Pyro

Wow, really?? My comp cam 292 is a huge fender shaker with a lot of top end (pulls to 7000 rpm). And not much vacuum at idle or toque below 3000 rpm. I guess it all depends on the duration at 0.050" lift. The comp cam 292 has 244 degrees duration at 0.050, the 280 has 230, and the 270 has 224. Did your machine shop guy give you anymore cam specs? duration at 0.050 or lobe center line? If the last cam you had (290) was mild then we might already be talking about the same thing. That is.... "using a smaller cam than a 306 duration". Cam manufactures rate the advertised durations differently. Some at 0.006" lift, some at 0.004, and other lifts which can make huge differences in the advertised duration of a cam (numbered name on the cam, 290, 306, etc). The duration at 0.050" is the main thing that determines how the cam is going to act. With your step-up (9.25:1 cr), a cam in the area of 230 degrees at 0.050" would work well. And I get the feeling that your new cam will be about that size. When I read that you were going to use a 306 duration , I was thinking 250+ degrees of duration at 0.050" which would be a very very big street/strip cam. And, like I wrote earlier. High performance valve springs are very important. I have made that mistake in the past. Weak springs will kill top end power. Please don't try to save money on springs. Good luck with your project.

That is right, a lot of inital timing will already be in the ignition curve. If you try to run the stock inital timing (8 to 10 degrees) with a cam that big, it will cause the headers will glow red at idle and the off idle responce will be very weak. Furthermore, those old style heads are not what we call "fast burn heads" so more timing is required to start the burn sooner which will allow the combustion process more time to complete. Typically, the new modern heads (fast burn design) only need about 34 degrees of total timing. With 0.030" over flat top pistons, 350 crank, and 76 cc heads, the compression will be about 9.25:1. If you use a 0.020" thick steel head gasket and shave the head 0.020" you should be able to get the compression up to 9.9:1. I would strongly recommend trying to increase the compression or use a smaller cam, like a comp magnum cam 270 or 280.

That cam seems about right. However, you will need at least 10:1 cr to get power out of a cam that big. 10.5 would be even better. Also you should set your ignition timing at 20 inital and 40 total and don't use the vacuum advance. You will also need some hp springs to keep the valves from floating at hp rpms.

That cam seems about right. However, you will need at least 10:1 cr to get power out of a cam that big. 10.5 would be even better. Also you should set your ignition timing at 20 inital and 40 total and don't use the vacuum advance. You will also need some hp springs to keep the valves from floating at hp rpms.

I have seen a 750 holley run great on a 58 VW bug with a 1600 cc engine with a draw through at 14 psi (11.9's at 120). So i'm sure a 650 will work with a 2.8. To figure hp gains from a turbo do the following equation. (14.7 + boost)/14.7 = "hp multiplier" Then use the "hp multiplier" on the hp of the engine WITHOUT a turbo and the new hp is estimated. For example: a L28 with 10 psi of boost. (14.7 + 10)/14.7 = 1.68 Stock hp at the wheels is 135 hp. 135 hp x 1.68 = 227 hp (at 10 psi of boost)

I guess the 77 vette would still be using the 882 heads. In the chevyhiperformance.com head flow data base the numbers of the 882's look like this. 0.050": I=39 cfm, E=34 cfm 0.100": I=70 cfm, E=58 cfm 0.200": I=125 cfm, E=108 cfm 0.300": I=175 cfm, E=135 cfm 0.400": I=204 cfm, E=141 cfm 0.500": I=205 cfm, E=142 cfm 0.600": I=206 cfm, E=142 cfm 1.94/1.50 valves, 76 cc chambers, 151 cc intake ports. A little over 0.400" lift is ideal. Lifting the valve to 0.500" on these heads will eat up power. Lift a valve quickly up to 0.420" and hold it there for awhile and these heads can make 400 hp (204 cfm x 2 = 408 hp). I have read engine building stories that used a head like this with a low lift cam but with long duration (300 degrees) and made good power (400 plus). It looks like more duration on the exhaust would also help. And don't forget to increase the compression if a long duration cam is used.

Nic, Maybe I can give a few reasons why people would build big cube engines without a 400 block. Good 400 engines are getting hard to find. However, aftermarket 400 cranks are cheap and easy to get (summit or jeps) and good 350 blocks are littering the planet. Heads don't require any modifications when used on 350 block. A machine shop would need to drill steam-holes in each cylinder head if a 400 block is used. Except when the stock 400 heads are used. There are mostly likely a few more reasons but these are the most common.

