I have a 396 (402) I just bought that was supposed to have 450 HP. I took it to a highly reputable engin builder in town today who had an engine dyno.
The guy at the dyno gave me some bad news. He ran in the cam fine but the valves started floating at about 4800 rpms on the first pull. He only got to about 323HP. He checked the valve springs and they only had about 50lbs seat pressure. I had him replace the valve springs and he got it to 5400 rpms and 360HP. He told me he was going to do a leakdown test on Monday to see if there was a bent valve or something. He was also concerned about the cam. He said that might be where the problem is.
As you can probably tell I am pretty bummed. I did not buy the engine from this guy I bought it from an internet company out in Arizona. Any ideas what I can try short of paying to ship this thing back? I am willing to put that money in this to get it right before fighting with those guys in Arizona and paying shipping two ways from Florida. Like I said my local guy is highly recommended, but he is expensive. I want to make sure we get this right the first time.

Here is the info on the engine.

402 bored 40 over
closed chamber 245cc (Truck) heads (2.19 in 1.88ex)
Domed Hyperutectic pistons
Custom Cam 292 (238I/248E Lift 540"I/540"E Lobe Sep 112)
Holley Avenger 780 carb
2" headers
MSD ignition and Distributer

Thanks in advance,

Steve :confused:

well the leakdown test will show if the rings and valves are sealing properly, then do a compression check to see if the cam is matched to the static compression ratio. On a new performance engine designed for street use on premium 175psi cranking compression should be good. 190-220 would be good with octane boost or race gas, 150-160 average for regular 87 octane pump gas. The problem could be the cam or not installed properly, definately something is wrong if it won't rev to 6000/6500. The cam should be good to 6500 I would think considering the amount of duration is has. Keep us posted

Well Steve I hope it wasn't Marks Performance Engines. If it was I'm afraid your out of luck, many people have been dooped by him. If so shoot me an email.


Dan

Thanks for the replies. I will have him do the compression test if the leakdown does not show anything. Then check out the cam. If that don't work I guess I will bring it home.

I guess there is a lesson to be learned here. Things that are a cheap usually cost a lot more in the long run. By the time I finish I will have probably paid more than I would have if I just bought a GM crate motor.

Dan, it wasnt Marks but thanks for the heads-up.

Steve

Explain the theory behind 2" headers, decent size cam, 5400+ RPM all with truck heads?? Peanut port heads are for low rpm torque and that would work better with small tube headers, low RPM and a much smaller cam duration @.050" lift than 238/248.

And that cam isnt custom, it a typical inexpensive Summit/Melling type grind. It won't make any decent power unless you throw 10.5:1 compression at it. Get a real cam in there.

Also, Jim is right. Those truck heads will make an "ok" street motor, but I think you'd be hard pressed to make any decent power, maybe 350 hp tops. Good street engine, but it isnt going to zing up to 6000 rpm like a rat should ( IMHO , of course).

You might post the head casting numbers here so those who know such things can verify the type of head they are.

I wouldn't trust a damn thing those mopes in AZ told you, but what is the compression supposed to be? Find out, and at least get a good cam in there, and have the shop do it, in case it wipes out. Hate to see you wipe a cam in this thing now.

You need to find out what compression is to make an intelligent cam choice.

The shop wouldnt have a set of 215 or 063 castings laying about, would they?

That cam is going to be lazy where you dont want it to be 2500-5000rpm. You want something with around 215-225 050 durations and on a tight 110 LSA to deliver peak mid range power at around 4000 rpm.

Bummer dude. Salvageable, but a bummer and I would send your friends in AZ a friggin mail-nail bomb for their courtesy.

I bet if you drop no more then a good old CC 268HE in her she will pick right up and be a great mild street motor with plenty of zip for running around town.

No powerhouse, but rather just a good mild street motor!!

And as stated the headers would be better if they were 1.75" ones..

Can you figure out just what your real CR. is b/c I just caught the mention of domed pistons..

pdq67

I agree with the last post about the truck heads. Switch to closed chamber big oval heads and you will probaly pick up at least 50hp. Are you sure that they are truck heads. Do the say truck underneath the valve cover?

call them and tell them you want to send it back.

