4424me

Tried searching but I could not find anything. Question is, with stock compression of 8.5 i believe on a 72 455 and Ga heads. bored .030 over. is it possible to get 400 hp out of this engine with these heads? Just trying to see what an engine with this compression ratio and heads is capable of.
thanks Dan

Gary's 2 442-S

I have a 72 with Ga heads also. I had my engine rebuilt in August of last year. It was bored .040 however. I know you are asking about .030 over but the ratio is 8.5. Now the machine shop that rebuilt it said its getting well over 425 hp. I do not know how true that is because I guess I have never been into hp just performance. But he is a highly regarded engine rebuilder and I take him at his word. He replaced all the valves and I cant remember what size they are. I can use regular pump gas as well.

4424me

Ok ya I cannot see the .010 diff on the bore having that huge a affect on the hp. Thanks for the reply. Exactly what i was looking to get. Did you get any porting done on the heads?

Gary's 2 442-S

No there was no porting done. I wanted the engine to be as close to stock as possible if there was a such thing. I looked at my paper work so see what were all the specs and its not on there, but one thing I can tell you is that the engine performs very good. i dont have to pump it to start it, It starts on the first try. The engine had rebuilt by someone before I got it, but I never could get it to run good at all. My engine builder said the engine had been redone for sure but not correct and he also said it had mismatched valves in it.

Vega

You can easily hit 425 with Ga heads. I love the G and Ga models myself, they have factory hardened valve seats that allow the usage of modern gas (other earlier heads, like C, in comparison need this done as part of the rebuild) also G/Ga has deeper spring seats for valve rotators which allow clearance for higher lift cams without having to machine the spring seats (again like C heads or A, B, E, F, etc).

And honestly, all factory iron heads besides maybe the J(unk) heads flow so extremely similar to each other that you'd never notice unless it was an all out drag car looking to dial in specific times. Also the allowance for larger lift cams can potentially get you higher horsepower without necessary machining from other heads. Dont let people talk you into getting rid of them for Cs or edelbrocks (as few as those people may be around here) Gs and GAs are great heads. Just ask BigJerr, he runs G or Ga i dont remember, but he has a rather budget-oriented build in a 4000 pound 72' Cutlass and hits mid 11s on all motor, and 10s with a 100 shot of NOS. Its a mean **** lol

EDIT: Sorry, i guess he runs C heads :/ but still, all iron BBO heads are extremely close performance-wise

Vega

Also id be surprised if your compression really was 8.5, stock at least. It seems those motors were actually closer to 8 or high 7s. Thats not a bad thing though, when theyre power houses at that low of compression imagine what they are at higher compressions. If youre getting it rebuild throw higher compression pistons in and a larger cam, it'll change everything for you. Then add intake, headers, carb, larger valves maybe, it'll be a mean street motor. Build it for torque, it'll do a lot more for you than horsepower numbers

4424me

All the positives towards the G's make me more confident. The motor has been built before but it appears that half the rods were installed backwards so needless to say half the rod bearings were shot as well as half the main crank bearings were wore right out. The motor was super tight to turn over even with the spark plugs out so i think the clearances may have been a bit off from the last builder. The heads had some port work done to them, a cam ( which i know nothing about) was put in it, engine looks to have been balanced. a performer intake and headers were installed. PO told me 400 hp which sounds to reason to be about correct. I also do not know what the compression ratio is of these pistons because they are not the original (0.030 oversize)
There are a few scores in the cylinder walls so i may need to get it bored to 0.040. If thats the case then new pistons are in order so possibly 9.5 comp? what ya think about that?
already got a new performer intake (old one was cracked at exhaust crossover on drivers side) new 750 cfm edelbrock, hooker headers, so that pretty much adds up the bolt on stuff. Just gotta find out whats good and whats bad as far as the rest of the bottem end goes. rods etc.

cutlassefi

Just curious on the rest of your combo.

4424me- I'll be dynoing a 455 in the next few weeks with stock Ga heads so we'll see.

Jmo but I like the KB Icon 886 pistons and they come in .040 over. Try to get your guy to hone it to that with torque plates.
Install the big intake valves and you should see 400 with out too much difficulty. Let me know if I can help with a cam.

By the way, installing the rods in reverse will really only effect bearing wear a little, the bearing will be offset and partially overhang into the undercut of the journal. Your cam would potentially suffer more as the **** holes (if equipped) would be pointed down. If the motor was tight to spin then you may have a tight rope seal or something else incorrect as mentioned. Any pix of the bearings?
And depending on the cam choice you may want to hold on to that Performer and maybe exchange it for an RPM. We'll see when I do the manifold shootout in a couple weeks.

Best of luck!!

Gary's 2 442-S

[QUOTE=cutlassefi;370630]Just curious on the rest of your combo.

