[Jay S]

Originally Posted by petes67bird

Thanks. I went to my local shop yesterday and chatted about some things. His train of thought was that my compression may be lower than what I had previously thought (he thinks it may be closer to 9:1 or even upper 8's) which would adversely affect the cam I have that he feels would benefit from a higher compression above 10:1. His suggestion was that we can leave the cam where it is, I can install heads (he wants me to drop to 72cc Eheads that he will go through and change the springs on and get me near 11:1), and cleanup my intake and 750cfm carb (said it looks like my accelerator pump is leaking gas). He said this should raise my compression, add about 50-80 horsepower and he can then time and curve everything for me on his equipment. He personally did not like the #96 heads, he also said that all the Kauffmans he has flow tested have not reached advertised numbers, which is why he is wanting me to go with the Edelbrock. We ended up chatting for several hours while he showed me all of his work, great guy.

Unless you plan to make some other changes, 72 cc heads with the way the rest of your engine is set up will require a lot higher octane fuels, 93 and up. The Eddy 87 cc and KRE 85cc d port are much better pump gas options.

[petes67bird]

Originally Posted by Jay S

Unless you plan to make some other changes, 72 cc heads with the way the rest of your engine is set up will require a lot higher octane fuels, 93 and up. The Eddy 87 cc and KRE 85cc d port are much better pump gas options.

Sorry to ask, but could you explain a bit to me. I am not questioning, but like to learn. The builders reasoning was that I can run up to 11:1 on 93 octane without worry with aluminum heads. I currently only run 93 in my build as it is.

[78w72]

Originally Posted by John Milner

That is basically the same cam he has in his engine. Specs on the Melling 26308 are: 231/240 .470 .470 113.

Should be a strong runner. Adding compression should help. I still feel like it should melt the tires at will with the 96 heads. I run a similar cam in a 10:1 428 with a 4 speed and 3:23 rear. I have never taken it to a race track and doubt I will but the first 2 gears are pretty useless if you crack the throttle open from a roll.

Didnt realize the 60919 was the same as a RA4 cam... regardless the 462 can probably benefit from a bigger cam than whats in there IMO, which cam I will leave up to others more experienced with cams for big cube engines like this.

Sounds like he is leaning towards aluminum heads to get more power and if so, a bigger cam is definitely better for better flowing heads & higher comp than the current 96 heads.

10.5-11:1 should be fine on pump gas... I run 72cc E-heads at ~ 10.7 with no issues at all using 91 no ethanol, can even run on 89 but prefer not to. Cliff has stated hes ran 89 with 11:1, just gets some run on when shutting off on hot summer days.

I agree 87 or 85cc D port alum heads are the better option for his combo & can keep the D-port manifolds or headers. Also consider the exhaust system, headers will make more power & need at least a good 2.5" full exhaust with free flowing mufflers like dynomax ultra flow or pypes race pro.

[Holeshot71]

I had a car one time that was real sluggish when taking off from a start. Turns out it was starting off in second gear due to a sticking Governor.
There’s a lot of good information posted here. You really should take the time and check things over before throwing more parts at it. That combo dialed in correctly should not be disappointing IMHO..

[Jay S]

If you plan to use 93 octane then the 72 cc heads are fine. But, it really isn’t worth the power gains in my opinion to go from the 84 cc to 72 cc. It really isn’t enough cam or head flow to see much for power gains with that extra compression.

The 87 cc E head d port with your combo would run on 87 octane and make around 450-460 HP with the RA manifolds. The 72 cc would probably be about another 10 or 15 HP and jump up close to 5 points on octane. If you want to run 93 and want the extra 10HP there is nothing wrong with the 72 cc heads.

There is someone on this forum with a 455HO combo that has 87cc E head round ports (factory 455 HO TA with RA manifolds) on the same short basic short block and cam as you have, that takes a minimum of 93 octane. On 91 he has to pull timing out because it pings. That car would not be close to running on 93 with 72 cc heads. The thinking that Aluminum heads can automatically run 11:1 compression not matter how the engine is set up is not true. Especially on something less than 93 octane.

I can’t buy 93 octane in many places, 91 is all I have available. Some places here in Nebraska 87 is all that is available. How long till that happens in your area?

Your engine as it is now should run on 87 octane. Running on 93 is actually making less HP than the lower octane fuel. Extra octane above what you need hurts performance some.

[chiphead]

Let's deal in real numbers here. I ran the compression through diamondracing's compression calculator.

