Im new to this forum, but it was recommended by a friend for a little help...so here goes: I have a Chevy 400 Im rebuilding Block# 3951511 Heads# 3973493 76cc Stock bore blah blah blah. Im looking for a few tips or even a link to see what specs this motor had from the factory. Id like to know what it had...because I want more (as we all do) Im looking for towing power, but I want to be able to jump on it and watch it go. Its going in a 78 Chevy c-20 Ive been slowly restoring. (the towing part is pulling a race car trailer). I guess I want the best of both worlds here, but if it comes down to torque vs hp I guess Ill take the torque. Main question is...what the best camshaft would be. Any help is appreciated and and thanx again. Donny.
Well my friend you need to read the rules first and go back and do your intro, then all will help you out. FYI.
I think your best bet would be the RV Performer package from Edlebrock. Heads ,cam and intake.Good gear in the rear also will help.
... Are you serious? Im only looking for a little info from people with experience down this road. Im not filling out a job application. All you have to do is ask. But thanks. On another note, I tried looking up the Edelbrock RV package, I keep coming up with power packages. I know RV cams have lots more torque so Ill keep looking. Thanks alot for your help.
From what I remember they had something like 400 ft lbs of torque at a very low rpm like in and around 2400(memory here) "A 400 in³ small-block was introduced in 1970 and produced for 10 years. It had a 4.125 inch bore and a 3.75 inch stroke. Initial output was 265 hp and was only available equipped with a 2-barrel carburetor. In 1974 a 4-barrel version of the 400 was introduced,while the 2-barrel version stopped production in 1975. 1976 was the last year that the 400 was used in a Chevrolet P***enger car, available in both the A-Body and B-Body line. While popular with circle-track racers, the engine was prone to cooling troubles if cylinder heads without steam holes were used."
My Dad had a suburban. We built a 400 sb for it with a rv cam and small valve heads since we did alot of pulling. It burned a valve anyway so I took a set of 993 heads, cut them for 2.02 and 1.6 valves and did a mild port job on them. It really made a big difference. You can gain a bunch with cylinder heads. Just look at the torque 396 and 402 bb made with the same bore and stroke, but better breathing heads. 1.6 rockers on an rv cam work well too. You need to remember mor=st standard grind camshafts are ground and rpm-rated for a 350. Jeff
Yes he was: Here and most any forum it is considered the proper thing to do. It doesn't have to be a resume, just an intro. On the 400, Cam, intake, free flowing exhaust and a well tuned ignition and carb. For the cam I'd get the info I had on the truck such as what else you intend to put on the engine, what trans and what rear end ratio and call the tech line at the cam grinder you prefer and ask for a recommendation. The cam that one of the other guys on the board or I may like may not be the right on for your application. Thanks for coming on and asking a question instead of trying to sell something on your first post though. Things could have gotten rough if you had done that. Now, about that intro?
I am Building a 400 for my 68 Chevy truck. I am using a Crane Energizer 272H which is 216@.050 duration. I am using different heads. I would suggest getting the compression up a little bit and for towing a cam between 205 to 215 @ .050. What octane fuel do you plan on using? Big cams get poor mileage and lower pumping compression. It is all about TORQUE.
Vortec heads, and a truck/towing cam made by crane or comp. Run like a 600cfm carb on a dual plane intake.
Thanks for the feedback everyone. I do have a set of 2.02 heads I thought about putting on, but I was worried about cylinder temp. I already know about drilling out the coolant holes so thats not a problem. 2.02's would bring it up to like 11 to 1 correct? I was thinking along the lines of somewhere between 210@50 and 218@50. Im pretty good with choosing cams for a 350, but this is my first 400 rebuild and I know they have lots of torque to begin with. It will be a pump gas motor. I did find a COMP cam I liked...XM256H 212/218@50, 447-462 lift. Im trying to keep my torque power range between 1000 and 3000 rpm. The truck has 3:73 's. 35" tires. Has anyone tried this cam before? Again thanks for all the feedback, you guys are great.