You can make a 396 cid small block by using a slightly stroked 400 crank in a 350 block bored 0.060" over. The stroke of the 400 can be increased from 3.76" to 3.83" by offset grinding the rod journals and then using small journal rods (327 rods). The stroke is increased by 0.007". So a V8 with 4.060" bore and a 3.83" stroke is 396.7 cid. A 0.030" over version is a 391 cid which normaly is a 383 cid if the stroke wasn't altered. I had this done to a 0.030" over 350 and now I have 362 cid instead of 355 cid (3.55" stroke instead of 3.48" stroke). On my next rebuild (+0.060) I will have a 368 cid.

More heat in the combustion chamber. Less heat loss allows more work to be done.

And.... With all things equal (chamber design, valve diameter, flow numbers, etc.) iron heads will make more power than alum. heads at compression ratios lower than about 9.5:1.

One more thing.... Make sure the ignition advance is working. No advance = no power. Distributors will lock-up sometimes.

I wouldn't. A comp cam 268 should be the absolute biggest you can go with a stock converter. A comp cam 260 might be a better cam for your setup. A light car (like a datsun) and higher gear (3.55 and up) actually lowers the stall of the converter even more. Also, I would not use a summit cam. Sure they are cheaper but those cams have very soft ramps (low intensity) which bleeds off cylinder pressure which effects low rpm and mid range power. Intensity is the advertised duration minus the duration at 0.050" lift. So a cam with a lower number has quicker ramps (more intense). Quick ramps increase cylinder pressure by closing the intake valve sooner and then allows more air into an engine because of longer duration over 0.050" lift. It is kind of like having the best of both worlds. Good low end torque and high rpm power. However, high intensity cams do wear out sooner. Except when you use a roller cam. I also think the summit cams have wider lobe centers which also lowers cylinder pressure by retarding the intake valve closing point and they also reduce cylinder filling because of less overlap. Less over lap (wider lobe centers) will make an engine less throttle responsive when using a carb. Wide lobe centers are good for emissions, efi, boost, and N20 but not for performance with a carb. 108 to 111 degrees of lobe center will work well for a carbed street engine and 112 to 116 for an efi or boosted engine. Anyway, that is my 2 cents.

FYI, a GM T5 from a V8 car is kind of hard to find.

I posted a photo of my IC tube routing in the HybridZ Picture Gallery. I hope it helps.

Ok... I posted my rear diff mount in the HybridZ Picture Gallery. Man my car looks dirty! No wonder I get so dirty when I work on my car! The mount has been slightly modified as described in my first post. I forgot that I had cut some of the length of the angle iron and weld in some side supports. It makes it easier to get to the mounting bolts when it angle is cut and welded this way. However, I also put one of these on my turbo car and left the the angle full length and without side support and it works fine. I also made the front mount solid by welding in tabs of metal between the upper part of the mount and lower part of the mount. The metal is used to bridge the rubber gap. And if you cut the upper part of the mount flush with the lower part of the mount it makes it much easier to remove the drive shaft bolts. But be ready for some burning mount rubber when you weld it. A little smokey but no problem.

I guess I could snap a shot of it but i'm not sure how to post a photo. However, I do know how to send a Jpeg file over to your e-mail.

I still use a stock bar but I added some reinforcement. I got a 6" piece of 2" angle iron that is made of 1/4" thick steel. Then I drilled two holes in it so I could place it over the top of the bar and bolt it to the diff cover using the two big bolts. Then I drilled a 1/2" hole through the angle iron and through the lower cross member. Then I ran a 1/2" bolt up through the crossmember to the angle iron. I also used a 1/2 water pipe around the bolt to allow the bolt to be tightened down without pulling the diff down. I run 10.7's at 134 mph with a 350, slicks, and 5 spd and I have never had any problems with bar. I also welded the front mount solid.

I turned the output of my turbo downwards and ran a 2" IC tube under the oilpan and up behind the alternator. Then I removed the charcol canister and ran it out the big hole in the radiator support (passenger side). Then to the IC and back into the engine compartment through the big hole in the radiator support on the driver side. I also relocated the AFM in front of the radiator. I plan on relcating my AFM into the trash once I install a new EFI system. It worked very well and I didn't need to mess with the fan or fan shoud. My car put down 235 hp at the wheels on a dyno using completely stock 1976 NA efi system and a FMU for fuel enrichment and 12 psi of boost. I also used a K&N filter on the end of the AFM that had a small elbow built into the filter which allowed me to space the filter off the IC and angle it down a little to prevent water ingestion.

