Want more HP, help me make a plan

Despite current issues I already know I want more power :devil:

So I need you guys to help me cook up a plan based on my current setup :stirpot:

Target HP is 300+ RWHP and I need to work out a few things before I can plan which parts I need and where to get them.

Current setup: SBC 350, 750 cfm carb, performer EPS intake, Accel super HEI, 64cc performer heads, 1.52 roller tip rockers, 0.052 compressed thickness headgaskets, Comp. XE268H cam, 13cc dished-4 reliefs cast pistons, stock crank, double roller timingset, 4 bolt main. Hooker Super Comp sidepipes. Calculated compression: 8.6:1

Shortblock dates 1997 and has less than 30k miles on it. Top end installed March this year.

As I see it I have three most likely routes:
A. Only replace pistons with 5 cc or less flattops and use thinner gaskets. This should bump compression to around 9.5:1 and really put that cam to work.

B. Swap shortblock for (better) 350 block with better crank, rods and pistons.

C. Swap for stroker shortblock. Stroker ofcourse has low cc flattops too.

Scenario A is cheapest part-wise, but involves the most machining and man-hours. Scenario B is more expensive in the parts section, but requires much less or none machining and man-hours. Scenario C is most expensive in parts, but would be most fun too. Man-hours and maching same as B.

Besides part cost decisions (buy new/buy used from TT for instance) I think I also need to take my top end in consideration. Will my heads and intake be able to flow enough to support fuel/air demands for that kind of horsepower? Should I step up to 1.6 rockers?

Any inpute is welcome! :beer:

I think you have to open it first and inspect and measure the bores, then see if new pistons and rings are an option.

Another option is to simply use a thinner head gasket and have the heads shaved to (for example) 52cc. You have to carefully measure valve to piston clearance - I'd do that with clay and using the old gaskets, then maybe another clay measurement with no gasket ... and then do the math from there.

OK first step, its ALMOST ALWAYS better to have a spare or second performance engine combo that you can swap into the car and a near standard engine that you can use for daily transportation, so the car never needs to be out of service for more than a weekend while you swap between the two.
theres ALWAYS delays and un-expected costs envolved in any performance engine build-up


you need to decide on your budget and know whats within,your skills/tools and abilitys

I can easily give you a decent combo, but if its NOT followed exactly it won,t produce the same results, and almost everyone thinks they can substitute a few components to save money or allow the engine build to go faster and get similar results....chances are EXCELLENT youll hurt the final results doing so.

IF your going to build a performance engine combo, the most cost effective combo is usually a 383 built with the more comon and cheaper components as it tends to maximize the displacement and use the comon 350 block as the basic component

start by reading thru this thread AND ALL THE SUB LINKS

http://www.chevytalk.org/fusionbb/showtopic.php?tid/131229/

I would strongly advise getting a CHEAP but decent engine stand and finding or purchasing a known good 350 block as the starting basis for that second engine,or you think about buying a crate engine for your second engine

http://www.dougherbert.com/383chevysbstrokerhighoutput-p-25857.html?cPath=614_615_748


http://www.ohiocrank.com/chev_sb_shortb.html
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=4420

http://www.larrysperformance.com/data/monthly.html

http://www.dougherbert.com/383chevybudgetstroker-p-26148.html?cPath=614_615_748

64cc performer heads? Why do people buy these 170cc runner heads? Granted, they are a good bit better than stock but only 170cc runners, not much room for improvement there or you'll need to hog them out. You won't make more than 400HP with those. The good thing is, you got them with the small chambers. The large chamber ones make even less power. (small chambers and flat tops make more power than large chambers and domes)

The crank an rods won't make power, the pistons will. A cast crank and some X rods is fine, of course there are better cranks and rods there, even on the cheap (like some powderforged rods)

I took some pics of the 4 bolt block, it's .030 over with flat tops, still have to measure piston to deck height. It's a 010 4 bolt block







Scenario A would be reasonalby cheap IF the bores are not tapered (no ridge), easy to check. A bottle brush and you can fit some fresh rings. Piston side clearance will be a thing to watch as you are matching new pistons to an already sized bore.

