[panhead59]

I've got a 1970 455 in a 66 gto. I had to rebuild the engine cuzz i am/was a dumb@$$ and didn't torque 6x heads correctly, so i blew both head gaskets within 1k miles. One cyl. Was not looking perfect so i just had the engine rebuilt by the best machinist around. Heads are ok and have the big valves and hardened seats. Its a 4 spd with 355 rear gears. Pistons are forged, .040 over , .005 in the hole, but otherwise stock bottom end. 3 2's for carbs. Lunati 10510704 cam. Flat tapet. Machinist cut block and heads to give me 9.3 comp. Ratio. Street car only. Here's my ? How's a set of kre 85cc heads (should give me about 10.3 to 1 comp. Ratio) and the edelbrock pro-flo 4 efi sound for an up grade in power ? Worth the $ ? And what would be best cam for that combo ? Kinda want to use current cam so i can avoid any lobe failures.
.

[hurryinhoosier62]

You still have the stock rods in the bottom end. For a street only engine it should be fine. They were magnafluxed, had quality bolts installed and resized, yes? The OE cast steel rods are going to be the limiting factor in future attempts to make more power. If it were me, I’d leave everything “as is” until you’re ready to freshen up the lower end.

[JLMounce]

I have a very similar engine. As cast KRE D ports on a forged piston 455. Stock rods and crank. Uses a FiTech for fueling.

I did go with a roller cam in my engine.

It's been fun and reliable. More than enough power to have as much fun as you'd like and still has some decent manners. Will run on 87 octane if I need to. For me the money was well spent. I was however replacing a set of #62's that had the engine at or above 11:1. I was running 100 octane fuel in the car at a cost of 7.50 per gallon and if the ambient temps were above 80 degrees, it would still ping.

For me the heads have paid for themselves at the fuel pump. The power difference was noticeable but not what I would call overwhelming.

[steve25]

Going by your info you posted on your 455 @ .040 over with 85 CC heads I come up with 9.55 to 1 compression and you really want to end up with 10.5 to 1 compression with aluminum heads.

[jerry455]

When I was going to redo my motor I looked at cylinder heads. For what it was going to cost to improve a set of cast iron factory head, I got a set of Edelbrock round port 72cc RPM heads. After a mild chamber clean up, the chambers are at 79 cc. With a 10cc dish Diamond piston I should end up about 10.3 :1 comp. ratio. I think the aftermarket heads are a great deal. I am going to make the heads look as stock as possible.

[steve25]

Gezz! You must of been intentionally shooting for a additional 7 CCs of chamber volume because a general clean should not add more then 3 to 4 CCs.

[panhead59]

Yes rods were resized with arp bolts. We were intentionally upping comp. Shooting for 9.5 to 1. Sounds like its not really worth the cost. $4500 for heads and efi and not a huge power gain ? My machinist calculates 9.3 comp., with current engine. Kre sales calculates 10.3 to 1 with 85cc heads. Kre says engine would produce around 500 hp with out of the box 85cc heads, and flat tappet cam. Guessing 400-425 hp with current engine, one would expect a huge seat of the pants improvement with 75 more horses.

[F ROCK]

Originally Posted by steve25

Going by your info you posted on your 455 @ .040 over with 85 CC heads I come up with 9.55 to 1 compression and you really want to end up with 10.5 to 1 compression with aluminum heads.

Respectfully;...Is that right? 455@.040 w/ 85 cc heads= 9.55:1?
Just curious because i'm building a .030 455 w/ 94 cc and the numbers from the many online calculators can vary from 9.2: -10.7

When I put 455@.040 w/ 85cc into Wallace racing calculator I get 11:1?
What is the best online calculator?

[JLMounce]

Originally Posted by panhead59

Yes rods were resized with arp bolts. We were intentionally upping comp. Shooting for 9.5 to 1. Sounds like its not really worth the cost. $4500 for heads and efi and not a huge power gain ? My machinist calculates 9.3 comp., with current engine. Kre sales calculates 10.3 to 1 with 85cc heads. Kre says engine would produce around 500 hp with out of the box 85cc heads, and flat tappet cam. Guessing 400-425 hp with current engine, one would expect a huge seat of the pants improvement with 75 more horses.

FWIW, On my combination, going from non-ported high comp iron heads to the as cast KRE's, I would say that a 60-75hp bump is likely what I got.

It's more a statement of opinion, 75hp increase is something you absolutely feel, but IMHO isn't overwhelming. It's not like with that extra 75 hp on tap the car is suddenly uncontrollable.

Even if I wasn't making the change to get away from running expensive fuel, I'd still be happy with the money I paid.

[Will]

Originally Posted by F ROCK

Respectfully;...Is that right? 455@.040 w/ 85 cc heads= 9.55:1?
Just curious because i'm building a .030 455 w/ 94 cc and the numbers from the many online calculators can vary from 9.2: -10.7

When I put 455@.040 w/ 85cc into Wallace racing calculator I get 11:1?
What is the best online calculator?

What numbers are you guys all using? steve says 9.55 and you're coming up with 11???

