[man-of-war]

HI stingray69
Yes, i was thinking the same about the manifold maybe that's the reason the needle on the vacuum gage was never steady and could only pull 10''at idle .I would replace it, any thoughts on what brand i should look into? OR does any one on this forum has a used intake manifold that meets stingray69 description, that i could buy?

I had this cam# 11-232-3 in the engine last year which made the engine run and sound gutless.Before the engine was rebuilt /when i first bought it, i could have gotten 60mph any given day, now with this cam /or the vacuum leak/intake manifold problem it gives 56mph if the lake is calm.this engine does not exceed 4800rpm is there a better cam that i could use?

I shop around today for the msd 6460 this thing cost $457.00 CA . ILL look into the HI-6 by Crane and see what there prices are. thanks for the help.

the engine block is a 4 bolt main. the block cast # looks more like 3935439? Ill take a better look on Saturday.

My mistake with the valves.

thanks for your help in advance.

 

[OldMagicfloat]

3935439....427.......68-69...2 or 4 bolt

 

[cfm]

11-232-2 XM 262H-12
Hydr flat tappet
262, 258 at .006"
218, 224 at .050"
.505, .515" lift with 1.7

at .006"
IVO 21 BTDC IVC 61 ABDC
EVO 68BBDC EVC 20 ATDC

===============================
Well, the cam is not too bad. It's specs are not causing the 10" of vacuum.

What is causing that low vacuum?

Something is very wrong. Your rings could do it....a worn out cam could do it........valves not seating correctly could do it...........improper timing could do it..............bad carb calibration could do it.............vacuum leaks could do it...............cam installed way incorrectly? (I'm reaching now)

I think I covered the majority.

===================================

So, you have many possible issues sitting on your plate. Each must be gone thru one by one.

Caution: If you find an issue, don't assume you don't have others. I see this way too many times.

Cause and effect are two different things. I see 'effects' being fixed a lot where the 'Cause' wasn't.

====================================

Also, please see: http://www.speedwake.com/upload/showthread.php?s=&threadid=33575&perpage=20&pagenumber=1

and take a good look thru the tech section. There is a ton of stuff we go over.

=====================================
Before addressing internal engine stuff, let's address the 'Red Flag' items that are bolted too the engine. :winker:

 

[OldMagicfloat]

From Summit search:
Consider:

Edelbrock Victor JR EDL-2904 ~ $215.88

Weiand Team G WND-7523 ~ $219.88

Dart DRT-41214000 ~ $399.95

Unfortunately, most have rectangle ports; a used oval port, single plane may be hard to find used, check SW, OSO classifieds, ebay, maybe call some builders that have used parts.

I don't suscribe to using rect port intakes on oval port heads, though some have with success, I deem it a risky trial and error project...unless you know of someone doing it and being satisfied.

http://www.compcams.com/Technical/CurrentCatalog/HTML/172-195.asp

See:11-236-4
XM-270H
in Xtreme Marine section.

Not the duration I would like, but a little better lift. Someone with more cam skill than me should be consulted, it is the most important choice you will make. Your cam, being new, is going to be easier on the wallet, but do you know for sure that it is STILL in good shape, lobewise?

After what I have seen from OSO, (when I could stomach going there), I would not use a flat tappet hydraulic without using an engine oil additive, as CFM has pointed out. There were MANY, MANY horror stories of premature lobe failure, and subsequant cam company/cam installer complaints, (which there were some that were responsible, bad cores/heat treat being primary) finally being attributed to oil with very little antiwear additives.

So much so that I have started using an additive, and I have an all-roller (hydraulic) motor.

 

[man-of-war]

Very informative post by cfm,now i know for a fact both cam's are junk . the old cam that came with the boat,got heat stroke when the oil line broke 2 miles from shore,ran the engine for 20 min @2000rpm to get to land.
the new 11-232-3 comp engine did not run for a full 15 to 20 min @2000 to break it in .not to mention the gas in the oil :dead: .
I will use that break in oil 159 this rebuild.
I did take a look at that cam11-236-4 you suggested stingray69, looks good to me.would it matter if my engine only goes to 4800rpm
Part Number 11-236-4
Engine 1965-1996 Chevrolet
396ci-454ci
8cyl.
Grind Number CB XM 270H-12
Description

--------------------------------------------------------------------------------

Intake Exhaust
Valve Adjustment 0 0
Gross Valve Lift 0.544 0.547
Duration At 0.006 Tappet Lift 270 286

--------------------------------------------------------------------------------

Valve Timing At 0.006
Open Close
Intake 25 65
Exhaust 77 29

--------------------------------------------------------------------------------

These Specs Are For The Cam Installed At 110 Intake CL
Intake Exhaust
Duration At 0.05 226 236
Lobe Lift 0.32 0.322
Lobe Separation 112

--------------------------------------------------------------------------------

Recommended Valve Springs 924-16


i also looked for an oval port/highrise intake manifold with no luck,but i did see these by edelbrock #7561 or 5061 .would these do the job?

cfm , you keep hitting that nail on the head .

Something is very wrong. Your rings could do it....a worn out cam could do it........valves not seating correctly could do it...........improper timing could do it..............bad carb calibration could do it.............vacuum leaks could do it...
ill make sure my mechanic from ''MISSISSAUGA ENGINES'' reads this post.
thanks again.