I think I know the seller of that engine on ebay. They now have a new name w/0 feedback. How conveinent!!

I would like to see the old name and feedback that they have.

Makes crate motors look better all the time huh?

Here's a link to the feedback and some BBB stuff

http://www.josheinstein.com/marks.htm

http://cgi2.ebay.com/aw-cgi/eBayISAPI.dll?ViewFeedback&userid=marksperfengines@cs.com

wow wow woweee wow wow wow
that guys got issues!!!!!!!
shane

When a ebay user is tossed, from ebay like MARK'S PERFORMANCE ENGINES, they can't just change there ID and resume business. They are done forever. What they can do (if they don't get caught) is just start a new account under a new name. Do you have the new ebay ID for this scum bag? It's crap baskets like this that hurt honest ebay sellers and give ebay a worse name. Don't get me wrong, ebay is the worst about helping a buyer or a seller in a dispute. They just refuse to look at the details or get involved. Here's a decent ebay dealer... graemlins/thumbsup.gif
Coastal Glides (http://www.stores.ebay.com/coastalraceglides)

There's only three people I can afford and trust to assemble an engine- me, myself, and I. I hope you end up with a good engine after all is done. :(

Thanks for the help. I really love this site.

Another reason I am posting all this is to possibly keep someone else from making the same mistake I have.

As for the seller it is NOT Mark's. I did get the engine on Ebay though. I would post their name here but I want to contact them first to give them a chance to make it good. If he doesnt stand up to his part of the deal I will be sure to pass along the name.

As for more info on the engine. I don't have the head castings but I will get them and post it. I do have a picture of it at http://www.67chevelleSS.com go to the photo album and click engine problems.

I do have another set of heads casting #'s 3964290. I have them on another motor. They are not stock, they have 2.19 in. and 1.88 ex. valves. Would it be better to add these?

The engine is SUPPOSED to have 9.6:1 compression. I was told a Comp Cams 292H would be a good choice. What do you guys think?

Thanks again for the help guys.

Sorry to hear about the problems.

That guy is horrible..

I found the numbers on those heads. It's 3933148.

I really appreciate the help.

Steve

Yikes, if you are getting people to buy trans stuff at those prices on eBay maybe I should check it out, lol. Not to bust on you, but $24.99 for a shift lever that has a LIST price of $17.00? :eek: I would gladly price match that! :D

Shift lever? What is that about?

I looked at the link in one of the above posts to a 'decent' eBay merchant. Saw a lever that normally goes out my door for $12 or $13 as a 'buy it now' for $24.99, lol. Just kind of got my attention. I have never really looked at eBay, and did not realize what went on there. Kind of interesting to see!

Yea come on over to ebay... ;) I looked at your prices too. :eek: Kinda interesting you chose to pick that one item. I can sell a cheaper one like you, but that one is pretty slick with the bolt thorough design as opposed to the weld-up ones. Yes, try ebay... graemlins/thumbsup.gif

I have a feeling your heads are regular open chambered heads that are along the lines of the -781's and a -049's so I don't think they are all that bad if your compression ratio is in the 9 to 9.5 to 1 range with the domed pistons you mentioned.

Mortec lists them as '69, 396, two barrel heads at 112 chamber size and open chambered ovals. Also used on the 366T and 427T motors. I do figure large ovals b/c I don't think GM put the peanut port heads on the '69, 396 two barrel motor..

pdq67

Don't mean to pick on those Assumed your "TRUCK" heads were peanut port. Happens to me all the time. I say I'm running TRUCK heads, get a puzzled look as to how a peanut port head works so well. All peanut port heads may be from trucks of a certain year, but not all TRUCK heads are peanut port. In your case the casting numbers show an early closed chamber Large oval head. So, the heads are probably not the limiting factor. You may be over cammed for the Static compression. I would suggest a cranking compression test with the current cam to get some Idea of the cylinder pressure. After doing that maybe post again for a cam recommendation from the Cam Guru's here.

Sorry guys I should have posted the date code also. The casting #'s are 3933148 with a date code of I 17 8 and I 16 8. That's 1978 truck heads right?

