365hp is a complete dog and feels like grandma's car up till 3500RPM but after 3500RPM she really kicks in and you better hold on and that's with a 4:11 rear. The cam in this motor just doesn't give you any power at all until you really have her rev'd up. Compared to a stock spec 327/300 the 300hp motor have more lower RPM torque for off-the-line performance than my car, but mine would end up taking the 300hp motor once the RPM's get into a higher range. Since different cam's will give you different power at different places throughout the RPM range do you see a difference at high or low RPM's?

 

[tomtom72]

HI md99, When you drive the car it feels like:

It has no power at all?
It hits a "wall" at a certian RPM?
It has no low rpm power? Like from Idle speed to say 35K?
It has no top end power?

Or is the motor behaving weird when you run diagnostics?

You have how much vacuum at idle? RPM? / Vac reading?
Your advance is working properly? Initial? Vaccum? total?
You checked Fuel pump preassure & volume?
The lag could be an adjustment on acclerator pump.
The carb jets/metering rods are enough for the increase in Cu. In.?*

Reason for * is I had an LT-1, 1972, it had kind of similar #'s on cam and it came from the factory with a 780 cfm holley. If I put a 650/4777 holley on it the car was a different in that the 650 starved it for fuel/air volume across any rpm range except idle to about 4K. Smallest I could use was a 750/4777 and still "feel" like an LT-1. I suggest if all is in order diagnostically then you may not have enough carb to feed new Cu. In. + new cam.

How did you adjust the Hyd lash? not too tight or too loose?
I assume the cam came as a kit? Lifters,springs etc?
The cam #'s look like a split profile cam, you installed it straight up, not advanced or retarded? I'm only asking because I always just put split profile cams in straight up for street motors. I'm not a mechanic so don't take that as a reliable fact. I always have had the problem of being too loose on my initial lash adj & wind up having to go back at least twice so obviously I'm not good at it!

I wonder if the increase in Cu. In. has made the carb too small. It sounds like you are good on the diagnostics & all is okay but it has no power. To me if that's the case might be time to run the calculation for carb. size vs displacement? Sorry this is so long & might not help, but sometimes we overlook simple things. Good luck & I'm sure this is something simple and not major. Tom

 

[Tempus_Fugit]

I would check

1) timing, sound like it might be retarded
should be set with vac hose disconnected
check centrifugal advance and with a timing light, make sure the timing changes when you rev it up

2) stuck or upside down installed heat riser

3) valve adjustment

John
Milwaukee

 

[61 Silver]

I had the same type of problem with my 65 250HP. I asked the engine part supplier and machinist to purchase only engine parts that were very close to original specifications. I was not looking to increase power but for a good cruser, one I could drive to Carlisle Pa. or other long distance trips.



The engine ran fine until it reached operating temperature, then it ran very poorly and would stall unless you had it at high RPMs. After weeks of adjusting valve lash, timing, carburetor (rebuilt for the second time) and any other adjustment that could be made I decided to pull the lifters and see exactly what the supplier provided. The lifters were not what I had ordered; they were a new anti-pump-up type lifter. To the best of my knowledge they are suppose to provide the performance of a solid lifter with the convenience and sound of a hydraulic lifter. The valve springs were of stock specifications and I needed to install valve springs (heavier) that were designed for this type of lifter. I choose to replace the lifters with original spec. hydraulic Lifters. The 250HP runs fine now.



I would check the setting specs for your lifters and spring combination. I have a feeling that is where you will solve your problem.



Ray

 

[redvett]

If you bored .060 and changed cams you have to rejet the carb. Just either the bore job or the cam will require a jet change.

 

[tomtom72]

Forgot the Heat Riser Valve

John from Milwaukee that is a part I completely forgot about! A good old exhaust restriction and that is easy to check. :duh

 

[milkdud99]

hey guys

The exhaust valve is in, and i wired it open all the time.... and the distributor is new cause the old one was bad oh and it is not a vaccum advanced distrib. Im starting to think it could be the carb... i wish i had a bigger one to put on and test it out..

As for the power, it has no low end power... when i stepped on it, it kind of just cruised up to 2000 rpms. then the secondaries kicked on and it had a noticable power gain.. but still nothin close to 300 hp.. im gonna try to fine tune it, and set the timeing by ear..

I dont think the valves are on too tight . what we did was loosend them until they clacked and then tightened them till they didn't anymore and then 1 full turn. (this was checked like 10 times each valve)

Thanks so far for the help guys!
Mike

 

[paul67]

Why did you choose a distributor without a vacuum advance unit? That may be the source of the problem.

 

[WayneC]

1. Shop manual says to adjust valve lash by turning rocker nut down slowly until clatter just stops; now turn down 1/4 turn and wait 10 seconds or until engine smooths out, repeat 3 more times.

2. Is the Mallory distributor new? Do you know for certain that it has an advance curve setting appropriate to your engine? Beg, borrow, or steal a vacuum advance distributor to try.

