[PMD1969]

What kind of performance can be gained from converting a 1bbl to a 4bbl using the 1bbl head? I would assume that changing out the cam to 4bbl cam would be necessary right?

[TheSilverBuick]

Both my OHC engines are going to be using 1bbl heads for compression reasons. First one will be using the 4bbl intake, second engine will have a custom intake. Other than compression (chamber depth), the ports are essentially the same with minor differences to account for the chamber shape difference (shorter versus longer inside radius).

My first engine will be first tested with a used 1bbl cam incase something goes wrong, but shortly afterwards I'll swap in a new 4bbl E cam.

As for actual performance gains, I'd expect some, but I don't know the actual amount.

[Cammer-6]

it will be baby steps with each item
it was the whole package that made 60 more HP
I would run the 1 bbl head and cam with 4 bbl intake and exhaust
to get a temporary motor while yours is freshened up.
This way youre not opening up a can of worms.

[66Post]

I have not converted a 1bb to 4bbl, but I have owned and driven both. The difference in big time noticable.
I wish I would have gone to the "6=8" performance recommendations with my 66 Tempest Sprint.

[PMD1969]

Originally Posted by Cammer-6

it will be baby steps with each item
it was the whole package that made 60 more HP
I would run the 1 bbl head and cam with 4 bbl intake and exhaust
to get a temporary motor while yours is freshened up.
This way youre not opening up a can of worms.

Correct me where I am wrong comparing a 69 1bbl to a 69 4bbl

The block/rods/crank/pistons/oil pump/ are all the same
I can transfer the dizzy/coil/intake/exhaust/fuel pump to the 1bbl block
I can install a regrind "H" cam that I was going to buy anyway

What I would need is to find a 4bbl head. I am guessing that a 68 or 69 redone should work.

What am I missing?

[Cammer-6]

balancer too
you could do all this but I was thinking you wanted a temporary motor to use while yours was being freshened up.
Swapping intake and exhaust and nothing else is an easy fix.
Be sure and do a compression and leakdown test on the donor before you get real excited about it.

[TheSilverBuick]

Are you going for a true sprint conversion? Yes the balancer is a bit larger for the Sprint engines, supposedly for the extra rpm since the rotating assembly is the same.

How out curiosity, where are you getting an H cam from? I thought only 4bbl E's were available?

[PMD1969]

Originally Posted by Cammer-6

balancer too
you could do all this but I was thinking you wanted a temporary motor to use while yours was being freshened up.
Swapping intake and exhaust and nothing else is an easy fix.
Be sure and do a compression and leakdown test on the donor before you get real excited about it.

Forgot that one.

Here's a picture of the motor I picked up today. The balancer on it is a two groove and "looks" even fatter than the one on my Sprint. I'll have to measure them to compare.

http://i263.photobucket.com/albums/i...105_164037.jpg

I do want a temporary motor but when I started going over everything I would need I wanted to know what it would take to do a complete conversion.

[PMD1969]

Originally Posted by TheSilverBuick

Are you going for a true sprint conversion? Yes the balancer is a bit larger for the Sprint engines, supposedly for the extra rpm since the rotating assembly is the same.

How out curiosity, where are you getting an H cam from? I thought only 4bbl E's were available?

I was told to get a donor cam to get one reground to the h profile.

[hpp]

Same balancer thats on my 69' looks like the marks are in alighnment.

[PMD1969]

Originally Posted by hpp

Same balancer thats on my 69' looks like the marks are in alighnment.

Do you have a Sprint balancer? I believe the diameter for a Sprint is 8 11/16.

[hpp]

Originally Posted by PMD1969

Do you have a Sprint balancer? I believe the diameter for a Sprint is 8 11/16.

I have the 69' 1bbl balancer same as in your pic not as large in diameter as the Sprint balancer.

Im also going to use the 4bbl set up w/ a 1bbl head lower compression. I have a new 1bbl cam that I will be running for a while but plan to change over to the 4bbl E cam down the road.

[PMD1969]

[Jeff Hamlin]

BIG CHUNK O METAL

[Cammer-6]

Mark,I guess you already know what your 69 Sprint balancer looks like.
They are getting very hard to find in nice shape.
I would do a freshen up of the 1bbl with new seals and gaskets,add 4 bbl intake and exhaust and have some fun.
If it blows up,you havent ruined a #s matching block.
Prep you old motor for long term storage and collect new parts for a rebuild.

[TheSilverBuick]

Originally Posted by PMD1969

I was told to get a donor cam to get one reground to the h profile.

I could very well be wrong, but if I'm not mistaken the only way to grind H cam spec's into even an E cam is to cut the cam core diameter some. Which will then require changing the valve stem height and/or running some kind of lash caps and/or shimming up the lash adjusters.

If you get one ground, find out what the cam core diameter was cut too versus a stock cam, then take half that diameter change as how much needs to be added to the valve stem side.

[Cammer-6]

Before cams were reproduced I was regrinding H grinds.
1st choice was an H grind with minor scuffing,nest was an E grind ,same.
Last was a clean 1 bbl.I m not sure if I have any left or not. Mostly cut the covers to match what was removed off cam.

[TheSilverBuick]

Ah, yes, shaving the covers works too. Of course the cam timing then gets slightly retarded (and more so if the block is decked) unless you have a Sprintbird timing sprocket or something similar.

[Cammer-6]

Originally Posted by TheSilverBuick

Ah, yes, shaving the covers works too. Of course the cam timing then gets slightly retarded (and more so if the block is decked) unless you have a Sprintbird timing sprocket or something similar.

no need to do that just re index the cam timing and relocate the pin.
You can even get elaborate and use an offset bushing to change the cam timing.