I would buy a nice ZZ4 crate engine IF you can, and then dump a nice modified LT1 DPFI system in there to go with it.....I know damn well that if a welder buddy and I can TIG up my LT1 off ebay that TT can do as well or better without much effort....runs like a raped ape....:yahoo:

the FI setup is then more affordable with costs cheep to help offset that damn fuel costs....

my '72 shark got average of 12-13 mpg as a stock car....I damn nearly doubled that figger for dumping a L98 injection on it....same muncie and 336 rear it got 24 mpg at 4000 rpm cruise doing 70-80 some odd....

wish I had stuck with that engine combo and just put in the overdrive auto...as it is I get 22.222 mpg at 90mph cruise....but this engine is essentially a ZZ4 I built some years ago with a slightly wilder cam so supposedly good for 400 hp now, at the crank....

Yeh, I have had some troubles along the way, but that's ME, not the build or the short block or much of anything else....it's a 'work in progress' shall we say.....or 'hobby car'....:bonkers::beer:

Thanks guys! Perhaps sum up current issue: my cam might have a wiped lobe. Future choices are ofcourse based on that outcome, but I like to know all my options when I find out (planned for the 23rd of August with a buddy).

I like the looks of your block Marck. What is the volume of those pistons? Yours seems a serious option: 355 cui, strong casting, 4 bolt and already has flattops. I also would not need to have any machining done and I could set it in the garage (on a stand) and build it from there myself.

A ZZ4 is out of budget and so is a crate longblock. A 383 combo like Grumpy is suggestion would be within reach: I can trade in my current shortblok at a local shop (didn't give me price yet, though) and for some extra cash get a refurbished 383.

Why these heads, well... I got some advise from experts :quote: and I was young and gullible (and stubborn), yadayada... you know :blush: I think 195 cfm is required for 400 horse (one of the links grumpy posted told me that), 170 would get me to about 350 hp (260 rwhp?).

But since they cost me 1500 euro's, I'd like to keep them for now. Milling is an option I'm willing to sonsider, but decent machineshops are rare and pricey over here. Marck, perhaps you know one or two shops?

You have an XEH274 right? Very likely to have a wiped lobe. Did you break it in with both springs installed? If so, a big no no! Use moly lube ON THE LOBES! Not on the journals, use assy lube on the lifter bodies and a dab of moly on the lifter face. Run with just the outer valve spring and use some kind of additive to bring up the zinc levels (barrier protection), may have to get some shell rimula (that's what rotella is named here)

The pistons are right around 6 or 7 cc's.

The block is ready to go. The camshaft is out as are the lifters but I have them all organized. It's not a very wild cam, just a mild one. Also still have the double roller timing set which is in good nick, not stretched.
Not sure exactly what it is, will have to check. For the rest, it's ready to run. Drop on some heads, manifold.

As for shops, Dymotrack and Post & Dros would be my suggestions. Not much else here in NL.

BTW, hate to say I told you so, but that was my initial thought...a wiped lobe. Very common as those XEHs are on the ragged edge of what can be done with a hydro lifter the diameter of the stock one (non mushroom), and the low inc levels don't help either.

What exact break in procedure did you guys use?

XE268H to be exact and told you so is no problem at all. Warned man counts for 2 or something along that line.

Except for the removal of the inner springs we followed the procedure as you described it. Using 15W40 mineral oil which should be with the zinc still in it and lots of assembly lube on the lobes and where applicable. First run 20 minutes at 2000~ish rpm, second run 20 minutes varying rpms.

There were no iron particles in the oil when I changed it at 700 or so miles after assembly, but I guess that doesn't say much.

If my cam is okay, I'll transfer it, if not... whole different story and I'll gladly buy yours I guess. I can always replace it when I have some extra cash laying around :noworry: My timing set is brand new (comp double roller), so I think I'll transfer that too, but let's not get ahead of things (yet).

Two questions remains:
1. Is milling the heads adviseable? Or should I try and sell these and buy othe ones?
2. Marck, PM me a price for that block (with/without the cam) :amused:

And now... :goodnight: have to be up and about in 6 hours :huh:

Milling the heads not too expensive @ dymotrack: EUR 248,- taxes included. Friend mechanic says milling doesn't really help though: anyone care to share their 2 cts?

Twin_Turbo said:

You have an XEH274 right? Very likely to have a wiped lobe. Did you break it in with both springs installed? If so, a big no no!