You will not have any problems with the valves hitting the pistons until you get to a very big cam. The problem you have is low compression. I think you should not use a cam bigger than the comp 268. Make sure to use the comp 268 valve springs, double roller timing chain, and long slot rockers. Use the comp cam, not the summit cam. The comp cam will make more power.

180 to 190 hp was about the stock setup. However, a cam, intake, carb, vortec heads, and some headers can quickly get that engine into the high 300's or low 400's. Don't pay too much for a used 190 hp engine since you can buy a new goodwrench 350 (250 hp with headers) for 1300.00.

You need to look up the engine stamping code not the casting numbers. The stamping code are the numbers on the front of the engine and will tell you year and engine size. However, 010 at the end of the casting number normally means 4 bolt main block 350. IMHO, build a 350 not a 302. Why do you what to build a engine for more money that makes less power? If you think a 302 revs better then I will disagree. I have been spinning my 350 up to 7200 rpm in my Z for the last 10 years without any problems. A 350 is a good reving engine as long as enough cam and valve spring used. Plus it supplies a much more useable power band (torque) for the street. In this case, becareful what you ask for because you just might get it. Meaning, I think you will be much happier with a standard 350. I know it sounds boring but a 350 just makes more power than a 302 or 327.

My mistake it was a 8 part story on the 350 goodwrench engine. Below is a summary of the 350 project. The Goodwrench Quest, Part VIII An Overview of Testing The Goodwrench 350 By Mike Petralia Photography: Ed Taylor What started out as a bread-and-butter basic buildup and dyno-test of GM’s brand-new service replacement engine, the Scoggin-Dickey–supplied Goodwrench 350 snowballed into a full-blown street thumper spread throughout seven stories in Chevy High Performance. During our trials with this crate motor, we learned a thing or two about how to build a better Mouse for less. We’d also like totake this time to acknowledge Ed Taylor of Ventura Motorsports who did all the work on the engine and Ken Duttweiler for the use of his dyno cell. Dyno-Flogging The Mouse To determine if all the bolt-ons we intended to trywere worth their pudding, we first flogged the 350 straight out of the box and were pleasantly surprised at how well this underrated rodent performed. Our Goodwrench 350 cranked out 239hp at 4,100 rpm and 324 lb-ft of torque at 3,700-rpm stone stock. This power level was acceptable considering we assumed it would only make 190 hp. Then we replaced the stock aluminum Q-jet intake manifold with an Edelbrock Performer and threw out the cast-iron exhaust manifolds in exchange for some healthy 15/8-inch Hooker headers. The Mouse liked this breath of fresh air and rewarded us with 26 more horsepower and 26 lb-ft of additional torque. Ported Heads And A New Cam With the normal bolt-on fare tackled in Part I, we tore into the top end to swap camshafts and pocket port the stock iron heads. We also milled the cylinder heads to ensure that the deck surface was true, which reduced the combustion chamber volume by 3cc’s. To further bump the compression ratio up over the pansy 7.8:1 where we calculated this engine to be, we installed a thinner head gasket that raised the compression to 8.4:1. This increase in compression combined with the pocket-ported heads netted a fair increase in power but not quite enough to justify all the effort. What this engine needed was a bigger cam. A new Comp Cams XE268H-10 camshaft was slipped in next to further improve the 350’s breathing, and on the following dyno-pull the 350 responded with more power. The new cam, intake manifold, and headers along with the pocket-ported heads were so far worth 97 hp and 57 lb-ft of torque over stock. Not bad for a few bolt-ons and some backyard wrenching. The Aluminum World. Part III began with Taylor bolting on a set of L-98 aluminum Corvette heads from GM Performance Parts with Comp Cams 1.5:1 ratio roller-tip rocker arms. The L-98 heads feature a very small 58cc combustion chamber, which bumped the Goodwrench’s squeeze up to 10.1:1. We felt that the compression increase alone would net a power increase, although it now required 92-octane fuel. As soon as the engine fired up on the dyno, the idle lope made the increase in compression obvious. Power pulls with the L-98 heads and higher compression didn’t net the increase we expected, gaining only 12 peak horsepower and actually losing some midrange torque. But since these figures compare the pocket-ported iron heads to the rock-stock L-98 heads, much can be said for the performance potential of these factory aluminum castings. Test No. 3-3 replaced the Edelbrock Performer intake and factory Q-jet carb with a PerformerRPM intake and 750-cfm Holley double-pumper. The new carb and intake combo pushed the torque to 402 lb-ft and also produced a slight horsepower gain. Then to mine a little morepower out of the Corvette heads, we pulled them off and gave them the same pocket-port treatment that the iron heads received. With our relatively long-duration cam and good-breathing intake and exhaust system, pocket porting the L-98 heads didn’t net anything notable in this case. It was clear by then that the best overall package so far had been the stock L-98 heads with the RPM intake,XE268H cam, and Holley 750 carb. Back In The Iron World The L-98 heads proved worthy, but there’s a new iron head in Chevy’s arsenal that we wanted to try out. The new Vortec iron head borrows its port designs from the very successful LT1 aluminumhead. A complete set of heads sell for $400 and may be the best deal on the planet for mild small-blocks. Taylor bolted the Vortec heads on our Mouse, and their 64cc combustion chamber instantly lowered compression to 9.1:1. We felt this might not present much of a challenge to the Corvette heads’ 10.1:1, but we forged ahead regardless.The first pull netted a peak power increase of 16hp, but low-rpm torque fell off slightly. The torque loss calculated out to only a 4 percent average over the entire rpm band, which would hardly be noticeable in a car, but it couldn’t be ignored for our test. Then for test No. 4-3, Taylor had Todd McKenzie of McKenzie’s Cylinder Heads perform some grinding magic on the Vortec heads. The pocket-ported Vortec heads still suffered in low-end torque compared to the Corvette heads but gained an additional 13 top-end horsepower. Fine-tuning was next on our list to see if we could push this bad boy over the 400hp mark. Taylor swapped out the thicker composition Fel-Pro head gaskets used in the last tests for an identical set of the thin, rubber-coated Fel-Pro gaskets used to make power in test No. 2-2. This increased compression from 9.1:1 to 9.4:1. This time the added compression did us a favor by bumping torque up 13 lb-ft (see test No. 5-2). The engine was now only 5 hp shy of 400, and we thought more valve lift may be the answer. Taylor bolted on a set of 1.6:1 ratio rocker arms from Comp Cams, and for the first time the Goodwrench 350 saw the other side of the 400hp fence, making 402 hp and 416 lb-ft of torque. Taylor now had a gut feeling that the exhaust was backing up and wanted to try some 1?-inch Hooker headers and better-flowing Borla XR-1 race mufflers. Those parts netted another 7hp and 14 lb-ft of torque. We were really smokin’ now. Back To Aluminum There’s a new aluminum head for 23-degree small-blocks available from TFS that we were aching to try on this engine. The TFS heads share a 64cc chamber volume with the Vortec heads, so compression didn’t change from its 9.4:1 state. The TFS heads right out of the box were not worth much improvement when compared to the ported Vortec heads, gaining only 7 top-end horsepower and losing some torque. But when you consider the lightweight benefits of aluminum casting and compare the overall costs of both sets of heads ($850 for the TFS heads complete and $650 [$400 stock + $250 for porting] for Vortec’s heads), the TFS heads shine as the better choice. After effectively testing seven sets of cylinderheads, three camshafts, three sets of rocker arms, three intake manifolds, two carburetors, and two exhaust systems, we learned what worked and what was wasted effort. In reality, almost any small-block would see similar results to these parts and modifications. By far the biggest improvement came from the cylinder heads, intake, exhaust, and cam installations. One thing’s for sure: The Goodwrench 350 crate engine is definitely a deal worth its weight in horsepower.

