[etd66ss]

So, it really does sound like I should just go with the 7k3 heads...

Will I be able to use the valvetrain off the #62 heads or am I looking at all new components?

[post toastie]

7k3's wont fix your carb problem.

[etd66ss]

Originally Posted by post toastie

7k3's wont fix your carb problem.

I know the engine builder said the carb still needed "work", but I don't see an issue with it atm.

It idles good when the vac advance is on manifold vacuum, Secondaries work like they are supposed to, and the plugs look good to me: http://i.imgur.com/01D4OyT.jpg

However, I have been eying up this: http://www.summitracing.com/parts/urm-14-4159

[72LuxuryLeMansLa.]

Originally Posted by etd66ss

I know the engine builder said the carb still needed "work", but I don't see an issue with it atm.

It idles good when the vac advance is on manifold vacuum, Secondaries work like they are supposed to, and the plugs look good to me: http://i.imgur.com/01D4OyT.jpg

However, I have been eying up this: http://www.summitracing.com/parts/urm-14-4159

Stay away from those generic Q-Jets! I've been there and they are no good. Try this one:http://www.smicarburetor.com/product...D2/9/sfID3/100

They are a little more expensive but if you decide on all of your build parameters such as compression and cam and call them they will build it to calibration for your combination.

[etd66ss]

Stay away from those generic Q-Jets! I've been there and they are no good.

Can you elaborate on the "no good". Meaning actual defective parts or just not tuned to your specific application?

[72LuxuryLeMansLa.]

Originally Posted by etd66ss

Can you elaborate on the "no good". Meaning actual defective parts or just not tuned to your specific application?

If you can imagine things you should not do to a carburetor they have done it. My carb was loosely put together and leaks to this day I'm sure. It was put together using parts from different part numbers and it wasn't calibrated.

[etd66ss]

I just contacted them about an E85 quadrajet, here is the response:

You can't run E85 with a quadrajet, the float bowl is too small.

[etd66ss]

So lets say I bought a new distributor, a new carb, and had my 7k3 heads redone. How much HP would I lose going to the low compression heads?

[72LuxuryLeMansLa.]

Originally Posted by etd66ss

So lets say I bought a new distributor, a new carb, and had my 7k3 heads redone. How much HP would I lose going to the low compression heads?

Those heads have massive chambers and you will be well below 9.0:1SCR......I am no expert but I would rather use dished pistons with the current head to stay above 9.0:1SCR!

[HWYSTR455]

Well, with a .030 over 400, .012 in the hole, with 96cc heads, 6cc valve reliefs, you will be about at 8.86. Assuming you might be at .008 in the hole, and the heads are cleaned up, maybe at 92cc, you would be at 9.28, so that's your range. Not too bad.

Keep the short seat 'RV' cam in there, and actually, you won't do too bad. Any HP you lose due to SCR, you will gain because you can run appropriate timing/tune. To answer, you will probably gain considering the cam that's in it.

And yes, you should be able to run the same valve train, like rockers, maybe pushrods, and possibly springs/retainers. But if you're having the heads done, I would opt for new springs (unless the ones you have are new and spec'd for that cam.).

I personally would go new distributor and carb if you wanted to get the most out of it.

.

[Burningbird]

I get closer to 8.3:1 for a .030 over 400, 96cc chambers, 6cc valve relief, 4.3 gasket bore diameter, .039 gasket thickness and with the pistons .012 down in the hole? 8.02:1 if the TRW/Speed Pro pistons are .030 down i the hole like mine where before the deck was cut. If you shave .060 of the 7k3's and use Cometic gaskets with 4.16 bore/.027 thickness you will end up with around 84cc chambers and 9.15:1 SCR.

[Squidward]

Originally Posted by 72LuxuryLeMansLa.

Those heads have massive chambers and you will be well below 9.0:1SCR......I am no expert but I would rather use dished pistons with the current head to stay above 9.0:1SCR!

Maybe it's just me, but I would MUCH rather swap a set of heads instead of pulling the engine to R/R pistons. Cost of new dished pistons? R/R pistons to rods? And I can't imagine one would re-use rod bearings and rings after pulling them out.