 

[rogue2800]

Ive got a good Edelbrock dual plane oval port for a quadrajet if you want to keep the Quad.

The cam that Sting suggested scares me as far a reversion goes. Guess it depends on your exhaust.

I use Edelbrock Torker 2 cams. .527, .553, 224, 232, 114 sep. A little safer but like he said, I have to replace one this year because of a poor casting.

 

[OldMagicfloat]

Look for KAAMA's posts.

http://www.speedwake.com/upload/showthread.php?s=&threadid=32089

 

[man-of-war]

Thanks for the offer rorue2800, but i'll stick with the Holley crab. I don't like that 1410 edelbrock.

I'll get the edelbrock 7561 intake manifold,and the comp 11-232-3 cam which might be a little safer for now.This weekend ill start tearing down the block to have it honed.When this engine can run a gas free oil ill go to a bigger cam and a good exhaust system.

How long does it take to hone 1 cylinder? THE LONGER THE BETTER?

 

[OldMagicfloat]

I'd verify a NEED first, then to only rough-up the bores, NOT remove any stock. Hard to put stock back on your pistons...

Your original cam choice should be satisfactory, once any sealing issues are addressed. I would like to see that you tried leaktesting the exhaust risers; I hafta doubt that they were annealed after welding, from the looks of the mating flanges...

 

[speter4205]

Any update? I've been following this thread, learing a great deal. :bigsmile:

 

[man-of-war]

The only update is in going to replace/ swap the #336781 heads with 2 used ones my mechanic has in stock. my question is, what's the size of the intake ports on the #336781 supposed to be. I think my ports were ported to big.

thanks

 

[man-of-war]

hi, i dismantled the engine block over the weekend, and the cylinders still have the hatch mark's in them.BUT the mechanic used KB 8.5 to 1 compression pistons .

My questions is, would the KB 203 .070 work with this bore size 4.320 thow,the heads are 118cc and the piston has to be flat top 9 to 1.
any thoughts?

 

[OldMagicfloat]

.070 overbore is getting seriously thin I wouldn´t recommend it.

why do you want to get rid of your heads?
I Believe they are just fine.

 

[OldMagicfloat]

Are the intake ports bigger than the gasket?

I don't think I understand what you are saying. :confused1

If bores still look good, (and measure round, and do not have excessive clearence), why change pistons?

If you want more cubes, change the crank out to a stroker crank. Sonic testing of the bores should be done to find if there IS material to allow a big overbore and still be thick enough to last. It just doesn't seem like you should need to go there.

 

[OldMagicfloat]

Even if they are over the gaskets the gaskets are easy to trim a little...also the intakes.

I´d go with a general rule...maximun overbore at .060 then toss it.
If wanting cubes a 4.25 crank is the way to go.
496 specially blown and those heads kick ***.
already NA and done right your´e looking at 650+ hp @ 6200-6300rpm and 570 @ 5400 up

 

[man-of-war]

hi guys, what i'm trying to do is, back track on what modifications were done to the engine that might have contributed to the gas getting pass the rings.
i'll take you guys advice on both subject's. the mechanic changed the valve gide's and machined the valves .
i'll tell the mechanic to reinstall those 8.5 to 1 kb pistons with new rings.
i'm going to the mechanic shop tomorrow i'll take some pic of the block.

 

[man-of-war]

i'm also looking into the ignition system, the module for the distributor was replaced .if the module was the wrong one, would it cause a change in the timing?
the thunderbolt IV has V8 24 stamp on the box.the engine timing was set by the marine mechanic at 16*. But the mechanic that rebuilt the engine took it back down to 8 initial and 34 advance. is it possible that the 8*initial is causing the low vacuum and the curb idle to be set in to far? Which is causing the gas to load up at idle?....

I ordered the crane HI-6M ignition box, i hope this box helps.

 

[PatriYacht]

Yes, that low timing can hurt your idle vacuum. A lot of guys use the V-6 module because it allows them to use more initial advance. Generally the more radical your cam, the more advance you want to use at idle. That is oversimplifying but it seems to work.

 

[OldMagicfloat]

hi guys, what i'm trying to do is, back track on what modifications were done to the engine that might have contributed to the gas getting pass the rings.
i'll take you guys advice on both subject's. the mechanic changed the valve gide's and machined the valves .
i'll tell the mechanic to reinstall those 8.5 to 1 kb pistons with new rings.
i'm going to the mechanic shop tomorrow i'll take some pic of the block.

the mechanic didn´t check the ring gaps IMO ..especially the 2nd ring which has to be larger than the top..if not there´s too much pressure between them for either to work correctly.

 

[man-of-war]

thanks for the replies, i would look into the ring gap with the mechanic. i ask the mechanic about the stroker crank for my engine,but he said that i'll need to replace my pistons to stroker pistons.he said my existing 8.5 to 1 KB are to tall
with this module that i have, which i'm assuming is for a V6, would i need to replace it for a V8 module? or would the Crane HI-6M ignition box correct or compensate this problem?
here are some pic of the block, the vertical lines my mechanic said its dirt?...