Morteck says,
3933148....69-84...oval...OPEN...'69 396/265hp, 366T, 427T, 112cc chamber

Thanks,

Steve

Is it worth going to eBay? I have not even ever taken a peek there before and am just curious if it is a good thing or not? The levers I have for $13 + shipping are the two-piecers also, I agree they are a much nicer part!

My listing shows closed chamber oval 69-76, 366T, 396, 427. not sure of the date code.

My core 454 '74/'75 P/U truck motor had a good set of -781's on it but they do have rotators on the exhaust valves so I would need spacers to use them properly.

pdq67

Can anyone tell from this picture if this is a Open or Closed Chamber head?

http://www.67chevelless.com/pictures/albums/engine_problems/head.jpg

Thanks

Steve

I am sorry to hear of your deal gone wrong on Ebay.It is a shady place where many bad things go on and Ebay will do nothing to stop it.
I try to stay away from it unless it is a small purchase and the sellor has a lot of good feedback.

You might also post a link to a picture that shows the intake port.
That way there will be no question about either.
This will help in selecting the cam and giving you a true estimate of HP.

Steve,
The picture looks very simalr to the heads I run. They are open chamber. Extra material removed from the quench area near the exhaust valve.

Thanks guys. Those are the only pics I have of the heads. I would take more but the engine is still on the dyno.


Dave,

What do you think about those heads? What cam are you running?

I do have another set of heads casting #'s 3964290. I have them on another motor. They are not stock, they have 2.19 in. and 1.88 ex. valves. Would it be better to add these?

The engine is SUPPOSED to have 9.6:1 compression. I was told a Comp Cams 292H would be a good choice. What do you guys think?


Thanks,

Steve

Steve,
If those heads are in fact large oval, they can provide respectable performance from a 396/402.
Do you know what size dome are on those pistons? The chambers on the heads you pictured are large, any where from 114-124cc. If a piston with a small(.100 orless) dome was used the static CR will be lower than 9:1. Combine that with a large (for a 402) hyd. Cam, I believe you said it was 292 advertised, the dynamic compression will be low. A cranking compression test will bear these " theories" out. If you have low cranking compression , your choices would likely be swapping to a closed chamber head to bump SCR to match your cam, or switching to a cam that would maximize the compression you have.
I run a Comp solid roller 236/248 @ .050(113 LSA) with 10.2:1 Staic compression and 3986136 Truck heads.

ha man.........what a mess i see.........i went and seen the photos of the engine and those pistons you have wont give you no 9.6 to 1 compression..........with those heads .......looks to be about 118 cc castings..........with the standard fel-pro head gasket and depending on your deck height you will be lucky to have have 8 to 1........

i ran those pistons in my 402 and with a very bad deck height of .050 down the hole and a .040 head gaskets with 118cc heads and my compression was 7.7 to 1 so you can do the math.

the domes on those pistons really dont do anything........they are more or less then a flat top piston.......the dome just barely will fill up the valve notches........

with those pistons and a closed set of heads (98cc) and a steel shimmed head gasket gave another engine of mine (402)8.8 to 1 compression with something like .025 down the hole......

so you wont ever get any decent compression out of those pistons.........for a hp motor.......

and on top of that those truck heads with a 245 cc runner wont ever really do for some hp for over 5000 rpms...........

i have made the standard oval port heads...like i think they run a 260cc runner..work for 10 sec 1/4's with porting.......

looks like to me getting 450 hp from your engine with current pistons and heads are kinda long shot..........

Ouch :(

i just seen those heads were 112 cc and they are the normal oval port heads........they would be ok and they would work ok for a hp motor..........but your compression will be a low.............since they are still open chambered heads..........

2" headers dont help those 396 engines any at all........i myself had tried 2" headers on my bbc 396 from 14's to high 11's in street trim and everytime i would slap them on just to see if i would gain anything at the track it would just flat out slow me down.........at one point they slowed me down a full second and i lost 8 mph thru the traps with no other changes........i finally sold them ......and have had the best luck with just the cheap summit headers for 80 bucks........i even run them on my 10 sec race car now..........now i wished i had the 2" headers to try on my 454 to see if they are worth anything......but that will have to wait......i have to find a set now........