The piston route would probably cost a cool grand. You could get a set of heads of appropriate chamber size done easily for a grand, possibly less, with good parts. And then you could bypass the giant BS factor of engine/piston removal.

[etd66ss]

Originally Posted by Squidward

Maybe it's just me, but I would MUCH rather swap a set of heads instead of pulling the engine to R/R pistons. Cost of new dished pistons? R/R pistons to rods? And I can't imagine one would re-use rod bearings and rings after pulling them out.

The piston route would probably cost a cool grand. You could get a set of heads of appropriate chamber size done easily for a grand, possibly less, with good parts. And then you could bypass the giant BS factor of engine/piston removal.

This is exactly it. Replacing heads I will do, new pistons, no.

One thing about the 7k3 heads, can they be drilled to use headers? Or how about these: http://www.spottsperformance.com/headLbracket?

[HWYSTR455]

I will have to re-run the numbers, but yeah, that's what I was getting at Wallace for a SCR. I may have left the gasket bore info out, but still, it's in the 8-range, which isn't too shameful. Mid-70s engines from the factory used to be in the high 7s and low 8s range, FYI.

If the heads are off the car, the best option is to drill the heads for the end bolts. The brackets work, but bolts work better.

General SCR chart from Wallace attached as an example.

.

[etd66ss]

If the heads are off the car, the best option is to drill the heads for the end bolts. The brackets work, but bolts work better.

The heads are off the car ofc, because the #62's are on the car

I'll have to take a look at them, I have read that some heads have enough material to drill, while others the casting is different and you can't machine & drill them.

[Interceptor]

Wouldn't it be easiest to just change the cam to something designed to bleed off a little compression? You guys must be able to recommend something.

Or ...sell both sets of heads and install a set of aluminums.

[etd66ss]

Wouldn't it be easiest to just change the cam to something designed to bleed off a little compression? You guys must be able to recommend something.

That has been recommended but I think I could still have the potential for a detonation issue on 93 octane.

Cost-wise, it seems the best for me to use the 7k3 heads with the existing valvetrain and just use the exhaust manifolds and not worry about headers.

I will be spending money on my 66 Chevelle restoration project this winter, and can't dump a lot of $$ into his driver GTO. I just want to be able to drive it next summer without fighting the pinging or buying 100 octane at $8.49/gallon.

[FrankieFeenixx]

Before you do anything else (spend any $$$), you should pull a head and check the actual combustion chamber volume so that you know what you are working with. I have a set of #16 heads here (which are similar to the #62), that measure 77cc. I'd have no problem running these on a 400 with a decent size cam. If you can get away with a cam swap and tuning, that's a lot cheaper than changing heads or pistons.
Alternatively, if you don't think the Q-jet is viable to run on E-85, you can always go to a Holley. They're a dime a dozen. Just my 2¢

[etd66ss]

I got my cheapo USB endoscope working this morning, here are some pics of 4 of the pistons: http://imgur.com/a/gC2WB#6

I can read the part number on one of them, L2262F 030, looks like these are the pistons: http://www.summitracing.com/parts/slp-l2262f

Will this info better help select a cam for leaving the #62 heads in place? Or is it still a big gamble to just popping a new cam in without checking the quench and measuring the combustion chamber? I made some assumptions on the SCR calculator ~10.75:1.

[Squidward]

In looking at the SCR calculation, don't forget that those pistons have a 6-7cc valve relief volume (dish), and they are 30 over (4.15 bore). That will juggle the numbers a tiny bit. Bigger bore will make SCR go up, the dish in the pistons for valve relief will make it go down.

I see nothing wrong with a 400 and 62 heads. I'm not sure those heads are truly 72 cc, maybe closer to actual 77 (my advertised 83 cc #47 heads cc'd out at an actual 87 cc's).

l'm sure if you laid out your boundary conditions for desired use and what parts you will keep, then you could get some good off the shelf recommendations. I've never heard anyone complain about the 068 cam or a Summit 2801.