my 408 build

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vtmopar

vtmopar

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Here's what I got 1973 360 block
set of j heads cleaned up and 2.02 valves installed.

pulled the motor today and disambled it. Hopefully the block is good. All the main bearings were in good shape and it was still stock bore.
Just need to clean it up and get it to the machine shop next week.

this is the kit I just recieved yesterday from Summit:

http://www.summitracing.com/parts/SCA-1-48035BI/

with the head's zero'd and with 65cc chambers I should be at 10.1 comp.

comp xs282s cam
Mopar M1 intake.
holley 3310 with a proform body
1 5/8 headers,and 2 1/2" exhaust
727 with a 3200 stall converter
3.91's with a sure grip
28" slicks


I wanted to go with a set of RHS heads I just could not afford it this year, I decided to build a good stout bottom end first.

it's going in a 71' swinger.
My goal is a good street strip car that will run in the 12's
the car weighs in around 3700 with me in it.

later on I can always go with the better heads,larger carb. and 1 3/4" headers and 3" exhaust.
 

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what kind of power do you guys think I will be looking at?
 
That is the same basic build I am doing. If you read the comments of others, a lot of them think the cam is too small and the J heads will hold it back. Although I think 12 second car with that combo is very doable.

I bought the cam with the complete Comp cams kit (K-231-4) and found out they include valve springs that require a higher installed height than what is available with stock mopar valves in the J heads. Comp Cams 986 springs came with kit have an installed height 1.75" , stock heads are good for 1.65" or so. Sort of Pissed me off, that they sell a cam kit for a mopar engine with the wrong springs in it!!

I went with a set of MP springs (P3412068 8) cause I had a spare set from my present engine that were basically unused). You could also go with a set of Comp cams 994 or 995 springs (mancinin sells the 995's ) which will work with the lower installed height, allow you plenty of lift before coil bind and have a slightly higher spring rate (not sure how that will effect cam wear or overall performance?!).
 
With the J heads... I figure about 400-420hp..GOBS of torque though.. Good of set of RHS heads could throw that puppy into the 450-475hp range. Just my thought though.:thumbrig:
 
racerbob said:
I bought the cam with the complete Comp cams kit (K-231-4) and found out they include valve springs that require a higher installed height than what is available with stock mopar valves in the J heads. Comp Cams 986 springs came with kit have an installed height 1.75" , stock heads are good for 1.65" or so. Sort of Pissed me off, that they sell a cam kit for a mopar engine with the wrong springs in it!!
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They sold the right springs to you...lol You just ran stock length valves...lol. It's common to cut the spring seats down, or use .110" longer valves, or a combination of those with tall retainers to get the required installed hieght. I always consider it a mild risk not using what the manufacturer spec'd, but, going slightly heavier should not hurt it so long as you break it in properly (without the inners) and use a good oil. These will definately be able to run way into the 12s in a street A body with these setups and properly matched drvielines.
 
It should make around 450hp with J's and close to 500 with the RHS heads like Brian does and a better carb on it, like a 950hp.

I had a friend with a 340 that Brian at IMM did. Eddy heads with light clean up, same cam/compression, victor intake, 1 5/8 step headers and 950hp. Made 455hp

The RHS heads you plan on using are as good or better than the eddies on that engine. IMO, an Air Gap would be a better intake.

It should run low 12's, and really should go in the 11's at around 115. Dat's one heavy swinger!
 
I am building a similar 408 with unported edelbrock heads. I am using the same cam, Comp recommended it for my combo. The cam is actually a take-out from my 360, and it ran 12.30's at 5800' track altitude. I am running 11.9 compression (static) to make up for the altitude up here, and an air gap with an 850 mech sec. carb. I am hoping for 450 hp to get my 3200# car into the 11's. I will know in a month or so.
 