Assume 95CC chambers: pistons .015" below deck, 6CC valve relief on a 30 over 455.

95CC Iron Heads: 9.26 compression
87CC heads: 9.88
72CC heads: 11.33

Theoretical 80CC head: 10.5 compression

11.33 compression is too high for a pump gas motor overseen by a non-expert. I wouldn't recommend over 10.25-10.5 with aluminum, just to keep some safety margin.

Over 10.75, the tuning window gets pretty small. One jetting mistake, timing mistake, bad fuel from an iffy gas station, overheat event and it'll blow a head gasket or worse. Lets not forget this is a stock rod motor with 4.21 stroke. It's already hard on the connecting rods. It'll be fun, until it goes BANG.

Maximum engine lifespan would dictate keeping the RPMs below 5500 and the engine out of detonation. Both of those are going to be hard north of 11:1 compression. Anything larger than a RAIV copy with high compression and good airflow is going to want to revv over 5500 in a 455, and we don't want that with stock rods.

I could rant on, but let's keep it simple. There are 3 realistic options as I see them: Each add complexity and cost.

1: The cheapest option is going to be super tuning the existing combination (Rhodes, adv cam 4*, etc) This may be enough, as the combo is respectable on paper.

2: Change the camshaft to 1 step smaller and super tune. I'd expect a massive improvement in street manners.

3: Swap the top end to increase the compression, headers, 3" exhaust, upgraded fuel system, etc. 10:1 with irons or 10.5 with aluminum is what I'm thinking. Have to bring the A game with tuning.

[78w72]

i dont doubt that stock rods are the weak point, but claiming they cant or wont live above 5500 is not true... I had a similar built 455 as the OP's back in the early 90's before better rods were readily available, did a budget but good quality rebuild with stock rods and beat the living crap out of that motor/car daily for almost 10 years & 100k miles, countless 6000 rpm shifts and racing anything I could day or night, beat many cars that came from out of town to cruise/race with mid to high 12 second time slips. Today its best to use stronger rods but well prepped stock rods can or should be able to handle 400-450hp up to 5500 without much problems.

Also good idea to keep compression around 10-10.5 on alum heads but if tuned right (cliff q-jet) and what sounds like less than ideal timing, detonation shouldnt be a concern with 91 or 93 gas... im in iowa in a decent sized 125k town and premium fuel isnt going anywhere, can get 93 10% eth or 91 straight gass pretty much anywhere in the city or surrounding smaller towns.

Also dont thing changing to a smaller cam would benefit anything in this case, just make less power than the current cam and OP never mentioned street manners being an issue, that cam is pretty tame for a 462.

10:1 with iron is a much bigger issue for detonation than 10.5 on aluminum... most stick to 9:1 for the average iron head street engine, and almost everyone with alum heads can do 10.5 with ease on premium fuel.

Lots of options to increase power for this engine & lots of opinions on how to do it, but 10.5 on alum heads with 91 octane should be very easy to do even without "A-game tuning". i run 10.72 with almost zero tuning, just a cliff built Q-jet and basic timing curve on the HEI... zero detonation on 91 gas and does low 11's with ease in any weather... been in use for almost 10 years now & lots of drag strip time.

My 72cc E-heads CC'd at 74.5, so factor that into the final compression, but bigger CC D-ports would be best for this to keep the D-port manifolds or headers.

[chuckies76ta]

Originally Posted by petes67bird

Thanks. I went to my local shop yesterday and chatted about some things. His train of thought was that my compression may be lower than what I had previously thought (he thinks it may be closer to 9:1 or even upper 8's) which would adversely affect the cam I have that he feels would benefit from a higher compression above 10:1. His suggestion was that we can leave the cam where it is, I can install heads (he wants me to drop to 72cc Eheads that he will go through and change the springs on and get me near 11:1), and cleanup my intake and 750cfm carb (said it looks like my accelerator pump is leaking gas). He said this should raise my compression, add about 50-80 horsepower and he can then time and curve everything for me on his equipment. He personally did not like the #96 heads, he also said that all the Kauffmans he has flow tested have not reached advertised numbers, which is why he is wanting me to go with the Edelbrock. We ended up chatting for several hours while he showed me all of his work, great guy.

Well, now your moving up to a whole different game. A look at your drive-train can become an issue. Like transmission, U-joints, Yokes, Rear-end and axles to name a few. Headers, Carburetor, Exhaust. Hopefully you'll still make enough vacuum for your brake booster to operate your brakes properly. If your gonna move to E-Heads I'd personally build from scratch with all forged internals. That's just me. Good luck with whatever route you go.