The Wallace Racing calculator shows about 10.3:1 with 85cc heads.

http://www.wallaceracing.com/cr_test2.php

Click 455, click +.040, Enter 85 for head cc, enter 4.25 for gasket bore diameter (it's close to this and a little bit one way or the other doesn't make a big difference), enter .005 for deck height. Doing that gives me 10.31

This number is very close to what you'll actually have, maybe slightly high if the gasket bore is bigger and it doesn't take into account space above the rings. Still should be over 10:1, regardless.

The EFI isn't going to buy you any power over a well tuned carb. EFI is great for many reasons, but it is NOT a power adder.

The heads will definitely give you some power. To really take advantage of them you'd want a roller cam but that adds significantly more cost.

If you have the money and want more power, this isn't a bad way to go. Plus, you have lots of room for even more in the future if you want to have the bottom end gone through and put in some forged rods.

[panhead59]

Tks for all the replies and opinions. Yes i realize the efi isn't for more power. I was more concerned that the 3 2's wouldn't 't be enough for the heads. Anyway, i've decided not to do this upgrade. I've got the $ that's not really an issue. I agree that one might as well go roller cam with the alum. Heads but then you might as well port em a little also. Thats an extra grand. Mission creep for sure. The most important issue here, imo, is vehicle use. Its a sunday driver. At most an occasional weekend short trip out of town. While i don't want some punk kid in a mustang to embarrass me, it won't hurt if it's a BUILT mustang ! So i'll just keep the 400 or so horses and the nostalgia of the 3 2's and be happy
After all, it is a 1966 GTO ! Tks again

[steve25]

Allow me to correct myself and the compression ratio I posted about for your motor with 85 CC heads.

The compression would be 10.69 to 1 with your essentially zero deck height, but if your 455 block has Intake valve notches in between the pairs of Bores then your compression works out to 10.45 to 1.

Sorry for the confusion here!

[geeteeohguy]

Originally Posted by panhead59

Tks for all the replies and opinions. Yes i realize the efi isn't for more power. I was more concerned that the 3 2's wouldn't 't be enough for the heads. Anyway, i've decided not to do this upgrade. I've got the $ that's not really an issue. I agree that one might as well go roller cam with the alum. Heads but then you might as well port em a little also. Thats an extra grand. Mission creep for sure. The most important issue here, imo, is vehicle use. Its a sunday driver. At most an occasional weekend short trip out of town. While i don't want some punk kid in a mustang to embarrass me, it won't hurt if it's a BUILT mustang ! So i'll just keep the 400 or so horses and the nostalgia of the 3 2's and be happy
After all, it is a 1966 GTO ! Tks again

I've been driving my two GTO's for the past 40-ish years. Back then, they were fast compared to everything else on the road. Now, a Camry would probably shut them down. But I enjoy driving them now more than ever. Just appreciate the fact you are driving a 50+ year-old classic, and be ok with that. There's something to be said for a stock-ish, torquey, totally reliable old car! The neat thing about NOT having 500 hp is not having to tear down the engine and work on it all the time. Mine haven't been apart in years and years.

[77 TRASHCAN]

Originally Posted by jerry455

When I was going to redo my motor I looked at cylinder heads. For what it was going to cost to improve a set of cast iron factory head, I got a set of Edelbrock round port 72cc RPM heads. After a mild chamber clean up, the chambers are at 79 cc. With a 10cc dish Diamond piston I should end up about 10.3 :1 comp. ratio. I think the aftermarket heads are a great deal. I am going to make the heads look as stock as possible.

Not easy to make E-heads look stock...You can grind the print off the center exhaust ports and paint them, that would help...

[Speargun]

Originally Posted by 77 TRASHCAN

Not easy to make E-heads look stock...You can grind the print off the center exhaust ports and paint them, that would help...

And JB-Weld "6X" on the center ports.
I saw a car done like this at a show. It took a minute to figure out what just wasn't right.

[track73]

I actually changed an 400 small block chevy to an 010 block to make it pass a cursory visual inspection. . It worked. I don't know if JB weld would hold up on the exhaust ports.

[steve25]

It's pretty dam hard to hide the fact the Aluminum heads have no freeze plugs at each end as factory heads do!

[77 TRASHCAN]

Originally Posted by steve25

It's pretty dam hard to hide the fact the Aluminum heads have no freeze plugs at each end as factory heads do!

Yes Steve, thats something that only some of the Pontiac folks would recognize, leaving the other 98% of all car enthusiasts to be baffled...LOL

[pastry_chef]

Originally Posted by 77 TRASHCAN

Yes Steve, thats something that only some of the Pontiac folks would recognize, leaving the other 98% of all car enthusiasts to be baffled...LOL

I guess it depends where you live.
A local here tried that, textured the heads, painted and even had numbers epoxied on. The "secret" was gone in less than 10 minutes!

[jerry455]

I am just going to make it look as stock as I can. I am not going to epoxy any casting numbers on just making them a little lees conspicuous. If it is all plain blue under the hood it won't draw much attention. I like sleepers or stock looking cars.