Okay....my 68 has run decent before I installed the new heads,and the new cam,but....BUT.....the rpms have always flucuated.Before I did the swap...I tuned,and tuned,and got the car where it was pretty streetable w/the 6x2s.
After the swap....I did the initial fire up w/a single carb,and the car was fine,and very responsive,but pouring oil out of the front/rear of the engine where the intake meets the top of the block.The short gaskets were loose.I wanted to put the 6x2s back on there,so used the same gaskets(about 100 miles on them),and guess what.....was leaking water,so pulled the intake,and got new gaskets,and no water leak now,but the rpms are jumping around everywhere.
Here's where I am heading w/this....the block is zero decked,and the heads are Brodix 180ccs,and were trued up,but not sure how much material was removed in the process when I had them redone.
I squirted starter fluid around the intake,and no change in the response,but the rpms go up,and down all over the place.I'm thinking w/the geometery of the machine work has my intake not sealing.I used light blue permatex around the water passages on the head,and the intake side of the gasket,and cured the water leaks,but didn't use the permatex around the runners.Guess I should have,huh?
I see where a guy in the C1/C2 section fought,and fought to find why the #1,and 4 cylinders were dead,and in the end...he borrowed another intake,and that was the problem.He had machine work done to the block/heads,and the angles were off just enough that he had 2 dead cylinders on the same 1/4 runner.
In that thread guys were saying he could run double gaskets,then seal the front/rear w/silicone.Is this a okay approach,and what is the process?I mean do I use some kinda sealer in between each gasket?
I know the correct fix is to have the intake plained for the angle of the block decking/and the heads trued,but I don't wanna pull the engine again.

First method of attack....I am going to try to retighten the bolts.I can't torque them cause of the accessability w/the crossram,so go by feel in sequence.
Then pull plugs to see if I'm running lean,and where,and if the problem still persists...I think I will pull the 6x2s,and put them on the shelf for now,and go w/the 750DP here.Maybe some nitrous.

Any suggestions/thoughts?I am doing this in the evenings,and on the weekends,and would really like to get this thing wrapped up,and put under cover,and move on.The 6x2 is like installing a puzzle,and there is no room for anything,so this isn't very fun.

Thanks fellas....

 

You're on the right track. First make sure that the gasket covers all edges of the runners from the bottom side, and in some cases with decked blocks I have had to round out the gasket bolt holes to get the runners centered in the gasket openings. Once I know the runners are all centered I dry fit everything and check the front and rear seal gaps with NO seals in yet. I've seen as large as a 3/8" gap. Use a large bead of high temp sealant on the front and rear, and tiny bead circles around the runners and water ports. Then set the gaskets, drop the manifold, double check your measurements making sure the runners are still centered in the openings, and insert your bolts. Tighten them down and again, check your measurements and front and rear sealant. Make sure it's not gapped anywhere and that the sealant completely fills the gaps.

Don't start it for 24 hours. I know they say it sets up in a few hours but I have seen too many sealant front and rear seal get dislodged because the engine was started too soon after laying the sealant.

 

durango sums it up here for you, maybe i need new glasses.....did you say 6-2's!!

 

I found the leak.....It was on the RH top of the gaskets.I wonder why it didn't change rpms when I used starting fluid?Doesn't matter.It had to come off anyways.I am going to put the 750DP back on for now,and will go back at the 6x2s for the car show season if I ever get paint on this rascal........
Yes...6x2s,and they are rare,awesome,but a pain in the ......
Well.....I was going to post picture,but at the shop,and for some reason this computer isn't letting me post it .Sorry.I'll show ya a picture later....

 

I wanna C2!!!

 

Try this:

Clean all the surfaces.

Dry fit without gaskets to check if you are hitting at the front and rear walls. If you are, machine off to clearance. Can be done by hand also, carefully. Not all that critical.

Again dry fit the intake without gaskets, but with thin vasoline around the head mating surfaces. Inspect other surface when removed. This will show if there is a serious angle misalignment. Again, milling might be needed. for angle only. Arylic artist paint works well here too.

If everything fits without gaskets, then make sure you have the appropriate gaskets. There are different port sizes available. Match the gasket to both the head and the intake.