[ta man]

How much power do you want? This may get expensive quickly especially with someone else doing all the work. I would spend some time with what you have to learn what is wrong..just costs time but a great learning experience. This book may help.

[Bruce Meyer]

Originally Posted by petes67bird

Thanks. I went to my local shop yesterday and chatted about some things. His train of thought was that my compression may be lower than what I had previously thought (he thinks it may be closer to 9:1 or even upper 8's) which would adversely affect the cam I have that he feels would benefit from a higher compression above 10:1. His suggestion was that we can leave the cam where it is, I can install heads (he wants me to drop to 72cc Eheads that he will go through and change the springs on and get me near 11:1), and cleanup my intake and 750cfm carb (said it looks like my accelerator pump is leaking gas). He said this should raise my compression, add about 50-80 horsepower and he can then time and curve everything for me on his equipment. He personally did not like the #96 heads, he also said that all the Kauffmans he has flow tested have not reached advertised numbers, which is why he is wanting me to go with the Edelbrock. We ended up chatting for several hours while he showed me all of his work, great guy.

He might be a great guy but he is wrong. I ran a bigger cam than you 239/247 @.050 with 8.5:1 compression on a 455 and it ran 12.70. It launched hard. My guess is your ignition timing is way off. Get that straightened out before you spend a bunch of money. Also there is nothing wrong with 96 heads. I guy I know went in the 11,s with them on a street car.

[b-man]

Originally Posted by Bruce Meyer

He might be a great guy but he is wrong. I ran a bigger cam than you 239/247 @.050 with 8.5:1 compression on a 455 and it ran 12.70. It launched hard. My guess is your ignition timing is way off. Get that straightened out before you spend a bunch of money. Also there is nothing wrong with 96 heads. I guy I know went in the 11,s with them on a street car.

Agreed.

Another low-compression 455 with an even bigger cam (244 / 252 @ .050 8.6:1 compression) running 12.0s, could easily have been high-11s in more favorable weather.

https://forums.maxperformanceinc.com...5&postcount=19

Surely some basic tuning should wake your combo up. Easy to visually check for full-throttle with the air cleaner off, get your wife or a friend to mash on the pedal while you look.

Get a good timing light and check for total advance with the vacuum hose disconnected and plugged, you should be somewhere in the 32 to 38 degree range. When I was first sorting out my bracket 455 was conservatively timed at 30 degrees, when I bumped the timing up to 38 it picked up at least 4 tenths.

No way will those #96 heads give you less than 9:1 compression, your 9.3 number is pretty close and even 9.5 isn’t too far fetched.

[Verdoro 68]

Jumping in late, but +1 to the others who mentioned spending time dialing in your combo before throwing more parts at it. The combo is solid on paper. My bet is your issues are likely a combo of small things that need to be tweaked - fuel mixture, timing curve, maybe cam advance. I like the suggestion of chassis dyno time to get a baseline.

[petes67bird]

Originally Posted by b-man

Agreed.

Another low-compression 455 with an even bigger cam (244 / 252 @ .050 8.6:1 compression) running 12.0s, could easily have been high-11s in more favorable weather.

https://forums.maxperformanceinc.com...5&postcount=19

Surely some basic tuning should wake your combo up. Easy to visually check for full-throttle with the air cleaner off, get your wife or a friend to mash on the pedal while you look.

Get a good timing light and check for total advance with the vacuum hose disconnected and plugged, you should be somewhere in the 32 to 38 degree range. When I was first sorting out my bracket 455 was conservatively timed at 30 degrees, when I bumped the timing up to 38 it picked up at least 4 tenths.

No way will those #96 heads give you less than 9:1 compression, your 9.3 number is pretty close and even 9.5 isn’t too far fetched.

I plan on checking the timing first, but I cant see that the timing is so far off to make a different. The car has started and drove extremely well for 2 years and almost 3k miles without a hiccup, I drive it everywhere. The guy in the example had those heads ported, mine are not are are likely 190-200cfm.

[b-man]

You haven’t checked the timing so you really don’t know.

My car was running fine and pretty fast too until I adjusted the timing and it went from being mired in the bottom-13s straight into the mid-12s just by adding timing.

[ta man]

How old is the harmonic balancer?