 

[JohnZ]

That cam is a mismatch with the rest of your stock components; 218*/230* at .050" is fairly radical for a stock 327/300 intake, and will kill your low-end torque. You don't need a bigger carb - the one you have is more than adequate. I suspect the rest of your issues are related to valve adjustment (1/2-turn down from clatter is plenty) and lack of proper vacuum advance. Have you mapped the centrifugal advance curve in the distributor - when it starts, what the max advance is, and when it's all in? Until you know that, you don't know where to go with your initial timing anyway, as you don't want to exceed 34*-36* total timing with full centrifugal advance. The centrifugal-only Mallory distributor is next to useless on a street-driven car, but Summit and Jeg's LOVE to sell them anyway; I'd send it back - it'll never run right on the street without vacuum advance. You also don't need the high-performance oil pump; the stock pump and oiling system works just fine.

With the original cam grind and a properly-curved vacuum advance distributor, it should run like gangbusters and have loads of low-end torque.

 

[milkdud99]

That cam is a mismatch with the rest of your stock components; 218*/230* at .050" is fairly radical for a stock 327/300 intake, and will kill your low-end torque. You don't need a bigger carb - the one you have is more than adequate. I suspect the rest of your issues are related to valve adjustment (1/2-turn down from clatter is plenty) and lack of proper vacuum advance. Have you mapped the centrifugal advance curve in the distributor - when it starts, what the max advance is, and when it's all in? Until you know that, you don't know where to go with your initial timing anyway, as you don't want to exceed 34*-36* total timing with full centrifugal advance. The centrifugal-only Mallory distributor is next to useless on a street-driven car,

Is this cam a bad one to put in the car... when i talked to a crane tech guy he said its like the second "notch" up cam... meaning its good for a dialy driver.
and i might go ahead and put the old distributor back in (the one with a vac advance) The only reason on why i didn't get one with a vac advance is because no one around the daytona beach area had one with a tach drive on it... Not even ecklers!! so i got the next best thing that was available ASAP

i might go 2day and drop in the old one with the vac advace.... i at least knew that the old one worked

do you have any tips on how to map the centrifugal advance curve??? ive never done it before
thanks for all your help guys. its greatly appreciated!!
mike

 

[JohnZ]

Mike, shoot me an e-mail (just click on my username and click on the box to send me an e-mail) and give me your e-mail address, and I'll send you back the text of an article I wrote in the December, 2003 issue of "Corvette Enthusiast" magazine on how to map your advance curve at home. Or, you can call the magazine at 800-572-6885 and order a back issue with the article and photos.

 

[milkdud99]

ok.... i took the car out for a drive today... and have figured out that there is ABSOLUTLY NO low end power. the car gets up and goes at around 2300 rpms, but it can barely keep up with traffic leaving a red light... (with full throttle) is this normal for the cam i bought?

(this is still with the malory distrib)

 

[youwish2bme]

Seriously doubt the Mallory is your problem.. I know most say it's Racerboy stuff but the Mechanical advance works fine, will not cause you overheating issues if you have you engine and cooling system in order. I have a Mallory unilite that has been in my motor for the last year.. I drive the car all the time all weather conditions.. No overheating issues 11 degrees initial all in at 36 degrees at 2500 rpm's. No miss no detenation etc... Some will tell you if it ain't stock it ain't right... Well the general did very good on engineering however if you want fuel economy you might consider the vac advance style distributor... It really sounds as others have mentioned that it's your cam.... Dave...

 

[carrollm]

Make sure your carb's secondaries are opening, and your carb linkage is adjusted to give you full throttle. Also might have your float adjustment checked by a competent mechanic. Sounds like it is starving for gas/air
if you give it full throttle and go nowhere.

Does it start up easily?
does it shut off easily?

64Mike

 

[milkdud99]

Make sure your carb's secondaries are opening, and your carb linkage is adjusted to give you full throttle. Also might have your float adjustment checked by a competent mechanic. Sounds like it is starving for gas/air
if you give it full throttle and go nowhere.

Does it start up easily?
does it shut off easily?

64Mike

The secondaries are kicking on around 2300 rpms. and when we rebuilt the carb, the floats were measured to specs on how low there supose to sit... the car starts up without pumping the pedal.. and shuts off great. its just that when i go from a stop light and stomp on it, it gets beat by s10's and such THAT AREN"T EVEN RACING.. im thinking more and more that the cam is not right for the engine, OR the carb was rebuilt wrong. i might go out and buy an edelbrok 750 cfm performer and stik it on there to see how it runs. and i might go get it gyno'd and maybe see if they can find somthing wrong with it.

if anyones got more help... im all ears

thanks again mike

 

[BarryK]

Mike

go back and reread the advice by JohnZ. You already have the answer to your question on the lack of low-end torque and low power.
You are new to the forum so may not know but John is one of if not the most knowledgeable person on here and knows more about these cars than 99% of the people in the Corvette world.