Gaskets are available in different thicknesses too, I think from .045 to .120. If necesary you can double up 2 sets of thinner ones, but DO NOT use silicone sealer on the runners, just a bit on the water passages is ok. The resulting beads in the runners will screw up runner flow.

Don't use the gaskets on the end walls, just clean with thinner and a thick bead of silicone, making sure it seals tight when torqued and let cure.

 

never never never re use intake gaskets never never never. jmho

 

I'm surprised you did that, they take a set and then never seal again. Next time its apart, you may be able to paint it with Prussian Blue and "slide" the intake a tiny bit to see if it has high/low spots.

 

Well...the single 4 is back on the car,and drove around the neighborhood in the sleet,and all is well,but even timed in good....she still doesn't have the performance that the 6x2s have.

I usually don't reuse intake gaskets,but thought that I may get away w/it cause there was probably not even 100 miles on it.More like 50,and it was late,so.......didn't work out for me,and had to change the oil again.

Some days......I hate cars!

The gaskets i am buying stock in are the Fel-pro 1204s that Brodix says to use on their web site.before I put it back together w/the 6x2s last time.....I used a light long file to make sure that the intake was straight,and it checked out okay.It's just the angles of the block being zero decked,and the heads trued up.I still need to figure something out,cause not going to be happy until the 6x2s are back on there.That's why I picked this car,and the custom exhaust.

Thanks for the replys.

 

I fought a leak for a long time until I realized that my engine was true, but the swap meet intake bolted to it was milled prior to me buying it.

 

6x2s???? what is that an offenhauser with 2 barrels or what????, big block or small block???

ops, you have a small block, just noticed the 180cc heads, but still what intake/carb setup??

 

I don't believe it is the intake,but the angles.This car has been untouched since it was built in 71 until I got in there.I did pull the 6x2s off it when I got it to have them rebuilt,and they had the 2 center carbs blocked off.I undid them,and if they are there....I wanna use them.Even when I got it on there after I got them rebuilt it never has run great at idle.I did have it tweeked where it was finally streetable,but not right.

I'm gonna call my machine guy tomorrow,and see what he can do w/the intake angles.

 

It's a old Edelbrock X1 w/6 custom 2110 Holley 2 barrels w/no power valve provisions.Vic Edelbrock broke the land speed record w/one of these in 57.They are pretty rare,and unique.When I pop my hood....noone has seen one of these at the car shows.I like weird/different induction systems that other people don't have,or run.

 

Kevin, thanks for posting some pic"s. I never seen or even heard of one of those. Thats quiet a unique piece you have there !

 

Thanks!
They are pretty rare,and not many people have seen the Edelbrock X1s.Offy made a 6x2 that alot of the hot rodders run on their cars,and those are pretty rare,but not like this one.Every since I got this....everywhere I have read,and the guy that does my machinining,and rebuild of the carbs have said to not run them,cause they are only good at about 4 grand up,but I didn't listen.

 

If your head and intake angles are reasonable, this should take care of your problems. This is a procedure I developed that works very well to establish proper intake gasket clamp up. But, the heads need to be loose in order to do this procedure. Put the heads on the block for final installation, but only FINGER TIGHTEN the head bolts for now. Then temporarily install intake manifold with it's intended gaskets, but no sealer, and no end gaskets/sealer. (You will be using the intake only to position the heads here, the manifold can be installed permanently later on) Position the intake manifold centered over the bolt holes as you normally would. Install all intake bolts, but only tighten them MEDIUM SNUG, do not fully tighten them. The heads have now been pulled up tight against the intake manifold for proper even gasket clamp-up (the heads will have some "float" even with dowel pins in place, we are not talking spacecraft precision here) . Now torque the head bolts in the normal sequence, while the snug intake bolts hold heads in the proper position inboard/outboard. When done torquing the heads, remove the intake and install it permanently whenever you like. Now you have the heads in pefect alignment with YOUR intake and it's specific machining, for the best gasket clamp-up you'll ever get on YOUR particular combo.

 

Thank you.I hate to pull the headers,but w/all the time that I have in intake leaks....could have done accomplished it this way.Thank you,and this forum ROCKS!