[jhein]

No offense meant to the OP at all, but I'm still not sure what the performance problem is. It's not a race car so there are no time slips. It's just the seat-of-the-pants Dyno. And there's nothing wrong with that. We all use that as a measure of performance but it can vary quite a bit from person to person. As others have said, your combo, even if not in perfect tune, should still smoke the tires pretty easy. Can it do that? If it can't then there's definitely something wrong. If it can then maybe it just needs some tuning, or maybe it's fine. Also what is your frame of reference for performance? If you're used to modern performance cars then maybe an old 420 hp muscle car just won't measure up.

My thought is that, if there is a problem, it seems more like the carb than anything else. I know it's a Cliff carb, but was it built for this combo? Is it an older build? Has it been modified since it left his hands? Could it be gummed up with gunk or debris? I've had problems with Quadrajet secondary function for various reasons. Anything interfering with proper functioning of the secondaries will really put a wet blanket on your performance. Of course, you need to check everything including timing, base, vacuum and mechanical. The timing curve data that you posted looks OK, but if your base timing is way off then you could still have major problems.

[b-man]

Originally Posted by ta man

How old is the harmonic balancer?

This.

If the outer ring on the balancer has slipped setting the timing will be impossible.

Verify TDC on your balancer using a piston stop.

Recent thread where this was the issue with a poor running combo:

https://forums.maxperformanceinc.com...d.php?t=876134

[petes67bird]

Originally Posted by jhein

No offense meant to the OP at all, but I'm still not sure what the performance problem is. It's not a race car so there are no time slips. It's just the seat-of-the-pants Dyno. And there's nothing wrong with that. We all use that as a measure of performance but it can vary quite a bit from person to person. As others have said, your combo, even if not in perfect tune, should still smoke the tires pretty easy. Can it do that? If it can't then there's definitely something wrong. If it can then maybe it just needs some tuning, or maybe it's fine. Also what is your frame of reference for performance? If you're used to modern performance cars then maybe an old 420 hp muscle car just won't measure up.

My thought is that, if there is a problem, it seems more like the carb than anything else. I know it's a Cliff carb, but was it built for this combo? Is it an older build? Has it been modified since it left his hands? Could it be gummed up with gunk or debris? I've had problems with Quadrajet secondary function for various reasons. Anything interfering with proper functioning of the secondaries will really put a wet blanket on your performance. Of course, you need to check everything including timing, base, vacuum and mechanical. The timing curve data that you posted looks OK, but if your base timing is way off then you could still have major problems.

My car before this was a 1980 Camaro Z28 with a Powercrate 350 from Year One that was 400hp/400tq, 9.7:1, roller cam, reverse valve body TH400, 373 gears, eaton posi, holley 750 double pumper. That vehicle felt significantly faster.

I do want to clarify this is not a Cliff built carb, it was supposed to say Cliff Rec carb, he recommended someone he knew who built it for me. The guy did take all the specs of my build. My distributor was the same way, the guy asked for all my specs. I am pretty sure, as long as they followed those specs, I did everything I could. Its been negative 3 degrees here, and in an attached garage, I cant really check the timing safely. I cant drive it somewhere due to salt on the roads. So its either wait till the spring to verify this which will be too late to do all this work, or just do it and then tune it over after doing everything. Once April/May comes, I typically am driving it 3-4 days a week to shows or gatherings.

[petes67bird]

Originally Posted by b-man

You haven’t checked the timing so you really don’t know.

My car was running fine and pretty fast too until I adjusted the timing and it went from being mired in the bottom-13s straight into the mid-12s just by adding timing.

I completely understand, I have been told to check the timing so many times already. Unfortunately beyond my control, I cannot check the timing right now. Its been negative 3 degrees outside and I have an attached garage so that limits my options with salt on the roads, which was why I was looking at other options. Typically over the winter, is when I tear into things and do upgrades. I didnt think about the timing being an issue since I paid a reputable shop to do it for me so I assumed it has to be something else.

[b-man]

A friend of mine built a 421 for me, a talented amateur builder who’s built dozens of engines for his friends and fellow club members.

He broke in the cam on his run stand and ran it for about an hour total.

I installed it in my car, never touching the distributor. After several hundred miles I put a timing light on it even though it was running strong and drove great. The initial timing was 5 degrees which was likely the stock setting. I’m sure my friend was being cautious and didn’t try to maximize the timing during the crucial initial break in.

I bumped the timing to 12 initial, added to the 23 degrees of mechanical advance built into the distributor I have 35 degrees total now.

So I’m sure the shop set your timing well enough to drive and enjoy your car just like my friend did for me, but when circumstances are optimal check and adjust as needed.