Yeah full car I could be wrong maybe it's not that heavy but I weigh in @ 300 so thats alot of it.
When its time for RHS heads I'm talking to brian.
What do I need for a harmonic balancer?
Is there anything I should be prepared for that I may need?
I just ordered my subframe connectors from seymour scamp.
Boy the headers are a tight huh? I'm going to make sure I have a damn good starter in it dont need to pulling that on a regular basis.
This is my first Mopar build I have been playing with chevy's for the last 20 years.
 
moper said:
They sold the right springs to you...lol You just ran stock length valves...lol. It's common to cut the spring seats down, or use .110" longer valves, or a combination of those with tall retainers to get the required installed hieght. I always consider it a mild risk not using what the manufacturer spec'd, but, going slightly heavier should not hurt it so long as you break it in properly (without the inners) and use a good oil. These will definately be able to run way into the 12s in a street A body with these setups and properly matched drvielines.
Click to expand...

The machine shop told me that cutting the spring seats down by .100 was too much. They did end up cutting them .020 or so to use the springs I ended up with.

I did not think much about it until I was reading the Mancini Racing flyer and saw the Comp Springs they had for sale. I looked up the specs on them and realized they were double springs that were sized to fit on Mopar with stock val;ves and they cost the samme as the springs Comp Cams had included in the kit. DUH, if they make springs that fit the MOPAR why not recommend those for use and include them in the kit???

Guy at shop told me they had the same issue with a Buick engine using Comp cams kit just recently, and it happens all the time.
 
The harmonic balancer I am using is a TCI Rattler. It is for internal balance. The eagle crank I am using is internally balanced, but make sure that is what you have. There are several balnacers available for small blocks depending on how much$$ you want to spend. I always use SFI balancers just to be safe.
 
66dartman said:
The harmonic balancer I am using is a TCI Rattler. It is for internal balance. The eagle crank I am using is internally balanced, but make sure that is what you have. There are several balnacers available for small blocks depending on how much$$ you want to spend. I always use SFI balancers just to be safe.
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Where are you getting it from?

I was planning on using a ProSport SFI balancer from Mancini for $155.
 
I got it from Summit, bit it was over double the $155 you are paying. I have found sfi dampners on ebay for $100, but they are offshore and need to be honed to fit the crank snout. I used the Mancini dampner on my external 360 and it worked great. I believe it cost me $199 5 years ago.
 
I had to hone the TCI rattler for my crank - the press fit i was looking for was 1.5 thou - the balancer came in at 2.5 IIRC
 
DO NOT buy the cheap balancer at Mancini, Hughes, or anything that starts with "Pro" or "Professional" in the name. They are NOT a quality product. Trust me. DJV can back that up. If you aren't spending money and a top quality name brand balancer you are rolling the dice these days.
 
I went with an ATI balancer on my 410.It was pricey,but cheap compared to the price of my engine.#-o
 
thanks for the input,I will be getting my block and the parts to the machine shop this week.
I will continue to post pics updates.
need to some clean up and replacing some of the 40 year old wiring on the car while the engines out.
Front seal on my trans. leaks a little need to repair that while i'm at it.
I have been gsthering parts all winter.
next couplle months will be busy.
Would have started earlier but needed to wait until the plow season was over.
We still have 20" of snow in the yard here,looong winter!
 
Use the search function here to research the Blueprint engines. I think at least one member had a bad experience with one, maybe more. As far as building your own engine, you know what you are capable of better than anybody else here. I prefer to build my own engine, even if it costs me more than a crate motor. That way I know exactly what was done, what components were used, etc. Also, if something goes wrong, I have a pretty good idea who's to blame.
 
RDupont01 said:
I am interested in putting a 408 Stroker in my '73 Swinger. Was curious I would be cheaper/better to build my own or buy a crate motor like the one summit has here: http://summitracing.com/parts/MLL-BPC4081CT
It's listed at $5800.
Click to expand...

Build it yourself. You know what you have after.
I will probably end up around $3500 by the time I'm done.
Thats with the ported J heads though.
add another 1500 for better heads.
 
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