Click to expand...

So I ask the question. A gazillion GM engines were broke in with both stock springs installed. (I can assure you they don't do things twice). How is this a big deal? Just asking, really.:huh:

The stock GM cam profiles are not nearly as extreme as those used in those XEH cams. With the stock lifter foot print there's jsut so much you realistically can do when it comes to acceleration ramps. I suggest you read up on the cam rules as posted by iskenderian.

Which is why I choose the XE268H, or is that to extreme as well?

Nobody on milling the heads?

Just throwing in another option here:
Mill the heads, use thinner gasket and leave pistons alone. Instead spend your money on a roller cam, either with retro lifters (expensive) or stock GM lifters and machine the block for the stock GM "spiders" that hold the lifters.
If you were here in the US where you can get a roller block cheap it would be a no-brainer (block and stock GM roller lifters are not more expensive than a retro kit for a non roller block).....

You only have to drill the cam tunnel for 2 studs to hold the spider plate, and then you have to spot face the lifter bores and clearance the walls for the lifter retainers (dog bones) and clearance the dog bones also. Then you can use the 60 deg. V6 oem hydraulic roller lifters, just make sure you don't use a cam with a small base circle or the lifter will drop out and you loose oil pressure. Also, you're limited to around .55 lift.

Worship79 said:

Milling the heads not too expensive @ dymotrack: EUR 248,- taxes included. Friend mechanic says milling doesn't really help though: anyone care to share their 2 cts?

Click to expand...

I have this general opinion that head/block milling should ONLY be done for straightness...take off a few mills so the gaskets stay happy, that's IT....

to significantly change head volume and thereby bump comp ratio by milling amounts to shaving so much off, you most certainly will mess up strength and then the all important intake plane...don't ask how I know this...please...:bomb:

IMO.....I think something like TT showed with a decent roller cam, I like rollers as they don't require any thing today that is a 'weird' oil....something about them taking some metal?/chemical? out of the engine oils on left side of the pond....and I not sure but that's bad for flat tappet cams.....

IMO, one of the most difficult things about old cars is updating the things for REASONABLE enough price, and of course get more power as well as economy enough it can well be a daily driver without feeling all GUILTY about it 'wasting' gas.....tall assignment...

but then, hotrodding is FUN....:bounce::bounce::3rd:

so another set of heads, I like the old L98 aluminum heads #113 which are on my car now....10.5 comp ratio....but combined with DPFI, well back to my previous post....decent enough fuel economy plus plenty power so I can do 150 mph with my top/windows down.....:crap::bounce:

Rollers don't need the higher zinc content, also rollers don't need to be broken in.

60deg. V6 lifters aren't that expensive at all.

The 60 degree V6 roller lifter is the same OD as the V8 lifter, the roller is the same diameter and width also. The internals are the same, the only difference is the lifter body is .4" shorter and this is why it suits the older blocks that don't have the revised (taller) lifter bores.
You will have to use shorter than stock pushords, these lifters, although shorter than V8 rollers are .4 or so inch longer than reg. flat tappets.

Here's some pics:

60deg V6 vs. V8 lifter, note pos. of orifice!


Prepping block by facing the lifter bore castings and clearancing the walls. Also drilling cam gallery for retainer studs





Everything together:

TT that damn block got almost as much sex appeal as Mae West....but the problem is....machine work on a older block HERE is not worth it, not what with the junkyard blocks all over the joint, that have all that done already....

now over THERE, I dunno, but any GM truck would have one from '88 up I would think....untill the LS anyway...

that's what my engine is...a old truck engine....

:smash:

Just when I thought I had grips on all my options, you guys pitch in a few more ideas :skeptic:



No, keep 'm coming, although I'm very much leaning towards lower tech (read: search and replace) type of options. All input is ver much appreciated! :thumbs:

mrvette said:

TT that damn block got almost as much sex appeal as Mae West....but the problem is....machine work on a older block HERE is not worth it, not what with the junkyard blocks all over the joint, that have all that done already....

now over THERE, I dunno, but any GM truck would have one from '88 up I would think....untill the LS anyway...

that's what my engine is...a old truck engine....

:smash:

Click to expand...

It's a 400 in those pics.