[GreysonWinfieldEsq]

Decisions decisions! This is a great thread that has made it all that more difficult for me to make a decision on which engine I want. The 350 that came with the car or a transplant 400/455. Well time to flip a coin or discuss it with my 6 year old daughter. Great info guys Thanks!

[70LeMANS]

Keep the 350 and show those 400/455 your tail lights at the track Now, I got another question (im full of'em!). How would i know if i ahve the th-350 or the 400? I was reading along some of the old post about 350, and a user said the that 70's cars that came with an a/c had 400's is this true?

[bmpmdf]

If you was under the car looking up, and your pan is square with one corner kinda knocked off, it is a 350 th. The 400th has a longer pan that nearly comes to a point at the back. Hope it helps.

[70LeMANS]

yes, sorry, i know it was kind of a stupid question (I did some research after posting). I guess i should research first and then post.

[bmpmdf]

A stupid question is one that doesn't get asked when someone doesn't know the answer.

[70LeMANS]

OK, i got the cash and bought the intake, and carb...Im very sorry to ask this...AGAIN, but im narrowed it down to these 2 cams. Melling SPC-7 or the Summit 2800. What to choose and why? I should start the build tues.

[shotgun]

Whichever is closer to Jagtecs.

[Jagtec1]

Thanks shotgun! Here are the specs on the cam in my, well, not my 350 anymore!!

Crane 272
Lift .454/.480 with 1.5 rockers
Duration 216/228
112 LSA

[tp's lemans sport]

I also gave the 70 buildup alot of thought before I started on the engine rebuild. 70 lemans and I were involed in a similar thread about a year ago. I decided that I wanted to keep it stock, while increasing the the hp to the 300 range. This is what is happning as I type. The engine is being rebuilt, I am having a stock 350 4bl cam, attached to a 350 HO intake manfiel with a Qjet carb. The valves are getting a 5 sided grind (not quite sure what the difference is between a 3 sided grind and a 5 sided) but its getting it. Compression ratio will increase to about 9.8 to1. Stock gm HEI ingnition and 2 inch duel exhaust exiting through the stock exhaust manifolds. So what do you guys think? Also if you could shed some light on the 3 sided vs the 5 sided grind.

Thanks

[bmpmdf]

It really depends on the angles used and how good of a job they do doing them. I have seen some multiangle jobs that were so bad, that the factory single angle was better.

[Hattmann68]

Man what a great topic. I am doing my own 350 build-up in a 68 Tempest. the Engine is a 1976 block"XP" with 6X-4 heads. Was going to set the engine aside for a 455 engine but couldn't resist upon reading this post. Am replacing the current heads for 1970 "16" Heads 78CC and installing a Summit 2801 camshaft. My question to you 350 builders is the pistons are flatop without valve reliefs and have a "JJ" stamped on them? Never paid attention before as I always assumed most 350's had valve reliefs. I love this topic.

[bmpmdf]

Hattmann68; if you already have the cam, advance it 4 degrees. And use 1.65 rockers on the intake side. While it is apart, make sure you clearence the intake pushrod holes so you won't have inteference. On your pistons, it must be an aftermarket rebuilder special type cast piston. Those things normally are way down in the hole.(.025" +) If the bottom end is together, not much to do. If it isn't, at a min try for different pistons with valve reliefs. Then you can mill the deck to bring the piston to 0 deck. Use the 3.960" Cometic head gaskets. Alot better combustion process and more power compared to the felpro 4.300" bore gaskets.

[Hattmann68]

Hey Bmpmdf, Thanks for the reply, The 350 engine was rebuilt about 20,000 miles ago and is in good condition. Took it apart and everything looks good. Had the Camshaft/Lifters (2801) & Timing Chain set from Summit laying around from another project. I did install the Cam 4 degrees advanced like you said. Just thought it was weird that the pistons are a flat top without valve reliefs and it is .005 from top of deck. Will be checking with the heads installed valve clearence on the pistons. The 1970 400 "16" Heads are 78cc Chamber . Had them setting around, the exhaust is tapped for headers, and have to get the intake studs tapped for screw in studs. Have a Performer Intake with a Qjet. Headers are Summit, with 2 1/4 exhaust pipe. Tranny is a Th400 with a 11" TCI Stall. Rear Axle is a 10 bolt with 3.23 gears.q

[Hattmann68]

Sorry , got cut off. Am trying to build it on a budget.Trying to reuse most everything on the engine I can. Just curious how it will run. I've never run a 350 engine before, only 400's and 455's. Just reading back on the thread it looks like the 350 can run good(14's & 13's sec.). Where I live everytime you go look at a Pontiac Engine, 8 out 10 are 350's. Also what are the heads you using and what is the best for a 350 engine? Thanks

[bmpmdf]

Just think, for cast pistons for 350's, some do not have valve reliefs, while others for 400's have too many valve reliefs. You think chevy guys would put up with it?

[72blackbird]

Originally Posted by screamingchief

Yeah like them #46 small valves on B-mans too, had a pair(or two)myself that I was going to use on a build like these,had to let em go when I moved once. I have the 350 shortblock out of my 72 firebird that I'm putting a 455 in and all this talk has me wanting to put that back in something(ohmygodnotANOTHERcar!)just gotta track down the right heads which is a piece of cake cuz hardly anyone desires these all that highly(woohoo bonus!).

Coincidence?- I guess some '72 Firebirds 'force' their owners to install 455's under the hood sooner or later. I'm going with a 455 too, but was thinking of putting my 350 short block to work while I build the 455.

My 350 shortblock has a Crane 272H in it now, but if I put a set of ported no.13's on it I might run a 60242 instead. I'll also swap the Holley 750 v/s and e-performer from the 400 in the car right onto the 350 as well, just rejet for the 350. The shortblock is a stocker (cast pistons, rods, just overhauled w/ fresh rings,bearings, etc.) so I think it qualifies as a low budget refresh.

Geno

[shotgun]

Holy crap, I opened this post and dust came out of my monitor!

[big_gto]

how is it that a 224/234 cam is too big on a 350 when the chebby guys run that big of a cam?

[Dick Boneske]

You can spend less money and get better results by replacing the 350 with a 400 or 455. In stock form, the bigger engines will make more power than the 350 with the mods some are suggesting. The 400 or 455's can still be found for only a few hundred dollars, they weigh the same as the 350, they cost the same amount to rebuild, and the same speed equipment bolts onto them as the 350.

Do whatever you want, but if better performance is your goal, you will do better with more cubic inches with a Pontiac engine. JMHO.

[big_gto]

Wasn't there a thread of a P350 making 350hp & 450tq? This would be perfect for my FSJ Jeep Cherokee, or any Darksider.