I recently swapped out my 305 for a reconditioned 350 (1974 block).

I don't have much info on the engines internals. A guy brought it for a project car and never got round to using it, and he had bought it off someone else in another city who had had it reconditioned etc etc and I have not been able to track them down. The engine was still wrapped in plastic on it's crate ex the reconditioners.

I only have anecdotal evidence from the guy I bought it off (it was cheap!)

It's supposed to be running 327 (64cc?) heads and dished pistons with a CR in the high 9's, and a street cam (I do have a cam spec sheet). It's running standard looking valvetrain.

I just replaced the failing cc quad and dizzy with a new 600 Holley and vacuum Mallory HEI. Just after doing this I took the car to a track meet and ran a best of 15.7! 0.6 worse than my best with the 305.

Yesterday I took the car in to be tuned on a rolling Dyno and it turned out that the Holley was running slightly rich on the std jets and was dropped down a size, and the timing advanced by 6°.

The results were a 33 ft/lb max torque increase, and a 50 ft/lb increase between 2000 to 3000 rpm. The max horsepower was up 11, but shows a 30 hp increase in the 2000 - 3000 rpm range. Note these results are the rear wheels.

The peak figures were 304.7 ft/lb torque at 2900 rpm and 202 hp at 3800 rpm.

From what I have read on the net this would equate to roughly 390 ft/lb and 260-270 HP at the flywheel??

How does this stack up with your expectations? And given the increases, any guess on a revised et??

Your thoughts would be appreciated.

Cheers.

 

Seems about right for a 70's 350. They were dogs except for like 71 and 72.

I'd think maybe you'll have a tenth or so improvement in the 1/4.

 

I'd say you at least got what you paid for.

"327 heads" is a pretty meaningless performance characteristic. Most 327 heads were performance junk. Your 305 heads, with 1.94/1.50" valves and basic bowl clean-up, would most likely flow as well or better than the best 327 heads. And, you most likely don't have the best 327 heads.

64cc chambers and dished pistons are not going to yield high-9's compression. Mid-8's is more like it.

From the peak torque/HP RPM #'s, it's probably a good "RV" cam. Post the specs.

ET will probably go down a little with the dyno tuning, but not signficantly.

 

It really doesnt have a lot to do with what year the engine is when you build it. What really matters is that someone probably made a poor heads/cam/compression choice, and now you are paying for it.

 

Yeah I'm feeling a bit ripped, but as you say I got what I paid for.

The cam is locally manufactured with the following specs ( I don't know what's important so will give you the lot ;-) :

Lobe seperation: 112
Centre: In 109 Ex 115
In lobe lift: 0.278 Ex lobe lift: 0.292
In valve lift: 0.410 Ex valve lift: 0.430
Ratio 1.5

@ 0.005
In opens: 23 closes: 61 Dur: 264
Ex opens: 72 closes: 22 Dur: 274

@ 0.50
In opens: -8 Closes: 30 Dur: 202
Ex opens: 41 closes: -9 Dur: 212

Says approximate power range 1000 - 4500 rpm.

I don't know what the cc rating of heads are, was taking a punt there.

How can I find out the CR without knowing the physical dimensions? Buy doing a compression test??

Thanks for your advice.

 

The casting #'s off the heads would help.

You probably have a good base, it just needs the right stuff on top of it.

 

Actually, it could easily be in the 9's depending on the size of the dish, but I don't think that's the big problem. I agree with ljnowell that it's probably just not a well planned combination.
Also, that cam is pretty weak, I agree with whoever called it an RV motor.

All is not lost though - swap the cam, and then a slightly bigger carb (the 600 is going to make wicked torque, but will choke out HP after around 250) and you'll be fine.

I know I'm opening myself up to flaming with this, but I'm finding that around 300HP and 350 lbs/ft is plenty for the street. With a set of 3.73's my car is a monster for just about every situation. Is there faster cars at the track? Sure, but I drive it every day.

With the changes I suggested (try a comp 268XE cam), you should be making at least 250HP and will be a happy camper.

 

I made the effort to get both the block and head casting numbers with some interesting and contradicting results.

The block casting is 3970014 =1970-73, 350,200hp,300ft/lb,2/4 bolt
Front stamp = T0715CMJ
= 1974 police version

Head casting no's are 333882
= 1970-80,350/400,1.94,1.5,76cc.