A goodwrench 350 gm crate engine is a very good deal! Brand new engine is hard to beat! It also makes a good staring point for a high performance engine. Chevy High Performance mag did a 4 or 5 part "hop up" on that engine. If you go to ChevyHiperformance.com you can find those old stories. If I rememeber correctly, it made 250 hp out of the box then a simple 5 minute bowl blending job was worth 20 hp. Then a fairly mild cam with a set of vortec heads made 400 hp. Finally a super charger on that low buck engine made over 500 hp! 1300.00 is about the going price. If you buy it out of state you can also avoid the taxes but get higher shipping cost.

Those old heads were good in their day but not anymore. A set a vortec heads and performer rpm airgap intake could add 40 hp. Or you could do a little bowl work on your heads for the cost of a new set of gaskets. Torker intakes don't work that well. A performer rpm intake will help make more hp and torque. Or add some more cubic inches. Slide a flat top piston 350 block under those old heads. You will get more hp and some killer torque for the street. I don't know what mild cam you are using but a little more cam shaft will also help a lot. A 268 comp cam or a 270 comp mag cam will still have pretty good street manors. Or you could spray a 100 shot of N20. New valve springs can also increase hp. A lot of times people cut that corner to save money but end up loosing big hp.

storm280Z, Sorry, I was just replying to lee smith.