With the 35" tires the 3.73 gears will seem a little tall. Keep the compression down because of that or it will ping. I'd recomend a 70-76cc head and 2.02 valves. The xm256h cam looks good, I would cut the pushrod guide slots out so you could run 1.6 rockers some day if you wanted to. They move the pushrod socket in closer to the stud to get the higher ratio and the heads can run out of slot. It's easy to do now with the heads off. Sounds like you are on the right track. The only thing I see in the combination that may dog it down is the 35' tires with the 3.73 gears. Not a very good final ratio for towing. Jeff
I am running a 406 SB in my hiboy. I like the Comp Cams 4X4 high torque cams. Here's one from Summit. We put this one in my daughter's 69 Camaro with a 355 SB, Vortec heads, 700 r4. <TABLE id=recordSet cellSpacing=0 cellPadding=0 width="100%" border=0><TBODY><TR><TD width=32><FORM name=frmCCA-12-239-3 action=#><INPUT onclick="javascript:return addRemoveCompare('CCA-12-239-3')" type=checkbox value=CCA-12-239-3 name=SKU> </FORM></TD><TD cl***=img width=85></TD><TD cl***=partno width=100> CCA-12-239-3 </TD><TD cl***=description>COMP Cams Xtreme 4x4 Camshafts Camshaft, Hydraulic Flat Tappet, Advertised Duration 262/ 270, Lift .462/ .480, Chevy, Small Block, Each </TD><TD width=50>Today</TD><TD cl***=price width=75>$119.95</TD><TD cl***=cart width=150><FORM style="PADDING-RIGHT: 0px; PADDING-LEFT: 0px; PADDING-BOTTOM: 0px; MARGIN: 0px; PADDING-TOP: 0px" action="" method=post><INPUT maxLength=2 size=1 value=1 name=quan***y><INPUT ***le="Click here to add CCA-12-239-3 to your shopping cart." onclick="javascript:this.src='/global/images/1105/r_add_cart_btnX.gif';" type=image src="http://store.summitracing.com/global/images/1105/r_add_cart_btn.gif" align=middle></FORM></TD></TR></TBODY></TABLE> I have this one in my hiboy with Rhodes lifters, 406 SB, Trick Flow heads, two 500 CFM Edelbrocks on an inline Weiand intake. Gets 21 MPG on the road. <TABLE id=recordSet cellSpacing=0 cellPadding=0 width="100%" border=0><TBODY><TR><TD width=32><FORM name=frmCCA-12-243-3 action=#><INPUT onclick="javascript:return addRemoveCompare('CCA-12-243-3')" type=checkbox value=CCA-12-243-3 name=SKU> </FORM></TD><TD cl***=img width=85></TD><TD cl***=partno width=100> CCA-12-243-3 </TD><TD cl***=description>COMP Cams Xtreme 4x4 Camshafts Camshaft, Hydraulic Flat Tappet, Advertised Duration 270/ 278, Lift .480/ .498, Chevy, Small Block, Each </TD><TD width=50>Today</TD><TD cl***=price width=75>$119.95</TD><TD cl***=cart width=150><FORM style="PADDING-RIGHT: 0px; PADDING-LEFT: 0px; PADDING-BOTTOM: 0px; MARGIN: 0px; PADDING-TOP: 0px" action="" method=post><INPUT maxLength=2 size=1 value=1 name=quan***y><INPUT ***le="Click here to add CCA-12-243-3 to your shopping cart." onclick="javascript:this.src='/global/images/1105/r_add_cart_btnX.gif';" type=image src="http://store.summitracing.com/global/images/1105/r_add_cart_btn.gif" align=middle></FORM></TD></TR></TBODY></TABLE> Hope this helps.
You are on the right track. You need to figure out your cruise rpm when you are towing. How much weight you pull will influence your gear choice. I would purchase the MSD detonation sensor. You may need to change ignition advance curve when towing. I am curious to try the Digital E Curve MSD distributor I just purchased. It might be perfect for an application like yours.
Look for a good 5 or 6 speed ****** while you're at it. Good torque down low means you need to be able to cruise at low revs for decent mileage. One of those OD units might be another good option.
Remember how cheap 1.6 aluminum roller rockers are for those things! Hell, you can get stamped steel 1.6 rollers for almost the same as old school friction makers. You can make up for some lift there and keep the duration down.
Right on Jonny O. Whenever I build a 400sb I try to imitate the 396... They had 1.7 rockers and 2.06 valves in the lower performance engines. You can never go wrong going bigger with a 400 small block.... Jeff
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