Quite a different story. It would be conceivable then, that these are the original heads for this block?

 

I would say that those heads are your biggest problem. If you are running dished pistons, with 882's, you are waaaaaaaaay low on compression. YOur best bet would be to take them off, and keep all the good hardware from them, and pitch the castings. Find yourself some decent heads, apply what you have and buy what you dont. There may be some salvage parts from those heads (valves, springs, etc.) While you have the heads off is the perfect time to take care of that "pesky" little cam issue you have there.

 

With dished replacement pistons and their usual .020" down in the hole, and those heads, your actual compression is probably not much over 8:1; if it's even that high.

Don't worry about all the "police" business; I think one can rest assured that no special magical enhancements emanated from the somewhat unique paint job on the sheet metal, and installed themselves into the cast iron in such a way as to affect its current behavior.

Yes, it's possible that those heads and that block may have been together all of their life. They were both real typical mid-late 70s castings, that were in every kind of car and truck they made.

It's really no wonder at all that it's slow. You have essentially an exact duplicate of the 180HP 350s of the 70s, part number for part number; except for the cam. Which is really not a bad cam choice to go with the rest of the parts.

The heads have got to go, to get the power up. Your CR is just too low. 64cc heads would be good. Even better maybe, would be some 305 heads. 416 or 601 castings (the ones off of your old 305 in fact), with 1.94" intakes installed in them and some moderate , would dramatically outflow what's there now; and that one change, all by itself, would take the CR from right at 8:1, up to about 9.4:1... right about where it needs to be.

I'd leave the cam alone, honestly. It looks OK for the rest of the combo; especially if the car has highway type gears (3.08 or 2.73) and even more so if it's an automatic trans with stock converter.

I think that one change, putting 58cc heads on it, would net you at least a 20% increase in torque and probably 30-35% in horsepower.

 

Where ya located? I may have a set of 081 castings (305 heads) soon that I'll be porting a bit and selling.

That cam looks incredibly weak to me. Those lift numbers can't be right. With 1.5 rockers, it'd be .417int/.438exh lift as opposed to the 410/430 you listed. In either case, that's weak lift.

The durations are a bit on the low side as well. Get a cheap Summit cam for like $70 with 220-230ish durations with .480-.520ish lift (with 1.5 rockers), get some new heads on there, and that thing will become a beast rather quickly.

 

I also recommend a set of ported 416's. I had a set on top of a motor that sounds similar to yours in an 85 Z28. I had a bit bigger cam (218/218 .450/.450" lift) and it would run consistant 13.7's

Do some searching for posts by Sitting Bull, he has some links on porting 305 heads in his sig

 

It's a decent cam for what he has now. He needs all the cylinder pressure he can get at the moment. Sticking in a bigger cam without fixing the compression will just bleed off pressure, reducing what torque he's making right now.

 

Damn, LOL . I thought that might be one of the engines only redeeming qualities.

Thanks for the input everyone. All in all it looks like I, or rather me and the guy I got the engine off got shafted, mislead or whatever.

I still have my 305 but have been trying to sell it complete. I'm way over in NZ Duron so a bit far to ship those heads of yours.

In terms of the pistons and current CR how can I determine whats it's running at with the heads still in place?

The dished piston thing may be a load of bull too, and would kind of make sense if they weren't, as the engine is making about 270Hp at the flywheel. The dyno tuner commented that the results were typical of a std 350.

But now at least I have a plan with the heads and cam. Just a matter of how and when and $$.

The local speedshop dude was reccomending a set of Edelbrock heads and a comp cams 242 cam.

It's frigging annoying spending as much as I already have and being no further ahead.

 

Easiest way to tell what kind of pistons are in it, is to look.

You can just look in through a spark plug hole with a flashlight, and see them.

I would NOT buy heads until I knew for sure what the pistons are. It's too easy to either go too far and err on the opposite side of ideal, or make no improvement at all, or pass up the opportunity to get it right.

 

This is some of the best advice you can get. If you just buy heads you could end up with 7.5:1 or 12:1, you just dont know. Dont take the chance, its not worth it.

 

Understood. Thanks for your advice guys. Its much appreciated.