Thanks ddennis. I think I will put my closed chambered heads on there and see what that does.

Thanks,

Steve

http://www.67chevelless.com/pictures/albums/engine_problems/head.jpg

These are open chamber heads for sure. The General got a little wacky in the earl 70's and started making some of the "closed chamber heads larger in the quench area. A good example of this is the 290 casting they are closed chamber with a larger chamber. The head in this picture looks a lot like the 950 casting, open chamber truck head, 112 to 124 chamber. In that design they opened up the area around the exhaust valve. This all might been pointed out in this thread but if not .....

I hate it when I hit the quote instead of edit... to bad this BB does not let the author of a post delete it??????

Yes, those are standard, open chambered smog heads b/c GM removed the exhaust valve quench by squaring the chamber across.

Not the best head, imho when compared to the -781 or -049 heads, but good just the same. And a book I have lists them at 112 cc's.

I would cc them so I would know for sure their size chambers and then shoot for a piston dome/headgasket thickness/down in the hole piston number to hit right a 9.75 to 1 CR. so pump gas can be ran fine.

I know some run higher but I don't like hassles at all if things change fuel-wise in the future which it darn well could when the GOV. gets the ultra-low sulfur fuel across the board later on..

pdq67

Thanks everyone for all this help.

Here is what I plan. I am going bring the engine home. Then I am going to call the company that I bought it from and ask them what they plan to do. I am going to try and get them to take it back. If they won't, I plan to try and at least get them to pay my local engine builder to make the engine what it was supposed to be when I bought it. If that don't work I guess I will have to punt.

Thanks again everybody,

Steve

Good luck on getting that engine going. I have a recently rebuilt 402 mostly stock, and I put on a set of closed 1063 heads on mine and I am very impressed with the power I have. I have a friend with a 396 with truck heads and I woop up on his car all the time.
Steve

Put a smaller cam in it, tune it, and drive it. It will run great. Don't get hung up on dyno numbers. I think earler someone suggested a Comp HE268. That cam with mild compression will make a nice streetable engine with gobs of torque.

Originally posted by Georgia69:
Put a smaller cam in it, tune it, and drive it. It will run great. Don't get hung up on dyno numbers. I think earler someone suggested a Comp HE268. That cam with mild compression will make a nice streetable engine with gobs of torque. Good advice there..I would go with the Crane 272H,works well with 8.0-9.0 to 1..builds cylinder pressure well=torque

302A2LUN done on a 110 LSA would be the ticket, in the Comp line the XE262, or the X4262H, all keeping the intake duration below 220@.050 and all sporting a dual pattern with around .500 lift.

Me, I would get a handle on whrere compression is, and pick a cam accordingly. The aforremention cams if its below 9.5:1. Move up to a 220 duration cam if compression is 9.75 +.

sgaylord,
According to Mortec those are closed chamber 101cc heads! I don't if those heads would be much better than the ones you have on engine now. With 9.6CR need some nice Edelbrock Performer Heads! Yes they cost but thats where the power is! I also agree with need of at least a name brand cam! Doug Herbert @ 1-800-444-7373 is very well known and his prices are very reasonable! He will get you the right head and cam for your combo! I would have your local guy assist you all the way! Then if problems he could easily handle it for you! Of course your local guy could assist you with choices for you to decide what to build.
Good luck! :cool:

sgaylord,

Glad to hear you are going to try and return the engine. Plain and simple, you did not get even close to what you paid for, :mad: and deserve your money back. ;)

Bill

that would be the best thing to do.......try and get them to make the engine what you paid for.........spending that kinda money and being 100 hp shy of the advertised numbers is uncalled ..........its kinda sad to there compression ratio wasnt even close to advertised close to a full point under........cant believe they would put that cheap of a piston in a 3000 plus motor..............i had often wondered about those motors...i have seen them advertised..........and it was hard for me to swallow a 450 hp claim......with out alum heads and a decent size cam......

let us know how it goes im very interest in the out come........