Sorry just now getting back to you. I put in a call to my engine rebuilder today to find out if he remembered what was put into the engine, he was not there so I left message for him to call me and I am awaiting his call. I do know that all the pistons and rods were change as well as just about everything inside that engine. but the types of pistons and inserts I just cant remember, but when he was rebuilding it he called me over to his shop to show me what he was putting into the engine, so I did see the pistons and the rods, and the valves that he was going to put in it and now I know I should have written down what he said they were. I do know that he did put what he called a performance cam into the engine and I remember that he said that it would not be a radical cam. I have stock intake manifold which he checked for cracks,the 400 transmission behind it with 10 positive rear end and stock Rochester Quad carburetor. The engine when I got it came with a 650 Edlebrook and I took it off. Whatever he put into the engine is night and day over what is was and I am very pleased with it. I have to be really careful when I take off because unless I am easy on the gas pedal,it will burn rubber like a son of a gun.

4424me

thanks for going to all the trouble gary. what ratio is your rearend?

cutlassefi. I have been following your intake comparrison and am interested to see what results you come up with. I will deffinitely keep those pistons in mind if i need to go larger.
as for a cam, i want it to be as lumpy as i can get it. any reccomendations for that? would the RPM be a better intake as far as this criteria goes?
Its weird about the connecting rods because everyone that was "backwards" on the right side of the engine had severely cooked bearings, where as the left side were just barely starting to show wear. basically right down to copper on all and one had overheated badly enough that it shrunk and would not stay in the cap. i unfortuently was too depressed to think about taking pictures :P
the cam on the other hand looks to be in good shape, little to no wear.
Thanks for all the help guys!

cutlassefi

Cam choice will depend on your final combo, i.e. compression, intake etc. We can do something when you get that nailed down.

On the rod bearing wear, the ones that were backwards, was the wear even across the bearing? Localized? If you could give us more info that would help.

Thanks

Gary's 2 442-S

[QUOTE=4424me;370991]thanks for going to all the trouble gary. what ratio is your rearend?

I have 8.5" with 2.73 and it will smoke the heck out of the tires.

507OLDS

If you have not purchased your pistons yet,you can get ones with the smaller dish,to put you in the 9:5:1 range,but yes,you can make 400HP with yoru Ga heads.

4424me

ah yes same rear as I. it too would light them up with no problem.
Gotcha on the cam. makes sense. i will have to find out what my CR is and then go from there. As for the wear on the bearings they were even on the ones that were badly worn. The whole surface was copper. The ones that were starting to wear had wear at the edges ( say the tips of this U ) working down into the bottom of the bearings. Engine went to the machine shop today so i will keep posted on what more they can tell me when they tear it down all the way.
thanks!

cutlassefi

I would say your clearences were wrong. And if they were pinched at the parting lines that's even worse, that's were you should have the most amount of clearance, not the least.
Almost sounds like the caps were switched or they put new bolts in after they reconned them, if they reconned them.

Keep us posted on your final build specs.

Thanks.

4424me

ya that was my first thought too. Which would jive with the idea that the engine was tight.
Its really too bad because it had lots of power and ran good. oh well. Ill be sure to keep posted with updates!

4424me

So now for the rest of the story.
Once the second head was pulled off it was clear the engine had severly overheated. two of the pistons had gotten big enough to expand and score the cylinder walls pretty good. So right off the bat this is gonna be more expensive.
Maybe a little pre mature on this post but im getting a quote written up with the brands and itty gritty details.
but so far i know this much.
getting bored .040 over. which means new pistions. gonna stick with around 9.2 to 1 comp ratio so i dont have to run super expensive premium.
crank need to be machined. pretty good scoring on a few spots.
a number of pro oiling tricks are being performed.
The car i believe had pretty much the lumpiest cam in it(dont have any numbers sorry ) , which I was reccomended to tone down a bit to help improve bottom end.
Heads are getting rebuilt.
I had asked his opinion on the Performer vs. airgap. His reccomendation was that i go with the air gap.
Finally it came down to rockers.
He told me going to a roller rocker would gain me 25 hp. hmm. what do you guys think?
Thanks for listening!

Vega

Roller rockers are always good to have, 25hp is a stretch though. Maybe consider doing a roller cam? That will definitly pony up some free horsepower

4424me

my thoughts exactly.Ii would be totally up for doing that, but having to get the block reworked and new pistons in the line-up, has somewhat put me near the top end of my budget.
With that setup, with a 750 cfm edelbrock and new hooker headers, what would the knowledgeable (damn that word looks awkward) folks on classic olds think ill be pushing for hp and tq?

Vega

Could you list whats going into your build real quick? Pistons, cam, inake, etc

Just some specifics would help, but with a good tune id say 400hp/450tq to the crank wouldnt be out of the question. Give or take

4424me

I absolutely would, but im out of town and will not be able to acces the paperwork where I had it all written down for the specifics on cam and pistons. sorry, ill post up when i get back to town. hopefully this coming weekend.

Vega

Yep no problem. Estimates may differ depending on whats in it, but from what ive read you should hit those numbers i mentioned pretty easy with a good tune. Torque is going to be a pretty dead even 450-500 on any mild build, the cam will decide the horsepower, more cam will give you more hp and kill tq some and less cam will give more tq and less hp. Less cam is typically better for the street since youre mostly going to be using mid-range RPM, thatd be the spot to build towards on a street/strip mild rebuild. sounds like youve hit on it pretty well

4424me

ya pretty much my thoughts exactly. thanks for the replies vega. pretty much heard everything I was looking for. ill post more info when available and eventually the holy grail... possibly some pictures!

cutlassefi

A Ga headed 9.5:1 455 should make 400hp/500tq with the right cam, the Air Gap, headers and a 750 or so. I don't see an issue there.
However there ain't no way you're going to get 25 more hp from roller rockers, sorry. Maybe 10-15 depending on ratio etc.
If you can do a roller I would. They no doubt are more costly up front but I promise you you'll be spoiled. And Apples to Apples you can normally squeeze a bit more hp/tq out of one wiht less duration, that'll make it drive better for sure.

If your motor overheated that helps explain a lot. It's tough for the crank to push the rods when the pistons are tight against the walls. That'll cause bearing failure for sure.

Note: just so people don't get the wrong idea, gh5168 I'm glad and don't doubt yours runs well, but there's know way you're making 425hp with 8.5:1, stock intake and a mild cam, sorry.
I made 451 with Edelbrock heads, 10.3:1, a Holley 870 and Torker intake, just an fyi.

Vega

[QUOTE=cutlassefi;379559] If you can do a roller I would. They no doubt are more costly up front but I promise you you'll be spoiled. And Apples to Apples you can normally squeeze a bit more hp/tq out of one wiht less duration, that'll make it drive better for sure. [QUOTE]

Agreed, and for me the ability to re-use lifters alone is enough to sell me on it

4424me

Alright thanks. Ya when he said he figured they would gain me 25 I was skeptical.
Ya the pistons rubbing now make sense as to why the engine was so tight and the bearings were shot for sure.
I think im going to go for the rollers anways. they seem to be a great investment in everyones eyes so what the hell!
thanks for input

4424me

Holy Im driving myself crazy over here. Sorry if im driving you guys crazy too! Heres my question.
Ok With my setup.
455 bored .040
Forged pistions not sure what brand yet (9.5 to 1)
Ga heads.
Roller rocker setup.
750cfm edelbrock.
I have two questions. Ok The RPM edelbrock intake has a rpm range of 1500 to 6500 rpm. I do not plan on running above 5500 rpm for any reason. Am i going to be missing out on the potential of this intake with these circumstances?
Secondly could you reccomend a cam for the RPM and one if i stick with the performer intake. I want to stick with the comp-cam extreme energy camshaft. So if you guys could pick out two cams from that category that would be great! thanks.

cutlassefi

Why the Xtreme energy with stock heads?
And don't take the rpm ranges on intakes at face value. On a 400 it'd probably work best at 2000-6000, on a 455 maybe 1500 to 5500 depending on cam compression and the rest of your combo.
I should be going to the dyno in the next week with a 10.0:1 mildly camm

cutlassefi

Why the Xtreme energy with stock heads?
And don't take the rpm ranges on intakes at face value. On a 400 it'd probably work best at 2000-6000, on a 455 maybe 1500 to 5500 depending on cam compression and the rest of your combo. See what I mean?
I should be going to the dyno in the next week or so with a 10.0:1 mildly cammed 455, I'll be testing both intakes with a 750 Quick Fuel carb.

4424me

that is the cam that the machinest i deal with was reccomending. Ok i see where you going with the rpm ranges. makes sense. I look forward to seeing your results!
Is there a problem running the xtreme energy cam with the heads i have?

cutlassefi

Yes imo because I don't recommend any of the fast ramp stuff with stock heads, whether it's the Xtreme or VooDoo.
Here read this;
http://forums.highperformancepontiac...1.html#9120276

I'm fastoneefi on there. Read the first page then the last few. This is the second time one of my grinds has outperformed their grinds on the dyno sym, and by a lot. And it's an Erson, not Engle like they mentioned.
And Pontiacs, like Oldsmobiles with older heads need the off the seat time, a fast ramp doesn't offer that advantage. And ask yourself one question, is it easier to climb a mountain 400' tall with a base that's 150' wide or with a base that's 200' wide? The fast ramps are harder on the valvetrains. I have fast ramp stuff available to me on the Erson side and I'm now a Lunati dealer as well. But a fast ramp cam is typically my last recommendation for iron headed V-8's.

Jmo.

4424me

ok wow lots of info there. Thanks! I will have to do some thinking on this then. I still have about a month to get this figured out. Ill talk to the builder and relay what you said! Thanks again!

Vega

Im learning from this too. I was pretty set on the 60804 or so Lunati but this has me re-thinking that move as id be using stock iron heads as well

JCMC64

Good thread!
Im interested in all this as I have Ga heads too (vega gave me similar info on Ga's) on a recent rebuild by the P.O., and will be tinkering with my 72' 455 intake\carb setup in coming months.
JC